U.S. patent application number 15/708560 was filed with the patent office on 2018-01-04 for systems, methods and devices for opportunistic networking.
This patent application is currently assigned to INTEL IP CORPORATION. The applicant listed for this patent is INTEL IP CORPORATION. Invention is credited to SHAFI BASHAR, JONG-KAE FWU, HWAN-JOON KWON, GENG WU.
Application Number | 20180006776 15/708560 |
Document ID | / |
Family ID | 54070555 |
Filed Date | 2018-01-04 |
United States Patent
Application |
20180006776 |
Kind Code |
A1 |
FWU; JONG-KAE ; et
al. |
January 4, 2018 |
SYSTEMS, METHODS AND DEVICES FOR OPPORTUNISTIC NETWORKING
Abstract
Opportunistic networking systems can utilize one or multiple
bands/channels that are shared with other radio access technologies
(RATs) (such as wireless local area networks (WLAN, such as Wi-Fi)
and mmWave). An unconventional carrier type (UCT) can be defined to
support opportunistic networking in licensed and/or unlicensed
spectrum. For example, a primary base station can determine a
secondary base station activated for use with user equipment (UE).
The primary base station can schedule data to be sent to the UE via
the secondary base station. The secondary base station can provide
discovery information, reserve a wireless channel, transmit the
data and/or release the channel (implicitly, explicitly, or by
reservation).
Inventors: |
FWU; JONG-KAE; (Sunnyvale,
CA) ; WU; GENG; (Plano, TX) ; BASHAR;
SHAFI; (Santa Clara, CA) ; KWON; HWAN-JOON;
(Santa Clara, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTEL IP CORPORATION |
Santa Clara |
CA |
US |
|
|
Assignee: |
INTEL IP CORPORATION
Santa Clara
CA
|
Family ID: |
54070555 |
Appl. No.: |
15/708560 |
Filed: |
September 19, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14580735 |
Dec 23, 2014 |
9794033 |
|
|
15708560 |
|
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|
61953634 |
Mar 14, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/0001 20130101;
H04L 5/0091 20130101; H04W 16/14 20130101; H04W 72/1215 20130101;
H04W 88/08 20130101; H04W 16/06 20130101; H04L 5/003 20130101 |
International
Class: |
H04L 5/00 20060101
H04L005/00; H04W 72/12 20090101 H04W072/12 |
Claims
1. An apparatus of a user equipment (UE), comprising: memory for
storing a licensed assisted access (LAA) subframe; a processor
configured to: decode, from a radio access network (RAN) node, the
LAA subframe to generate decoded LAA subframe data; identify a
primary synchronization signal (PSS), secondary synchronization
signal (SSS) and cell-specific reference signal (CRS) within the
decoded LAA subframe data; and determine that a discovery signal
exists within the LAA subframe based at least in part on
identifying the PSS, SSS and CRS within the decoded LAA subframe
data.
2. The apparatus of claim 1, wherein the UE is configured to add
the RAN node as a secondary cell.
3. The apparatus of claim 1, further comprising a first wireless
interface coupled to a transceiver configured to communicate using
LAA using a secondary cell operation.
4. The apparatus of claim 3, further comprising a second wireless
interface configured to communicate using long term evolution (LTE)
using a primary cell operation.
5. The apparatus of claim 1, wherein the processor is further
configured to perform secondary cell operations using LAA.
6. The apparatus of claim 1, further comprising a first wireless
interface coupled to a first transmitter using an unlicensed band
with LAA in a secondary cell operation.
7. The apparatus of claim 6, further comprising a second wireless
interface coupled to a second transmitter using an licensed band
with using long term evolution (LTE) in a primary cell
operation.
8. The apparatus of claim 1, wherein the processor is a baseband
processor.
9. An apparatus of a radio access network (RAN) node, comprising: a
first wireless interface coupled to a transmitter using a licensed
assisted access (LAA) band; a processor configured to: select a
first subframe for discovery measurement timing for a LAA discovery
signal, wherein the first subframe contains a primary
synchronization signal (PSS), secondary synchronization signal
(SSS) and cell-specific reference signals (CRS); generate a
periodic LAA discovery signal based at least in part on the
discovery measurement timing and the first subframe; and provide
the periodic LAA discovery signal for transmission using the first
wireless interface.
10. The apparatus of claim 9, wherein to provide the periodic LAA
discovery signal for transmission using the first wireless
interface further comprises to provide the periodic LAA discovery
signal for transmission using the first wireless interface when a
transmission subframe is active.
11. The apparatus of claim 9, further comprising a second wireless
interface configured as a primary cell interface.
12. The apparatus of claim 11, wherein the LAA band is an
unlicensed band.
13. The apparatus of claim 11, wherein the second wireless
interface is a long term evolution (LTE) interface.
14. The apparatus of claim 9, wherein the first wireless interface
is configured to transmit on a band that includes WLAN.
15. The apparatus of claim 9, wherein the first wireless interface
is configured as an LAA secondary cell interface.
16. The system apparatus of claim 9, wherein the processor is a
baseband processor.
17. A computer program product comprising a computer-readable
storage medium that stores instructions for execution by a
processor to perform operations of a radio access network (RAN)
node, the operations, when executed by the processor, to perform a
method, the method comprising: selecting a first occurring subframe
of a discovery signal period for a licensed assisted access (LAA)
discovery signal; generating a non-empty subframe including the LAA
discovery signal, a primary synchronization signal and a secondary
synchronization signal; and encoding the non-empty subframe for
transmission at a time of the first occurring subframe of the
discovery signal period.
18. The computer program product of claim 17, wherein the LAA
discovery signal is periodic based on the discovery signal
period.
19. The computer program product of claim 17, wherein the non-empty
subframe further comprises a cell specific reference signal
(CRS).
20. The computer program product of claim 17, wherein the method
further comprises providing a secondary cell to a user equipment
(UE) using LAA.
Description
RELATED APPLICATION
[0001] This application is a continuation of application U.S.
application Ser. No. 14/580,735, filed Dec. 23, 2014, entitled
"SYSTEMS, METHODS AND DEVICES FOR OPPORTUNISTIC NETWORKING" which
claims the benefit under 35 U.S.C. .sctn.119(e) of U.S. Provisional
Application No. 61/953,634 filed Mar. 14, 2014, entitled
"OPPORTUNISTIC NETWORKING SUPPORT FOR LTE CELLULAR SYSTEM" both of
which are incorporated by reference herein in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to wireless transmission
systems including systems for sharing wireless spectrum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1 is a diagram illustrating an opportunistic networking
system consistent with embodiments disclosed herein.
[0004] FIG. 2 is a block diagram illustrating use cases of an
opportunistic networking system consistent with embodiments
disclosed herein.
[0005] FIG. 3 is a diagram of a long term evolution (LTE) frame
consistent with embodiments disclosed herein.
[0006] FIG. 4 is a diagram illustrating use of an alignment gap to
synchronize transmissions consistent with embodiments disclosed
herein.
[0007] FIG. 5 is a diagram illustrating use of a preamble within an
alignment gap to synchronize transmissions consistent with
embodiments disclosed herein.
[0008] FIG. 6 is a diagram illustrating use of a super subframe to
synchronize transmissions consistent with embodiments disclosed
herein.
[0009] FIG. 7 is a diagram illustrating use of a reduced length
subframe to synchronize transmissions consistent with embodiments
disclosed herein.
[0010] FIG. 8 is a diagram illustrating use of primary
synchronization signals and/or secondary synchronization signals
(PSS/SSS) consistent with embodiments disclosed herein.
[0011] FIG. 9 is a diagram illustrating use of periodic
transmission of discovery subframes consistent with embodiments
disclosed herein.
[0012] FIG. 10 is a diagram illustrating unaligned subframes with
channel reservation consistent with embodiments disclosed
herein.
[0013] FIG. 11 is a diagram illustrating unaligned subframes with
channel reservation and a discovery subframe consistent with
embodiments disclosed herein.
[0014] FIG. 12 is a process chart illustrating a method for
cross-carrier transmission consistent with embodiments disclosed
herein.
[0015] FIG. 13 is a schematic diagram of a computing system
consistent with embodiments disclosed herein.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0016] A detailed description of systems and methods consistent
with embodiments of the present disclosure is provided below. While
several embodiments are described, it should be understood that the
disclosure is not limited to any one embodiment, but instead
encompasses numerous alternatives, modifications, and equivalents.
In addition, while numerous specific details are set forth in the
following description in order to provide a thorough understanding
of the embodiments disclosed herein, some embodiments can be
practiced without some or all of these details. Moreover, for the
purpose of clarity, certain technical material that is known in the
related art has not been described in detail in order to avoid
unnecessarily obscuring the disclosure.
[0017] Techniques, apparatus and methods are disclosed that enable
opportunistic networking that utilizes one or multiple
bands/channels that are used or shared with other radio access
technologies (RATs) (such as wireless local area networks (WLAN,
such as Wi-Fi) and millimeter wave (mmWave)). Conventional long
term evolution (LTE) uses one or multiple frequency bands that are
exclusively assigned to LTE (such as LTE carrier aggregation or New
Carrier Type (NCT)). An unconventional carrier type (UCT) can be
defined to support opportunistic networking in licensed and/or
unlicensed spectrum. LTE in a licensed carrier will be referred to
as LCT (licensed carrier type).
[0018] For example, a primary base station (which can provide a
primary carrier and a primary cell (PCell), which can transmit over
a primary medium, primary set of frequencies, primary spectrum,
primary band, etc.) can determine a secondary base station (which
can provide a secondary carrier and secondary cell (SCell), which
can transmit over a secondary medium, secondary set of frequencies,
secondary spectrum, secondary band, etc.) to activate for use with
user equipment (UE). The primary base station can schedule data to
be sent to the UE via the secondary base station. The secondary
base station can provide discovery information, reserve a wireless
channel, transmit the data and/or release the channel (implicitly,
explicitly, or by reservation).
[0019] In one embodiment, fast cell switching is used to
opportunistically use available spectrum. For example, mmWave
technologies may have limited availability under unfavorable
channel conditions (such as due to the high frequency effects).
Very fast cell switching can allow opportunistic use of mmWave when
available.
[0020] In another embodiment, more efficient sharing of a band of
frequencies can be supported by fast switching between dormant
(e.g., OFF) and active (e.g., ON) states. During dormant states, a
UCT system will refrain from transmission to reduce interference to
other RAT technologies using the spectrum. During active states,
the UCT system can perform downlink (DL) and/or uplink (UL) LTE
operations.
[0021] In one embodiment, dormant subframes can be used to perform
protocols to aid in the sharing of the spectrum. For example, a UCT
system can perform listen before talk (LBT) protocols and/or
channel reservation techniques. Once the spectrum is reserved
and/or available, the UCT can transition into an active state.
[0022] In another embodiment, a UCT system can reduce periodic
transmission of signals compared with an LCT system. Instead of
typical LCT signals, a discovery signal and/or synchronization
signal can be used. The discovery signal can be sent periodically,
even when a UCT system is in a dormant state (such as during a
dormant subframe).
[0023] The demand for wireless broadband data in cellular networks
is expected to increase. By considering user expectations of high
data rates along with seamless mobility more spectrum can be made
available for macro cells and small cells deployment. To support
the growing demand of wireless broadband data, opportunistic use of
additional available spectrum can be used. Such opportunistic
network/offloading opportunity can be used in the following three
scenarios to take advantage of the additional available spectrum in
either the licensed or unlicensed band:
[0024] In scenario (1) the unlicensed spectrum can be used with
LTE-A technology which is called LTE in Unlicensed (LTE-U) or
Licensed Assisted Access (LAA). LTE-U can extend the LTE technology
into unlicensed deployments, enabling operators and vendors to
leverage existing or planned investments in LTE/evolved packet core
(EPC) hardware in the radio and core network. LTE-U can also be
considered a Supplemental Downlink Component Carrier (CC) in a LTE
Carrier Aggregation (CA) configuration. The use of LTE in the
unlicensed band can be in co-existence of LTE with other incumbent
technologies deployed in the unlicensed band. Due to multiple LTE
operators using the same unlicensed spectrum, self-coexistence
among different LTE operators in the same band can also be
encountered.
[0025] In scenario (2) an opportunistic networking embodiment uses
the LTE licensed band together with another Radio Access Technology
(RAT) used in high frequency spectrum, such as millimeter wave
(mmWave). The option to opportunistically use the mmWave channel
cannot always be guaranteed, due to the potentially high path-loss
and restrictive beam forming requirements to achieve reasonable
link/channel quality. A design than includes support opportunistic
networking and use of mmWave (when channel condition is favorable)
can be beneficial to ensure the basic quality of service (QoS),
which can improve user experience. Cell densification can trigger
interest in applying the mmWave spectrum at densely populated areas
in order to provide local coverage without causing excessive
inter-cell interference. Use of a highly directional antenna array
and beam forming with mmWave communication can provide additional
coverage and capacity improvements. In some embodiments, the mmWave
bands can be regarded as an additional secondary carrier and SCell
in order to improve the existing LTE system performance.
[0026] In scenario (3) Device-to-Device (D2D) service can be used
in unlicensed spectrum together with the conventional LTE service
in licensed spectrum. The D2D service in unlicensed spectrum can be
used to opportunistically off-load the traffic demand in licensed
band LTE service and improve the overall data rate and user
experience.
[0027] The use of additional spectrum in the above examples can
lead to the coexistence of frequency bands with different
propagation characteristics within the same system. A framework can
be built on the concept of an unconventional carrier type (UCT)
concept together with the operation of quickly turning the cell
on/off to support opportunistic networking options and address
coexistence. Several concepts can be used in the design of
opportunistic networking, including: (A) utilize a concept of
licensed-assisted (LTE assisted) spectrum sharing scheme; (B)
utilize a carrier aggregation concept and (C) utilize a fast cell
on/off mechanism to support opportunistic use of spectrum and
networking.
[0028] These opportunistic networking concepts will be further
explored in the description of the unconventional carrier type
design heading. However, an introduction to a system that can use
opportunistic networking is first described to aid in the
comprehension of the design.
[0029] Wireless mobile communication technology uses various
standards and protocols to transmit data between a base station and
a wireless mobile device. Wireless communication system standards
and protocols can include the 3rd Generation Partnership Project
(3GPP) long term evolution (LTE) standard; the Institute of
Electrical and Electronics Engineers (IEEE) 802.16 standard, which
is commonly known to industry groups as worldwide interoperability
for microwave access (WiMAX); and the IEEE 802.11 standard, which
is commonly known to industry groups as Wi-Fi. Mobile broadband
networks can include various high speed data technologies, such as
3GPP LTE systems. In 3GPP radio access networks (RANs) in LTE
systems, the base station can include Evolved Universal Terrestrial
Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as
evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and/or Radio
Network Controllers (RNCs) in an E-UTRAN, which communicate with a
wireless communication device, known as user equipment (UE).
[0030] Turning to FIG. 1, an example of a portion of a radio access
network (RAN) system 100 includes a single cellular air interface
(such as an LTE/LTE-Advanced access link) being provided between an
primary base station 104 and a UE 102 (i.e., on Access Link A), and
an air interface (a supplemental network interface such as a LTE-U
based interface) being provided between a secondary base station
106 and the UE 102 (i.e., on Access Link B). The UE 102 is located
within a macro cell coverage 108. The UE 102 determines that
connection with the secondary base station 106 will be beneficial
to a user of the UE 102. In some embodiments, the UE 102 retains
Access Link A to the primary base station 104. The UE 102 can
offload some or part of wireless services onto Access Link A. In
other embodiments, the UE 102 disconnects from Access Link A and
moves all wireless services to Access Link B. In some embodiments,
Access Link A and Access Link B use the same frequency and
technology. In other embodiments, Access Link A and Access Link B
use different frequencies (e.g., LTE licensed frequencies and
unlicensed frequencies) and different link technology (e.g., LTE
and Wi-Fi). In other embodiments, Access Link A and Access Link B
use different frequencies and similar link technology (e.g., LTE
and LTE over mmWave).
[0031] FIG. 2 presents a chart 200 of different application
scenarios 202 for UCT. A UCT carrier design provides a general
framework to enable LTE to be deployed in scenarios where existing
LTE/LTE-A may not be suitable, while still meeting the above target
requirements. Although an enhancement for unlicensed band
deployment is an advantage for UCT, the UCT can be used in the
licensed band as well. It can be used as DL supplementary secondary
carrier (DSC) or supporting both DL and UL. It can be supported in
both frequency division duplexing (FDD) and time division duplexing
(TDD) modes.
[0032] When used in a single carrier operation 204, the UCT can
operate as a stand-alone carrier either in a licensed or an
unlicensed band (e.g., as primary carrier).
[0033] An application of UCT can be (1) as a secondary carrier
providing an SCell 212 on an unlicensed band in a carrier
aggregation (CA) 206 scenario, or (2) as a secondary carrier
providing an SCell 224 in a Master eNB (MeNB) group 218, or as a
secondary carrier providing an SCell 232 in an SeNB group 220 in
case of dual connectivity (DC) 208 scenarios. In some embodiments
of CA 206 (see also long term evolution release 12 specification
(LTE Rel-12)), the secondary carrier providing an SCell 212 is
assumed to be synchronized with a primary cell providing a PCell
210. However, due to the use of UCT in the unlicensed band,
additional CA 206 scenarios where the secondary carrier providing
SCell 212 is not synchronized with the primary cell providing PCell
210 can be described in future LTE releases (LTE Rel-13 and
beyond). In addition, UCT can also act as an supplementary primary
carrier providing an sPCell 230 in an SeNB group 220 in the DC
208.
[0034] The use of UCT as the primary carrier providing a PCell 210
in the CA 206 scenario and/or as the primary carrier providing a
PCell 222 in the MeNB group 218 in case of the dual connectivity
208 is also possible.
[0035] FIG. 3 is a schematic diagram 300 illustrating a long term
evolution (LTE) communication frame 304 of a 10 ms duration 302. In
one embodiment, each frequency allocation (carrier) can be in 108
kHz increments. In the diagram shown, a minimum of six carriers are
shown. This allows for a bandwidth of 1.08 MHz (six carriers times
180 kHz=1.08 MHz bandwidth). In some embodiments, the carriers can
be expanded to 110 blocks (110 carriers times 180 kHz=19.8 MHz).
The frame 304 can be 10 ms with each slot 308 being 0.5 ms (and
each subframe 306 being 1 ms).
[0036] The slot 308 at a carrier is a resource block 310, which
includes seven symbols at 12 orthogonal frequency-division
multiplexing (OFDM) subcarriers. A resource element 312 is one OFDM
subcarrier for the duration of one OFDM symbol. The resource block
310 can include 84 resource elements 312 when using a normal cyclic
prefix (CP). OFDM spacing between individual subcarriers in LTE can
be 15 kHz. A guard period of a CP can be used in the time domain to
help prevent multipath inter-symbol interference (ISI) between
subcarriers. The CP can be a guard period before each OFDM symbol
in each subcarrier to prevent ISI (such as due to multipath).
[0037] LTE frames can be altered for use with a UCT framework.
FIGS. 4-11 show various embodiments in which an LTE frame is used
with a UCT framework. FIG. 4 shows an alignment gap for
synchronization with a primary carrier. FIG. 5 shows channel
reservation in conjunction with a UCT. FIG. 6 shows an extended
subframe or super subframe used in synchronization. FIG. 7 shows a
reduced length subframe for use with synchronization. FIG. 8 shows
an example of an unsynchronized frame with PSS/SSS transmissions.
FIG. 9 shows an example of a synchronized frame that uses periodic
transmission of discovery subframes and channel reservation. FIG.
10 shows an unsynchronized subframe with channel reservation. FIG.
11 shows an unsynchronized subframe with channel reservation and
discovery subframes. These Figures will be described in conjunction
with UCT design including UCT types and variations. Unconventional
Carrier Type (UCT) design
[0038] Opportunistic networking utilizes one or multiple
bands/channels that are used or shared with other radio access
technologies (RATs) such as WLAN and mmWave, while the conventional
LTE (or simply referred to as LTE) uses one or multiple frequency
bands that are exclusively assigned to LTE (such as LTE carrier
aggregation or New Carrier Type (NCT). An unconventional carrier
type can support opportunistic networking in licensed and/or
unlicensed spectrum. In this description, such carrier is referred
to as an unconventional carrier type (UCT), while referring to LTE
in a licensed carrier as LCT (licensed carrier type).
[0039] In some embodiments, design objectives of UCT can include:
(1) opportunistic use of additional available spectrum using LTE
and other RATs (e.g., WLAN, mmWave, etc.) (this can be considered
as a spectrum sharing mechanism in conjunction with the use of LTE
technology, e.g., a licensed-assisted (LTE assisted) spectrum
sharing scheme); (2) efficient sharing of spectrum with other
incumbent RATs in the additional spectrum; (3) conforming to
regulatory restrictions of additional available spectrum for the
licensed or unlicensed band; and (4) lower interference to other
RATs or LTE in the same or an adjacent band.
Objective 1: Opportunistic Use of Additional Available Spectrum
Using LTE and other RATs such as WLAN, mmWave, etc.
[0040] Some challenges for RATs used in the high frequency band
(e.g., mmWave communications) include large path loss (especially
for non-line-of-sight scenarios) and, signal blocking/absorption by
various objects in the environment. Advanced antenna arrays with
smart beam selection/tracking algorithms can be used to address the
signal attenuation or path-loss issue. This can lead to a limited
availability under unfavorable channel condition on the high
frequency (e.g., mmWave) band. Therefore, very fast cell switching
or fast opportunistic use of the mmWave channel can be used in
leverage of the additional mmWave resource.
Objective 2: Efficient Sharing of Spectrum with other RATs in the
Additional Spectrum
[0041] Some embodiments aid efficient sharing of the unlicensed
band through the operation by fast switching of the UCT on the
unlicensed band between two states: Dormant (or OFF) and active (or
ON). The UCT subframes during the dormant state can be referred to
as dormant (OFF) subframes, whereas the UCT subframes during the
active state can be referred to as active (ON) subframes. UCT
activities during the dormant and active states can be categorized
into two separate tasks: design of active subframes and design of
dormant subframes.
[0042] During the active state/subframes, the UCT may perform DL
and/or UL LTE operations, whereas during the dormant subframe, the
UCT will refrain from transmission so as to reduce interference,
thus enabling the use of the unlicensed band for other incumbent
RATs. Therefore, the active state/subframe and the dormant
state/subframe can be regarded as the ON state/subframe and the OFF
state/subframe, respectively.
[0043] In one embodiment and when there is no LTE traffic, the UCT
can be in a dormant state, where all subframes are dormant
subframes. While the state is labeled as OFF or dormant, some
signaling or control channels can be transmitted on the UCT
secondary carrier for special purposes (such as synchronization,
signal strength/quality measurements, etc.) during this state.
These subframes conveying these signal/channels are still referred
to as OFF subframes (or OFF state) since there are no data
(traffic) transmissions (e.g., physical downlink shared channel
(PDSCHs)) in these subframes.
Objective 3: Conforming to the Regulatory Restrictions of the
Additional Available Spectrum for the Licensed or Unlicensed
Band
[0044] In order to follow restrictions (such as regulatory
restrictions) of the unlicensed band, the OFF/dormant subframes can
be used to perform protocols such as listen before transmit (LBT)
to scan if the wireless medium (also known as wireless spectrum,
wireless frequencies, channel, etc.) is busy or idle. Additionally,
the UCT can also reserve the medium from other RATs (such as by
performing a spoofing mechanism to reserve the channel for its own
transmission). Once the medium is reserved (or sensed idle in case
the reservation is not required depending on the LBT protocol), the
UCT can transition from the OFF/dormant state to the ON/active
state, and the active subframe is used for transmitting data (e.g.,
PDSCH).
Objective 4: Lower Interference to other Radio Access Technologies
(RAT) or LTE in the Same or Adjacent Band
[0045] In some embodiments and in order to aid in minimizing
transmission overhead and in reducing interference, the UCT design
can minimize the periodic transmission of signals normally
transmitted in LCT. For example and in DL LCT design, the following
signals are transmitted periodically in frequency division duplex
(FDD) and time division duplex (TDD).
[0046] In some embodiments of FDD DL, several signals are
transmitted periodically. Cell-specific reference signal (CRS) is
transmitted in every subframe, except the physical downlink shared
channel (PDSCH) portion of the multicast-broadcast single-frequency
network (MBSFN) subframe. PSS and SSS are transmitted in subframes
0 and 5. Physical broadcast channel (PBCH) is transmitted in
subframe 0. SIB-1 is transmitted in subframe 5 on the systems frame
number (SFN) satisfying the condition, SFN mod 2=0 (i.e., every
other frame). Paging in subframes 0, 4, 5 and 9 on frame satisfy
the equation SFN mod T, where T is the discontinuous reception
(DRX) cycle of the UE.
[0047] In some embodiments of TDD DL, several signals are
transmitted periodically. CRS is transmitted in every downlink
subframe, except the PDSCH portion of the MBSFN subframe. PSS are
transmitted in subframes 0 and 5. SSS are transmitted in subframes
1 and 6. PBCH is transmitted in subframe 0. SIB-1 is transmitted in
subframe 5 on the SFN satisfying the condition, SFN mod 2=0 (i.e.,
every other frame). Paging in subframes 0, 1, 5 and 6 on frame
satisfy the equation SFN mod T, where T is the DRX cycle of the
UE.
[0048] In addition, CRS transmissions can be reduced. CRS
transmission provides reference signal received power/reference
signal received quality (RSRP/RSRQ) measurement, fine-frequency
tracking and channel estimation. However, CRS transmission on empty
subframes (e.g., in the OFF/dormant subframe) can cause
interference with other RATs and/or LTE-U systems using the
spectrum. If a CRS transmission power exceeds a certain threshold,
the incumbent WLAN network can sense the medium as busy and refrain
from transmission. Reducing or removing the transmission of CRS on
UCT can improve the efficiency of medium use by other RATs.
[0049] Reduced transmission of CRS can be achieved in several
possible ways. In a first embodiment, CRS transmission can be
limited to active subframes. In dormant subframes, UCT can refrain
from CRS transmission. In a second embodiment, CRS is eliminated
from both active and dormant subframes. Alternative signals (such
as channel state information reference signal (CSI-RS),
demodulation reference signal (DM-RS), etc.) can be used to perform
these tasks of CRS, making CRS transmission potentially redundant.
In a third embodiment, a cell on/off mechanism can be introduced,
whereby UCT will be switched off when not transmitting data and
turned on when there is data available to be transmitted.
[0050] In some embodiments, transmission frames can be
synchronized. In some embodiments of LCT, PSS/SSS is used for
initial coarse time and frequency synchronization. In addition,
PSS/SSS can also be used for cell selection purposes during initial
access. Similar to transmission of CRS, periodic transmission of
PSS/SSS can introduce additional interference to the other RATs/LTE
network in the unlicensed band. In an embodiment, whether PSS/SSS
transmission is provided on UCT depends on the geographical
location and the spectrum location of a UCT secondary base station
with respect to a licensed primary base station. If both the
primary base station and secondary base station are co-located and
the secondary base station band is adjacent to the primary base
station (i.e., inter-band CA), then the PSS/SSS transmitted on the
primary base station can be used for secondary base station
synchronization. PSS/SSS transmission may be considered redundant
on the secondary base station. In a second example where the
secondary base station is not co-located with the primary base
station, or in case of intra-band CA, primary base station
synchronization may not be as effective when re-used for UCT
secondary base station synchronization purposes.
[0051] Several different design embodiments can be considered for
the transmission of such PSS/SSS signals. In a first embodiment,
PSS/SSS transmission can be eliminated on the UCT secondary base
station in case of co-located inter-band CA as described above.
[0052] In a second embodiment, PSS/SSS can follow transmission
timing as in an LCT primary carrier (e.g., in case of FDD, PSS and
SSS can be transmitted in subframes 0 and 5 in a frame). Actual
transmission can be limited to when the subframes 0 and 5 are
active subframes. In case of a dormant subframe, no PSS/SSS
transmission will occur.
[0053] In a third embodiment, transmission of PSS/SSS can follow
new timing, different from an LCT primary carrier. For example,
transmission of PSS/SSS can take place on a k-th active subframe in
a frame on UCT (i.e., every k active subframe).
[0054] In a fourth embodiment and instead of transmitting legacy
PSS/SSS for synchronization purposes, a new synchronization or
discovery signal can be used. In addition, a new subframe structure
can be designed to be used for transmitting only discovery signals
(such as subframes that include the discovery signal, which are
called discovery subframes). A discovery signal can be transmitted
during the OFF state, and the discovery signal may be used for cell
identification, radio resource management (RRM) measurements and
other purposes.
[0055] In some embodiments, transmission of PBCH/paging and other
system information can be eliminated from a UCT secondary base
station. Such information can be carried out on licensed primary
base station carriers. In case of stand-alone applications of a
UCT, however, such discovery signal may still be necessary. If a
stand-alone UCT is operated on an unlicensed band, then the legacy
schemes may not be readily applicable. Similar to the PSS/SSS
mechanisms as described above, new timing can be defined for
transmission of such signal on a UCT.
[0056] Using the description above, embodiments of a UCT system are
described below.
Type 1 UCT
[0057] In FIG. 4, an example of a type 1 UCT is shown. In this
example, the subframe/frame boundary of a UCT secondary eNB 404 is
aligned with the subframe/frame boundary of a legacy primary eNB
402. In this example, in the OFF/dormant subframes 418, the UCT
secondary eNB 404 refrains from transmission. Before the
transition/switch to an active state, the UCT secondary eNB 404 may
perform LBT that can include a channel reservation mechanism with
timing 412. Once the UCT secondary eNB 404 reserves the medium or
senses the channel idle, the UCT secondary eNB 404 can transmit
data in active subframes 416, i.e., transition to the ON/active
state. In order to maintain alignment with the primary carrier 402
subframes (406, 408 and 410), a portion of active states right
before the first active subframe is left unused. This gap is
referred to as an alignment gap 414.
[0058] In some embodiments and during the alignment gap 414, if no
signal is transmitted by LAA eNB or UE, then other incumbent RATs
(e.g., WLAN) as well as other LAA operators may determine the
medium is empty due to lack of transmission. The incumbent RATs or
LAA operators may attempt to transmit during an empty medium. To
keep the medium reserved for transmission in the first active
subframe, the LAA eNB or UE can transmit a signal to keep the
medium occupied until the first subframe. Several mechanisms can be
used to address this issue of medium reservation.
[0059] In FIG. 5, a chart 500 shows a mechanism for channel
reservation that can be used during an alignment gap 502. A signal
(shown here as WLAN preambles 504 and 506) can be transmitted
during the alignment gap 502 to keep the medium busy before
transmission of a subframe 508. In the embodiment shown in FIG. 5,
the signals transmitted are the 802.11 a preamble signals
consisting of Bus long STF (short training field), Bus LTF (long
training field) and 4us long signal field, a total duration of
20us. Multiple copies of the signal can be transmitted during an
alignment gap to keep the medium occupied. Other alternative
signals can also be considered. In different embodiments, the
signal can take the form of a noise signal (e.g. white noise,
pseudo-random sequence etc.), empty (if less than a duration of
time), a reservation message and/or a discovery signal. In a first
example embodiment, a form of a noise signal (such as pseudo-random
noise sequence) can be broadcast throughout the entire transmission
bandwidth. In a second embodiment and if the alignment gap is less
than a certain duration, then the alignment gap can be left empty
510. A WLAN access point/station (AP/STA) can wait/scan a duration
of at least short interframe space (SIFS), packet coordination
function (PCF) interframe space (PIFS) or distributed coordination
function (DCF) interframe space (DIFS) before transmitting
acknowledge (ACK) info, beacon and data frame respectively. If the
alignment gap is less than one of these values (e.g., less than
SIFS) then the alignment gap can be left empty.
[0060] In a third example, the secondary base station can transmit
some form of a signal that is understood by WLAN (e.g.,
physical(PHY) layer spoofing signal based on WLAN preambles 504 and
506, RTS message or CTS message, etc.). In FIG. 5, one example of
transmitting WLAN preambles 504 and 506 is shown. In the embodiment
shown an alignment gap is 50 microseconds (us). An LTE symbol
duration without CP is 66.7 us, which is larger than the alignment
gap of 50 us. Instead, transmission of the short training field
(STF), long training field (LTF) and signal field (SIG) are part of
a WLAN preamble that causes WLAN devices to see the medium as busy.
As an added benefit, a WLAN AP/STA can decode the SIG portion of
the signal and update their network allocation vector (NAV) for the
duration specified in the preambles 504 and 506. One or more copies
of a reservation message can be transmitted. Since a WLAN AP/STA
wait/scans a duration of at least SIFS, PIFS or DIFS before
transmitting ACK info, beacon and data frame respectively, if the
remaining alignment gap 510 after transmitting one or more such
preambles 504 and 506 is less than that the duration, then the
additional gap 510 can be left empty. In some embodiments, a clear
to send (CTS) message, request to send (RTS) message or RTS-CTS
message can also be used in place of the preamble(s) 504 and
506.
[0061] In a fourth example and if the duration is more than a LTE
symbol length, then an LTE discovery signal can be transmitted.
Depending on the duration, one or more symbols of an LTE signal can
be transmitted. Some example of discovery signals include PSS/SSS,
one or several symbols of CRS, CSI-RS, SRS, DMRS, PRS, etc. or an
enhanced version of these signals.
[0062] This alignment gap can be larger than one subframe. During
the gap, UE scheduling (including the selection of the target UE,
modulation and coding scheme (MCS), resource block (RB) allocation,
etc.) and encoding (e.g., PDSCHs) can be performed at the eNB.
[0063] In FIG. 6, a second mechanism 600 is shown, which can be
used for channel reservation. A primary eNB 602 transmits data over
frames 606, 608 and 610. A UCT secondary eNB 604 is scheduled to
transmit data during active subframes 616 and to transition to a
dormant state during dormant subframes 618. To synchronize
transmission of the primary eNB 602 and secondary eNB 604, a LBT
protocol and/or reservation mechanism 612 can be used to reserve
the channel. An alignment gap after the mechanism 612 is merged
with a first active subframe to create a super-subframe 614.
Alternatively, the alignment gap can be used to transmit discovery
signals as mentioned above.
[0064] In another embodiment shown in FIG. 7, a discovery subframe
714 is transmitted after a channel reservation 712 is performed. As
described earlier, the discovery subframe 714 can contain signals
for synchronization and RSRP measurement. To accommodate the
discovery subframe 714, a first active subframe immediately
following the discovery subframe 714 can be shortened to a reduced
length subframe 720. For example, a primary eNB 702 transmits data
over frames 706, 708 and 710. A UCT secondary eNB 704 is scheduled
to transmit data during active subframes 716 and to transition to a
dormant state during dormant subframes 718. To synchronize
transmission of the primary eNB 702 and secondary eNB 704, a LBT
protocol and/or reservation mechanism 712 can be used to reserve
the channel. A discovery subframe 714 is transmitted after the
LBT/reservation mechanism 712. A first active subframe is shortened
to create the reduced length subframe 720.
[0065] In FIG. 8, a legacy PSS/SSS 808 can be used as a discovery
signal. The legacy PSS/SSS 808 signal can be considered as a
special case of discovery signal. If the PSS/SSS 808 is
transmitted, then additional discovery subframes may not be
required. Instead the existing subframe (shown as subframe 0) can
accommodate such a signal. One such example is presented in FIG. 8.
Here, the PSS/SSS signal 808 is transmitted in the first subframe
(i.e., subframe 0). For example, the UCT can perform an LBT and
channel reservation 806 before transitioning to an active state.
During the active subframes 810, the PSS/SSS signal 808 is
transmitted. After transmission of the active subframes 810, the
UCT transitions to a dormant state 812.
[0066] In FIG. 9, another embodiment of type 1 UCT frames is shown
in which a discovery subframe 914 is periodically transmitted in
both dormant subframes 918 and active subframes 916. The
transmission of the discovery subframe 914 in this example is not
preceded by an LBT or channel reservation mechanism. The UCT
transmits the discovery subframe 914 (or signal) whether or not the
medium is busy. In another embodiment, the transmission of each
discovery subframe 914 can be preceded by an LBT scheme. To aid in
LBT, a transmission power of the discovery subframe 914 can be
limited, in accordance with a regulatory requirement. For example,
the UCT can perform LBT and channel reservation 912 before
transitioning to an active state (which may include an alignment
gap 922). During the active subframes 916, the discovery subframe
914 is transmitted. This can cause a subframe to become a reduced
length subframe 920. After transmission of the active subframes
916, the UCT transitions to a dormant state with dormant subframes
918. A discovery subframe 914 can be sent during the dormant
subframe 918 with or without using LBT.
Type 2 UCT
[0067] In FIG. 10, an embodiment 1000 of a type 2 UCT is shown in
primary eNB 1002 subframes 1006, 1008 and 1010, and UCT secondary
eNB 1004 subframes 1016 are not synchronized (or aligned). In this
example, the subframe/frame boundary of the UCT secondary eNB 1004
is not aligned with the subframe/frame boundary of the legacy
primary eNB 1002. During a dormant state 1018, the UCT refrains
from transmission. In order to move to an active state, the UCT
performs an LBT and channel reservation mechanism 1012. Since
alignment between the primary eNB subframe boundary and secondary
eNB subframe boundary is not required for type 2 UCT, unlike the
type 1 UCT, no alignment gap is defined. Once the medium is
reserved, LAA can start transmission. The active subframes 1016 in
a type 2 UCT are not aligned with the corresponding primary eNB
subframes 1006, 1008 or 1010.
[0068] In another embodiment 1100 of a type 2 UCT shown in FIG. 11,
a discovery subframe 1114 can be transmitted after an LBT and
channel reservation protocol 1112 before the first active subframe
in active subframes 1116. For example, the UCT can perform the LBT
and channel reservation 1112 and send the discovery subframe 1114
before transitioning to an active state. During the active
subframes 1116, data is transmitted (which includes sending and/or
receiving). After transmission of the active subframes 1116, the
UCT transitions to a dormant state with dormant subframes 1118. The
discovery subframe 1114 can be sent during the dormant subframe
1118 with or without using LBT.
[0069] Alternatively, a discovery signal similar to PSS/SSS can be
transmitted in the first subframe similar to FIG. 8 instead of
before the first subframe.
[0070] FIG. 12 shows an embodiment of a method 1200 of LTE
transmissions in an unlicensed band in accordance with the present
invention. In this embodiment, LTE-U transmissions can be based on
the following operations. It should be noted that some of the
operations can be omitted in some deployment scenarios. The method
1200 can be accomplished by a system 100 such as shown in FIG. 1,
including primary base station 104, secondary base station 106 and
UE 102.
[0071] In this embodiment, there are a PCell 1202, two UCT
secondary base stations 1204 and 1206, and a UE 1208. However, it
should be noted that the system can include more computing
resources than shown (e.g., the UE 1208 is one UE of many UEs
connected to the primary base station 1202, the UCT secondary base
stations 1204 and 1206 are two of many secondary base stations that
serve the UEs). Each secondary base station 1204 and 1206 transmits
discovery signals 1210 in ON subframes or OFF subframes.
[0072] The UE 1208 then optionally reports 1214 the measurement
results 1212 to the primary base station 1202, e.g., through a
licensed band. The measurement reports 1214 can include RSRP/RSRQ
and other interference conditions for each secondary base station
1204 and 1206. Each secondary base station 1204 and 1206 can also
optionally measure interference power and report 1216 to the
primary base station 1202.
[0073] The primary base station 1202 selects one or multiple
bands/channels to be used for PDSCH transmissions, e.g., based on
the measurement reports from one or multiple UEs and/or from the
secondary base stations. The bands/channels selection can be
UE-specific, a group of UE-specific, or primary base
station-specific. Once one or more bands/channels are selected, the
bands/channels selection information can be sent 1220 to the UE(s)
1208 (e.g., through licensed bands using one or multiple of
physical broadcast channel (PBCH), physical downlink control
channel (PDCCH), enhanced physical downlink control channel
(ePDCCH), and PDSCH).
[0074] The selected secondary base station may transmit reference
signals 1222 (such as CSI-RS) that can be used for CSI feedback by
UE 1208. The CSI-RS transmission can be preceded by an LBT or can
be simply transmitted using a predetermined set of resources. Then,
UE 1208 reports 1224 to the primary base station 1202 CSI (e.g.,
rank indicator (RI), precoding matrix indicator (PMI), and channel
quality indicators (CQIs)) for all or a part of the selected
secondary base station(s) 1204 and 1206 (in this case, it is
secondary base station 2 (1206)). In an embodiment, the CSI can be
measured based on the discovery signals 1210.
[0075] The primary base station 1202 schedules 1226 PDSCH
transmission of each selected secondary base station 1206 based on
the measurement reports and CSI reports from the UE 1208 (often
multiple UEs at once). The scheduling for each secondary base
station 1204 and 1206 may include decision on Tx power, target UE,
amount of resources (i.e., number of RBs), data rate (modulation
and coding scheme), rank, precoding matrix, etc. The secondary base
station 1204 and 1206 scheduling by the primary base station 1202
is referred to as cross-carrier scheduling.
[0076] When a particular subframe of an secondary base station 1206
is scheduled (i.e., the secondary base station 1206 transmits one
or more PDSCHs in the particular subframe), the secondary base
station 1206 transitions 1228 from an OFF state to an ON state
(i.e., the secondary base station 1206 is turned on) and transmits
a PDSCH(s) 1232. At the same subframe (or at a predefined time
instance), the primary base station 1202 transmits a PDCCH(s) 1230
to each target UE (such as the UE 1208) that conveys at least UE
identification, secondary base station identification (indicating
which secondary base station 1206 transmits the PDSCH 1232 and
other information needed for PDCSH decoding). Each PDCCH 1230
transmitted by the primary base station 1202 is associated with the
PDSCH 1232 transmitted by the secondary base station 1206. The
PDSCH 1232 transmitted by the secondary base station 1206 can be
preceded by an LBT (and/or a channel reservation).
[0077] After transmission of the PDSCH 1232 to the UE 1208, the UE
1208 can report the PDSCH 1232 transmission to the primary base
station 1202 through a hybrid automatic repeat request (HARD)
report 1234. If no more data is scheduled, then the secondary base
station 1206 can turn off 1236).
[0078] If the secondary base station 1204 is not scheduled, i.e.,
no PDSCH is transmitted, the secondary base station 1204 stays in
an OFF state (or transitions from an ON state to an OFF state). The
transition between ON/OFF states within the UCT secondary base
station 1204 can be on a subframe basis or on a group of subframes
basis.
[0079] A discovery signal can be one or a combination of various
signals in LTE (e.g., PSS, SSS, CRS, CSI-RS, etc.), which may
include modifications to these signals. The discovery signal
transmissions 1210 can be periodic or aperiodic. In case of being
aperiodic, the discovery signal transmission 1210 can be preceded
by an LBT scheme which may include the channel reservation for the
discovery signal transmission 1210. In another embodiment, the
discovery signals 1210 can be transmitted without sensing the
channel, i.e., they can be transmitted regardless of ongoing
transmissions of other RATs or LTE-U transmissions by other
operators. The UE 1208 can obtain at least coarse frequency/time
synchronization using the discovery signals 1210 (or subframes).
The UE 1208 can use the discovery signals 1210 to measure the
quality of UCT signals such as RSRP/RSRQ. The UE 1208 can also
measure interference power using the discovery signal 1210 (or
other schemes, e.g., total received power).
[0080] Principles of the above embodiment can also be applied to
support opportunistic networking of high frequency (e.g., mmWave)
communication with the following four operations.
[0081] (1) A UCT transmits discovery signals (or discovery
subframes or synchronization) on the mmWave spectrum. The discovery
signal transmissions can be periodic or aperiodic. In case of
aperiodic transmissions of discovery signals, a UE can obtain at
least coarse frequency/time synchronization using the discover
signals (or subframes). The UE can optionally use the discovery
signals to measure the quality of UCT signals such as RSRP/RSRQ.
The UE can also measure interference power using the discovery
signals (or other schemes such as total received power, etc.).
[0082] (2) A UE then reports measurements to the primary base
station (e.g., through a licensed band). The measurement report can
include RSRP/RSRQ and other interference conditions.
[0083] (3) The primary base station selects one or multiple
bands/channels to be used for PDSCH transmissions (e.g., based on
the measurement reports from one or multiple UEs or other
information related to the mmWave beam forming). If channel
conditions are favorable, one or more bands/channels can be
selected for opportunistic data transmission in the mmWave
spectrum.
[0084] (4) The primary base station turns on the secondary base
station and schedules PDSCH transmissions on the secondary base
station UCT to one or multiple UEs (e.g., via cross-carrier
scheduling). The scheduling may also be done in the secondary base
station (self-scheduling or non-cross-carrier scheduling). In one
embodiment, the scheduling is only done in the secondary base
station if the control channel or scheduling can be transmitted
reliably in the secondary base station.
[0085] While UEs, primary base stations, secondary base stations
and other systems have been discussed in the singular for ease of
understanding, it should be recognized that embodiments may include
multiples of these systems and operate in parallel fashion (such as
scheduling multiple UEs for transmission timing).
[0086] FIG. 13 is an example illustration of a mobile device, such
as a UE, a mobile station (MS), a mobile wireless device, a mobile
communication device, a tablet, a handset, or another type of
mobile wireless device. The mobile device can include one or more
antennas configured to communicate with a transmission station,
such as a base station (BS), an eNB, a base band unit (BBU), a
remote radio head (RRH), a remote radio equipment (RRE), a relay
station (RS), a radio equipment (RE), or another type of wireless
wide area network (WWAN) access point. The mobile device can be
configured to communicate using at least one wireless communication
standard including 3GPP LTE, WiMAX, HSPA, Bluetooth, and Wi-Fi. The
mobile device can communicate using separate antennas for each
wireless communication standard or shared antennas for multiple
wireless communication standards. The mobile device can communicate
in a WLAN, a wireless personal area network (WPAN), and/or a
WWAN.
[0087] FIG. 13 also provides an illustration of a microphone and
one or more speakers that can be used for audio input and output
from the mobile device. The display screen can be a liquid crystal
display (LCD) screen or other type of display screen, such as an
organic light emitting diode (OLED) display. The display screen can
be configured as a touch screen. The touch screen can use
capacitive, resistive, or another type of touch screen technology.
An application processor and a graphics processor can be coupled to
internal memory to provide processing and display capabilities. A
non-volatile memory port can also be used to provide data
input/output options to a user. The non-volatile memory port can
also be used to expand the memory capabilities of the mobile
device. A keyboard can be integrated with the mobile device or
wirelessly connected to the mobile device to provide additional
user input. A virtual keyboard can also be provided using the touch
screen.
[0088] Many of the systems described include computing resources
and systems. A computing system can be viewed as an information
passing bus that connects various components. A computing system
includes a processor having logic for processing instructions.
Instructions can be stored in and/or retrieved from memory and a
storage device that includes a computer-readable storage medium.
Instructions and/or data can arrive from a network interface that
can include wired or wireless capabilities. Instructions and/or
data can also come from an I/O interface that can include such
things as expansion cards, secondary buses (e.g., USB, etc.),
devices, etc. A user can interact with the computing system through
user interface devices and a rendering system that allows the
computer to receive and provide feedback to the user.
[0089] Embodiments and implementations of the systems and methods
described herein may include various operations, which may be
embodied in machine-executable instructions to be executed by a
computer system. A computer system may include one or more
general-purpose or special-purpose computers (or other electronic
devices). The computer system may include hardware components that
include specific logic for performing the operations or may include
a combination of hardware, software, and/or firmware.
[0090] Computer systems and the computers in a computer system may
be connected via a network. Suitable networks for configuration
and/or use as described herein include one or more local area
networks, wide area networks, metropolitan area networks, and/or
Internet or IP networks, such as the World Wide Web, a private
Internet, a secure Internet, a value-added network, a virtual
private network, an extranet, an intranet, or even stand-alone
machines which communicate with other machines by physical
transport of media. In particular, a suitable network may be formed
from parts or entireties of two or more other networks, including
networks using disparate hardware and network communication
technologies.
[0091] One suitable network includes a server and one or more
clients; other suitable networks may contain other combinations of
servers, clients, and/or peer-to-peer nodes, and a given computer
system may function both as a client and as a server. Each network
includes at least two computers or computer systems, such as the
server and/or clients. A computer system may include a workstation,
laptop computer, disconnectable mobile computer, server, mainframe,
cluster, so-called "network computer" or "thin client," tablet,
smart phone, personal digital assistant or other hand-held
computing device, "smart" consumer electronics device or appliance,
medical device, or a combination thereof.
[0092] Suitable networks may include communications or networking
software, such as the software available from Novell.RTM.,
Microsoft.RTM., and other vendors, and may operate using TCP/IP,
SPX, IPX, and other protocols over twisted pair, coaxial, or
optical fiber cables, telephone lines, radio waves, satellites,
microwave relays, modulated AC power lines, physical media
transfer, and/or other data transmission "wires" known to those of
skill in the art. The network may encompass smaller networks and/or
be connectable to other networks through a gateway or similar
mechanism.
[0093] Various techniques, or certain aspects or portions thereof,
may take the form of program code (i.e., instructions) embodied in
tangible media, such as floppy diskettes, CD-ROMs, hard drives,
magnetic or optical cards, solid-state memory devices, a
nontransitory computer-readable storage medium, or any other
machine-readable storage medium wherein, when the program code is
loaded into and executed by a machine, such as a computer, the
machine becomes an apparatus for practicing the various techniques.
In the case of program code execution on programmable computers,
the computing device may include a processor, a storage medium
readable by the processor (including volatile and nonvolatile
memory and/or storage elements), at least one input device, and at
least one output device. The volatile and nonvolatile memory and/or
storage elements may be a RAM, an EPROM, a flash drive, an optical
drive, a magnetic hard drive, or other medium for storing
electronic data. The eNB (or other base station) and UE (or other
mobile station) may also include a transceiver component, a counter
component, a processing component, and/or a clock component or
timer component. One or more programs that may implement or utilize
the various techniques described herein may use an application
programming interface (API), reusable controls, and the like. Such
programs may be implemented in a high-level procedural or an
object-oriented programming language to communicate with a computer
system. However, the program(s) may be implemented in assembly or
machine language, if desired. In any case, the language may be a
compiled or interpreted language, and combined with hardware
implementations.
[0094] Each computer system includes one or more processors and/or
memory; computer systems may also include various input devices
and/or output devices. The processor may include a general purpose
device, such as an Intel.RTM., AMD.RTM., or other "off-the-shelf"
microprocessor. The processor may include a special purpose
processing device, such as ASIC, SoC, SiP, FPGA, PAL, PLA, FPLA,
PLD, or other customized or programmable device. The memory may
include static RAM, dynamic RAM, flash memory, one or more
flip-flops, ROM, CD-ROM, DVD, disk, tape, or magnetic, optical, or
other computer storage medium. The input device(s) may include a
keyboard, mouse, touch screen, light pen, tablet, microphone,
sensor, or other hardware with accompanying firmware and/or
software. The output device(s) may include a monitor or other
display, printer, speech or text synthesizer, switch, signal line,
or other hardware with accompanying firmware and/or software.
[0095] It should be understood that many of the functional units
described in this specification may be implemented as one or more
components, which is a term used to more particularly emphasize
their implementation independence. For example, a component may be
implemented as a hardware circuit comprising custom very large
scale integration (VLSI) circuits or gate arrays, or off-the-shelf
semiconductors such as logic chips, transistors, or other discrete
components. A component may also be implemented in programmable
hardware devices such as field programmable gate arrays,
programmable array logic, programmable logic devices, or the
like.
[0096] Components may also be implemented in software for execution
by various types of processors. An identified component of
executable code may, for instance, comprise one or more physical or
logical blocks of computer instructions, which may, for instance,
be organized as an object, a procedure, or a function.
Nevertheless, the executables of an identified component need not
be physically located together, but may comprise disparate
instructions stored in different locations that, when joined
logically together, comprise the component and achieve the stated
purpose for the component.
[0097] Indeed, a component of executable code may be a single
instruction, or many instructions, and may even be distributed over
several different code segments, among different programs, and
across several memory devices. Similarly, operational data may be
identified and illustrated herein within components, and may be
embodied in any suitable form and organized within any suitable
type of data structure. The operational data may be collected as a
single data set, or may be distributed over different locations
including over different storage devices, and may exist, at least
partially, merely as electronic signals on a system or network. The
components may be passive or active, including agents operable to
perform desired functions.
[0098] Several aspects of the embodiments described will be
illustrated as software modules or components. As used herein, a
software module or component may include any type of computer
instruction or computer-executable code located within a memory
device. A software module may, for instance, include one or more
physical or logical blocks of computer instructions, which may be
organized as a routine, program, object, component, data structure,
etc., that perform one or more tasks or implement particular data
types. It is appreciated that a software module may be implemented
in hardware and/or firmware instead of or in addition to software.
One or more of the functional modules described herein may be
separated into sub-modules and/or combined into a single or smaller
number of modules.
[0099] In certain embodiments, a particular software module may
include disparate instructions stored in different locations of a
memory device, different memory devices, or different computers,
which together implement the described functionality of the module.
Indeed, a module may include a single instruction or many
instructions, and may be distributed over several different code
segments, among different programs, and across several memory
devices. Some embodiments may be practiced in a distributed
computing environment where tasks are performed by a remote
processing device linked through a communications network. In a
distributed computing environment, software modules may be located
in local and/or remote memory storage devices. In addition, data
being tied or rendered together in a database record may be
resident in the same memory device, or across several memory
devices, and may be linked together in fields of a record in a
database across a network.
[0100] Reference throughout this specification to "an example"
means that a particular feature, structure, or characteristic
described in connection with the example is included in at least
one embodiment of the present invention. Thus, appearances of the
phrase "in an example" in various places throughout this
specification are not necessarily all referring to the same
embodiment.
[0101] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials may be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on its presentation
in a common group without indications to the contrary. In addition,
various embodiments and examples of the present invention may be
referred to herein along with alternatives for the various
components thereof. It is understood that such embodiments,
examples, and alternatives are not to be construed as de facto
equivalents of one another, but are to be considered as separate
and autonomous representations of the present invention.
[0102] Furthermore, the described features, structures, or
characteristics may be combined in any suitable manner in one or
more embodiments. In the following description, numerous specific
details are provided, such as examples of materials, frequencies,
sizes, lengths, widths, shapes, etc., to provide a thorough
understanding of embodiments of the invention. One skilled in the
relevant art will recognize, however, that the invention may be
practiced without one or more of the specific details, or with
other methods, components, materials, etc. In other instances,
well-known structures, materials, or operations are not shown or
described in detail to avoid obscuring aspects of the
invention.
[0103] Although the foregoing has been described in some detail for
purposes of clarity, it will be apparent that certain changes and
modifications may be made without departing from the principles
thereof. It should be noted that there are many alternative ways of
implementing both the processes and apparatuses described herein.
Accordingly, the present embodiments are to be considered
illustrative and not restrictive, and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalents of the appended claims.
[0104] Those having skill in the art will appreciate that many
changes may be made to the details of the above-described
embodiments without departing from the underlying principles of the
invention. The scope of the present invention should, therefore, be
determined only by the following claims.
EXAMPLES
[0105] The following examples pertain to further embodiments.
[0106] Example 1 is a primary base station for cross-carrier
scheduling that is configured to select a secondary base station
for cross-carrier scheduling for communication with a mobile device
over a set of frequencies shared with another radio access
technology (RAT). The primary base station is further configured to
send a request for cross-carrier scheduling to the secondary base
station. The primary base station is also configured to provide the
secondary base station with a schedule for transmitting data to a
mobile device. The primary base station is further configured to
cause the secondary base station to transmit the data in a portion
of a second frame that aligns with a first frame of the primary
base station.
[0107] In Example 2, the primary base station of Example 1 can
optionally be configured to receive a transmission quality report
from user equipment (UE) that describes transmission quality
measurements between the UE and the secondary base station.
[0108] In Example 3, the primary base station of Examples 1-2 can
optionally be configured to receive a transmission quality report
from the secondary base station that describes transmission quality
measurements between the secondary base station and a user
equipment (UE).
[0109] In Example 4, the primary base stations in Example 1-3 can
optionally be configured to receive a report indicating receipt of
the data by a user equipment (UE) from the secondary base
station.
[0110] In Example 5, the report of Example 4 can optionally be a
hybrid automatic repeat request (HARQ) message.
[0111] Example 6 is an enhanced node B (eNB) for cross-carrier
transmission comprising a first network interface, a second network
interface and a processor. The first network interface is
configured for communicating with a user equipment (UE) over a
first set of wireless spectrum. The second network interface
configured for communicating with network infrastructure that
includes an unconventional carrier type (UCT). The processor is
configured to receive a report from the UE including a measurement
of a UCT discovery signal sent from the UCT over a second set of
wireless spectrum. The processor is further configured to select
the UCT for transmission of data to the UE and schedule
transmission of the data over the UCT.
[0112] In Example 7, the UCT of Example 6 can optionally provide
the physical downlink control channel (PDCCH) to the UE.
[0113] In Example 8, the eNB of Example 6 can optionally provide
the physical downlink control channel (PDCCH) to the UE.
[0114] In Example 9, the eNB of Examples 6-8 can optionally include
receiving the report from the UE including the measurement of a
periodic UCT discovery signal from the UCT.
[0115] In Example 10, the UE of Examples 6-8 can optionally be
configured to receive the report from the UE including the
measurement of an aperiodic UCT discovery signal from the UCT.
[0116] Example 11 is a method of transmitting data comprising
providing a primary medium of communication with a user equipment
(UE) using a first band of frequencies. The method can further
include receiving a report describing transmission quality of a
secondary base station with the UE over a secondary medium using a
second band of frequencies shared with at least one radio access
technology (RAT). The method can also further include selecting the
secondary base station for use in cross-carrier transmission with
the UE. The method can also include reserving the secondary medium
for communication with the UE. The method can further include
scheduling a set of data for transmission over the secondary medium
by the secondary base station to the UE. The method can include
causing at least a subset of the set of data to be transmitted over
the secondary medium using a third generation partnership project
(3GPP) compatible protocol.
[0117] In Example 12, the method of Example 11 can optionally
include performing a listen before talk protocol.
[0118] In Example 13, the method of Examples 11-12 can optionally
use an unlicensed set of frequencies as the secondary medium.
[0119] In Example 14, the method of Examples 11-12 can optionally
use an unlicensed set of frequencies as the secondary medium.
[0120] In Example 15, the method of Example 14 can optionally
include transmitting a control channel scheduling the set of data
over the primary medium.
[0121] In Example 16, the method of Examples 11 can optionally
include performing a listen before talk protocol; transmitting a
control channel scheduling the set of data over the primary medium;
transmitting a channel reservation signal over the secondary medium
to reserve the secondary medium; transmitting the subset of the set
of data asynchronously over the secondary medium as compared with
the primary medium; aligning subframes of the secondary medium with
subframes of the primary medium; using an unlicensed set of
frequencies as the secondary medium; or using a licensed set of
frequencies as the secondary medium.
[0122] In Example 17, the method of Example 11 can optionally
include aligning subframes of the secondary medium with subframes
of the primary medium.
[0123] In Example 18, the method of Example 17 can optionally
transmitting a channel reservation signal over the secondary medium
to reserve the secondary medium.
[0124] In Example 19, the method of Example 18 further includes
forming an alignment gap between the channel reservation signal
sent over the secondary medium and an aligned subframe of the
secondary medium.
[0125] In Example 20, the method of Example 19 can optionally
include transmitting at least a portion of a wireless local area
network (WLAN) preamble during at least a portion of the alignment
gap.
[0126] In Example 21, the method of Example 19 can optionally
include transmitting at least a noise signal during at least a
portion of the alignment gap.
[0127] In Example 22, the method of Examples 19 is optionally
transmitting at least a portion of a discovery signal during at
least a portion of the alignment gap.
[0128] In Example 23, the method of Examples 19 can optionally
determining that a duration of the alignment gap is less than a
threshold amount and refraining from transmission during the
alignment gap.
[0129] In Example 24, the method of Example 19 can optionally
include one or more of transmitting at least a portion of a
wireless local area network (WLAN) preamble during at least a
portion of the alignment gap; transmitting at least a noise signal
during at least a portion of the alignment gap; transmitting at
least a portion of a discovery signal during at least a portion of
the alignment gap; or determining that a duration of the alignment
gap is less than a threshold amount and refraining from
transmission during the alignment gap.
[0130] In Example 25, the method of Example 17 can include forming
a super subframe that includes an alignment gap.
[0131] In Example 26, the method of Example 17 can optionally
include forming a reduced length subframe for transmission over the
secondary medium.
[0132] In Example 27, the method of Example 11 can optionally
transmitting the subset of the set of data asynchronously over the
secondary medium as compared with the primary medium.
[0133] Example 28 is an comprising means to perform a method as
described in any of claims 11-27.
[0134] Example 29 is machine readable storage including
machine-readable instructions that when executed implement a method
or realize an apparatus as claimed in any of claims 11-27.
* * * * *