U.S. patent application number 16/899338 was filed with the patent office on 2020-09-24 for disjoint bearer routing.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Gavin Bernard HORN, Vikas JAIN, Ozcan OZTURK.
Application Number | 20200305141 16/899338 |
Document ID | / |
Family ID | 1000004885635 |
Filed Date | 2020-09-24 |
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United States Patent
Application |
20200305141 |
Kind Code |
A1 |
OZTURK; Ozcan ; et
al. |
September 24, 2020 |
DISJOINT BEARER ROUTING
Abstract
Methods and apparatus for switching bearers between radio access
technologies (RATs) are described. According to aspects of the
present disclosure, the uplink part of a bearer may be served by
one RAT, while the downlink part of the bearer is served by another
RAT. A part of a bearer may be served by more than one RAT. Methods
and apparatus for communicating via bearer with parts served by
differing RATs are also described.
Inventors: |
OZTURK; Ozcan; (San Diego,
CA) ; HORN; Gavin Bernard; (La Jolla, CA) ;
JAIN; Vikas; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
1000004885635 |
Appl. No.: |
16/899338 |
Filed: |
June 11, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14454449 |
Aug 7, 2014 |
10716097 |
|
|
16899338 |
|
|
|
|
61864298 |
Aug 9, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 28/08 20130101;
H04W 76/16 20180201; H04W 88/10 20130101; H04W 72/0406 20130101;
H04W 88/06 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04W 76/16 20060101 H04W076/16; H04W 28/08 20060101
H04W028/08; H04W 88/06 20060101 H04W088/06 |
Claims
1. A method for wireless communications by a first base station
(BS), comprising: establishing a data connection with a user
equipment (UE) via one or more data bearers; making, for a first
data bearer of the one or more data bearers, a first determination
to route uplink traffic from the UE during a period via the first
BS or a second BS different from the first BS; making, for the
first data bearer of the one or more data bearers, a second
determination to route downlink traffic to the UE during the period
via the first BS or the second B S; receiving, during the period,
uplink traffic for the first data bearer according to the first
determination, and transmitting, during the period, downlink
traffic for the first data bearer according to the second
determination.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present Application is a Continuation of U.S.
application Ser. No. 14/454,449, filed Aug. 7, 2014, which claims
the benefit of U. S. Provisional Application No. 61/864,298, filed
Aug. 9, 2013, both of which are assigned to the assignee of the
present application and hereby expressly incorporated by reference
herein in their entireties.
BACKGROUND
Field of the Disclosure
[0002] Certain aspects of the present disclosure generally relate
to wireless communications and, more particularly, to techniques
for switching bearers between radio access technologies (RATs).
Description of the Related Art
[0003] Wireless communication systems are widely deployed to
provide various types of communication content such as voice, data,
and so on. These systems may be multiple-access systems capable of
supporting communication with multiple users by sharing the
available system resources (e.g., bandwidth and transmit power).
Examples of such multiple-access systems include Code Division
Multiple Access (CDMA) systems, Time Division Multiple Access
(TDMA) systems, Frequency Division Multiple Access (FDMA) systems,
3.sup.rd Generation Partnership Project (3GPP) Long Term Evolution
(LTE) systems, Long Term Evolution Advanced (LTE-A) systems, and
Orthogonal Frequency Division Multiple Access (OFDMA) systems.
[0004] Generally, a wireless multiple-access communication system
can simultaneously support communication for multiple wireless
terminals. Each terminal communicates with one or more base
stations via transmissions on the forward and reverse links. The
forward link (or downlink) refers to the communication link from
the base stations to the terminals, and the reverse link (or
uplink) refers to the communication link from the terminals to the
base stations. This communication link may be established via a
single-input single-output, multiple-input single-output or a
multiple-input multiple-output (MIMO) system.
[0005] As wireless communication technology advances, a growing
number of different radio access technologies are being utilized.
For instance, many geographic areas are now served by multiple
wireless communication systems, each of which can utilize one or
more different air interface technologies. In order to increase
versatility of wireless terminals in such a network environment,
there recently has been an increasing trend toward multi-mode
wireless terminals that are able to operate under multiple radio
technologies. For example, a multi-mode implementation can enable a
terminal to select a system from among multiple systems in a
geographic area, each of which may utilize different radio
interface technologies, and subsequently communicate with one or
more chosen systems.
[0006] In some cases, such a system may allow traffic to be
offloaded from one network, such as a wireless wide area network
(WWAN) to a second network, such as a wireless local area network
(WLAN).
SUMMARY
[0007] Certain aspects of the present disclosure provide a method
for wireless communications performed by a base station (BS). The
method generally includes establishing a data connection with a
user equipment (UE) via one or more data bearers, making a first
determination whether to route uplink traffic for each data bearer
from the UE via a first radio access technology (RAT) or a second
RAT, making a second determination whether to route downlink
traffic for each data bearer to the UE via the first RAT or the
second RAT, and participating in the data connection based on the
first and second determinations.
[0008] Certain aspects of the present disclosure provide a method
for wireless communications performed by a user equipment (UE). The
method generally includes receiving a configuration indicating one
or more data bearers are to be sent via a first radio access
technology (RAT) and a second RAT, wherein the uplink and downlink
traffic for data bearers is independently configured for routing
via the first RAT and the second RAT, and sending a configuration
complete message in response to the received configuration.
[0009] Certain aspects of the present disclosure provide an
apparatus for wireless communications. The apparatus generally
includes a processor configured to establish a data connection with
a user equipment (UE) via one or more data bearers, make a first
determination whether to route uplink traffic for each data bearer
from the UE via a first radio access technology (RAT) or a second
RAT, make a second determination whether to route downlink traffic
for each data bearer to the UE via the first RAT or the second RAT,
and participate in the data connection based on the first and
second determinations, and a memory coupled to the processor.
[0010] Certain aspects of the present disclosure provide an
apparatus for wireless communications. The apparatus generally
includes a processor configured to receive a configuration
indicating one or more data bearers are to be sent via a first
radio access technology (RAT) and a second RAT, wherein the uplink
and downlink traffic for data bearers is independently configured
for routing via the first RAT and the second RAT, and send a
configuration complete message in response to the received
configuration and a memory coupled to the processor.
[0011] Various aspects and features of the disclosure are described
in further detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above-recited features of
the present disclosure can be understood in detail, a more
particular description, briefly summarized above, may be had by
reference to aspects, some of which are illustrated in the appended
drawings. It is to be noted, however, that the appended drawings
illustrate certain typical aspects of this disclosure and are
therefore not to be considered limiting of its scope, for the
description may admit to other equally effective aspects.
[0013] FIG. 1 illustrates an example multiple access wireless
communication system in accordance with certain aspects of the
present disclosure.
[0014] FIG. 2 illustrates a block diagram of an access point and a
user terminal in accordance with certain aspects of the present
disclosure.
[0015] FIG. 3 illustrates various components that may be utilized
in a wireless device in accordance with certain aspects of the
present disclosure.
[0016] FIG. 4 illustrates an example multi-mode mobile station, in
accordance with certain aspects of the present disclosure.
[0017] FIG. 5 illustrates two reference cellular-WLAN interworking
architectures for a wireless local area network (WLAN) and a 3GPP
eNodeB with disjoint bearer routing, in accordance with certain
aspects of the present disclosure.
[0018] FIG. 6 illustrates an example process for switching bearers
between radio access technologies (RATs), in accordance with
certain aspects of the present disclosure.
[0019] FIG. 7 sets forth exemplary operations performed by a base
station for switching bearers between radio access technologies
(RATs), in accordance with certain aspects of the present
disclosure.
[0020] FIG. 8 sets forth exemplary operations performed by a user
equipment for switching bearers between radio access technologies
(RATs), in accordance with certain aspects of the present
disclosure.
DETAILED DESCRIPTION
[0021] As demand for wireless services increases, network operators
may desire to offload user device traffic from a wireless wide area
network (WWAN), for example, a cellular network, to a wireless
local area network (WLAN), for example, a Wi-Fi WLAN, to reduce
congestion on the WWAN, and because operator deployed WLANs are
often under-utilized. According to aspects of the present
disclosure, a user equipment (UE) may be simultaneously connected
to a base station of a WWAN (e.g., an eNodeB) and a base station of
a WLAN (e.g., a Wi-Fi AP), which provide radio access links to
transport signaling and data traffic to and from the UE. Data for
each active service (e.g., services carrying voice traffic for a
phone call, email services, web-browser services, etc.) on a UE may
be carried via one or more bearers to or from network entities
(e.g., core network servers). A bearer establishes a "virtual"
connection or pipeline between two endpoints so that traffic can be
sent between the endpoints. A bearer typically carries traffic both
to and from a UE (e.g., downlink and uplink traffic). According to
certain aspects of the present disclosure, bearers for some
services may be routed over one or more WLANs (e.g., Wi-Fi WLANs),
while bearers for other services are routed over a WWAN (e.g., a
3GPP radio access network (RAN)). The present disclosure provides
methods and apparatuses to enable traffic for a bearer to a UE to
be carried via a WLAN BS while traffic for the same bearer from the
UE is carried via a WWAN BS, and vice-versa. The WWAN BS and the
WLAN BS may be collocated or non-collocated. According to certain
aspects of the present disclosure, methods to determine whether to
switch bearers and configure them to be served on a WWAN or a WLAN
are described. According to certain aspects of the present
disclosure, whether to switch bearers may be determined based on
the main objectives of serving bearers with a "better" link for
each bearer, while maximizing a system utility function. In certain
aspects, the better link may be determined based in part on a
user's channel conditions, traffic, and other users sharing the
same link.
[0022] Various aspects of the disclosure are described more fully
hereinafter with reference to the accompanying drawings. This
disclosure may, however, be embodied in many different forms and
should not be construed as limited to any specific structure or
function presented throughout this disclosure. Rather, these
aspects are provided so that this disclosure will be thorough and
complete, and will fully convey the scope of the disclosure to
those skilled in the art. Based on the teachings herein one skilled
in the art should appreciate that the scope of the disclosure is
intended to cover any aspect of the disclosure disclosed herein,
whether implemented independently of or combined with any other
aspect of the disclosure. For example, an apparatus may be
implemented or a method may be practiced using any number of the
aspects set forth herein. In addition, the scope of the disclosure
is intended to cover such an apparatus or method that is practiced
using other structure, functionality, or structure and
functionality in addition to or other than the various aspects of
the disclosure set forth herein. It should be understood that any
aspect of the disclosure disclosed herein may be embodied by one or
more elements of a claim.
[0023] The word "exemplary" is used herein to mean "serving as an
example, instance, or illustration." Any aspect described herein as
"exemplary" is not necessarily to be construed as preferred or
advantageous over other aspects.
[0024] Although particular aspects are described herein, many
variations and permutations of these aspects fall within the scope
of the disclosure. Although some benefits and advantages of the
preferred aspects are mentioned, the scope of the disclosure is not
intended to be limited to particular benefits, uses, or objectives.
Rather, aspects of the disclosure are intended to be broadly
applicable to different wireless technologies, system
configurations, networks, and transmission protocols, some of which
are illustrated by way of example in the figures and in the
following description of the preferred aspects. The detailed
description and drawings are merely illustrative of the disclosure
rather than limiting, the scope of the disclosure being defined by
the appended claims and equivalents thereof.
An Example Wireless Communication System
[0025] The techniques described herein may be used for various
wireless communication networks such as Code Division Multiple
Access (CDMA) networks, Time Division Multiple Access (TDMA)
networks, Frequency Division Multiple Access (FDMA) networks,
Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA)
networks, etc. The terms "networks" and "systems" are often used
interchangeably. A CDMA network may implement a radio technology
such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc.
UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR).
CDMA2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA
network may implement a radio technology such as Global System for
Mobile Communications (GSM). An OFDMA network may implement a radio
technology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16,
IEEE 802.20, Flash-OFDM.RTM., etc. UTRA, E-UTRA, and GSM are part
of Universal Mobile Telecommunication System (UMTS). Long Term
Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA.
UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an
organization named "3rd Generation Partnership Project" (3GPP).
CDMA2000 is described in documents from an organization named "3rd
Generation Partnership Project 2" (3GPP2).
[0026] Single carrier frequency division multiple access (SC-FDMA)
is a transmission technique that utilizes single carrier modulation
at a transmitter side and frequency domain equalization at a
receiver side. The SC-FDMA has similar performance and
substantially the same overall complexity as those of OFDMA system.
However, SC-FDMA signal has lower peak-to-average power ratio
(PAPR) because of its inherent single carrier structure. The
SC-FDMA has drawn great attention, especially in the uplink
communications where lower PAPR greatly benefits the mobile
terminal in terms of transmit power efficiency. It is currently a
working assumption for uplink multiple access scheme in the 3GPP
LTE and the Evolved UTRA.
[0027] An access point ("AP") may comprise, be implemented as, or
known as NodeB, Radio Network Controller ("RNC"), eNodeB, Base
Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base
Station ("BS"), Transceiver Function ("TF"), Radio Router, Radio
Transceiver, Basic Service Set ("BSS"), Extended Service Set ("ES
S"), Radio Base Station ("RB S"), or some other terminology.
[0028] An access terminal ("AT") may comprise, be implemented as,
or known as an access terminal, a subscriber station, a subscriber
unit, a mobile station, a remote station, a remote terminal, a user
terminal, a user agent, a user device, user equipment, a user
station, or some other terminology. In some implementations, an
access terminal may comprise a cellular telephone, a cordless
telephone, a Session Initiation Protocol ("SIP") phone, a wireless
local loop ("WLL") station, a personal digital assistant ("PDA"), a
handheld device having wireless connection capability, a Station
("STA"), or some other suitable processing device connected to a
wireless modem. Accordingly, one or more aspects taught herein may
be incorporated into a phone (e.g., a cellular phone or smart
phone), a computer (e.g., a laptop), a portable communication
device, a portable computing device (e.g., a personal data
assistant), an entertainment device (e.g., a music or video device,
or a satellite radio), a global positioning system device, or any
other suitable device that is configured to communicate via a
wireless or wired medium. In some aspects, the node is a wireless
node. Such wireless node may provide, for example, connectivity for
or to a network (e.g., a wide area network such as the Internet or
a cellular network) via a wired or wireless communication link.
[0029] Referring to FIG. 1, a multiple access wireless
communication system according to one aspect is illustrated in
which procedures described for reducing the time to begin
acquisition of wireless networks may be performed. An access point
100 (AP) may include multiple antenna groups, one group including
antennas 104 and 106, another group including antennas 108 and 110,
and an additional group including antennas 112 and 114. In FIG. 1,
two antennas are shown for each antenna group; however, more or
fewer antennas may be utilized for each antenna group. Access
terminal 116 (AT) may be in communication with antennas 112 and
114, where antennas 112 and 114 transmit information to access
terminal 116 over forward link 120 and receive information from
access terminal 116 over reverse link 118. Access terminal 122 may
be in communication with antennas 106 and 108, where antennas 106
and 108 transmit information to access terminal 122 over forward
link 126 and receive information from access terminal 122 over
reverse link 124. In a FDD system, communication links 118, 120,
124, and 126 may use different frequency for communication. For
example, forward link 120 may use a different frequency then that
used by reverse link 118.
[0030] Each group of antennas and/or the area in which they are
designed to communicate is often referred to as a sector of the
access point. In one aspect of the present disclosure, each antenna
group may be designed to communicate to access terminals in a
sector of the areas covered by access point 100.
[0031] In communication over forward links 120 and 126, the
transmitting antennas of access point 100 may utilize beamforming
in order to improve the signal-to-noise ratio of forward links for
the different access terminals 116 and 122. Also, an access point
using beamforming to transmit to access terminals scattered
randomly through its coverage causes less interference to access
terminals in neighboring cells than an access point transmitting
through a single antenna to all its access terminals.
[0032] FIG. 2 illustrates a block diagram of an aspect of a
transmitter system 210 (also known as the access point) and a
receiver system 250 (also known as the access terminal) in a
multiple-input multiple-output (MIMO) system 200. At the
transmitter system 210, traffic data for a number of data streams
is provided from a data source 212 to a transmit (TX) data
processor 214.
[0033] In one aspect of the present disclosure, each data stream
may be transmitted over a respective transmit antenna. TX data
processor 214 formats, codes, and interleaves the traffic data for
each data stream based on a particular coding scheme selected for
that data stream to provide coded data.
[0034] The coded data for each data stream may be multiplexed with
pilot data using OFDM techniques. The pilot data is typically a
known data pattern that is processed in a known manner and may be
used at the receiver system to estimate the channel response. The
multiplexed pilot and coded data for each data stream is then
modulated (i.e., symbol mapped) based on a particular modulation
scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data
stream to provide modulation symbols. The data rate, coding, and
modulation for each data stream may be determined by instructions
performed by processor 230. Memory 232 may store data and software
for the transmitter system 210.
[0035] The modulation symbols for all data streams are then
provided to a TX MIMO processor 220, which may further process the
modulation symbols (e.g., for OFDM). TX MIMO processor 220 then
provides N.sub.T modulation symbol streams to N.sub.T transmitters
(TMTR) 222a through 222t. In certain aspects of the present
disclosure, TX MIMO processor 220 applies beamforming weights to
the symbols of the data streams and to the antenna from which the
symbol is being transmitted.
[0036] Each transmitter 222 receives and processes a respective
symbol stream to provide one or more analog signals, and further
conditions (e.g., amplifies, filters, and upconverts) the analog
signals to provide a modulated signal suitable for transmission
over the MIMO channel. N.sub.T modulated signals from transmitters
222a through 222t are then transmitted from N.sub.T antennas 224a
through 224t, respectively.
[0037] At receiver system 250, the transmitted modulated signals
may be received by N.sub.R antennas 252a through 252r and the
received signal from each antenna 252 may be provided to a
respective receiver (RCVR) 254a through 254r. Each receiver 254 may
condition (e.g., filters, amplifies, and downconverts) a respective
received signal, digitize the conditioned signal to provide
samples, and further process the samples to provide a corresponding
"received" symbol stream.
[0038] An RX data processor 260 then receives and processes the
N.sub.R received symbol streams from N.sub.R receivers 254 based on
a particular receiver processing technique to provide N.sub.T
"detected" symbol streams. The RX data processor 260 then
demodulates, deinterleaves, and decodes each detected symbol stream
to recover the traffic data for the data stream. The processing by
RX data processor 260 may be complementary to that performed by TX
MIMO processor 220 and TX data processor 214 at transmitter system
210.
[0039] A processor 270 periodically determines which pre-coding
matrix to use. Processor 270 formulates a reverse link message
comprising a matrix index portion and a rank value portion. Memory
272 may store data and software for the receiver system 250. The
reverse link message may comprise various types of information
regarding the communication link and/or the received data stream.
The reverse link message is then processed by a TX data processor
238, which also receives traffic data for a number of data streams
from a data source 236, modulated by a modulator 280, conditioned
by transmitters 254a through 254r, and transmitted back to
transmitter system 210.
[0040] At transmitter system 210, the modulated signals from
receiver system 250 are received by antennas 224, conditioned by
receivers 222, demodulated by a demodulator 240, and processed by a
RX data processor 242 to extract the reserve link message
transmitted by the receiver system 250. Processor 230 then
determines which pre-coding matrix to use for determining the
beamforming weights, and then processes the extracted message.
[0041] FIG. 3 illustrates various components that may be utilized
in a wireless device 302 that may be employed within the wireless
communication system illustrated in FIG. 1. The wireless device 302
is an example of a device that may be configured to implement the
various methods described herein. The wireless device 302 may be a
base station 100 or any of user terminals 116 and 122.
[0042] The wireless device 302 may include a processor 304 that
controls operation of the wireless device 302. The processor 304
may also be referred to as a central processing unit (CPU). Memory
306, which may include both read-only memory (ROM) and random
access memory (RAM), provides instructions and data to the
processor 304. A portion of the memory 306 may also include
non-volatile random access memory (NVRAM). The processor 304
typically performs logical and arithmetic operations based on
program instructions stored within the memory 306. The instructions
in the memory 306 may be executable to implement the methods
described herein.
[0043] The wireless device 302 may also include a housing 308 that
may include a transmitter 310 and a receiver 312 to allow
transmission and reception of data between the wireless device 302
and a remote location. The transmitter 310 and receiver 312 may be
combined into a transceiver 314. A single transmit antenna or a
plurality of transmit antennas 316 may be attached to the housing
308 and electrically coupled to the transceiver 314. The wireless
device 302 may also include (not shown) multiple transmitters,
multiple receivers, and multiple transceivers.
[0044] The wireless device 302 may also include a signal detector
318 that may be used in an effort to detect and quantify the level
of signals received by the transceiver 314. The signal detector 318
may detect such signals as total energy, energy per subcarrier per
symbol, power spectral density and other signals. The wireless
device 302 may also include a digital signal processor (DSP) 320
for use in processing signals.
[0045] The various components of the wireless device 302 may be
coupled together by a bus system 322, which may include a power
bus, a control signal bus, and a status signal bus in addition to a
data bus.
[0046] In order to expand the services available to subscribers,
some mobile stations (MS) support communications with multiple
radio access technologies (RATs). For example, as illustrated in
FIG. 4, a multi-mode MS 410 may support LTE for broadband data
services and code division multiple access (CDMA) for voice
services. Illustratively, LTE is shown as a first RAT 420.sub.1,
CDMA is shown as a second RAT 420.sub.2, and Wi-Fi is shown as a
third RAT 422.sub.1.
[0047] In certain applications, multi-RAT interface logic 430 may
be used to exchange information between both long-range RATs (i.e.,
WWANs) and short-range RATs (i.e., WLANs). This may enable a
network provider to control how (through which RAT) an end user of
the multi-mode MS 410 actually connects to the network. The
interface logic 430 may support, for example, local IP connectivity
or IP connectivity to a core network.
[0048] For example, a network provider may be able to direct the
multi-mode MS to connect to the network via short-range RAT (e.g.,
Wi-Fi), when available. This capability may allow a network
provider to route traffic in a manner that eases congestion of
particular air resources. In effect, the network provider may use
short-range RATs to distribute some air traffic (of a long-range
RAT) into a wireline network or to distribute some air traffic from
a congested wireless network to a less congested wireless network.
The traffic may be re-routed from the short-range RAT when
conditions mandate, such as when a mobile user increases speed to a
certain level not suitable for a short-range RAT.
[0049] Further, since long-range RATs are typically designed to
provide service over several kilometers, the power consumption of
transmissions from a multi-mode MS when using a long-range RAT is
non-trivial. In contrast, short-range RATs (e.g., Wi-Fi) are
designed to provide service over several hundred meters.
Accordingly, utilizing a short-range RAT when available may result
in less power consumption by the multi-mode MS 410 and,
consequently, longer battery life.
[0050] FIG. 5 illustrates a reference WWAN-WLAN interworking
architecture for a WLAN AP 506 (e.g., a Wi-Fi AP) and a WWAN BS 504
(e.g., a 3GPP eNodeB). The architecture is one embodiment of
interworking functionality between 3GPP and WLAN systems. This
permits use of a WLAN access service by 3GPP subscribers. As
illustrated, the WWAN BS and WLAN BS may be collocated or
non-collocated. A user equipment (UE) 502 may use different
Internet protocol (IP) addresses and separate packet data network
(PDN) connections with the WWAN BS and at the WLAN AP. The data
planes for WLAN and 3GPP are substantially independent, and there
may be no session continuity (e.g., mobility support for the WLAN)
for the UE. In other words, the UE 502 may become aware of a WLAN
AP independently and establish a new session with each WLAN AP the
UE finds or becomes aware of. Certain aspects of the present
disclosure provide techniques for a cellular network controlling a
UE accessing and offloading traffic to a WLAN.
[0051] A UE such as UE 502 may become aware of WLAN APs by
performing scanning procedures as specified in IEEE 802.11, which
generally include passive scanning and active scanning. Passive
scanning, as defined in IEEE 802.11, may be inefficient for the UE,
as the UE waits, with receiver on, for the reception of a WLAN
beacon from a WLAN AP. As the beacon transmission interval is
approximately one-hundred milliseconds and there may be dozens of
channels to scan, passive scanning may result in high power
consumption for scanning and high scan latency. Active scanning may
be faster than passive scanning, but active scanning adds traffic
to the WLAN, namely probe requests and probe responses. Active
scanning is also power intensive.
[0052] IEEE 802.11u has defined additional mechanisms for a UE to
discover further information about an AP without being associated
with the AP. For example, a generic advertisement service (GAS) may
provide a transport of an advertisement protocol's frames between
the UE and a server in the network. The AP may be responsible for
the relay of a mobile device's query to a server in the carrier's
network and for delivering the server's response back to the
mobile. An example of another mechanism for a UE to discover
information about an AP is access network query protocol (ANQP),
which is generally a query advertisement protocol for access
network information retrieval by the UE/STA from the AP that is
transported over the generic advertisement service (GAS).
Information retrieved via ANQP may include a Hotspot operator's
domain name, roaming partners accessible via the Hotspot along with
their credential type and extensible authentication protocol (EAP)
method supported for authentication, IP address type availability,
and other metadata useful in the UE's network selection
process.
[0053] A UE may not have to associate with a WLAN AP in order to
provide measurements of the WLAN AP to network entities (e.g., a
mobility management entity (MME) or radio network controller
(RNC)). The UE may support a subset of additional procedures as
defined in IEEE 802.11k, IEEE 802.11u and Hotspot 2.0. With regards
to a radio access network (RAN), there may be no interface between
the AP and the BS, as illustrated in the non-collocated WWAN BS and
WLAN AP of FIG. 5. ANQP may be utilized to determine information
regarding operator-controlled WLAN APs that do not exchange loading
or neighbor information with WWAN base stations over the backhaul.
However, in the case of a collocated AP and WWAN BS, IEEE 802.11k,
IEEE 802.11u, and Hotspot 2.0 information on the AP may be known in
the WWAN BS (e.g., via a backhaul link) and the UE may not be
required to perform ANQP to acquire the information. When efficient
passive scanning is enabled, the AP may transmit its beacons at the
time advertised by the RAN. In other words, the AP may acquire
cellular timing and system frame number (SFN) of the WWAN, and may
transmit beacons at beacon transmission times advertised by the
RAN. For certain aspects, two levels of reporting may be used to
identify the AP: identifying the AP (e.g., based on BSSID), i.e.,
from beacon only, and providing IEEE 802.11k, IEEE 802.11u, or
Hotspot 2.0 identifying information using ANQP (e.g., in the case
of a non-collocated AP and eNB).
Disjoint Bearer Routing
[0054] According to certain aspects of the present disclosure, a
user may be simultaneously connected to both a WWAN BS (e.g., an
LTE eNB) and a WLAN BS (e.g., a Wi-Fi AP). This dual connectivity
may provide radio access links to transport signaling and data
traffic of the user, as described above with reference to FIG. 5.
The user data or signaling bearers may be served by either WWAN or
WLAN radio links, or both. Aspects of the present disclosure
provide techniques to determine whether to switch bearers and to
configure bearers to be served on WWAN or WLAN.
[0055] In some cases, whether to switch bearers for a UE may be
determined based on certain objectives, such as serving bearers
with a "better" link for each bearer, while maximizing a system
utility function. According to certain aspects, the better link may
be determined based in part on a user's channel conditions,
traffic, and other users sharing the same link. The WWAN BS (e.g.,
an eNB) may make the decision to switch bearers between WWAN and
WLAN and may configure the UE via RRC, as shown in FIG. 6.
[0056] A radio bearer for a UE may have two directional parts. For
example, one directional part may be from the UE and one
directional part may be to the UE, called uplink and downlink,
respectively, in 3GPP terminology. According to certain aspects of
the present disclosure, the downlink and uplink parts of a radio
bearer are not necessarily served on the same access link.
According to these aspects, a data bearer's downlink (i.e. to the
UE) may be served on a WLAN (e.g., Wi-Fi) access link, while the
data bearer's uplink may be served on a WWAN (e.g., LTE) access
link, or vice-versa. According to these aspects, the data traffic
may be served by one access link in each direction at a given
time.
[0057] According to aspects of the present disclosure, a
directional part of a data bearer may be served by more than one
access link. In aspects wherein a directional part of a data bearer
is served by more than one access link, each packet of a
transmission being carried by the data bearer may be transmitted
via any of the access links serving the directional part of the
data bearer. For example, a UE may be connected to a WWAN BS (e.g.,
an eNodeB) and a WLAN AP (e.g., a Wi-Fi AP), and a web-browser of
the UE may request a web page from a server on the Internet. In the
example, a downlink part of a data bearer serving the web-browser
may be served by both the WWAN BS and the WLAN BS. In the example,
some packets of data of the web page may be transmitted to the UE
via the data bearer by the WWAN BS, while other packets of data of
the web page may be transmitted to the UE via the data bearer by
the WLAN AP. In a scenario wherein an access link is used to
transmit downlink data to a UE but not uplink data from the UE, the
access link may be referred to as a supplement downlink (SDL).
[0058] In the previously described example, the downlink part of a
data bearer was served by more than one access link, but the
disclosure is not so limited. According to aspects of the present
disclosure, the uplink part of a data bearer may be served by more
than one access link. In aspects of the present disclosure, both
the uplink part and the downlink part of a data bearer may be
served by more than one access link, and not necessarily the same
access links.
[0059] When uplink and downlink parts of a bearer are served on
different access links, the transmission of control messages on
these links may need to be modified. For the RLC Acknowledged Mode
(AM) in 3GPP, a bearer's downlink and uplink parts carry feedback
messages for the other link, i.e. DL feedback messages are carried
on UL and vice-versa. In current (e.g., Rel-8) wireless
communications standards, this may present a problem when uplink
and downlink of a bearer are served on different RATs. For example,
a UE may receive a packet of data of a web page on a data bearer
via a WLAN AP (e.g., a Wi-Fi AP), and transmit an acknowledgment
(e.g., an ACK) of the packet on the data bearer via a WWAN BS
(e.g., an eNodeB). In the example, the WLAN AP should attempt to
transmit the same packet to the UE, if the WLAN AP is not informed
of the acknowledgment from the UE. Solutions to the described
problem are described in aspects of the present disclosure.
[0060] FIG. 6 illustrates a call flow of an exemplary process
wherein WWAN BS 504 (e.g., an eNB) may follow in switching data
bearers. At 1a and 1b, the eNB may obtain information regarding the
channel conditions at the UE 502 (e.g., a CQI Report) and the
operating statistics of the WLAN AP 506 (e.g., AP Statistics).
According to some aspects, the eNB may obtain WLAN statistics from
the UE. At 2, the eNB may make the bearer switching decision. At 3,
the eNB may send RRC connection reconfiguration commands to the UE,
and at 4, the eNB may receive a RRC connection reconfiguration
complete message from the UE.
[0061] Since switching bearers between a WWAN (e.g., LTE) and a
WLAN (e.g., Wi-Fi) may have a cost (e.g., interruption, delay, and
possible performance impacts on upper layers), it is important to
avoid excessive and unnecessary handovers. "Excessive" handovers
may include ping-pong and too frequent switching, and "unnecessary"
handovers may include handovers providing little gain or even
losses, i.e., in total throughput, for the system as a whole.
[0062] According to certain aspects of the present disclosure, a
bearer's control messages may be always served on a WWAN (e.g.,
LTE) while other (e.g., data) messages of the bearer (UL or DL) may
be served on a different RAT (e.g., WLAN). In other words, a bearer
may be configured such that control messages of the bearer are
always routed via a WWAN access link, while other messages of the
bearer are routed by one or more other RATs (e.g., Wi-Fi).
[0063] According to certain aspects of the present disclosure,
control messages may be passed from a WLAN AP (e.g., a Wi-Fi AP) to
a WWAN BS (e.g., an eNB) when transmitted from the UE to the WLAN
AP. This may occur when an UL part of a bearer is being served by a
WLAN AP. According to certain aspects of the present disclosure,
control messages may be passed from an eNB to an AP when
transmitted from the eNB to the UE. This may occur when the DL
bearer is being served by an AP.
[0064] In some cases, the decision for switching a bearer may
involve using statistics collected on each RAT. These statistics
may include the following:
TABLE-US-00001 RAT Statistics that may used in a bearer switching
decision LTE CQI and MCS per UE DL Buffer sizes per bearer and UL
Buffer Status Report from the UE Wi-Fi MCS and RSSI per UE
Transmitted and received traffic, failed and dropped packets, retry
attempts Channel Load for the AP
[0065] According to certain aspects of the present disclosure,
switching decision processes may be initiated periodically. For
example, an eNB with a collocated WLAN AP may initiate a switching
process once each 1.28 seconds, using statistics gathered from the
eNodeB, the WLAN AP, and served UEs to determine if bearers of
served UEs should be switched to or from LTE to or from the
WLAN.
[0066] According to certain aspects of the present disclosure, an
event may trigger a switching decision process to enable the system
to react to changing channel conditions. For example, a WLAN AP
collocated with an eNB may detect a change to channel conditions
for a served UE and trigger a switching decision process. In the
example, the UE may have one or more bearers switched from the WLAN
to LTE.
[0067] According to certain aspects of the present disclosure, for
a bearer being served by Wi-Fi, a switching decision process may be
triggered when the STA to AP RSSI is less than a threshold, or when
the AP cannot select the lowest MCS during a time interval.
[0068] According to certain aspects of the present disclosure, for
a bearer being served by LTE, the LTE CQI or MCS being lower than a
threshold during a time interval may trigger a switching decision
process.
[0069] According to certain aspects of the present disclosure, for
a switch in either direction, the target link (i.e., the access
link being switched to) should have channel conditions that are
better than the source link (i.e., the access link being switched
from). For example, an eNB with a collocated Wi-Fi AP system may be
serving an uplink part of a bearer for a UE via LTE and a downlink
part of the bearer via Wi-Fi. In the example, the system initiates
a switching process and determines that the Wi-Fi link has better
channel conditions than the LTE link. In the example, the system
may switch the uplink part of the bearer to the Wi-Fi link, while
the system may not switch the downlink part of the bearer to LTE,
because the Wi-Fi link's channel conditions are superior to the LTE
link's channel conditions.
[0070] According to certain aspects of the present disclosure, at
switching instance times, the selection of bearers to be served on
WWAN (e.g., LTE) or WLAN (e.g., Wi-Fi) may be the result of system
optimization performed iteratively at switching instances.
According to these aspects, the optimization may be for maximizing
a total system utility, which may be defined based on a
Proportional Fairness (PF) metric for the combined (e.g.,
LTE+Wi-Fi) system.
[0071] According to certain aspects of the present disclosure,
fairness between bearers may be determined based on a PF metric.
According to these aspects, at every switching time instance, the
goal may be to increase the total system utility by the maximum
amount. This goal may be achieved by an allocation of bearers to
RATs maximizing the following function:
F(S)=.DELTA.(X_k)/X_k (1)
such that S=(S_k), wherein S_k=1 if a bearer k is on LTE and 0
otherwise. In the function, k is a bearer index, .DELTA.(X_k) is
the expected throughput for bearer k in the next switching interval
period, and X_k is the total throughput of bearer k for the most
recent measurement period (time indices are omitted in this
notation for brevity). Note that S determines the "assignment" of
each bearer to be served on either LTE or Wi-Fi. F(S) corresponds
to the total system utility function.
[0072] In the above proportional fairness function, bearer index
"k" may be for all of the bearer links in the system, including
bearer links that may not be allowed to switch due to their
configuration. Including bearer links that may not be switched
incorporates the impact of all bearers in the system optimization.
Furthermore, "k" may consider direction, in the sense that uplink
parts and downlink parts of bearers may be considered
separately.
[0073] According to certain aspects of the present disclosure,
uplink parts and downlink parts of bearers may be always switched
together. For these aspects, enforcing switching uplink parts and
downlink parts of bearers together may be accomplished by
discarding points S which do not obey this restriction in the PF
algorithm.
[0074] According to certain aspects of the present disclosure, the
above formulation gives the same priority to all bearers regardless
of the traffic type or quality of service (QoS) class identifier
(QCI) of any particular bearer. According to these aspects, LTE and
Wi-Fi networks may continue to offer QoS to bearers via packet
scheduling. If, for example, these schedulers give absolute higher
priority between different QoS classes, the function F(S) may be
modified to align the system utility with these schedulers. This
can be done by defining F(S) such that it takes a vector value
wherein each component of the vector is calculated as in (1) but
for bearers in a particular QoS. The comparison of F(S) may then
follow the priority order used by the mentioned scheduler.
[0075] According to certain aspects of the present disclosure, X_k
may be an infinite impulse response (IIR) filtered value of the
instantaneous throughput with a time constant larger than the
switching interval. For both LTE and Wi-Fi, this may be measured at
the eNB and/or AP. For these aspects, there may be two main
operations for the solution of
TABLE-US-00002 Step Operation 1 Estimate .DELTA.(X_k) 2 Determine
the optimal point S maximizing the sum in (1)
[0076] Estimation of .DELTA.(X_k) may be accomplished by any of a
number of estimating methods that may be performed by an eNB or
other base station.
[0077] The optimal point S maximizing the sum in (1) may be
determined by any of a number of maximizing methods that may be
performed by an eNB or other base station. A probabilistic
component can be added to the optimization step so that the best
optimal point is not always selected, in order to prevent the
algorithm from being stuck at a local optimum over an extended
period of time.
[0078] FIG. 7 sets forth exemplary operations 700 for switching
data bearers between RATs at a wireless node. The operations 700
may be performed, for example, by a BS (e.g., an eNodeB or other
type of base station/access point).
[0079] Operations 700 begin at 702, wherein the BS establishes a
data connection with a user equipment (UE) via one or more data
bearers. At 704, the BS makes a first determination whether to
route uplink traffic for each data bearer from the UE via a first
radio access technology (RAT) or a second RAT. At 706, the BS makes
a second determination whether to route downlink traffic for each
data bearer to the UE via the first RAT or the second RAT. At 707,
the BS may optionally provide a radio resource control (RRC)
message indicating at least one of the first and second
determinations. At 708, the BS participates in the data connection
based on the first and second determinations. At 710, the BS may
optionally send uplink traffic of all data bearers via the first or
second RAT. At 712, the BS may optionally send downlink traffic of
all data bearers via the first and second RAT.
[0080] According to certain aspects of the present disclosure, the
first determination may comprise a determination to send uplink
traffic of all data bearers via the first RAT.
[0081] According to aspects of the present disclosure, the second
determination may comprise a determination to send downlink traffic
of one or more data bearers via both the first RAT and the second
RAT.
[0082] In aspects of the present disclosure, the first RAT may
comprise a wireless wide-area network (WWAN), and the second RAT
may comprise a wireless local area network (WLAN).
[0083] According to certain aspects of the present disclosure, at
least one of the first or second determinations may be based on a
predetermined configuration that specifies at least one of uplink
or downlink traffic should be routed to a particular RAT.
[0084] According to certain aspects of the present disclosure, at
least one of the first or second determinations may be based on
optimization of a system utility function comprising expected
performance of one or more data bearers routed via the first RAT or
second RAT. According to certain aspects of the present disclosure,
the system utility function may consider both uplink and downlink
traffic of the data bearers. In certain aspects of the present
disclosure, the system utility function may consider at least one
of a current assignment of data bearers to each RAT, channel and
traffic conditions on the first RAT and the second RAT, and
resource utilization and channel loads on each RAT. According to
certain aspects of the present disclosure, the system utility
function may comprise a proportional fairness function.
[0085] According to certain aspects of the present disclosure, the
first and second determinations may be made periodically.
[0086] According to certain aspects of the present disclosure, the
routing of downlink and uplink traffic from one RAT to the other
RAT may be switched based on a deterioration of channel conditions
of the one RAT without waiting for a periodic determination.
[0087] According to certain aspects of the present disclosure, a
first delay of a certain time after switching the routing of uplink
or downlink traffic of a data bearer may be implemented before
switching the routing again.
[0088] According to certain aspects of the present disclosure, the
number of times a routing of uplink or downlink traffic of a data
bearer may be switched during a time period may be limited.
[0089] FIG. 8 sets forth exemplary operations 800 for switching
bearers between radio access technologies (RATs), in accordance
with certain aspects of the present disclosure. The operations 800
may be performed by a UE, for example.
[0090] Operations 800 begin at 802, wherein the UE may optionally
send a channel conditions report. At 804, the UE receives a
configuration indicating one or more data bearers are to be sent
via a first radio access technology (RAT) and a second RAT, wherein
the uplink and downlink traffic for data bearers is independently
configured for routing via the first RAT and the second RAT. At
806, the UE sends a configuration complete message in response to
the received configuration. At 808, the UE may optionally send
uplink traffic for a bearer via the first RAT. At 810, the UE may
optionally receive downlink traffic for the bearer via the first
RAT and the second RAT.
[0091] According to aspects of the present disclosure, the UE may
receive the configuration in an RRC message. For example, an eNodeB
may send an RRC message configuring a served UE to send UL traffic
for all data bearers via LTE to the eNodeB, receive DL traffic for
phone calls via LTE, and receive DL traffic for web-browsing via
Wi-Fi.
[0092] The various operations of methods described above may be
performed by any suitable means capable of performing the
corresponding functions. The means may include various hardware
and/or software component(s) and/or module(s), including, but not
limited to a circuit, an application specific integrated circuit
(ASIC), or processor. Generally, where there are operations
illustrated in Figures, those operations may have corresponding
counterpart means-plus-function components with similar
numbering.
[0093] As used herein, the term "determining" encompasses a wide
variety of actions. For example, "determining" may include
calculating, computing, processing, deriving, investigating,
looking up (e.g., looking up in a table, a database or another data
structure), ascertaining and the like. Also, "determining" may
include receiving (e.g., receiving information), accessing (e.g.,
accessing data in a memory) and the like. Also, "determining" may
include resolving, selecting, choosing, establishing and the
like.
[0094] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
[0095] The various operations of methods described above may be
performed by any suitable means capable of performing the
operations, such as various hardware and/or software component(s),
circuits, and/or module(s). Generally, any operations illustrated
in the Figures may be performed by corresponding functional means
capable of performing the operations.
[0096] The various illustrative logical blocks, modules and
circuits described in connection with the present disclosure may be
implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array signal (FPGA) or
other programmable logic device (PLD), discrete gate or transistor
logic, discrete hardware components or any combination thereof
designed to perform the functions described herein. A general
purpose processor may be a microprocessor, but in the alternative,
the processor may be any commercially available processor,
controller, microcontroller or state machine. A processor may also
be implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0097] The steps of a method or algorithm described in connection
with the present disclosure may be embodied directly in hardware,
in a software module executed by a processor, or in a combination
of the two. A software module may reside in any form of storage
medium that is known in the art. Some examples of storage media
that may be used include random access memory (RAM), read only
memory (ROM), flash memory, EPROM memory, EEPROM memory, registers,
a hard disk, a removable disk, a CD-ROM and so forth. A software
module may comprise a single instruction, or many instructions, and
may be distributed over several different code segments, among
different programs, and across multiple storage media. A storage
medium may be coupled to a processor such that the processor can
read information from, and write information to, the storage
medium. In the alternative, the storage medium may be integral to
the processor.
[0098] The methods disclosed herein comprise one or more steps or
actions for achieving the described method. The method steps and/or
actions may be interchanged with one another without departing from
the scope of the claims. In other words, unless a specific order of
steps or actions is specified, the order and/or use of specific
steps and/or actions may be modified without departing from the
scope of the claims.
[0099] The functions described may be implemented in hardware,
software, firmware or any combination thereof. If implemented in
software, the functions may be stored as one or more instructions
on a computer-readable medium. A storage media may be any available
media that can be accessed by a computer. By way of example, and
not limitation, such computer-readable media can comprise RAM, ROM,
EEPROM, CD-ROM or other optical disk storage, magnetic disk storage
or other magnetic storage devices, or any other medium that can be
used to carry or store desired program code in the form of
instructions or data structures and that can be accessed by a
computer. Disk and disc, as used herein, include compact disc (CD),
laser disc, optical disc, digital versatile disc (DVD), floppy
disk, and Blu-ray.RTM. disc where disks usually reproduce data
magnetically, while discs reproduce data optically with lasers.
[0100] Thus, certain aspects may comprise a computer program
product for performing the operations presented herein. For
example, such a computer program product may comprise a computer
readable medium having instructions stored (and/or encoded)
thereon, the instructions being executable by one or more
processors to perform the operations described herein. For certain
aspects, the computer program product may include packaging
material.
[0101] Software or instructions may also be transmitted over a
transmission medium. For example, if the software is transmitted
from a website, server, or other remote source using a coaxial
cable, fiber optic cable, twisted pair, digital subscriber line
(DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of transmission
medium.
[0102] Further, it should be appreciated that modules and/or other
appropriate means for performing the methods and techniques
described herein can be downloaded and/or otherwise obtained by a
user terminal and/or base station as applicable. For example, such
a device can be coupled to a server to facilitate the transfer of
means for performing the methods described herein. Alternatively,
various methods described herein can be provided via storage means
(e.g., RAM, ROM, a physical storage medium such as a compact disc
(CD) or floppy disk, etc.), such that a user terminal and/or base
station can obtain the various methods upon coupling or providing
the storage means to the device. Moreover, any other suitable
technique for providing the methods and techniques described herein
to a device can be utilized.
[0103] It is to be understood that the claims are not limited to
the precise configuration and components illustrated above. Various
modifications, changes and variations may be made in the
arrangement, operation and details of the methods and apparatus
described above without departing from the scope of the claims.
[0104] While the foregoing is directed to aspects of the present
disclosure, other and further aspects of the disclosure may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *