U.S. patent application number 15/803013 was filed with the patent office on 2018-03-15 for establishment of dual connectivity.
The applicant listed for this patent is Telefonaktiebolaget LM Ericsson (publ). Invention is credited to Icaro L. J. da Silva, Gunnar Mildh, Johan Rune, Jari Vikberg, Pontus Wallentin.
Application Number | 20180077614 15/803013 |
Document ID | / |
Family ID | 52672310 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180077614 |
Kind Code |
A1 |
Vikberg; Jari ; et
al. |
March 15, 2018 |
Establishment of Dual Connectivity
Abstract
A wireless device establishes multi-connectivity to a wireless
communication network. In particular, the wireless device transmits
a request for a connection to a third network element over a second
wireless link. The third network element is a candidate for
establishing the multi-connectivity. The wireless device also
enables the third network element to connect to a first network
element already connected to the wireless device via a second
network element communicating with the wireless device over a first
wireless link. This enabling includes transmitting information
identifying the first network element to the third network element.
The wireless device also transmits an identifier of the wireless
device to the third network element to establish the
multi-connectivity for the wireless device. The first and second
network elements serve the wireless device with different network
functions at least after the establishing of the
multi-connectivity.
Inventors: |
Vikberg; Jari; (Jarna,
SE) ; da Silva; Icaro L. J.; (Solna, SE) ;
Mildh; Gunnar; (Sollentuna, SE) ; Rune; Johan;
(Lidingo, SE) ; Wallentin; Pontus; (Linkoping,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Telefonaktiebolaget LM Ericsson (publ) |
Stockholm |
|
SE |
|
|
Family ID: |
52672310 |
Appl. No.: |
15/803013 |
Filed: |
November 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14435290 |
Apr 13, 2015 |
9838917 |
|
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PCT/SE2015/050173 |
Feb 13, 2015 |
|
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15803013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 36/0033 20130101;
H04W 76/15 20180201; H04W 36/0027 20130101 |
International
Class: |
H04W 36/00 20090101
H04W036/00; H04W 76/02 20090101 H04W076/02 |
Claims
1. A method, implemented in a wireless device, of establishing
multi-connectivity to a wireless communication network, the method
comprising: transmitting a request for a connection to a third
network element over a second wireless link, the third network
element being a candidate for establishing the multi-connectivity;
enabling the third network element to connect to a first network
element already connected to the wireless device via a second
network element communicating with the wireless device over a first
wireless link, the enabling comprising transmitting information
identifying the first network element to the third network element;
transmitting an identifier of the wireless device to the third
network element to establish the multi-connectivity for the
wireless device; wherein the first and second network elements
serve the wireless device with different network functions at least
after the establishing of the multi-connectivity.
2. The method of claim 1, wherein the different network functions
comprise a network function that is served by the second network
element and is synchronous to a timing of the second wireless
link.
3. The method of claim 2, wherein the different network functions
further comprise a network function that is served by the first
network element that is not synchronous to the timing of the second
wireless link.
4. The method of 1, further comprising receiving a message
confirming that the multi-connectivity has been established,
wherein the message is received from the third network element, the
second network element, or the first network element via the second
or third network element.
5. The method of claim 1, wherein the first and second wireless
links use different radio access technologies.
6. The method of claim 5, wherein the different network functions
comprise a network function that is served by the second network
element and is specific to the radio access technology of the
second wireless link.
7. The method of claim 6, wherein the different network functions
comprise a network function that is served by the first network
element and is not specific to the radio access technology of the
second wireless link.
8. The method of claim 7, wherein the network function that is
served by the first network element and is not specific to the
radio access technology of the second wireless link is common to
the first and second wireless links.
9. The method of claim 1, wherein the transmitting of the
information identifying the first network element to the third
network element is responsive to receiving the information from the
first network element.
10. The method of claim 1, further comprising: transmitting a
further request for a further connection to a fourth network
element being a different candidate for participating in the
established multi-connectivity, the request being transmitted to
the fourth network element over a third wireless link; enabling the
fourth network element to connect to the first network element by
transmitting the information identifying the first network element
to the fourth network element; transmitting the identifier of the
wireless device to the fourth network element to enable the fourth
network element to participate in the multi-connectivity for the
wireless device.
11. A wireless device comprising: wireless communication hardware
configured to communicate over an air interface; processing
circuitry communicatively connected to the wireless communication
hardware and configured to: transmit a request for a connection to
a third network element over a second wireless link via the
wireless communication hardware, the third network element being a
candidate for establishing multi-connectivity to a wireless
communication network; enabling the third network element to
connect to a first network element already connected to the
wireless device via a second network element communicating with the
wireless device over a first wireless link, the enabling comprising
transmitting, via the wireless communication hardware, information
identifying the first network element to the third network element;
transmitting, via the wireless communication hardware, an
identifier of the wireless device to the third network element to
establish the multi-connectivity for the wireless device; wherein
the first and second network elements serve the wireless device
with different network functions at least after the establishing of
the multi-connectivity.
12. The wireless device of claim 11, wherein the different network
functions comprise a network function that is served by the second
network element and is synchronous to a timing of the second
wireless link.
13. The wireless device of claim 12, wherein the different network
functions further comprise a network function that is served by the
first network element that is not synchronous to the timing of the
second wireless link.
14. The wireless device of 11, wherein the processing circuitry is
further configured to receive a message via the wireless
communication hardware confirming that the multi-connectivity has
been established, wherein the message is received from the third
network element, the second network element, or the first network
element via the second or third network element.
15. The wireless device of claim 11, wherein the first and second
wireless links use different radio access technologies and the
wireless communication hardware supports each of the different
radio access technologies.
16. The wireless device of claim 15, wherein the different network
functions comprise a network function that is served by the second
network element and is specific to the radio access technology of
the second wireless link.
17. The wireless device of claim 16, wherein the different network
functions comprise a network function that is served by the first
network element and is not specific to the radio access technology
of the second wireless link.
18. The wireless device of claim 17, wherein the network function
that is served by the first network element and is not specific to
the radio access technology of the second wireless link is common
to the first and second wireless links.
19. The wireless device of claim 11, wherein the processing
circuitry is further configured to: transmit a further request for
a further connection to a fourth network element being a different
candidate for participating in the established multi-connectivity,
the request being transmitted to the fourth network element over a
third wireless link via the wireless communication hardware;
enabling the fourth network element to connect to the first network
element by transmitting the information identifying the first
network element to the fourth network element via the wireless
communication hardware; transmitting, via the wireless
communication hardware, the identifier of the wireless device to
the fourth network element to enable the fourth network element to
participate in the multi-connectivity for the wireless device.
20. A non-transitory computer readable medium storing a computer
program product for controlling a programmable wireless device, the
computer program product comprising software instructions that,
when executed by processing circuitry of the programmable wireless
device, cause the programmable wireless device to: transmit a
request for a connection to a third network element over a second
wireless link, the third network element being a candidate for
establishing multi-connectivity to a wireless communication
network; transmit information identifying the first network element
to the third network element to enable the third network element to
connect to a first network element already connected to the
wireless device via a second network element communicating with the
wireless device over a first wireless link; transmit an identifier
of the wireless device to the third network element to establish
the multi-connectivity for the wireless device; wherein the first
and second network elements serve the wireless device with
different network functions at least after the establishing of the
multi-connectivity.
Description
[0001] The present application is a continuation of prior U.S.
patent application Ser. No. 14/435,290 filed on 13 Apr. 2015, which
was the U.S. National Stage of International Application No.
PCT/SE2015/050173 filed on 13 Feb. 2015, the disclosures of each of
which are expressly incorporated by reference herein in their
entireties.
TECHNICAL FIELD
[0002] The present disclosure generally relates to dual
connectivity, and particularly relates to methods and apparatus for
supporting establishment of dual connectivity where the wireless
device is connected over a first link and initiates the selection
of a second link.
BACKGROUND
[0003] Evolved Packet System (EPS) is the evolved 3.sup.rd
Generation Partnership Project (3GPP) Packet Switched Domain. EPS
includes Evolved Packet Core (EPC), and Evolved Universal
Terrestrial Radio Access Network (E-UTRAN). FIG. 1 shows an
overview of the EPC architecture in a non-roaming context, which
architecture includes a Packet Data Network (PDN) Gateway (PGW), a
Serving Gateway (SGW), a Policy and Charging Rules Function (PCRF),
a Mobility Management Entity (MME) and a wireless device also
called a User Equipment (UE). The radio access, E-UTRAN, consists
of one or more eNodeBs (eNB).
[0004] FIG. 2 shows the overall E-UTRAN architecture and includes
eNBs, providing the E-UTRA user plane and control plane protocol
terminations towards the UE. The user plane control terminations
comprise Packet Data Convergence Protocol (PDCP), Radio Link
Control (RLC), Medium Access Control (MAC), and a Physical Layer
(PHY). The control plane control terminations comprise Radio
Resource Control (RRC) in addition to the listed user plane control
terminations. The eNBs are interconnected with each other by means
of an X2 interface. The eNBs are also connected by means of the S1
interface to the EPC, more specifically to the MME by means of the
S1-MME interface and to the SGW by means of the S1-U interface.
[0005] The main parts of the EPC Control Plane and User Plane
architectures are shown in FIG. 3 and FIG. 4, respectively.
[0006] Long Term Evolution (LTE) Overview
[0007] LTE uses Orthogonal Frequency Division Multiplexing (OFDM)
in the Downlink (DL) and Direct Fourier Transform (DFT)-spread OFDM
in the Uplink (UL). The basic LTE DL physical resource can thus be
seen as a time-frequency grid as illustrated in FIG. 5, where each
resource element corresponds to one OFDM subcarrier during one OFDM
symbol interval.
[0008] In the time domain, LTE DL transmissions are organized into
radio frames of 10 ms, each radio frame consisting of ten
equally-sized subframes of length T.sub.frame=1 ms (see FIG. 6).
Furthermore, the resource allocation in LTE is typically described
in terms of resource blocks (RB), where a RB corresponds to one
slot (0.5 ms) in the time domain and 12 contiguous subcarriers in
the frequency domain. A pair of two adjacent RBs in time direction
(1.0 ms) is known as a RB pair. RBs are numbered in the frequency
domain, starting with 0 from one end of the system bandwidth. The
notion of virtual RBs (VRB) and physical RBs (PRB), has been
introduced in LTE. The actual resource allocation to a UE is made
in terms of VRB pairs. There are two types of resource allocations,
localized and distributed. In the localized resource allocation, a
VRB pair is directly mapped to a PRB pair, hence two consecutive
and localized VRB are also placed as consecutive PRBs in the
frequency domain. On the other hand, the distributed VRBs are not
mapped to consecutive PRBs in the frequency domain; thereby
providing frequency diversity for data channel transmitted using
these distributed VRBs.
[0009] DL transmissions are dynamically scheduled, i.e., in each
subframe the base station transmits control information about to
which terminals data is transmitted and upon which RBs the data is
transmitted in the current DL subframe. This control signaling is
typically transmitted in the first 1, 2, 3 or 4 OFDM symbols in
each subframe and the number n=1, 2, 3 or 4 is known as the Control
Format Indicator (CFI). The DL subframe also contains Common
Reference Symbols (CRS) which are known to the receiver and used
for coherent demodulation of, e.g., the control information. A DL
system with CFI=3 is illustrated in FIG. 7.
[0010] LTE Control and User Plane Architecture
[0011] Conventional control and user plane protocol architectures
highlighting the radio interface on the eNB-side are shown in FIGS.
8a and 8b. The control and user plane consists of the following
protocol layers and main functionality: [0012] Radio Resource
Control, RRC (control plane only) [0013] Broadcast of system
information for both Non-access stratum (NAS) and Access stratum
(AS) [0014] Paging [0015] RRC connection handling [0016] Allocation
of temporary identifiers for the UE [0017] Configuration of
signaling radio bearer(s) for RRC connection [0018] Handling of
radio bearers [0019] QoS management functions [0020] Security
functions including key management [0021] Mobility functions
including: [0022] UE measurement reporting and control of the
reporting [0023] Handover [0024] UE cell selection and reselection
and control of cell selection and reselection [0025] NAS direct
message transfer to/from the UE [0026] Packet Data Convergence
Protocol, PDCP [0027] There exists one PDCP entity for each radio
bearer for the UE. PDCP is used for both control plane (RRC) and
for user plane [0028] Control plane main functions, including
ciphering/deciphering and integrity protection [0029] User Plane
main functions, including ciphering/deciphering, header compression
and decompression using Robust Header Compression (ROHC), and
in-sequence delivery, duplicate detection and retransmission
(mainly used during handover) [0030] Radio Link Control, RLC [0031]
The RLC layer provides services for the PDCP layer and there exists
one RLC entity for each radio bearer for the UE [0032] Main
functions for both control and user plane include segmentation or
concatenation, retransmission handling (using Automatic Repeat
Request (ARQ), duplicate detection and in-sequence delivery to
higher layers. [0033] Medium Access Control, MAC [0034] The MAC
provides services to the RLC layer in the form of logical channels,
and performs mapping between these logical channels and transport
channels [0035] Main functions are: UL and DL scheduling,
scheduling information reporting, hybrid-ARQ retransmissions and
multiplexing/demultiplexing data across multiple component carriers
for carrier aggregation [0036] Physical Layer, PHY [0037] The PHY
provides services to the MAC layer in the form of transport
channels and handles mapping of transport channels to physical
channels. [0038] Main functions for DL performed by the eNB (OFDM)
are: [0039] Sending of DL reference signals [0040] Detailed steps
(from "top to down"): CRC insertion; code block segmentation and
per-code-block CRC insertion; channel coding (Turbo coding); rate
matching and physical-layer hybrid-ARQ processing; bit-level
scrambling; data modulation (QPSK, 16QAM, or 64QAM); antenna
mapping and multi-antenna processing; OFDM processing, including
Inverse Fast Fourier Transform (IFFT), and Cyclic Prefix (CP)
insertion resulting in time domain data sometimes referred to as IQ
data or digitalized Radio Frequency (RF) data); digital-to-analog
conversion; power amplifier; and sending to antenna. [0041] Main
functions for UL performed by the eNB (DFT-spread OFDM) are: [0042]
Random access support [0043] Detailed steps (from "top to down"):
CRC removal, code block de-segmentation, channel decoding, rate
matching and physical-layer hybrid-ARQ processing; bit-level
descrambling; data demodulation; Inverse Discrete Fourier Transform
(IDFT); antenna mapping and multi-antenna processing; OFDM
processing, including Fast Fourier Transform (FFT) and CP removal;
Analog-to-Digital conversion; power amplifier; and receiving from
antenna.
[0044] The described eNB functionality can be deployed in different
ways. In one example, all the protocol layers and related
functionality are deployed in the same physical node, including the
antenna. One example of this is a pico or femto eNodeB. Another
deployment example is a so called Main-Remote split. In this case,
the eNodeB is divided into a Main Unit and a Remote Unit that are
also called Digital Unit (DU) and Remote Radio Unit (RRU)
respectively. The Main Unit or DU contains all the protocol layers,
except the lower parts of the PHY layer that are instead placed in
the Remote Unit or RRU. The split in the PHY-layer is at the time
domain data level (IQ data, i.e. after/before IFFT/FFT and CP
insertion/removal). The IQ data is forwarded from the Main Unit to
the Remote Unit over a so called Common Public Radio Interface
(CPRI) which is a high speed, low latency data interface. The
Remote Unit then performs the needed Digital-to-Analog conversion
to create analog RF-data, power amplifies the analog RF-data and
forwards the analog RF data to the antenna. In still another
deployment option, the RRU and the antenna are co-located, creating
a so called Antenna Integrated Radio (AIR).
[0045] Carrier Aggregation
[0046] The LTE Rel-10 specifications have been standardized,
supporting Component Carrier (CC) bandwidths up to 20 MHz, which is
the maximal LTE Rel-8 carrier bandwidth. An LTE Rel-10 operation
wider than 20 MHz is possible and appears as a number of LTE CCs to
an LTE Rel-10 terminal. The straightforward way to obtain
bandwidths wider than 20 MHz is by means of Carrier Aggregation
(CA). CA implies that an LTE Rel-10 terminal can receive multiple
CCs, where the CCs have or at least have the possibility to have,
the same structure as a Rel-8 carrier. CA is illustrated in FIG. 9.
The Rel-10 standard support up to five aggregated CCs, where each
CC is limited in the RF specifications to have one of six
bandwidths, namely 6, 15, 25, 50, 75 or 100 RB corresponding to
1.4, 3, 5, 10, 15, and 20 MHz respectively. The number of
aggregated CCs as well as the bandwidth of the individual CCs may
be different for UL and DL. A symmetric configuration refers to the
case where the number of CCs in DL and UL is the same whereas an
asymmetric configuration refers to the case that the number of CCs
is different in DL and UL. It is important to note that the number
of CCs configured in the network may be different from the number
of CCs seen by a terminal. A terminal may for example support more
DL CCs than UL CCs, even though the network offers the same number
of UL and DL CCs.
[0047] CCs are also referred to as cells or serving cells. More
specifically, in an LTE network, the cells aggregated by a terminal
are denoted primary Serving Cell (PCell), and secondary Serving
Cell (SCell). The term serving cell comprises both PCell and one or
more SCells. All UEs have one PCell. Which cell is a UE's PCell is
terminal specific and is considered "more important", i.e., vital
control signaling and other important signaling is typically
handled via the PCell. UL control signaling is always sent on a
UE's PCell. The component carrier configured as the PCell is the
primary CC whereas all other CCs are SCells. The UE can send and
receive data both on the PCell and SCells. For control signaling
such as scheduling commands this could either be configured to only
be transmitted and received on the PCell. However, the commands are
also valid for SCell, and the commands can be configured to be
transmitted and received on both PCell and SCells. Regardless of
the mode of operation, the UE will only need to read the broadcast
channel in order to acquire system information parameters on the
Primary Component Carrier (PCC). System information related to the
Secondary Component Carrier(s) (SCC), may be provided to the UE in
dedicated RRC messages. During initial access, an LTE Rel-10
terminal behaves similar to a LTE Rel-8 terminal. However, upon
successful connection to the network, a Rel-10 terminal
may--depending on its own capabilities and the network--be
configured with additional serving cells in the UL and DL.
Configuration is based on RRC. Due to the heavy signaling and
rather slow speed of RRC signaling, it is envisioned that a
terminal may be configured with multiple serving cells even though
not all of them are currently used. In summary, LTE CA supports
efficient use of multiple carriers, allowing data to be sent and
received over all carriers. Cross-carrier scheduling is supported,
avoiding the need for the UE to listen to all carrier-scheduling
channels all the time. A solution relies on tight time
synchronization between the carriers.
[0048] LTE Rel-12 Dual Connectivity
[0049] Dual connectivity (DC) is a solution currently being
standardized by 3GPP to support UEs connecting to multiple carriers
to send and receive data on multiple carriers at the same time. The
following is an overview description of DC based on the 3GPP
standard. E-UTRAN supports DC operation, whereby a UE with multiple
receivers and transmitters, which is in RRC_CONNECTED mode, is
configured to utilize radio resources provided by two distinct
schedulers, located in two eNBs interconnected via a non-ideal
backhaul over the X2. eNBs involved in DC for a certain UE may
assume two different roles. An eNB may either act as a Master eNB
(MeNB), or as a Secondary eNB (SeNB). In DC, a UE is connected to
one MeNB and one SeNB. The radio protocol architecture that a
particular bearer uses depends on how the bearer is setup. Three
alternatives exist: Master Cell Group (MCG) bearer, Secondary Cell
Group (SCG) bearer, and split bearer. Those three alternatives are
depicted in FIG. 10. Signal Radio Bearers (SRBs) are always of the
MCG bearer and therefore only use the radio resources provided by
the MeNB. Note that DC can also be described as having at least one
bearer configured to use radio resources provided by the SeNB.
[0050] Inter-eNB control plane signaling for DC is performed by
means of X2 interface signaling. Control plane signaling towards
the MME is performed by means of S1 interface signaling. There is
only one S1-MME connection per UE between the MeNB and the MME.
Each eNB should be able to handle UEs independently, i.e. provide
the PCell to some UEs while providing SCell(s) for SCG to others.
Each eNB involved in DC for a certain UE owns its radio resources
and is primarily responsible for allocating radio resources of its
cells. Coordination between MeNB and SeNB is performed by means of
X2 interface signaling. FIG. 11 shows Control Plane (C-plane)
connectivity of eNBs involved in DC for a certain UE. The MeNB is
C-plane connected to the MME via S1-MME, the MeNB and the SeNB are
interconnected via X2-C. FIG. 12 shows User Plane (U-plane)
connectivity of eNBs involved in DC for a certain UE. U-plane
connectivity depends on the bearer option configured. For MCG
bearers, the MeNB is U-plane connected to the S-GW via S1-U, and
the SeNB is not involved in the transport of user plane data. For
split bearers, the MeNB is U-plane connected to the S-GW via S1-U
and in addition, the MeNB and the SeNB are interconnected via X2-U.
For SCG bearers, the SeNB is directly connected with the S-GW via
S1-U.
[0051] Centralization of Radio Access Network (E-UTRAN)
Functionality
[0052] Possible future evolution of the current Radio Access
Network (RAN) architecture has been discussed. From a starting
point in a macro site based topology, introduction of low power
cells, an evolution of the transport network between different
radio base station sites, a radio base station hardware evolution,
and an increased need for processing power to give some examples,
have given rise to new challenges and opportunities. Several
strategies are proposed for the RAN architecture, pulling in
sometimes different directions. Some strategies, like the gains of
coordination, hardware pooling gains, energy saving gains and the
evolution of the backhaul/fronthaul network, are working in favor
of a more centralized deployment. At the same time, other
strategies are working towards de-centralization, such as very low
latency requirements for some 5G use cases, e.g., mission critical
Machine Type Communication (MTC) applications. The terms fronthaul
and backhaul are used in relation to the base station. The
traditional definition for fronthaul is the CPRI based fiber link
between the baseband Main Unit and the Remote Unit. The backhaul
refers to the transport network used for S1/X2-interfaces.
[0053] The recent evolution in backhaul/fronthaul technologies has
indeed opened up the possibility to centralize the baseband, often
referred to as C-RAN. C-RAN is a term that can be interpreted in
different ways. For some it means a "baseband hotel" like solutions
in which the basebands from many sites are collocated to a central
site, although there is no tight connection and fast exchange of
data between the baseband units. The most common interpretation of
C-RAN is maybe "Centralized RAN" where there is at least some kind
of coordination between the basebands. A potentially attractive
solution is the smaller centralized RAN that is based on a macro
base station and the lower power nodes covered by it. In such a
configuration, a tight coordination between the macro and the low
power nodes can often give considerable gains. The term
"Coordinated RAN" is an often used interpretation of C-RAN that
focuses on the coordination gains of the centralization. Other more
futuristic interpretations of C-RAN include "cloud" based and
"virtualized" RAN solutions where the radio network functionality
is supported on generic hardware such as general purpose
processors, and possibly as virtual machines.
[0054] A centralized deployment can be driven by one or several
forces like, e.g., a possible ease of maintenance, upgrade and less
need for sites, as well as harvesting of coordination gains. A
common misconception is that there is a large pooling gain and a
corresponding hardware saving to be done by the centralization. The
pooling gain is large over the first number of pooled cells but
then diminishes quickly. One key advantage of having the basebands
from a larger number of sites co-located and interconnected is the
tight coordination that it allows. Examples of these are UL
Coordinated Multi-Point (CoMP), and a combining of several sectors
and/or carriers into one cell. The gains of these features can
sometimes be significant in relation to the gains of looser
coordination schemes such as, e.g., enhanced inter-cell
interference coordination (eICIC) that can be done over standard
interfaces (X2) without co-location of the baseband.
[0055] An attractive C-RAN deployment from a coordination gain
perspective is the C-RAN built around a larger macro site, normally
with several frequency bands, and a number of lower power radios,
covered by the macro site, that are tightly integrated into the
macro over high-speed interconnect. The largest gains are expected
to be seen in deployment scenarios such as for stadiums and malls.
An important consideration for any C-RAN deployment is the
transport over the fronthaul, i.e., the connection between the
centralized baseband part and the radios, sometimes referred to as
"the first mile". The cost of the fronthaul, which vary rather
greatly between markets, needs to be balanced against the
benefits.
SUMMARY
[0056] Ongoing discussions in the wireless industry in different
fora seem to move towards a direction where the functional
architecture of the 5G radio access network should be designed
flexibly enough to be deployed in different hardware platforms and
possibly in different sites in the network. A functional split as
illustrated in FIG. 13 has been proposed. In this example, the RAN
functions are classified in synchronous functions (SF) and
asynchronous functions (AF). Asynchronous functions are functions
with loose timing constraints, and synchronous functions are
typically executing time critical functionality. The synchronous
network functions have requirements on processing timing which are
strictly dependent on timing of a radio link used for communicating
with the wireless device. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of the radio link, or even independent on the timing of the
radio link. The synchronous functions may be placed in a logical
node called eNB-s and the asynchronous functions may be placed in a
logical node called eNB-a. The instances of functions associated to
the eNB-s, i.e. the synchronous functions, are placed at a network
element close to the air interface. The synchronous functions will
form what is called a synchronous function group (SFG). The
instances of the asynchronous functions associated to the eNB-a can
be flexibly instantiated either at the network element close to the
air interface, i.e. at the same network element as the eNB-s or in
other network elements such as fixed network nodes (FNNs). If it is
assumed that the functions are E-UTRAN functions, the split of
functions may lead to the functional architecture for the control
plane and the user plane illustrated in FIGS. 14a and 14b, where
one new interface will be needed.
[0057] In order to support DC or multi-connectivity features, such
as user plane aggregation for aggregated data rates, or
control/user plane diversity for e.g. reliability and fast packet
switching, instances of asynchronous functions can be made common
to multiple instances of synchronous functions. In other words, a
same instance associated to a functions of an eNB-a can control
multiple instances associated to an eNB-s function. In the case of
the current LTE functionality (see section "LTE control and user
plane architecture" above), this may lead to common instances for
RRC and PDCP functions associated to N multiple instances of
RLC/MAC/PHY. N is the number of nodes that the UE can be connected
to at the same time. One example scenario is illustrated In FIG. 15
where the UE is connected via both network element eNB-s1 and
network element eNB-s2 to network element eNB-a. The network
element eNB-a contains in general the asynchronous functions, i.e.
the protocols that are common for both control plane (RRC and PDCP)
and user plane (PDCP).
[0058] It is envisioned that 5G radio accesses will be composed by
multiple air interfaces, e.g. air interface variants or air
interfaces for different RATs. These multiple air interfaces may be
tightly integrated, meaning that it is possible to have common
function instances for multiple air interfaces. It is also
envisioned that one of the air interfaces in a 5G scenario may be
LTE-compatible, e.g. an evolution of LTE, while another one is
non-LTE compatible. Therefore, in order to address such a multi-RAT
integrated architecture, the multi-connection scenario must support
network elements from different access technologies. The
non-LTE-compatible network elements are likely to support different
lower layer protocols than LTE-compatible ones support, e.g. due to
the high frequencies a 5G network is supposed to operate and the
new use cases it is required to address. Therefore standardized CA
between LTE and the new 5G radio accesses may not be possible. The
standardized DC solution contains different levels of user plane
aggregation but no means for Dual Control Plane between two
different LTE-carriers or between LTE-compatible and
non-LTE-compatible carriers.
[0059] Therefore, the previously described functional split between
eNB-a and eNB-s can be extended so that the same instance of
asynchronous functions are defined for multiple air interfaces,
where the UE can be connected to the multiple air interfaces at the
same time or during mobility procedures. The multiple air
interfaces will then have different synchronous functional groups
per air interface, e.g. for compatible-LTE and non-compatible LTE
parts of the 5G radio access.
[0060] The split illustrated in FIG. 13 may be applied to DC
between different RATs, e.g. one LTE RAT and one 5G RAT. In this
case the eNB-a can contain common support for both control and user
plane for the asynchronous functions. An eNB-s for each RAT
contains the synchronous functions, thus enabling that the
synchronous functions are RAT-specific, e.g. different for LTE RAT
and 5G RAT. Such a scenario is shown in FIG. 16 where the eNB-a is
called "5G & LTE eNB-a" and the eNB-s are called "LTE eNB-s1"
and "5G eNB-s2" respectively.
[0061] The functional split and RAN architecture such as the one
described above with reference to FIGS. 15 and 16, or any other RAN
functional split where groups of functions are instantiated in
different network elements, implies a possibility to have common
function instance(s) associated to multiple network elements and/or
links from the same or multiple air interfaces. However, there is
no known procedure to establish DC for a wireless device in such a
RAN architecture, when it is the wireless device that initiates the
selection of the second link for the DC. For example, in the
example scenario in FIG. 15, when a wireless device connected via
eNB-s1 to eNB-a over a first link wants to establish a dual
connection to eNB-s2 over a second link, the instances of the eNB-a
of this wireless device must be located in order to establish an
association between the eNB-s2 and eNB-a. The association is needed
e.g. to enable the eNB-s2 to download UE-specific information.
[0062] An object may be to alleviate or at least reduce one or more
of the above mentioned problems. This object and others are
achieved by the methods, the wireless device, and the network
elements according to the independent claims, and by the
embodiments according to the dependent claims.
[0063] According to a first aspect, a method for supporting
establishment of dual connectivity for a wireless device is
provided. The wireless device is connected to a first network
element via a second network element of a wireless communication
network. The second network element and the wireless device are
communicating over a first wireless link. Network functions serving
the wireless device are split between the first network element and
the second network element. The method is performed in the wireless
device and comprises transmitting a request for a connection to a
third network element which is a candidate network element for
establishing dual connectivity. The request is transmitted to the
third network element over a second wireless link. The method also
comprises transmitting information identifying the first network
element to the third network element, such that the third network
element can establish connectivity to the first network element.
The method further comprises transmitting an identifier of the
wireless device to the third network element, for enabling the
establishment of dual connectivity for the wireless device.
[0064] According to a second aspect, a method for supporting
establishment of dual connectivity for a wireless device is
provided. The wireless device is connected to a first network
element via a second network element of a wireless communication
network, the second network element and the wireless device
communicating over a first wireless link. Network functions serving
the wireless device are split between the first network element and
the second network element The method is performed in a third
network element being a candidate network element for the
establishment of dual connectivity for the wireless device. The
method comprises receiving a request for a connection to the third
network element. The request is received from the wireless device
over a second wireless link. The method also comprises receiving
information identifying the first network element and an identifier
of the wireless device from the wireless device, and establishing
connectivity to the first network element using the information
identifying the first network element. The method further comprises
sending an indication to the first network element that the
wireless device has connected to the third network element, the
indication comprising the identifier of the wireless device.
[0065] According to a third aspect, a method for supporting
establishment of dual connectivity for a wireless device is
provided. The wireless device is connected to a first network
element via a second network element of a wireless communication
network. The second network element and the wireless device are
communicating over a first wireless link. Network functions serving
the wireless device are split between the first network element and
the second network element. A third network element is a candidate
network element for the establishment of dual connectivity for the
wireless device. The third network element and the wireless device
are communicating over a second wireless link. The method is
performed in the first network element, and comprises establishing
connectivity to the third network element upon request from the
third network element. The method also comprises receiving an
indication from the third network element that the wireless device
has connected to the third network element, the indication
comprising the identifier of the wireless device. The method
further comprises determining to establish dual connectivity for
the wireless device over the first and second links, and retrieving
information related to a context of the wireless device using the
identifier of the wireless device. The method also comprises
transmitting the information related to the context to the third
network element.
[0066] According to a fourth aspect, a wireless device configured
to support establishment of dual connectivity for the wireless
device is provided. The wireless device is connected to a first
network element via a second network element of a wireless
communication network. The second network element and the wireless
device are communicating over a first wireless link. Network
functions serving the wireless device are split between the first
network element and the second network element. The wireless device
is further configured to transmit a request for a connection to a
third network element being a candidate network element for
establishing dual connectivity. The request is transmitted to the
third network element over a second wireless link. The wireless
device is also configured to transmit information identifying the
first network element to the third network element, such that the
third network element can establish connectivity to the first
network element. The wireless device is further configured to
transmit an identifier of the wireless device to the third network
element, for enabling the establishment of dual connectivity for
the wireless device.
[0067] According to a fifth aspect, a third network element being a
candidate network element for the establishment of dual
connectivity for a wireless device. The third network element is
configured to support the establishment of the dual connectivity.
The wireless device is connectable to a first network element via a
second network element of a wireless communication network. The
second network element and the wireless device are communicating
over a first wireless link. Network functions serving the wireless
device are split between the first network element and the second
network element. The third network element is configured to receive
a request for a connection to the third network element, the
request being received from the wireless device over a second
wireless link. The third network element is also configured to
receive information identifying the first network element and an
identifier of the wireless device from the wireless device. The
third network element is further configured to establish
connectivity to the first network element using the information
identifying the first network element, and send an indication to
the first network element that the wireless device has connected to
the third network element, the indication comprising the identifier
of the wireless device.
[0068] According to a sixth aspect, a first network element is
configured to support establishment of dual connectivity for a
wireless device. The wireless device is connectable to the first
network element via a second network element of a wireless
communication network. The second network element and the wireless
device are communicating over a first wireless link. Network
functions serving the wireless device are split between the first
network element and the second network element. A third network
element is a candidate network element for the establishment of
dual connectivity for the wireless device. The third network
element and the wireless device are communicating over a second
wireless link. The first network element is configured to establish
connectivity to the third network element upon request from the
third network element, and receive an indication from the third
network element that the wireless device has connected to the third
network element, the indication comprising the identifier of the
wireless device. The first network element is further configured to
determine to establish dual connectivity for the wireless device
over the first and second links, and retrieve information related
to a context of the wireless device using the identifier of the
wireless device. The first network element is also configured to
transmit the information related to the context to the third
network element.
[0069] According to further aspects, the object is achieved by
computer programs and computer program products corresponding to
the aspects above.
[0070] One advantage of embodiments is that establishment of DC for
a wireless device where it is the wireless device that initiates
the selection of the second link is enabled in a RAN function
architecture where the RAN functions providing the communication
service to the wireless device are split in two. As the RAN
functions are split they may be distributed in different physical
network elements.
[0071] Other objects, advantages and features of embodiments will
be explained in the following detailed description when considered
in conjunction with the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0072] The various aspects of embodiments disclosed herein,
including particular features and advantages thereof, will be
readily understood from the following detailed description and the
accompanying drawings.
[0073] FIG. 1 is a block diagram schematically illustrating a
non-roaming EPC architecture for 3GPP accesses.
[0074] FIG. 2 is a block diagram schematically illustrating an
E-UTRAN overall architecture.
[0075] FIG. 3 schematically illustrates an EPC Control Plane
protocol architecture.
[0076] FIG. 4 schematically illustrates an EPC User Plane protocol
architecture.
[0077] FIG. 5 schematically illustrates the basic LTE DL physical
resource.
[0078] FIG. 6 schematically illustrates an LTE time-domain
structure.
[0079] FIG. 7 schematically illustrates a DL subframe.
[0080] FIGS. 8a and 8b schematically illustrate control and user
plane protocol layers for a conventional eNB radio interface.
[0081] FIG. 9 schematically illustrates CA of five CC.
[0082] FIG. 10 schematically illustrates a Radio Protocol
Architecture for DC.
[0083] FIG. 11 is a block diagram schematically illustrating
C-Plane connectivity of eNBs involved in DC.
[0084] FIG. 12 is a block diagram schematically illustrating
U-Plane connectivity of eNBs involved in DC.
[0085] FIG. 13 schematically illustrates one example of a
functional split between network elements.
[0086] FIGS. 14a and 14b schematically illustrate an eNB split into
eNB-a and eNB-s.
[0087] FIG. 15 schematically illustrates DC established for a
wireless device.
[0088] FIG. 16 schematically illustrates a Multi-RAT DC established
for a wireless device.
[0089] FIG. 17 schematically illustrates a backward handover
according to embodiments.
[0090] FIG. 18 schematically illustrates a first example network
architecture for illustrating embodiments of the invention.
[0091] FIG. 19 schematically illustrates a second example network
architecture for illustrating embodiments of the invention.
[0092] FIG. 20 is a signaling diagram schematically illustrating
signaling according to embodiments of the invention.
[0093] FIGS. 21a-b are flow charts schematically illustrating
embodiments of a method for a wireless device according to various
embodiments.
[0094] FIGS. 22a-b are flow charts schematically illustrating
embodiments of a method for a network element according to various
embodiments.
[0095] FIGS. 23a-b are flow charts schematically illustrating
embodiments of a method for another network element according to
various embodiments.
[0096] FIGS. 24a-b are block diagrams schematically illustrating
embodiments of wireless device and network elements according to
various embodiments.
DETAILED DESCRIPTION
[0097] In the following, different aspects will be described in
more detail with references to certain embodiments and to
accompanying drawings. For purposes of explanation and not
limitation, specific details are set forth, such as particular
scenarios and techniques, in order to provide a thorough
understanding of the different embodiments. However, other
embodiments that depart from these specific details may also
exist.
[0098] Embodiments are described in a non-limiting general context
in relation to the establishment of DC for a UE in the example
scenario illustrated in FIG. 15, where the network functions are
split between eNB-a and eNB-s1/e-NB-s2 based on whether they are
asynchronous or synchronous. The same instance of asynchronous
functions eNB-a may be defined for multiple air interfaces, where
the UE can be connected to the multiple air interfaces at the same
time. The multiple air interfaces will then have different
synchronous function groups per air interface. eNB-s1 and eNB-s2 in
FIG. 15 may be from the same RAT, and may be owned by the same
operator or by different operators. Alternatively, eNB-s1 and
eNB-s2 may be from different RATs, e.g. LTE-compatible and
non-LTE-compatible 5G accesses. Also in this second case they may
be owned by the same operator or by different operators. The
embodiments described herein are mainly given in the context of
multiple RATs, for example LTE and 5G RATs. However, the described
embodiments may also apply for single RAT cases, especially in the
cases when a single eNB-s is connected to multiple different
operator networks, as in these cases a single RAT may be used in
both first and second accesses.
[0099] Although the functions in this example scenario are
differentiated based on whether they are synchronous or not, it
should be noted that embodiments of the invention may be applied to
any other network function architecture where the network functions
are split into two logical network nodes based on some other
criteria than whether the function is synchronous or not. One
example is to split functions in a multi-RAT scenario based on
whether they are common for the multiple RATs or specific to one of
the RATs.
[0100] Although embodiments are described in relation to a DC case,
the embodiments may also be applied to a scenario where the UE
enters multi-connectivity, where "multi" implies more than
dual/two, by adding yet another link that can be from the same or
from a different access layer or RAT than the other links. The
procedure for adding such further link for multi-connectivity is
similar to the addition of the second link when the UE enters DC,
and embodiments of the invention may thus easily be applicable to
the multi-connectivity scenario.
[0101] The problem of non-existing procedures for establishing DC
for a wireless device in the example scenario illustrated in FIG.
15, when it is the UE that initiates the selection of the second
link for the DC, is addressed by a solution enabling the location
of the existing instance of an asynchronous function currently
serving the UE via a first link.
[0102] Different solutions are described based on how the second
link is connected to the cellular operator network in which the
existing asynchronous function (or group of functions) currently
serving the UE resides. These solutions vary depending on if the
base station providing the second link has an existing secure
connection to the cellular operator network or if such a secure
connection needs to be dynamically established.
[0103] In embodiments of the invention, the UE performs a method
for supporting the establishment of DC. The UE is connected to a
first network element eNB-a via a second network element eNB-s1,
and the first network element eNB-a therefore holds a UE context
for the UE. The UE communicates with the second network element
eNB-S1 over a first link. Based on a trigger, the UE initiates a
procedure to connect to a third network element eNB-s2 over a
second link, while still maintaining the connection to the second
network element over the first link. The procedure to connect to
the third network element eNB-s2 comprises transmitting one or more
messages to the eNB-s2 over the second link identifying the
UE-context in the eNB-a. These one or more messages may comprise a
UE identity and information identifying the eNB-a.
[0104] On the network side, the third network element eNB-s2
receives the request for establishing DC. The information
identifying the first network element, eNB-a, makes it possible for
the third network element, eNB-s2, to establish connectivity with
the first network element, eNB-a. The third network element,
eNB-s2, may then send the UE identity and an indication to the
first network element, eNB-a, that the UE has connected to the
third network element via the second link for the purpose of
establishing DC. The first network element eNB-a may determine to
establish DC for the UE, retrieve the UE context for the identified
UE, and transmit the UE context to the third network element
eNB-s2, optionally with a confirmation that the DC has been
established.
[0105] Locating an Existing Instance of the Asynchronous Functions
in Case of "Backward Handover"
[0106] In this section, the procedure of "backward handover" is
described and compared to the procedure of "forward handover".
Methods for how to setup the connection to a second link will be
described, as well as how to change connection between different
nodes of one RAT. Although this procedure is referred to as a
handover procedure ("backward" or "forward handover"), it should be
noted that the procedure is different from a traditional handover
procedure in that the connection to the first link is kept when the
connection to the second link is established for the purpose of
providing DC. The term "backward/forward handover" is thus used
hereinafter to describe that the conventional "backward/forward
handover" principles are used for DC establishment.
[0107] "Forward handover" is the main principle currently supported
when performing for example Packet Switched (PS) handover in 3GPP
networks. The principle of "forward handover" is that a source
node, i.e. the node that the UE is currently connected to, decides
when it is time to perform handover to a target node. This decision
in the source node can be based on different information such as
measurement reports on possible target cells received from the UE
and cell-level load information received from the different
possible target nodes. Once the source node decides to initiate
handover, it triggers a handover preparation phase towards the
target node. The main purpose is to reserve resources on the target
node and to allow the target node to give instructions for the UE
about how to access the target node, by letting the target node
prepare a so called "handover command" message. The "handover
command" message is then sent from the target node to the source
node which sends it to the UE if the source node still wants to
handover the UE to the target node. This later part is called
handover execution. The UE uses the information received in the
"handover command" message to access the target node and the
handover can be completed by for example releasing resources on the
source node side. The source node is thus in control of the
handover and selects the target node for the UE, which may be seen
as a kind of forwarding of the UE to the target node. This explains
the name of "forward handover".
[0108] "Forward handover" may also work with the split of
functionality such as in scenario with the eNB-a and eNB-s split.
In the most common case, the UE may be served by the same eNB-a
both after and before the handover. Therefore the handover
preparation and handover execution are both controlled by the same
eNB-a, and the procedure would be similar to the existing handover
except that it would be used for establishment of Dual
Connectivity. Even if the source and the target cells are
controlled by separate eNB-a entities, similar principles may be
applied. However, there are cases when the "forward handover" is
unsuitable, e.g. in the case when many small cells are deployed in
a macro cell thus resulting in physical cell identities of small
cells that are not unique. In these cases, the UE would need to
perform a procedure similar to Automatic Neighbor Relation (ANR)
before a "forward handover" can be triggered. "Forward handover"
also implies that connections are pre-established between the
different eNB-a and eNB-s, even for the case when these are owned
by different operators. In such cases it may be advantageous to use
a "backward handover" procedure instead.
[0109] Another situation when it may be advantageous to use the
"backward handover" procedure is when an existing connection
between a wireless device and a single eNB-s (where the eNB-s in
turn is connected to an eNB-a) is getting poor, so that measurement
reports on the uplink and control commands on the downlink cannot
be reached. In this case, the "backward handover" procedure may be
used so that the wireless device can establish a new link with a
second eNB-s in order to send measurement reports and receive
control commands from the previously assigned eNB-a. The UE is
losing the first link with an eNB-s1 and therefore tries to
establish a second link with an eNB-s2 using a "backward handover"
procedure. This is not a conventional handover where there is a
context transfer, but rather a context copy. Embodiments described
throughout this disclosure may also be applied for this case of
establishing connectivity, although it in this case is not a DC
situation.
[0110] "Backward handover" is different from "forward handover" in
the sense that it is the UE that initiates the handover and decides
which target cell or node to connect to. In addition, the UE
provides information about the source node to the target node, and
the target node may use this information to request UE specific
information from the source node, and indicate that the UE has
moved to another node. In LTE, the procedure called "RRC Connection
Reestablishment" is one variant of a "backward handover". However,
the "backward handover" procedure introduces problems when DC is to
be supported, and when a split functionality architecture is
deployed such as the one described with reference to FIG. 15 above.
When the UE is initially connected over a first link to eNB-a and
eNB-s1, the UE needs to provide additional information to the new
target eNB-s2 so that the eNB-s2 can connect to the correct eNB-a.
This is due to that the eNB-s2 can be connected to multiple eNB-a
(eNB-a1 and eNB-a2) as illustrated in FIG. 17, and must therefore
select or locate the correct eNB-a (illustrated by the arrow with
the interrogation point to eNB-a1 in FIG. 17). Furthermore, eNB-s2
must refer to the asynchronous function instances that are actually
associated to that UE in eNB-a1, thus requiring input related to
the UE context.
[0111] The solution may be even more complex depending on how
eNB-s2 is connected to the cellular operator network in which the
network element of the existing asynchronous function, i.e. eNB-a1,
currently serving the UE resides. The first aspect is if a secure
connection, e.g. an IPsec tunnel or transport mode, or a Secure
Sockets Layer/Transport Layer Security (SSL/TLS), is needed from
the eNB-s2 to the cellular network of the eNB-a1. In the case
secure connections are needed, the next aspect is if the eNB-s2 has
an existing secure connection to the cellular network of eNB-a1, or
if such a secure connection needs to be established dynamically.
Solutions for these different cases are described in the next
section.
[0112] Embodiments for Different Network Scenarios
[0113] When an eNB-s (e.g. eNB-s1 or eNB-s2 in FIG. 17) has located
an eNB-a (e.g. eN B-a1 or eNB-a2 in FIG. 17), it can also retrieve
information required to establish a UE context in the eNB-s. The
eNB-a can transfer information related to the UE context to the
eNB-s. The information may e.g. be configuration data for the
protocol layers handled by the eNB-s. From the point of view of the
eNB-a, this information transfer may possibly involve retrieving
parts of the relevant information from an eNB-s that the UE was
previously connected to, and which the UE may remain connected
to.
[0114] The network and the UE support the possibility to have DC
for Control Plane only, or for both Control Plane and User
Plane.
[0115] eNB-s1 and eNB-s2 can support the same RAT, e.g. LTE or 5G,
or they can support different RATs. eNB-s1 may for example support
LTE while eNB-s2 may support 5G. The example scenarios described
below are assumed to be of the latter case i.e. the Multi-RAT case.
In the example network scenarios below there exists two instances
of eNB-a and eNB-s respectively, and these are called eNB-a1,
eNB-a2, eNB-s1 and eNB-s2. However, in the general case the number
of instances is not limited to two.
[0116] Embodiments of the invention adapted for three different
network scenarios are described hereinafter:
[0117] Scenario 1: Managed network case, no secure connections
needed between eNB-a and eNB-s (illustrated in FIG. 18).
[0118] Scenario 2: Unmanaged network case, secure connections used
and pre-established between eNB-a and eNB-s (illustrated in FIG.
19).
[0119] Scenario 3: Unmanaged network case, secure connections used
but not pre-established. The secure connections therefore need to
be established between eNB-a and eNB-s (illustrated in FIG.
19).
[0120] Scenario 1
[0121] In this case the different eNB-a and eNB-s are connected to
the same transport network and no secure connections are used
between these nodes. The network architecture is illustrated in
FIG. 18.
[0122] A UE is initially connected to eNB-a1 and eNB-s1. The
solution is based on the UE providing the needed information to
eNB-s2 to locate and establish connectivity towards eNB-a1. As an
alternative, the connectivity between eNB-a1 and eNB-s2 may already
be established and then eNB-s2 selects the one of its eNB-a
connections that leads to eNB-a1 based on the information provided
by the UE. eNB-s2 also signals to eNB-a1 that the UE has connected
to it, together with a UE identifier. This allows the eNB-a1 to
activate DC for the UE. As mentioned above, at this point eNB-a1
may transfer information to eNB-s2 that is needed to establish a UE
context, e.g. configuration information for lower protocol
layers.
[0123] FIG. 20 is a signaling diagram illustrating the steps of the
method according to embodiments of the invention. It should be
noted that step 4 and 9 are not part of the method for this
scenario as no secure connections or tunnels are needed:
[0124] Step 1: The UE 2050 is initially connected to eNB-a1 2010
and eNB-s1 2020. LTE protocols are used for the air interface
protocol between eNB-s1 and the UE. As described above, this means
the protocol layers PHY, MAC and RLC. The upper layers between the
UE and eNB-a1 are RRC and PDCP and these may be based solely on LTE
or already at this point indicate the support also for 5G.
[0125] Step 2: "Backward handover" is used as the mobility
mechanism in the network and the UE detects eNB-s2 as a possible
candidate for the UE to establish DC.
[0126] Step 3: UE connects to eNB-s2 using 5G RAT mechanisms and
provides information about eNB-a1 to eNB-s2. In addition, the UE
provides a UE identifier that is known in the eNB-a1, so that the
UE RAN context can be identified within eNB-a1. The UE identifier
could be anything that uniquely identifies the UE within eNB-a1.
With LTE terminology it could for instance be a Cell Radio Network
Temporary Identifier (C-RNTI). In such a case the C-RNTI has
probably been allocated by the MAC layer in eNB-s1. So in order for
this to work, eNB-s1 should have informed eNB-a1 about the C-RNTI
allocation and the UE should complement the C-RNTI with an
identifier of the cell. With LTE terminology the identifier of the
cell could be the E-UTRAN Cell Global Identifier (E-CGI) or the
Physical Cell Identifier (PCI) when providing it to eNB-s2. The
cell identifier is needed to ensure the uniqueness of the
combination of the two identifiers, because the C-RNTI is unique
only within a single cell. Furthermore the uniqueness must be
ensured also for the case where the UE is already in DC or
multi-connectivity through more than one previous cell/eNB-s, and
has been allocated one C-RNTI in each of those cells/eNB-s. This
implies that it may be preferable to rely on an identifier
allocated to the UE by eNB-a1, e.g. an identifier pertaining to a
higher protocol layer than MAC, such as the RRC layer. Another
alternative is to use an identifier allocated by the core network,
which is known to eNB-a1. Other examples of possible UE identifiers
to utilize could be the System architecture evolution-Temporary
Mobile Subscriber Identity (S-TMSI) or the Globally Unique
Temporary Identifier (GUTI) used in LTE. It may also be possible to
simply use a special "UE context locator identifier" allocated by
eNB-a1 specifically for the purpose of locating the UE context in
conjunction with backward handover.
[0127] Step 5: The eNB-a1 information, i.e. the information
identifying the eNB-a1, can be in different formats. It is used by
eNB-s2 to locate eNB-a1 and establish connectivity to eNB-a1. A
list of the alternative formats of the information identifying the
eNB-a1 is given below:
[0128] IP-address of eNB-a1: In this case the UE is aware of an
IP-address of the eNB-a1, and eNB-s2 uses this information to
locate eNB-a1. The locating may include either selection of an
existing interface between the eNB-s2 and eNB-a1, or establishment
of such an interface dynamically. The IP address has preferably
been provided to the UE by eNB-a1, e.g. when the UE connected to
eNB-a1 via eNB-s1 or some other eNB-s. In case the current LTE RRC
message procedures are used, the IP address could e.g. have been
provided in a new IE in the RRCConnectionSetup message or in an
RRCConnectionReconfiguration message.
[0129] Fully Qualified Domain Name (FQDN) of eNB-a1: In this case
the UE is aware of a FQDN of the eNB-a1, and the eNB-s2 uses this
information to locate eNB-a1. In this case, the eNB-s2 uses a
Domain Name Server (DNS) to resolve an eNB-a1 IP-address based on
the FQDN. After this step, the locating may include either
selection of an existing interface between the eNB-s2 and eNB-a1,
or an establishment of such an interface dynamically. The eNB-s2
may also directly select an existing interface without the DNS step
if it has performed this step previously and stored/cached the
resolved IP address after that. The FQDN has preferably been
provided to the UE by eNB-a1, e.g. when the UE connected to eNB-a1
via eNB-s1 or some other eNB-s. In case the current LTE RRC message
procedures are used, the FQDN address could e.g. have been provided
in a new IE in the RRCConnectionSetup message or in an
RRCConnectionReconfiguration message.
[0130] "Interface identity" of eNB-a1: In this case a specific
"Interface identity" is used when a signaling interface is
established between the eNB-a1 and eNB-s2. This interface needs to
be pre-established before "backward handover" can be performed. The
eNB-a1 also informs the UE about the "Interface identity", e.g. as
described above for the cases of IP address and FQDN. The UE
provides the "interface identity" to the eNB-s2 which uses it to
select one of the multiple interfaces it has towards different
eNB-a. One example of an "Interface identity" is an eNB-a1 address,
for example in the format of a 32 bit string. Another example of
the "interface identity" is an eNB-a1 name, for example in the
format of a text-string.
[0131] Uniform Resource Locator (URL): A URL can be used as a
combination to address both the eNB-a1 and the UE RAN context. This
solution makes a separate UE identifier redundant. Such a URL may
e.g. be of the format:
[0132] UE-Identifier@eNBaddentifier.specific.network.rock; or
[0133] eNB-Identifier.specific.network.rock/UE-Identifier.
[0134] When the UE sends such a URL to eNB-s2 it can be used as
follows. The FQDN part of the URL, i.e. the part after "@" in the
first example or before "/" in the second example, is used by
eNB-s2 to resolve an IP-address of eNB-a1 via DNS. Once this is
done, the username part of the URL, i.e. the part before "@" or
after "/", is used as the UE identity towards eNB-a1.
[0135] Identity of eNB-a1: The UE may have received an identity of
eNB-a1 from eNB-a1, e.g. as described above for the cases of IP
address and FQDN, and provides this to eNB-s2 together with the UE
identity. eNB-s2 uses the eNB-a1 identity and the UE identity to
construct a URL, which is then used as described above in the case
where the UE provides a URL to eNB-s2.
[0136] The FQDN/DNS variant can be generalized by having any eNB-a1
identity that can be mapped to an eNB-a1 address via some database,
i.e. it doesn't necessarily need to be FQDN and DNS that are
used.
[0137] Step 6: Once the connectivity between eNB-s2 and eNB-a1 is
established, the eNB-s2 sends an indication to the eNB-a1 that the
UE has connected to it. The eNB-s2 also sends the UE identifier it
received from the UE to the eNB-a1. In return, eNB-a1 may transfer
information that enables eNB-s2 to establish a context for the UE,
such as configuration information for the protocol layers handled
by eNB-s2.
[0138] Step 7: eNB-a1 decides that DC for Control Plane only or for
both Control and User plane is activated for the UE via both LTE
and 5G, and informs the UE accordingly.
[0139] Step 8: As a result, the UE may use DC via both LTE and 5G,
either for Control Plane only, or for both Control and User
plane.
[0140] Scenario 2
[0141] The network architecture of this scenario is illustrated in
FIG. 19. The different eNB-a and eNB-s are connected to different
transport networks and secure connections are used between these
nodes, either directly between the nodes or via separate Security
Gateways (SEGVV), SEGW1 and SEGW2. In another example scenario, the
eNB-a and eNB-s may be connected to the same unsecure transport
network. In both examples, the secure connections may be
pre-established either when the different functions and nodes are
taken into service in case of secure tunnel connections to one or
more SEGW, or during operation using Self Organizing Network (SON)
functionality, such as Automatic Neighbor Relation (ANR).
[0142] There are different additional variants depending on if the
secure connection is terminated in the eNB-a (e.g. in eNB-a1) or if
there is a separate SEGW between the eNB-a and the eNB-s (e.g.
eNB-a1 and eNB-s2). An example of the security connection
terminated in the eNB-a is IPsec transport mode or usage of SSL/TLS
as the security mechanism. In this case the selection of the secure
connection is combined with the selection of the connectivity to
eNB-a, as both are pre-established. An example of the case of
separate SEGW is the usage of an IPsec tunnel mode. In this case
establishment of connectivity to an eNB-a is a two-step process. In
a first step, the selection of the secure tunnel connection is
performed, followed by a second step of selecting an existing
interface to an eNB-a or establishing an interface to an eNB-a.
[0143] With reference to FIG. 19, the UE is initially connected to
eNB-a1 and eNB-s1. As in scenario 1, the solution is based on the
UE providing the needed information to eNB-s2 to locate and
establish connectivity towards eNB-a1. However, in this case, the
locating may consist of both selecting the correct secure
connection and selecting the correct eNB-a. It is also possible
that the eNB-s1 is connected to the eNB-a1 via a SEGW and secure
tunnel connection, even if FIG. 19 shows the case when eNB-s1 is
directly connected to the eNB-a1.
[0144] FIG. 20 illustrates the steps of the method according to
this embodiments of the invention as well. The initial step of
pre-establishing secure tunnel connections between eNB-s2 2030 and
SEGW1 2040, and between eNB-s2 2030 and SEGW2 is not illustrated.
Steps 1 through 3 are the same as in scenario 1 (see above). With
respect to steps 4 and 5, the eNB-a1 information can be in
different formats and is used by eNB-s2 to locate eNB-a1 and to
both select a secure connection and establish connectivity to
eNB-a1 as follows:
[0145] IP-address of eNB-a1: In this case the UE is aware of an
IP-address of the eNB-a1, and eNB-s2 uses this information to
locate eNB-a1. The IP address has preferably been provided to the
UE by eNB-a1, e.g. when the UE connected to eNB-a1 via eNB-s1 or
some other eNB-s. In case the current LTE RRC message procedures
are used, the IP address may e.g. be provided in a new IE in the
RRCConnectionSetup message or in an RRCConnectionReconfiguration
message.
[0146] With respect to direct secure connections between eNB-a1 and
eNB-s2 (i.e. without any intermediate SEGW1), the locating
comprises selecting existing secure tunnel connection and interface
between the eNB-s2 and eNB-a1.
[0147] With respect to separate SEGW1 between eNB-a1 and eNB-s2,
the eNB-s2 may use the information to first select a secure tunnel
connection based on information about eNB-a addresses accessible
via a specific SEGW. This would be possible in the case when
globally unique IP-addresses are used for eNB-a (e.g. Public IPv4
or IPv6 addresses) and when the SEGW announces the eNB-a addresses
together with all other addresses accessible via it. In this case
two SEGW would not announce the same eNB-a address. This case would
apply especially for the different operator network case i.e. when
the eNB-a1 and eNB-a2 in FIG. 19 are located in different operator
networks and different secure domains. It may also be so that the
eNB-s2 is configured with knowledge about the IP address space of
the operator network(s) it is connected to. That knowledge is
enough to select the SEGW leading to the correct operator network
for the received eNB-a1 IP address.
[0148] FQDN of eN B-a1: In this case the UE is aware of a FQDN of
the eNB-a2 and the eNB-s2 uses this information to locate eNB-a1.
The FQDN has preferably been provided to the UE by eNB-a1, e.g.
when the UE connected to eNB-a1 via eNB-s1 or some other eNB-s. In
case the current LTE RRC message procedures are used, the FQDN
address can e.g. be provided in a new IE in the RRCConnectionSetup
message or in the RRCConnectionReconfiguration message.
[0149] With respect to direct secure connections between eNB-a1 and
eNB-s2 i.e. without any intermediate SEGW, the eNB-s2 uses the FQDN
to select an existing secure connection, optionally also using DNS.
The basic principle in this case is that the secure connection is
associated with either the FQDN or the IP-address of eNB-a1.
[0150] With respect to separate SEGW between eNB-a1 and eNB-s2, the
eNB-s2 uses the FQDN to first select a pre-established secure
tunnel connection based on the FQDN, and then acts as described for
scenario 1.
[0151] "Interface identity" of eNB-a1: The following is valid for
both direct secure connections between eNB-a1 and eNB-s2 i.e.
without any intermediate SEGW and with a separate SEGW between
eNB-a1 and eNB-s2. The option is based on the eNB-a to eNB-s
interfaces being both pre-established and associated with a
specific secure connection. In this case specific "Interface
identity" is used when a signaling interface is established between
eNB-a1 and eNB-s2. This interface needs to be pre-established
before "backward handover" can be performed. eNB-a1 also informs
the UE about the "Interface identity", e.g. as described above for
the cases of IP address and FQDN. The UE provides the "interface
identity" to eNB-s2 which uses it to select one of the multiple
interfaces it has towards different eNB-a. One example of an
"Interface identity" is eNB-a1 address, for example in the format
of a 32 bit string. Another example of an "interface identity" is
eNB-a1 name, for example in the format of a text-string.
[0152] URL: A URL can be used as a combination to address both the
eNB-a1 and the UE (i.e. it makes a separate UE identifier
redundant). Such a URL may consist of the format
UE-Identifier@eNBaddentifier.specific.network.rock or
eNB-Identifier.specific.network.rock/UE-Identifier. When the UE
sends such a URL to eNB-s2 it can be used as follows. The FQDN part
of the URL (the part after "@" in the first example or the part
before "/" in the second example) is used by eNB-s2 resolve an
IP-address of eNB-a1 via DNS. Once this is done, the username part
of the URL (the part before "@" or the part after "/") is used as
the UE identity towards eNB-a1. The IP-address of eNB-a1 is then
used as described above under bullet a).
[0153] Identity of eNB-a1: The UE may have received an identity of
eNB-a1 from eNB-a1, e.g. as described above for the cases of IP
address and FQDN, and provides this to eNB-s2 together with the UE
identity. eNB-s2 uses the eNB-a1 identity and the UE identity to
construct a URL, which is then used as described above in bullet d)
where the UE provides a URL to eNB-s2.
[0154] The FQDN/DNS variant can be generalized by having any eNB-a1
identity that can be mapped to an eNB-a1 address via some database,
i.e. it doesn't necessarily need to be FQDN and DNS that are
used.
[0155] Steps 6 through 8 are the same as in scenario 1 (see above).
The UE may thus use DC via both LTE and 5G, either for Control
Plane only, or for both Control and User plane.
[0156] Step 9: In this scenario, this means that a secure tunnel
corresponding to the select secure connection (see step 4 and 5
above) between the eNB-s2 and the SEGW1 is used.
[0157] Scenario 3
[0158] The network architecture of this scenario is illustrated in
FIG. 19. The difference from scenario 2 is that the secure
connections are not pre-established, nor are the interfaces between
eNB-a and eNB-s. The secure connections therefore need to be
established.
[0159] It is assumed that the eNB-s connect to eNB-a via separate
SEGW(s) and that eNB-a (at least eNB-a1) is deployed in the secure
domain inside the SEGW(s), while eNB-s (at least eNB-s1 and eNB-s2)
are deployed outside said secure domain and SEGW(s). As in
scenarios 1 and 2, the UE is initially connected to eNB-a1 and
eNB-s1. The solution is based on the UE providing the needed
information to eNB-s2 to enable eNB-s2 to establish connectivity
towards eNB-a1. In this case, this consist of both establishment of
the secure tunnel connection to a correct SEGW and establishment of
the interface to the correct eNB-a. On the other hand, if the
secure connection is terminated in the interconnected eNB-a and
eNB-s, the establishment of the secure connection and of the
interface between eNB-a and eNB-s may be combined.
[0160] FIG. 20 illustrates the steps of the method according to
this embodiment of the invention. Steps 1 through 3 are the same as
in scenario 1 and 2 (see above). In steps 4 and 5, the eNB-a1
information can be in different formats and is used by eNB-s2 to
locate eNB-a1 and to establish both a secure connection (directly
or via a tunnel to a SEGW) and an interface to eNB-a1 as
follows:
[0161] IP-address of eNB-a1: In this case the UE is aware of an
IP-address of the eNB-a1, and eNB-s2 uses this information to
locate eNB-a1. The IP address has preferably been provided to the
UE by eNB-a1, e.g. when the UE connected to eNB-a1 via eNB-s1 or
some other eNB-s. In case the current LTE RRC message procedures
are used, the IP address may e.g. be provided in a new IE in the
RRCConnectionSetup message or in an RRCConnectionReconfiguration
message.
[0162] With respect to a direct secure connections between eNB-a1
and eNB-s2 (i.e. without any intermediate SEGW1), the eNB-s2 uses
the eNB-a1 IP address to establish the secure connection and
interface between the eNB-s2 and eNB-a1.
[0163] With respect to a separate SEGW1 between eNB-a1 and eNB-s2,
in this case eNB-s2 may be able to resolve a SEGW IP-address using
the IP-address of eNB-a1. One possibility would be to first use
Reverse DNS for the IP-address, receive a FQDN, and then derive
another FQDN for example by enriching/modifying the first FQDN with
"segw", and then sending a DNS query for the second FQDN to
retrieve a SEGW IP-address. This would enable eNB-s2 to first
establish the secure tunnel connection towards the SEGW IP-address
followed by establishment of the interface towards eNB-a1
(traversing the secure tunnel and SEGW). This variant is possible
if globally unique IP-addresses are used for eNB-a (e.g. Public
IPv4 or IPv6 addresses) so that the Reverse DNS query can return a
unique FQDN for eNB-a1. Furthermore, the methods to locate a
suitable SEGW when the eNB-a1 information consists of an IP address
that are described for scenario 2 can be used in this scenario as
well.
[0164] FQDN of eNB-a1: In this case the UE is aware of a FQDN of
the eNB-a2 and the eNB-s2 uses this information to locate eNB-a1.
The FQDN has preferably been provided to the UE by eNB-a1, e.g.
when the UE connected to eNB-a1 via eNB-s1 or some other eNB-s. In
case the current LTE RRC message procedures are used, the FQDN
address can e.g. be provided in a new IE in the RRCConnectionSetup
message or in the RRCConnectionReconfiguration message.
[0165] With respect to direct secure connections between eNB-a1 and
eNB-s2, i.e. without any intermediate SEGW, eNB-s2 uses DNS to
resolve an IP-address to establish the secure connection and
interface between eNB-s2 and eNB-a1.
[0166] With respect to separate SEGW between eNB-a1 and eNB-s2, in
this case eNB-s2 may be able to resolve a SEGW IP-address using the
FQDN of the eNB-a1. One possibility is to derive another FQDN for
example by enriching/modifying the eNB-a1 FQDN with "segw", and
then sending a DNS query for this modified FQDN to retrieve a SEGW
IP-address. This would enable eNB-s2 to first establish the secure
tunnel connection towards the SEGW IP-address followed by
establishment of the interface towards eNB-a1 via the secure tunnel
to the SEGW (after DNS query on FQDN of eNB-a1).
[0167] URL: A URL can be used as a combination to address both the
eNB-a1 and the UE (i.e. it makes a separate UE identifier
redundant). Such a URL may consist of the format
UE-Identifier@eNBaddentifier.specific.network.rock or
eNB-Identifier.specific.network.rock/U E-Identifier. When the UE
sends such a URL to eNB-s2 it can be used as follows. The FQDN part
of the URL (the part after "@" in the first example or the part
before "/" in the second example) is used by eNB-s2 resolve an
IP-address of eNB-a1 via DNS. Once this is done, the username part
of the URL (the part before "@" or the part after "/") is used as
the UE identity towards eNB-a1. The IP-address of eNB-a1 is then
used as described above for this scenario.
[0168] Identity of eNB-a1: The UE may have received an identity of
eNB-a1 from eNB-a1, e.g. as described above for the cases of IP
address and FQDN, and provides this to eNB-s2 together with the UE
identity. eNB-s2 uses the eNB-a1 identity and the UE identity to
construct a URL, which is then used as described above in bullet d)
where the UE provides a URL to eNB-s2.
[0169] The FQDN/DNS variant can be generalized by having any eNB-a1
identity that can be mapped to an eNB-a1 address via some database,
i.e. it doesn't necessarily need to be FQDN and DNS that are
used.
[0170] Steps 6 through 8 are the same as in scenario 1 and 2 (see
above). The UE may thus use DC via both LTE and 5G, either for
Control Plane only, or for both Control and User plane.
[0171] Step 9: In this scenario, this means that a secure tunnel
corresponding to the established secure connection (see steps 4 and
5 above) between the eNB-s2 and the SEGW1 is used.
[0172] Potential Additional Security
[0173] To prevent a malicious UE from making an eNB-s access using
the context of another UE in an eNB-a, additional security means
may be applied. One such means could come in the form a security
token that is allocated by the eNB-a to the UE. The token could
e.g. be a randomly generated bit string with the optional
constraint that it should be unique within the eNB-a as long as the
UE context remains in the eNB-a. The security token should be
delivered to the UE when ciphering is activated between the UE and
the eNB-a. In LTE this could be done in a new IE in an
RRCConnectionReconfiguration message or using a new RRC message.
The UE should provide the token to the eNB-s together with the
above described parameters for locating and identifying the UE
context. The eNB-s then includes it in its message indicating the
UE context to the eNB-a, i.e. when the eNB-s informs the eNB-a that
the UE is connecting to the eNB-s. The eNB-a then verifies the
token and, if the verification is successful, accepts the context
access and the information that the UE is connecting to the eNB-s.
The eNB-a may return information that the eNB-s needs to establish
a UE context, such as configuration information for lower layer
protocols. If the token has to be transferred unencrypted from the
UE to the eNB-s, the eNB-a should allocate a new token to the UE
every time it has been used. An alternative is that the UE encrypts
the token in a manner agreed with eNB-a, e.g. using a shared
symmetric key, when transferring it to the eNB-s. In this way the
token would not be exposed and could be reused multiple times.
[0174] An alternative to the above described verification principle
could be that the eNB-s does not include the token in the request
to the eNB-a. Instead, the eNB-a includes the token when it
acknowledges the message from the eNB-s and returns the information
that facilitates UE context establishment to the eNB-s. The eNB-s
can then compare the token received from the eNB-a with the one
received from the UE and verify that they match.
[0175] Idle-to-Connect Case
[0176] Similarly to the above described scenarios 1-3 for
establishing DC using "backward handover", there is no known
procedure for the case where the wireless device is in idle state
and thus has no connectivity to any eNB-s at all, but wants to
establish such connectivity. Also in this scenario there may be an
instance of eNB-a pertaining to the wireless device which has to be
located. One such scenario may be when a given wireless device has
its eNB-a instance associated to an eNB-s of a first link and after
some time stops to transmit. The device association at the eNB-a is
kept. From the network perspective the wireless device is still
connected to the eNB-a. When the wireless device wants to transmit
again over the same first link or over another link, the
association between the eNB-s and eNB-a has to be re-established.
Embodiments of the invention may be applicable also in such a
scenario.
[0177] Embodiments of Methods Described with Reference to FIGS.
21-23
[0178] FIG. 21a is a flowchart illustrating one embodiment of a
method for supporting establishment of DC for a wireless device
2050. The wireless device is connected to a first network element
2010 via a second network element 2020 of a wireless communication
network. The first network element 2010 may be the eNB-a1 in the
example embodiments of scenarios 1-3 above, and the second network
element 2020 may be the eNB-s1. The second network element and the
wireless device are communicating over a first wireless link.
Network functions serving the wireless device are split between the
first network element and the second network element. The method is
performed in the wireless device and comprises:
[0179] 2110: Transmitting a request for a connection to a third
network element 2030 being a candidate network element for
establishing DC, the request being transmitted to the third network
element over a second wireless link. The third network element may
be the eNB-s2 in the example embodiments of scenarios 1-3 above.
The first and the second wireless links may both be associated with
one RAT, or each associated with different RATs, such as LTE and
5G.
[0180] 2120: Transmitting information identifying the first network
element to the third network element, such that the third network
element can establish connectivity to the first network element.
The information identifying the first network element may be
received from the first network element, and may comprise one or
more of the following: an IP address of the first network element;
a FQDN of the first network element; an identity of an interface to
the first network element; and a URL of the first network
element.
[0181] 2130: Transmitting an identifier of the wireless device to
the third network element, for enabling the establishment of DC for
the wireless device.
[0182] FIG. 21b is a flowchart illustrating another embodiment of
the method in the wireless device. The method may comprise:
[0183] 2105: Detecting the third network element (as in signal 2)
of the signaling diagram in FIG. 20).
[0184] 2110: Transmitting a request for a connection to a third
network element 2030 being a candidate network element for
establishing DC, the request being transmitted to the third network
element over a second wireless link. The third network element may
be the eNB-s2 in the example embodiments of scenarios 1-3 above.
The first and the second wireless links may both be associated with
one RAT, or each associated with different RATs, such as LTE and
5G.
[0185] 2120: Transmitting information identifying the first network
element to the third network element, such that the third network
element can establish connectivity to the first network element.
The information identifying the first network element may be
received from the first network element, and may comprise one or
more of the following: an IP address of the first network element;
a FQDN of the first network element; an identity of an interface to
the first network element; and a URL of the first network
element.
[0186] 2130: Transmitting an identifier of the wireless device to
the third network element, for enabling the establishment of DC for
the wireless device.
[0187] 2140: Receive a message in response to the transmitted
request, confirming that DC has been established, wherein the
message is received from one of the third network element, the
second network element, or the first network element via the second
or third network element.
[0188] 2150: Using the established DC over the first and the second
wireless links for at least one of control plane and user plane
communication
[0189] In any of the above described embodiments, the network
functions of the first network element may be asynchronous network
functions, and the network functions of the second and third
network elements may be synchronous network functions. The
synchronous network functions of the second network element have
requirements on processing timing which are strictly dependent on
timing of the first wireless link. The synchronous network
functions of the third network element have requirements on
processing timing which are strictly dependent on timing of the
second wireless link. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of any of the first or second wireless links.
[0190] FIG. 22a is a flowchart illustrating one embodiment of a
method for supporting establishment of DC for a wireless device
2050. The wireless device is connected to a first network element
2010 via a second network element 2020 of a wireless communication
network. The second network element and the wireless device are
communicating over a first wireless link. Network functions serving
the wireless device are split between the first network element and
the second network element. The method is performed in a third
network element 2030, which is a candidate network element for the
establishment of DC for the wireless device. The method
comprises:
[0191] 2210: Receiving a request for a connection to the third
network element. The request is received from the wireless device
over a second wireless link. The first and the second wireless
links may both be associated with one RAT, or each associated with
different RATs, such as LTE and 5G.
[0192] 2220: Receiving information identifying the first network
element and an identifier of the wireless device from the wireless
device. The information identifying the first network element may
comprise one or more of the following: an IP address of the first
network element; a FQDN of the first network element; an identity
of an interface to the first network element; and a URL of the
first network element.
[0193] 2230: Establishing connectivity to the first network element
using the information identifying the first network element.
[0194] 2240: Sending an indication to the first network element
that the wireless device has connected to the third network
element, the indication comprising the identifier of the wireless
device.
[0195] FIG. 22b is a flowchart illustrating another embodiment of
the method in the third network element 2030. The method may
comprise in addition to the steps 2210-2240 described above with
reference to FIG. 22a:
[0196] 2250: Receiving information related to a context of the
wireless device from the first network element in response to
sending 2240 the indication.
[0197] 2260: Establishing the context of the wireless device
according to the received information related to the context.
[0198] In embodiments, the method may further comprise:
[0199] 2270: Receiving a confirmation from the first network
element that DC has been established.
[0200] 2280: Transmitting a message to the wireless device
confirming that DC has been established. Transmitting the message
may simply comprise forwarding the confirmation from the first
network element to the wireless device. The third network element
may e.g. forward the message transparently.
[0201] In any of the embodiments described above, establishing 2230
connectivity may comprise locating the first network element based
on the received information identifying the first network element,
and establishing connectivity to the located first network element.
This is applicable to any of the scenarios 1-3 described above.
Furthermore, establishing 2230 connectivity may further comprises
either selecting an existing secure connection between the third
network element and the first network element for establishing the
connectivity as in scenario 2 where the secure connections are
pre-established; or establishing a secure connection between the
third network element and the first network element as in scenario
3. It should be noted that a secure connection between the third
network element and the first network element may be a secure
connection directly between the third network element and the first
network element. Alternatively it may be a secure connection
between the third network element and a SEGW placed between the two
network elements, i.e. the secure connection terminates at the
SEGW.
[0202] In any of the above described embodiments, the network
functions of the first network element may be asynchronous network
functions, and the network functions of the second and third
network elements may be synchronous network functions. The
synchronous network functions of the second network element have
requirements on processing timing which are strictly dependent on
timing of the first wireless link. The synchronous network
functions of the third network element have requirements on
processing timing which are strictly dependent on timing of the
second wireless link. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of any of the first or second wireless links.
[0203] FIG. 23a is a flowchart illustrating one embodiment of a
method for supporting establishment of DC for a wireless device
2050. The wireless device is connected to a first network element
2010 via a second network element 2020 of a wireless communication
network. The second network element and the wireless device are
communicating over a first wireless link. Network functions serving
the wireless device are split between the first network element and
the second network element. A third network element 2030 is a
candidate network element for the establishment of DC for the
wireless device. The third network element and the wireless device
are communicating over a second wireless link. The method is
performed in the first network element. The method comprises:
[0204] 2310: Establishing connectivity to the third network element
upon request from the third network element. Establishing
connectivity may comprise establishing a secure connection between
the third network element and the first network element upon
request from the third network element, as in scenario 3 when the
secure connection is terminated in the first network element and
not in the SEGW.
[0205] 2320: Receiving an indication from the third network element
that the wireless device has connected to the third network
element. The indication comprises the identifier of the wireless
device.
[0206] 2330: Determining to establish DC for the wireless device
over the first and second links.
[0207] 2340: Retrieving information related to a context of the
wireless device using the identifier of the wireless device.
[0208] 2350: Transmitting the information related to the context to
the third network element.
[0209] FIG. 23b is a flowchart illustrating another embodiment of
the method in the first network element 2010. The method may
comprise in addition to the steps 2310-2350 described above with
reference to FIG. 23a:
[0210] 2360: Transmitting a confirmation to the third network
element that DC has been established.
[0211] In any of the above described embodiments, the network
functions of the first network element may be asynchronous network
functions, and the network functions of the second and third
network elements may be synchronous network functions. The
synchronous network functions of the second network element have
requirements on processing timing which are strictly dependent on
timing of the first wireless link. The synchronous network
functions of the third network element have requirements on
processing timing which are strictly dependent on timing of the
second wireless link. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of any of the first or second wireless links.
[0212] Embodiments of Apparatus Described with Reference to FIGS.
24a-b
[0213] Wireless Device
[0214] An embodiment of a wireless device 2050 is schematically
illustrated in the block diagram in FIG. 24a. The wireless device
is configured to support establishment of DC for the wireless
device. The wireless device is connected to a first network element
2010 via a second network element 2020 of a wireless communication
network. The second network element and the wireless device are
communicating over a first wireless link. Network functions serving
the wireless device are split between the first network element and
the second network element.
[0215] The wireless device is further configured to transmit a
request for a connection to a third network element 2030 being a
candidate network element for establishing DC. The request is
transmitted to the third network element over a second wireless
link. The wireless device is also configured to transmit
information identifying the first network element to the third
network element, such that the third network element can establish
connectivity to the first network element. The wireless device may
be configured to receive the information identifying the first
network element from the first network element. The information
identifying the first network element may comprise at least one of
the following: an IP address of the first network element; a FQDN
of the first network element; an identity of an interface to the
first network element; and a URL of the first network element. The
wireless device is further configured to transmit an identifier of
the wireless device to the third network element, for enabling the
establishment of DC for the wireless device.
[0216] In embodiments, the wireless device 2050 may be further
configured to detect the third network element. Furthermore, the
wireless device 2050 may be configured to receive a message in
response to the transmitted request, confirming that DC has been
established. The message may be received from either the third
network element, or the second network element, or from the first
network element via the second or third network element. In
embodiments, the wireless device 2050 may be further configured to
use the established DC over the first and the second wireless links
for at least one of control plane and user plane communication. The
first and the second wireless links may both be associated with one
RAT, or each associated with different RATs, such as LTE and
5G.
[0217] In any of the above described embodiments, the network
functions of the first network element may be asynchronous network
functions, and the network functions of the second and third
network elements may be synchronous network functions. The
synchronous network functions of the second network element have
requirements on processing timing which are strictly dependent on
timing of the first wireless link. The synchronous network
functions of the third network element have requirements on
processing timing which are strictly dependent on timing of the
second wireless link. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of any of the first or second wireless links.
[0218] As illustrated in FIG. 24a, the wireless device 2050 may
comprise a processing circuit 2051 and a memory 2052 in embodiments
of the invention. The wireless device 2050 may also comprise a
communication interface 2053 configured to communicate with the
second and third network elements over the first and second
wireless links. The wireless device 2050 may in embodiments
comprise a transceiver adapted to communicate wirelessly with the
second and third network elements. The memory 2052 may contain
instructions executable by said processing circuit 2051, whereby
the wireless device 2050 may be operative to transmit a request for
a connection to the third network element 2030 being a candidate
network element for establishing DC. The request is transmitted to
the third network element over a second wireless link. The wireless
device 2050 may also be operative to transmit information
identifying the first network element to the third network element,
such that the third network element can establish connectivity to
the first network element. The wireless device 2050 may be further
operative to transmit an identifier of the wireless device to the
third network element, for enabling the establishment of DC for the
wireless device.
[0219] In an alternative way to describe the embodiment in FIG. 24a
illustrated in FIG. 24b, the wireless device 2050 may comprise a
first transmitting module 2055 adapted to transmit a request for a
connection to a third network element 2030 being a candidate
network element for establishing DC. The request is transmitted to
the third network element over a second wireless link. The wireless
device 2050 may also comprise a second transmitting module 2056
adapted to transmit information identifying the first network
element to the third network element, such that the third network
element can establish connectivity to the first network element.
The wireless device may be configured to receive the information
identifying the first network element from the first network
element. The information identifying the first network element may
comprise at least one of the following: an IP address of the first
network element; a FQDN of the first network element; an identity
of an interface to the first network element; and a URL of the
first network element. The wireless device 2050 may further
comprise a third transmitting module 2057 adapted to transmit an
identifier of the wireless device to the third network element, for
enabling the establishment of DC for the wireless device.
[0220] In embodiments, the wireless device 2050 may further
comprise a detecting module adapted to detect the third network
element. Furthermore, the wireless device 2050 may comprise a
receiving module adapted to receive a message in response to the
transmitted request, confirming that DC has been established. The
message may be received from either the third network element, or
the second network element, or from the first network element via
the second or third network element. In embodiments, the wireless
device 2050 may further comprise a communication module adapted to
use the established DC over the first and the second wireless links
for at least one of control plane and user plane communication. The
first and the second wireless links may both be associated with one
RAT, or each associated with different RATs, such as LTE and
5G.
[0221] The modules described above are functional units which may
be implemented in hardware, software, firmware or any combination
thereof. In one embodiment, the modules are implemented as a
computer program running on a processor.
[0222] In still another alternative way to describe the embodiment
in FIG. 24a, the wireless device 2050 may comprise a Central
Processing Unit (CPU) which may be a single unit or a plurality of
units. Furthermore, the wireless device 2050 may comprise at least
one computer program product (CPP) with a computer readable medium
in the form of a non-volatile memory, e.g. an EEPROM (Electrically
Erasable Programmable Read-Only Memory), a flash memory or a disk
drive. The CPP may comprise a computer program stored on the
computer readable medium, which comprises code means which when run
on the CPU of the wireless device 2050 causes the wireless device
2050 to perform the methods described earlier in conjunction with
FIGS. 21a-b. In other words, when said code means are run on the
CPU, they correspond to the processing circuit 2051 of the wireless
device 2050 in FIG. 24a.
[0223] Third Network Element
[0224] An embodiment of the third network element 2030 is
schematically illustrated in the block diagram in FIG. 24a. The
third network element 2030 is initially a candidate network element
for the establishment of DC for the wireless device 2050. The third
network element 2030 is configured to support the establishment of
the DC. The wireless device is connectable to the first network
element 2010 via the second network element 2020 of a wireless
communication network. The second network element and the wireless
device are communicating over a first wireless link. Network
functions serving the wireless device are split between the first
network element and the second network element.
[0225] The third network element is configured to receive a request
for a connection to the third network element. The request is
received from the wireless device over a second wireless link. The
first and the second wireless links may both be associated with one
RAT, or each associated with different RATs, such as LTE and 5G.
The third network element is further configured to receive
information identifying the first network element and an identifier
of the wireless device from the wireless device, and establish
connectivity to the first network element using the received
information identifying the first network element. The information
identifying the first network element may comprise at least one of
the following: an IP address of the first network element; a FQDN
of the first network element; an identity of an interface to the
first network element; and a URL of the first network element. The
third network element is also configured to send an indication to
the first network element that the wireless device has connected to
the third network element. The indication comprises the identifier
of the wireless device.
[0226] In embodiments, the third network element 2030 may be
further configured to receive information related to a context of
the wireless device from the first network element in response to
sending the indication, and establish the context of the wireless
device according to the received information related to the
context.
[0227] The third network element may be further configured to
establish connectivity to the first network element by locating the
first network element based on the received information identifying
the first network element, and establishing connectivity to the
located first network element. In some embodiments, the third
network element may be further configured to establish connectivity
by selecting an existing secure connection between the third
network element and the first network element for establishing the
connectivity, or establishing a secure connection between the third
network element and the first network element. It should be noted
that a secure connection between the third network element and the
first network element may be a secure connection directly between
the third network element and the first network element.
Alternatively it may be a secure connection between the third
network element and a SEGW placed between the two network elements,
i.e. the secure connection terminates at the SEGW.
[0228] In embodiments, the third network element 2030 may be
further configured to receive a confirmation from the first network
element that DC has been established, and transmit a message to the
wireless device confirming that DC has been established. The third
network element 2030 may be configured to transmit the message by
forwarding the confirmation from the first network element to the
wireless device.
[0229] In any of the above described embodiments, the network
functions of the first network element may be asynchronous network
functions, and the network functions of the second and third
network elements may be synchronous network functions. The
synchronous network functions of the second network element have
requirements on processing timing which are strictly dependent on
timing of the first wireless link. The synchronous network
functions of the third network element have requirements on
processing timing which are strictly dependent on timing of the
second wireless link. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of any of the first or second wireless links.
[0230] As illustrated in FIG. 24a, the third network element 2030
may comprise a processing circuit 2031 and a memory 2032 in
embodiments of the invention. The third network element 2030 may
also comprise a communication interface 2033 configured to
communicate with the wireless device 2050 over the second wireless
link, and with the first network element 2010. The third network
element 2030 may in embodiments comprise a transceiver adapted to
communicate wirelessly with the wireless device 2050. The memory
2032 may contain instructions executable by said processing circuit
2031, whereby the third network element 2030 may be operative to
receive a request for a connection to the third network element,
where the request is received from the wireless device over a
second wireless link. The third network element 2030 may also be
operative to receive information identifying the first network
element and an identifier of the wireless device from the wireless
device, and establish connectivity to the first network element
using the received information identifying the first network
element. The third network element 2030 may be further operative to
send an indication to the first network element that the wireless
device has connected to the third network element, where the
indication comprises the identifier of the wireless device.
[0231] In an alternative way to describe the third network element
illustrated in FIG. 24b, the third network element 2030 may
comprise a first receiving module 2035 adapted to receive a request
for a connection to the third network element, where the request is
received from the wireless device over a second wireless link. The
third network element 2030 may also comprise a second receiving
module 2036 adapted to receive information identifying the first
network element and an identifier of the wireless device from the
wireless device. The information identifying the first network
element may comprise at least one of the following: an IP address
of the first network element; a FQDN of the first network element;
an identity of an interface to the first network element; and a URL
of the first network element. The third network element 2030 may
also comprise an establishing module 2037 adapted to establish
connectivity to the first network element using the received
information identifying the first network element. The third
network element 2030 may also comprise a sending module 2038
adapted to send an indication to the first network element that the
wireless device has connected to the third network element, where
the indication comprises the identifier of the wireless device.
[0232] In embodiments, the third network element 2030 may further
comprise a third receiving module adapted to receive information
related to a context of the wireless device from the first network
element, and a further establishing module adapted to establish the
context of the wireless device according to the received
information related to the context. Furthermore, the third network
element 2030 may comprise a fourth receiving module adapted to
receive a confirmation from the first network element that DC has
been established, and a transmitting module adapted to transmit a
message to the wireless device confirming that DC has been
established.
[0233] The modules described above are functional units which may
be implemented in hardware, software, firmware or any combination
thereof. In one embodiment, the modules are implemented as a
computer program running on a processor.
[0234] In still another alternative way to describe the embodiment
in FIG. 24a, the third network element 2030 may comprise a Central
Processing Unit (CPU) which may be a single unit or a plurality of
units. Furthermore, the third network element 2030 may comprise at
least one computer program product (CPP) with a computer readable
medium in the form of a non-volatile memory, e.g. an EEPROM
(Electrically Erasable Programmable Read-Only Memory), a flash
memory or a disk drive. The CPP may comprise a computer program
stored on the computer readable medium, which comprises code means
which when run on the CPU of the third network element 2030 causes
the third network element 2030 to perform the methods described
earlier in conjunction with FIGS. 22a-b. In other words, when said
code means are run on the CPU, they correspond to the processing
circuit 2031 of the third network element 2030 in FIG. 24a.
[0235] First Network Element
[0236] An embodiment of the first network element 2010 is
schematically illustrated in the block diagram in FIG. 24a. The
first network element 2010 is configured to support establishment
of DC for the wireless device 2050. The wireless device is
connectable to the first network element via a second network
element 2020 of the wireless communication network, where the
second network element and the wireless device are communicating
over a first wireless link. Network functions for serving the
wireless device are split between the first network element and the
second network element. A third network element 2030 is a candidate
network element for the establishment of DC for the wireless
device, where the third network element and the wireless device are
communicating over a second wireless link.
[0237] The first network element 2010 is configured to establish
connectivity to the third network element upon request from the
third network element, and receive an indication from the third
network element that the wireless device has connected to the third
network element, where the indication comprises the identifier of
the wireless device. The first network element 2010 is also
configured to determine to establish DC for the wireless device
over the first and second links. Furthermore, the first network
element 2010 is configured to retrieve information related to a
context of the wireless device using the identifier of the wireless
device, and transmit the information related to the context to the
third network element.
[0238] In embodiments, the first network element 2010 may be
configured to establish connectivity to the third network element
by establishing a secure connection between the third network
element and the first network element upon request from the third
network element. The first network element 2010 may be further
configured to transmit a confirmation to the third network element
that DC has been established.
[0239] In any of the above described embodiments, the network
functions of the first network element may be asynchronous network
functions, and the network functions of the second and third
network elements may be synchronous network functions. The
synchronous network functions of the second network element have
requirements on processing timing which are strictly dependent on
timing of the first wireless link. The synchronous network
functions of the third network element have requirements on
processing timing which are strictly dependent on timing of the
second wireless link. The asynchronous network functions have
requirements on processing timing not strictly dependent on the
timing of any of the first or second wireless links.
[0240] As illustrated in FIG. 24a, the first network element 2010
may comprise a processing circuit 2011 and a memory 2012 in
embodiments of the invention. The first network element 2010 may
also comprise a communication interface 2013 configured to
communicate with the second and third network elements 2020 and
2030. The memory 2012 may contain instructions executable by said
processing circuit 2011, whereby the first network element 2010 may
be operative to establish connectivity to the third network element
upon request from the third network element, and receive an
indication from the third network element that the wireless device
has connected to the third network element. The indication
comprises the identifier of the wireless device. The first network
element 2010 may be further operative to determine to establish DC
for the wireless device over the first and second links. The first
network element 2010 may also be operative to retrieve information
related to a context of the wireless device using the identifier of
the wireless device, and transmit the information related to the
context to the third network element.
[0241] In an alternative way to describe the first network element
2010 illustrated in FIG. 24b, the first network element 2010 may
comprise an establishing module 2015 adapted to establish
connectivity to the third network element upon request from the
third network element. The first network element 2010 may comprise
a receiving module 2016 adapted to receive an indication from the
third network element that the wireless device has connected to the
third network element, the indication comprising the identifier of
the wireless device. The first network element 2010 may also
comprise a determining module 2017 adapted to determine to
establish DC for the wireless device over the first and second
links. Furthermore, the first network element 2010 may comprise a
retrieving module 2018 adapted to retrieve information related to a
context of the wireless device using the identifier of the wireless
device, and a transmitting module 2019 adapted to transmit the
information related to the context to the third network
element.
[0242] In embodiments, the first network element 2010 may further
comprise a further transmitting module adapted to transmit a
confirmation to the third network element 2030 that DC has been
established.
[0243] The modules described above are functional units which may
be implemented in hardware, software, firmware or any combination
thereof. In one embodiment, the modules are implemented as a
computer program running on a processor.
[0244] In still another alternative way to describe the embodiment
in FIG. 24a, the first network element 2010 may comprise a Central
Processing Unit (CPU) which may be a single unit or a plurality of
units. Furthermore, the first network element 2010 may comprise at
least one computer program product (CPP) with a computer readable
medium in the form of a non-volatile memory, e.g. an EEPROM
(Electrically Erasable Programmable Read-Only Memory), a flash
memory or a disk drive. The CPP may comprise a computer program
stored on the computer readable medium, which comprises code means
which when run on the CPU of the first network element 2010 causes
the first network element 2010 to perform the methods described
earlier in conjunction with FIGS. 23a-b. In other words, when said
code means are run on the CPU, they correspond to the processing
circuit 2011 of the first network element 2010 in FIG. 24a.
[0245] The above mentioned and described embodiments are only given
as examples and should not be limiting. Other solutions, uses,
objectives, and functions within the scope of the accompanying
patent claims may be possible.
* * * * *