U.S. patent application number 13/570260 was filed with the patent office on 2013-02-14 for method for data transmission and base station and user equipment using the same.
This patent application is currently assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. The applicant listed for this patent is Chun-Yen Wang. Invention is credited to Chun-Yen Wang.
Application Number | 20130039297 13/570260 |
Document ID | / |
Family ID | 47677510 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130039297 |
Kind Code |
A1 |
Wang; Chun-Yen |
February 14, 2013 |
METHOD FOR DATA TRANSMISSION AND BASE STATION AND USER EQUIPMENT
USING THE SAME
Abstract
A method for data transmission, a base station using the same
and a user equipment (UE) using the same are proposed. The present
disclosure configures at a base station at least two user
equipments into a UE group for aggregate transmission by sending a
control message from the base station to the at least two user
equipments. Next, the base station transmits aggregated data to the
UE group containing a aggregated PDU format containing a unique
group identifier. Next, the base station receives a response signal
from the UE group based on whether the first transmission is
received or not. The base station re-transmits the aggregated data
to the UE group if the first transmission is not received. After
all the aggregate transmission is complete, the base station
de-configures the UE group from the aggregate transmission.
Inventors: |
Wang; Chun-Yen; (Tainan
City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wang; Chun-Yen |
Tainan City |
|
TW |
|
|
Assignee: |
INDUSTRIAL TECHNOLOGY RESEARCH
INSTITUTE
Hsinchu
TW
|
Family ID: |
47677510 |
Appl. No.: |
13/570260 |
Filed: |
August 9, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61522050 |
Aug 10, 2011 |
|
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|
Current U.S.
Class: |
370/329 ;
370/328 |
Current CPC
Class: |
H04W 76/25 20180201;
H04W 72/042 20130101 |
Class at
Publication: |
370/329 ;
370/328 |
International
Class: |
H04W 4/00 20090101
H04W004/00; H04W 72/04 20090101 H04W072/04 |
Claims
1. A method of transmitting data, adapted for a base station, the
method comprising: configuring an aggregate transmission;
transmitting a control signal to establish the aggregate
transmission; and transmitting aggregate data after the aggregate
transmission is established, wherein the aggregate data comprises
data for the aggregate transmission.
2. The method of claim 1, wherein the step of transmitting
aggregate data comprises: transmitting the aggregate data
comprising an aggregate header to be followed by payloads for the
aggregate transmission.
3. The method of claim 1 further comprising: receiving a response
signal; and re-transmitting the aggregate data according to the
response signal.
4. The method of claim 1, further comprising: de-configuring the
aggregate transmission by sending another control message to an
individual to de-configure the individual from the aggregate
transmission.
5. The method of claim 1, further comprising: starting a timer; and
de-configuring the aggregate transmission when the timer
expires.
6. The method of claim 3, wherein the response is either an
aggregate response or a dedicated response for an individual of the
aggregate transmission.
7. The method of claim 1, wherein the control signal comprising a
group identity information, location information for each division
of the aggregate data, and an indicator to establish or
de-configure the aggregate transmission.
8. The method of claim 2, wherein the aggregate header comprises:
an aggregate transmission indicator; sizes of the payloads; and a
bitmap comprising indicating bits.
9. The method of claim 3, wherein the step of transmitting
aggregate data comprises: transmitting the aggregate data
comprising an aggregate control signal which indicates the location
of resource allocation used for the transmission; and
re-transmitting to the aggregate data comprising another aggregate
control signal which indicates the location of resource allocation
used for the re-transmission.
10. The method of claim 3, wherein the step of transmitting
aggregate data comprises: transmitting the aggregate data
comprising an aggregate control signal which indicates the location
of resource allocation used for the transmission; and
re-transmitting the aggregate data without a control signal
overhead indicating the location of resource allocation used for
the re-transmission.
11. The method of claim 3, wherein the step of transmitting
aggregate data comprises: transmitting the aggregate data without a
control signal overhead indicating the location of resource
allocation used for the transmission; and re-transmitting the
aggregate data comprising an aggregate control signal which
indicates the location of resource allocation used for the
re-transmission.
12. The method of claim 3, wherein the step of transmitting
aggregate data comprises: transmitting the aggregate data without a
control signal overhead indicating the location of resource
allocation used for the transmission; and re-transmitting the
aggregate data without a control signal overhead indicating the
location of resource allocation used for the re-transmission.
13. A method of transmitting data, adapted for a user equipment
(UE), the method comprising: receiving a control signal; being
configured into an aggregate transmission according to the control
signal; and receiving aggregate data after being configured for
aggregate transmission, wherein the aggregate data comprises data
for the user equipment and data not for the user equipment.
14. The method of claim 13, wherein the step of receiving aggregate
data after being configured for aggregate transmission comprises:
receiving the aggregate data comprising an aggregate header to be
followed by payloads for the aggregate transmission and optionally
a group identifier.
15. The method of transmitting data of claim 13 further comprising:
transmitting a response signal; and receiving re-transmitted
aggregate data after sending the response signal.
16. The method of claim 13 further comprising: de-configuring from
the aggregate transmission by receiving another control
message.
17. The method of claim 13 further comprising: starting a timer;
and de-configuring from the aggregate transmission when the timer
expires.
18. The method of claim 15, wherein the response is either an
aggregate response or an individual response.
19. The method of claim 13, wherein the control signal comprising a
group identity information, location information for each division
of the aggregate data, and an indicator to configure into or to
de-configure from the aggregate transmission.
20. The method of claim 14, wherein the aggregate header comprises:
an aggregate transmission indicator; sizes of the payloads; and a
bitmap comprising indicating bits.
21. The method of claim 15, wherein the step of receiving aggregate
data comprises: receiving the aggregate data comprising an
aggregate control signal which indicates the location of resource
allocation used for the transmission; and receiving the
re-transmitted aggregate data comprising another aggregate control
signal which indicates the location of resource allocation used for
the re-transmission.
22. The method of claim 15, wherein the step of receiving aggregate
data comprises: receiving the aggregate data comprising an
aggregate control signal which indicates the location of resource
allocation used for the transmission; and receiving the
re-transmitted aggregate data without a control signal overhead
indicating the location of resource allocation used for the
re-transmission.
23. The method of claim 15, wherein the step of receiving aggregate
data comprises: receiving the aggregate data without a control
signal overhead indicating the location of resource allocation used
for the transmission; and receiving the re-transmitted aggregate
data comprising an aggregate control signal which indicates the
location of resource allocation used for the re-transmission.
24. The method of claim 15, wherein the step of receiving aggregate
data comprises: receiving the aggregate data without a control
signal overhead indicating the location of resource allocation used
for the transmission; and receiving the re-transmitted aggregate
data without a control signal overhead indicating the location of
resource allocation used for the re-transmission.
25. The method of claim 2, wherein the aggregate data further
comprising a group identifier.
26. A base station, comprising: a transceiver, configured to
transmit and receive wireless signals; and a processor, connected
to the transceiver, configured for: configuring an aggregate
transmission; transmitting a control signal to establish the
aggregate transmission; and transmitting aggregate data after the
aggregate transmission is established, wherein the aggregate data
comprises data for the aggregate transmission.
27. The base station of claim 26, wherein the processor is
configured for transmitting the aggregate data comprises:
transmitting the aggregate data comprising an aggregate header to
be followed by payloads for the aggregate transmission.
28. The base station of claim 26 wherein the processor is further
configured for: receiving a response signal; and re-transmitting
the aggregate data according to the response signal.
29. The base station of claim 26 further comprising: de-configuring
an individual from the aggregate transmission by sending another
control message to the individual to de-configure the individual
from the aggregate transmission.
30. The base station of claim 26 further comprising: starting a
timer; and de-configuring the aggregate transmission when the timer
expires.
31. The base station of claim 28, wherein the response is either an
aggregate response or a dedicated response for an individual of the
aggregate transmission.
32. The base station of claim 26, wherein the control signal
comprising a group identity information, location information for
each division of the aggregate data, and an indicator to setup or
release the aggregate transmission.
33. The base station of claim 27, wherein the aggregate header
comprises: an aggregate transmission indicator; sizes of the
payloads; and a bitmap comprising indicating bits.
34. The base station of claim 28, wherein the processor is
configured for transmitting the aggregate data comprises:
transmitting the aggregate data comprising an aggregate control
signal which indicates the location of resource allocation used for
the transmission; and re-transmitting the aggregate data comprising
another aggregate control signal which indicates the location of
resource allocation used for the re-transmission.
35. The base station of claim 28, wherein the processor is
configured for transmitting the aggregate data comprises:
transmitting the aggregate data comprising an aggregate control
signal which indicates the location of resource allocation used for
the transmission; and re-transmitting the aggregate data without a
control signal overhead indicating the location of resource
allocation used for the re-transmission.
36. The base station of claim 28, wherein the processor is
configured for transmitting the aggregate data comprises:
transmitting the aggregate data without a control signal overhead
indicating the location of resource allocation used for the
transmission; and re-transmitting the aggregate data comprising an
aggregate control signal which indicates the location of resource
allocation used for the re-transmission.
37. The base station of claim 28, wherein the processor is
configured for transmitting the aggregate data comprises:
transmitting the aggregate data without a control signal overhead
indicating the location of resource allocation used for the
transmission; and re-transmitting the aggregate data without a
control signal overhead indicating the location of resource
allocation used for the re-transmission.
38. The base station of claim 27, wherein the aggregate data
further comprising a group identifier.
39. A user equipment (UE) comprising: a transceiver, configured to
transmit and receive wireless signals; and a processor, connected
to the transceiver, configured for: receiving a control signal;
being configured into an aggregate transmission according to the
control signal; and receiving aggregate data after being configured
for aggregate transmission, wherein the aggregate data comprises
data for the user equipment and data not for the user
equipment.
40. The UE of claim 39, wherein the processor is configured for
receiving the aggregate data comprises: receiving the aggregate
data comprising an aggregate header to be followed by payloads for
the aggregate transmission.
41. The UE of claim 39 wherein the processor is further configured
for: transmitting a response signal; and receiving re-transmitted
aggregate data after sending the response signal.
42. The UE of claim 39 further comprising: de-configuring from the
aggregate transmission by receiving another control message.
43. The UE of claim 39 further comprising: starting a timer; and
de-configuring from the aggregate transmission when the timer
expires.
44. The UE of claim 41, wherein the response is either an aggregate
response or an individual response.
45. The UE of claim 39, wherein the control signal comprising a
group identity information, location information for each division
of the aggregate data, and an indicator to configure into or to
de-configure from the aggregate transmission.
46. The UE of claim 40, wherein the aggregate header comprises: an
aggregate transmission indicator; sizes of the payloads; and a
bitmap comprising indicating bits.
47. The UE of claim 41, wherein the processor is configured for
receiving the aggregate data comprises: receiving the aggregate
data comprising an aggregate control signal which indicates the
location of resource allocation used for the transmission; and
receiving the re-transmitted aggregate data comprising another
aggregate control signal which indicates the location of resource
allocation used for the re-transmission.
48. The UE of claim 41, wherein the processor is configured for
receiving the aggregate data comprises: receiving the aggregate
data comprising an aggregate control signal which indicates the
location of resource allocation used for the transmission; and
receiving the re-transmitted aggregate data without a control
signal overhead indicating the location of resource allocation used
for the re-transmission.
49. The UE of claim 41, wherein the processor is configured for
receiving the aggregate data comprises: receiving the aggregate
data without a control signal overhead indicating the location of
resource allocation used for the transmission; and receiving the
re-transmitted aggregate data comprising an aggregate control
signal which indicates the location of resource allocation used for
the re-transmission.
50. The UE of claim 41, wherein the processor is configured for
receiving the aggregate data comprises: receiving the aggregate
data without a control signal overhead indicating the location of
resource allocation used for the transmission; and receiving the
re-transmitted aggregate data without a control signal overhead
indicating the location of resource allocation used for the
re-transmission.
51. The UE of claim 40, wherein the aggregate data further
comprising a group identifier.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefits of U.S.
provisional application Ser. No. 61/522,050, filed on Aug. 10,
2011. The entirety of the above-mentioned patent applications is
hereby incorporated by reference herein and made a part of this
specification.
TECHNICAL FIELD
[0002] The present disclosure generally relates to a method for
data transmission, a base station using the same and a user
equipment (UE) using the same.
BACKGROUND
[0003] In current wireless broadband standards such as Third
Generation Partnership Project Long Term Evolution (3GPP LTE), the
control channel capacity usually is highly limited. Specifically,
there may be about 10 Physical Downlink Control Channel (PDCCH)
signaling which can be sent in one Transmission Time Interval (TTI)
in a 10 MHz system bandwidth scenario, in which about at most 10
User Equipments (UEs) can be scheduled for either Downlink (DL) or
Uplink (UL) data transmission. While dedicated UEs need to follow
scheduling information carried by PDCCH, in fact a large proportion
of Control Channel Elements (CCEs) has to be used for
non-dedicated/common functions. For instance, about a total of 41
CCEs is available when 3 OFDM symbols are allocated for PDCCH, but
out of the 41 available CCEs, up to 16 Control Channel Elements
(CCEs) are commonly allocated for Common Search Space (CSS)
including control functionalities such as System Information (SI),
Paging, Random Access (RA), Transmission Power Control (TPC), and
so like. This leaves only about 25 CCEs available for dedicated UE
scheduling. For another example, in a scenario where 2 OFDM symbols
are allocated for PDCCH, only about 10 CCEs out of a total of 25
CCEs are available for dedicated UE scheduling.
[0004] Moreover, the channel capacity is further limited under the
circumstance of Carrier Aggregation (CA). In Carrier Aggregation
(CA), cross-carrier scheduling may be used to schedule resources on
another serving cell and therefore reduce inter-cell interference
in Heterogeneous Networks. In addition, cross carrier scheduling
may be used to schedule resources on non-backward compatible
carriers. For instance, when a wireless communication system is
operating with extension carriers, during a sub-frame in which the
allocated frequency band for a first carrier (CC1) may contain data
in the Physical Downlink Shared Channel (PDSCH) and a close by
frequency band of a second carrier (CC2) may contain data in its
PDSCH, the control region of a first carrier (CC1) may actually
contain PDCCH for both CC1 and CC2 while no PDCCH would exist in
the control region of CC2 in order to avoid interference to control
region of other cells. For another example of non-backward
compatible carriers, the control region for the single carrier may
contain control signaling for both backward and non-backward
compatible PDSCH regions, while the control region for a
neighboring PDSCH is suppressed in order to avoid interference to
control regions of other cells. This means that using carrier
aggregation would further limit control channel capacity.
[0005] In a practical scenario, for example, the applications of
instant communications (e.g. messages services and social networks)
have long packet inter-arrival time while intermittent transmission
of small amounts of data is used. In additional, the time of
arrivals between packets may be large. If a scheme of periodic
resource allocation is adopted, it would result in a waste of
resource allocation if the scheduled period were short but would
otherwise adversely affect interactivity if the period were long.
For real time services such as gaming, video surveillance, remote
control, and so like, tight delay and frequency transmissions of
small amounts of data having variable sizes and arrival intervals
may occur. Also for machine type of communication in general, such
as machine-to-machine traffic, a large amount of small data traffic
with variable sizes is required. Therefore, all that has been
described necessitate a need for a mechanism to reduce the control
signal (e.g. PDCCH) overhead.
[0006] Semi-Persistent Scheduling (SPS) could be used to reduce the
control signal overhead. For services involving a semi-static
packet rate such as VoIP, SPS can be configured to reduce the
control signal overhead. For this kind of service to be
implemented, the timing and the amount of radio resources require
predictability. The SPS enables radio resources to be
semi-statically configured and allocated to a UE for a longer time
period than one sub-frame, and the SPS may avoid the need for
transmitting specific downlink assignment messages or uplink grant
messages over the PDCCH for each sub-frame. However, the SPS may
not be suitable for other Internet applications such as social
network applications since information on the social network
website could not be easily predicted.
SUMMARY
[0007] Accordingly, the present disclosure is directed to a method
for data transmission, a base station using the same and a user
equipment (UE) using the same.
[0008] The present disclosure directs to a method which configures
at a base station at least one user equipments into a UE group for
aggregate transmission by configuring an aggregate transmission,
transmitting a control signal to establish the aggregate
transmission; and transmitting aggregate data after the aggregated
transmission is established, wherein the aggregate data comprises
data for the aggregate transmission.
[0009] The present disclosure directs to a base station which
comprises a transceiver to transmit and receives wireless signal
and a processor which configures at a base station at least one
user equipments into a UE group for aggregate transmission by
configuring an aggregate transmission, transmitting a control
signal to establish the aggregate transmission; and transmitting
aggregate data after the aggregated transmission is established,
wherein the aggregate data comprises data for the aggregate
transmission.
[0010] The present disclosure directs to a method of transmitting
data adapted for an user equipment, the method contains the steps
of receiving a control signal, being configured into an aggregate
transmission according to the control signal, and receiving
aggregate data after being configured for aggregate transmission,
wherein the aggregate data comprises data for the user equipment
and data not for the user equipment.
[0011] The present disclosure directs to an user equipment which
comprises a transceiver to transmit and receive wireless signals
and a processor which transmits and receives wireless information
by receiving a control signal, being configured into an aggregate
transmission according to the control signal, and receiving
aggregate data after being configured for aggregate transmission,
wherein the aggregate data comprises data for the user equipment
and data not for the user equipment.
[0012] The accompanying drawings are included to provide a further
understanding of the disclosure and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the disclosure and, together with the description,
serve to explain the principles of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates a wireless communication system including
an eNB communicating with at least one UEs in accordance with an
exemplary embodiment.
[0014] FIG. 2 is a flowchart illustrating a method of aggregating
small data traffic for a plurality of UEs in a MAC PDU in
accordance with an exemplary embodiment.
[0015] FIG. 3 illustrates a sequential flow of communication
information between an eBN and a UE in accordance with an exemplary
embodiment.
[0016] FIG. 4 illustrates a content of a RRC message which contains
indicators in accordance with an exemplary embodiment.
[0017] FIG. 5A is a schematic diagram illustrating an UE acquiring
its resource allocation assignment through extracting information
in a control region by using a group identifier according to an
exemplary embodiment.
[0018] FIG. 5B illustrates the UA MAC PDU format configured to send
aggregated UE data in accordance with an exemplary embodiment.
[0019] FIG. 6 illustrates a MAC PDU format of the MAC Payload for a
single UE within the UA MAC PDU in accordance with an exemplary
embodiment.
[0020] FIG. 7 illustrates transmission of user aggregated data
according to the first embodiment of the present disclosure.
[0021] FIG. 8 illustrates transmission of user aggregated data
according to the second embodiment of the present disclosure.
[0022] FIG. 9 illustrates transmission of user aggregated data
according to the third embodiment of the present disclosure.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0023] In this disclosure, we use 3GPP-like keywords or phrases are
used merely as examples to present inventive concepts in accordance
with the present disclosure; however, the same concept presented in
the disclosure can be applied to any other systems such as IEEE
802.11, IEEE 802.16, WiMAX, and so like by persons of ordinarily
skilled in the art.
[0024] Throughout the disclosure, the term PDCCH is used to
represent the a control region or a downlink control channel to
indicate downlink (DL)/uplink (UL) resource allocation assignment,
the same concept by the present disclosure can also be applied to
other downlink control channels including DL-MAP, UL-MAP, MBS-MAP,
and so like through simple analogy.
[0025] The term "eNodeB" in this disclosure may be, for example, a
base station (BS), a Node-B, an advanced base station (ABS), a base
transceiver system (BTS), an access point, a home base station, a
relay station, a scatterer, a repeater, an intermediate node, an
intermediary, and/or satellite-based communication base stations,
and so like.
[0026] The term "user equipment" (UE) in this disclosure may be,
for example, a mobile station, an advanced mobile station (AMS), a
server, a client, a desktop computer, a laptop computer, a network
computer, a workstation, a personal digital assistant (PDA), a
tablet personal computer (PC), a scanner, a telephone device, a
pager, a camera, a television, a hand-held video game device, a
musical device, a wireless sensor, and so like. In some
applications, a UE may be a fixed computer device operating in a
mobile environment, such as a bus, train, an airplane, a boat, a
car, and so like.
[0027] Presently, with the applications using small data packets
with diverse data sizes are on the rise, the control region in a
sub-frame carrying control information may require more and more
space in order to accommodate the increase of the control signaling
space. However, since the PDCCH capacity in the control region is
highly limited, there is a need to either reduce the PDCCH overhead
or to increase the control region. In this present disclosure, a
method for data transmission and a base station and a user
equipment using the same method are proposed to enhance the data
transmission by aggregating data traffic for a plurality of
UEs.
[0028] FIG. 1 illustrates a wireless communication system according
to an exemplary embodiment. The wireless communication system
includes an eNodeB (101) in communication with at least one UEs
(103, 105, . . . 10x) in accordance with a wireless communication
standard. Each UE may contain, for example, at least a transceiver
circuit (111), an analog to digital/digital to analog converter
(113), and a processing circuitry (115) or processor. The
transceiver circuitry (111) is capable of transmitting uplink
signal and/or receives downlink signal wirelessly. The transceiver
circuitry (111) may also perform operations such as low noise
amplifying, impedance matching, frequency mixing, up or down
frequency conversion, filtering, amplifying, and so like. The
transceiver circuitry (111) may also include an antenna unit (not
shown in FIG. 1). The analog-to-digital (A/D)/digital-to-analog
(D/C) converter (113) is configured to convert from analog signal
format to digital signal format during downlink signal processing
and digital signal to analog signal during uplink signal
processing. The processing circuitry (115) is configured to process
digital signal and to perform procedures of the proposed method for
data transmission in accordance with exemplary embodiments of the
present disclosure. Also, the processing circuitry (115) may
include a memory unit (not shown in FIG. 1) to store data or record
configurations assigned by the eNB 101. The eNB 101 contains
similar elements which lead to the converted digital signal to be
processed by its processing circuitry (117) or processor so as to
implement the method for data transmission in accordance with
exemplary embodiments of the present disclosure.
[0029] A method for data transmission is proposed to enhance data
transmission for a wireless communication system. According to some
embodiments of the disclosure, the concept of the method for data
transmission is to aggregate small packet data traffic for
different UEs in a UA (user aggregated) Medium Access Control
Protocol Data Unit (MAC PDU) so that the small packet data traffic
can be transmitted to UEs with less PDCCH signaling, thereby
reducing the control signaling overhead even when the number of
users (or UEs) served by a base station is huge. Conventionally, a
Downlink Control Information (DCI) or a single PDCCH is assigned to
each individual UE. However, this present disclosure proposes a
method to transmit a group of UE signaling under the same PDCCH so
as to reduce the overall control signal overhead during data
transmission. Also in some circumstances, this present disclosure
presents another method to omit the transmission of PDCCH entirely
for the temporarily/dynamically configured group of UEs. Here the
temporarily/dynamically configured group of UEs may be called a
user aggregation (UA) group. Additionally, an eNB may assign one UE
to more than one UA group(s) depending upon practical operation
requirements.
[0030] FIG. 2 is a flow chart of a method for data transmission in
accordance with an exemplary embodiment of the present disclosure.
FIG. 3 illustrates a sequential flow of delivering communication
information between an eNB (303) and a UE group (301) in accordance
with an exemplary embodiment of the present disclosure. From an
perspective, FIG. 3 may be seen the same as FIG. 2 except that FIG.
3 shows the relationship between an eNB (303) and a UE group (301).
Referring to FIGS. 1, 2, and 3 together, in step S201 some
individual UEs (103, 105, . . . 10x) are configured or
re-configured by an eNB (101 or 303) into at least one UE group
(301) for aggregate transmission so that all UEs (301) belong to
the same group may receive together as a group using the same
PDCCH.
[0031] In step S203, after one or more UE groups are aggregated,
the eNB (303) may send an aggregated data to a UE group (301).
Here, the aggregated data may include data and/or control signaling
of UL/DL resource allocation assignment to at least one UE in the
UE group or to the UE group. Next, in step S205, the UE (301) group
optionally send a response signal in the form of ACK/NACK
feedback(s) back to the eNB (303) which acknowledges whether the
transmission was received or not. Next in step S207, depending on
the response of ACK/NACK, a re-transmission (S309) of the
aggregated data from the eNB (S207) might be required. Afterwards,
in step S209, a determination as to whether the process will
continue may be made by the eNB (303). If the eNB (303) determines
that the process continues, then the step S203 to the step S207
will be repeated. Otherwise, step S211 is performed to possibly
de-configure the aggregate transmission. Here, the de-configuration
of the aggregate transmission may include de-configure at least one
UE from the previously assigned group of UEs (the UE group or the
UA group). In FIG. 3, the steps S303, S305 and S307 are
respectively similar to the steps S203, S205 and S207 in FIG. 2.
Each of the steps of FIG. 2 will be illustrated in more details as
follow.
[0032] In the step S201, the wireless network (e.g. through the eNB
(303)) may send a RRC message such as a
RRCconnectionReconfiguration message to aggregate multiple UEs
together so as to achieve configuring or re-configuring UEs for
subsequent aggregate transmission. In some embodiments, not all of
UEs support the function of the aggregate transmission. Hence, UEs
may provide its UE capability information to inform the network
whether or not it can support the aggregate transmission, and the
network may send the RRC message to configure UEs with the
capability of the aggregate transmission into a UA group for the
subsequent aggregate transmission. Here, the aggregated
transmission is configured to deliver data and/or control signaling
of UL/DL resource allocation assignment to at least one UE in the
UE group or to the UE group(s). However, an eNB (303) may determine
how to aggregate multiple UEs into a UE group (301). The user
aggregation may be based on similar channel condition such as a
possible criteria for the grouping of UEs. One of these following
channel conditions may be used as the criteria: CQI, CSI, PMI, RI,
PTI, bit error rate (BER), RSRP, RSRQ, and so forth. For example,
the eNB may read the CQI reports from UEs so that UEs with similar
CQI values or similar BER values can be assigned as a UE group,
since the eNB can use the same Modulation Coding Scheme (MCS) for
all these UEs. For example, currently, the CQI of an individual UE
is represented by 4 bits which can be translated into a resolution
of 16 possible levels. If supposedly two UEs have an identical CQI
level, then the two UEs may be considered to be similar. Then, the
eNB may group these two UEs into an identical UA group. For another
example, the eNB may obtain RI reports from UEs. The RI of an
individual UE may have 8 possible levels. If supposedly a plurality
of UEs have an identical RI level, then the eNB may group these UEs
with the same RI value into an identical UA group.
[0033] The UE aggregation can also be based on UEs having similar
Quality of Service traffic parameter. For instance, UEs under VoIP
application tend to have similar QoS traffic, or UEs operating
under similar applications, such as gaming, may also have similar
QoS so as to be aggregated into the same UE group. However, since a
UE may experience different levels of traffic using different
applications, a UE may belong or may be assigned to one or more UE
aggregation group. In other words, a UE may be configured with more
than one configuration for aggregate transmission.
[0034] Referring to FIG. 4 which illustrates the some content/some
fields of a RRC message. The RRC message is transmitted from the
eNB to individual UEs to aggregate the UEs into a group. The RRC
message (400) transmitted from the eNB may include various
parameters/fields. One of the RRC message parameter may contain a
group identity information (e.g., a group-radio network temporary
indicator (G-RNTI) or SPS cell-radio network temporary indicator
(C-RNTI)) (401) which can be used to obtain the Downlink Control
Information (DCI) by decoding the PDCCH. In other words, the RRC
message may assign each UE group an identity, and this group
identity information may be used in the PDCCH to indicate the DL/UL
assignment information for the aggregate transmission. For example,
parameters such as G-RNTI and/or SPS C-RNTI may be encoded and/or
decoded with the cyclic redundant code (CRC) of the DCI in the
PDCCH.
[0035] The RRC message also includes location information of UEs'
data in the UA MAC PDU (403). For example, it may indicate which
bit in the bitmap of the UA MAC header is used to indicate whether
the data of a certain UE is present in the UA MAC PDU or not.
Alternatively, it may contain information related to the data
location in the UA MAC PDU by indicating the data location of each
UE in the UA MAC PDU, or by indicating that the data of the UEs in
the UA MAC PDU are arranged according to a
predefined/pre-configured order. Under the presence of this
parameter, the bitmap in the UA MAC header may be omitted so the
bitmap is an optional field/element in the UA MAC header.
Furthermore, the RRC message may contain numerous optional
indicators which are described as follows.
[0036] The RRC message may contain a setup or release indicator
(405) which is configured by the eNB to setup or release the
aggregate transmission. For example, the eNB may add an UE into a
UE group by setting the indicator to be "setup", or eNB may
de-configure or release an aggregated UE group (or a UA group) by
setting the indicator to be "release".
[0037] The RRC message may include a logical Channel Identity
(LCID) indicator which may be used in the User Aggregation MAC (UA
MAC) header to serve as an identification in order to indicate that
the corresponding MAC PDU is a UA MAC PDU in accordance with the
present disclosure rather than an ordinary or conventional PDU.
[0038] The RRC message may periodically include a sub-frame pattern
configuration information such as semiPersistSchedInvervalDL (which
may indicate Semi-Persistent Scheduling interval for downlink
transmission) in order to indicate which sub-frame may be used for
aggregate transmission. An eNB may not transfer data packet of the
aggregation transmission in every single sub-frame of data
transmission; therefore, a sub-frame pattern configuration
information (e.g., a periodicity) may be configured to indicate
which sub-frame may be used for aggregate transmission. The
sub-frame configuration information may include an periodicity of
data transmission in a manner similar to Semi-Persistent Scheduling
(SPS).
[0039] The RRC message also may optionally include a ACK/NACK
Resource parameter such as n1-PUCCH-AN-PERSISTLIST to indicate the
resource for HARQ (hybrid automatic retransmission and request)
ACK/NACK feedbacks. Also, the RRC message may include HARQ
information indicators which may contain information for UE(s) to
derive a HARQ process ID such as numberOfConfSPS-Processes (which
may indicate the number of configured HARQ processes) and/or a
maximum number of HARQ re-transmission. The purpose of the HARQ
information indicators is configured for the UE to know the HARQ
information associated with each aggregate transmission such as the
timing as to when ACK/NACK should be transmitted or received and
also how many times a HARQ re-transmission may be performed. An
example of a HARQ indicator is shown in equation (1).
HARQ Process
ID=[floor(CURRENT_TTI/semiPersistSchedIntervalDL)]modulo
numberOFConfSPS-Processes equation (1).
[0040] In the equation (1), floor refers to a flooring function, a
parameter "Current_TTI" refers to a current transmission time
interval (TTI) or a current sub-frame identifier, a parameter
"semiPersistSchedIntervalDL" refers to a scheduling interval for
downlink transmission, modulo refers to a modulo function and a
parameter "numberOfConfSPS-Processes" refers to a number of
configured HARQ processes.
[0041] The RRC message may optionally include a MCS indicator to
indicate the modulation and code rate used for aggregate
transmission.
[0042] The RRC message may optionally include data size information
to indicate the total data size of the UE group and/or indicate the
data size of the specific UE in the UA MAC PDU in each aggregate
transmission.
[0043] The RRC message may optionally include a parameter similar
to the "SPS-Config" used in the Semi-Persistent Scheduling (SPS)
configuration. The RRC message in the present disclosure may be
regarded as a configuration message from another perspective.
[0044] After performing the step S201 of FIG. 2 in which the
wireless network sends a RRC message to configure or re-configure
multiple UEs for aggregate transmission, in the step S203 of FIG. 2
or equivalently in the step S305 of FIG. 3, the eNB (303) may
transmit data by using an unconventional MAC PDU format
specifically configured for multiple UE aggregation.
[0045] FIG. 5A is a schematic diagram illustrating an UE acquiring
its resource allocation assignment through extracting information
in a control region by using a group identifier according to an
exemplary embodiment. Referring to FIG. 5A, within a pre-determined
TTI, there may be allocated a sub-frame. For example, there may be
10 sub-frames in a frame of 10 ms. Each UE extract information from
a sub-frame to obtain a control region and a data region. For
example, an UE may obtain a control region 50 and a data region 51
in a sub-frame#1. The same operations may be applied to other
sub-frames such as sub-frame#2 or sub-frame#8 to obtain their
respective control region or data region. The control region 50 in
the present embodiment may include PDCCH; the data region 51 in the
present embodiment may be physical downlink shared channel (PDSCH),
but the present disclosure is not limited thereto. UEs may blindly
decode the control region 50 and obtain a plurality of DCIs with
different identifiers such as C-RNTI, G-RNTI, P-RNTI, SI-RNTI, SPS
C-RNTI, . . . . For example, a UE is previously assigned with a
group identifier G-RNTI# in a previously transmitted RRC message,
then the UE may decode a DCI by the G-RNTI# and the DCI may
indicate that the UE's DL resource is allocated in a resource
block#22 (RB#22) in the data region 52. Subsequently, the UE may
decode the data in the resource block#22 to form a UA MAC PDU or a
MAC PDU, where the UA MAC PDU will be further illustrated in more
details.
[0046] FIG. 5B illustrates the format of an user aggregation MAC
PDU (UA MAC PDU) (500) used to send aggregated UE data (S305) from
an eNB (303) to a UE group (301). The user aggregate (UA) MAC PDU
(500) may contain an user aggregate (UA) MAC header (503) or (user
aggregate header in a plainer expression) and at least one of the
MAC payloads (515, 517, 519) which sequentially follows the UA MAC
PDU (500), for instance, MAC Payload for UE#1 (515), MAC Payload
for UE#2 (517), and the i-th Payload for UE#i (519). Each MAC
payload of a certain UE may contain the data traffic for the
certain UE. In other words, user aggregate header may contain
information regarding the location information for each division of
the aggregate data.
[0047] The UA MAC header (503) may include an indicator to indicate
that itself is a UA MAC PDU, rather than a conventional MAC PDU. In
other words, the UA MAC header (503) may contain an aggregate
transmission indicator. For example, the UA MAC header may use a
logical channel ID (LCID) to indicate itself as a UA MAC PDU. The
UA MAC header (503) may also include information related to the
payload size or the size of the data for a certain UE (509, 511,
513) in this UA MAC PDU (500) as well as the information related to
where the payload configured for a certain UE is located in the UA
MAC PDU (500). However, if the data size information is present in
the RRC message, the size parameter in the UA MAC header may be
omitted. The UA MAC header (503) may also optionally contain a
Bitmap (507) or a bit string with each bit dynamically set as 1 or
0 to indicate the presence or absence of communication data for a
certain UE in the aggregate MAC payload.
[0048] As an example, FIG. 5 shows a possible format of the UA MAC
header (503). The UA MAC header (503) may begin with a Bitmap (507)
to be followed by data of MAC payload sizes for each of the UEs
(509, 511, 513), for instance, size of MAC payload of UE#1 (509),
size of MAC payload of UE#2 (511), and size of MAC payload of UE#i
(513).
[0049] The Bitmap (507) located within the UA MAC header 503 may be
a string of dynamically assigned bits with each bit corresponds to
a different one of the UE in the UE group, and each bit is used to
indicate whether the data for the corresponding UE is present in
the UA MAC PDU (500) or not in the aggregate MAC payload. For
example, in a scenario where a UE group contains 5 individual UEs,
not all 5 UEs would be transmitted data in any given moment. Under
the circumstance when an individual UE is not actively
communicating with the eNB or has left the cell (or a radio service
area of an eNB), a corresponding bit located within the Bitmap
(507) would be set zero by the eNB, otherwise the bit is set to one
if the UA MAC PDU includes MAC Payload for the individual UE. The
Bitmap (507) may be configured to serve a useful purpose in a way
that an individual UE of a UE group can be dynamically added or
removed by setting their corresponding bit in the bitmap (507) to 1
or zero. Otherwise, the eNB may communicate to a UE group that one
of its member has already left, and may constantly re-configure
existing UE groups. Additionally, the aggregate MAC PDU in the
aggregate MAC PDU may include MAC payload for UE#1 (515), MAC
payload for UE#2 (517), . . . , MAC payload for UE#i (519) and an
optional padding field.
[0050] FIG. 6 illustrates an example of a typical MAC PDU of an
individual UE from a configured UE group (301). The MAC PDU for the
i-th UE or UE#i (519) located within the UA MAC PDU (500) may
contain a specific format. The specific format of the MAC Payload
for UE#i as illustrated in FIG. 5 may be a conventional MAC PDU and
therefore the technical content of the MAC PDU will not be
explained in detail. In general, the MAC PDU may include MAC header
60, and the MAC payload for UE#i may include MAC control element 1
(60), MAC control element 2 (61), a plurality of MAC service data
units (SDU) (62, 63, . . . , 69), and optional padding bits. The
proposed UA MAC PDU (500) can aggregate small data packet data
traffic for multiple users configured into the same UE group into
an aggregated MAC PDU, and this aggregated data would then be
transmitted from the eNB using the same control signalling (e.g.,
PDCCH) and therefore reduces the control signal overhead.
[0051] After UEs data traffic are aggregated to be sent from an eNB
to a UE group, control signal overhead can also be saved based on
how downlink assignments to an aggregated UE group are transmitted
(S203) and re-transmitted (S207). In principle, during transmission
and re-transmission, the group identity information such as G-RNTI
or SPS C-RNIT is embedded within PDCCH to inform each aggregated UE
group of its resource allocation. In accordance with the present
disclosure, four different exemplary embodiments are proposed below
in order to save control information overhead during data
transmission and re-transmission.
[0052] The first embodiment uses PDCCH in downlink assignments
during the first transmission and the subsequent re-transmissions
to inform a UE group of its resource allocation based on the RNTI
information. The first embodiment saves PDCCH overhead since a
group of UEs are already aggregated in a MAC PDU and therefore,
only one PDCCH is needed per UA group for its aggregated data
transmission. In other words, an aggregate control signal which
indicates the location of resource allocation could be used for the
transmission and re-transmission. The second embodiment further
saves PDCCH overhead in comparison with the first embodiment by
only using PDCCH during the first transmission but not subsequent
re-transmissions because by synchronizing HARQ in a periodic basis,
G-RNTI information is then not needed for subsequent data
re-transmissions. The third embodiment saves control signal
overhead by using PDCCH only during data re-transmission, but the
PDCCH is not used during the first transmission. This embodiment
can be implemented similar to SPS. Since the period of transmission
is already pre-configured, the information related to resource
allocation is not required during the first transmission but
otherwise required for subsequent data re-transmissions. The fourth
embodiment uses PDCCH for neither the first transmission nor any
subsequent re-transmissions. The fourth embodiment can be
implemented in a scenario where flexibility for scheduling and
resource allocation are not needed and therefore can be configured
under a fixed periodic resource allocation without any G-RNTI
information for transmission nor re-transmission. In other words,
the aggregate data may optionally include the group identifier
(e.g., G-RNTI). For each embodiment, more detailed information is
provided as follows.
First Exemplary Embodiment
[0053] In the first embodiment, PDCCH is used for both the first
transmission and the subsequent re-transmission of aggregated user
data. For the first embodiment, FIG. 7 which illustrates
transmission and re-transmission of user aggregated data will be
referred. First in step S701, an eNB assigns a group identity such
as G-RNTI to a UE group when the aggregation transmission is
configured. The eNB can use the group identity in the control
channel (e.g., PDCCH) to inform the UE group the location of its
resource allocation assignment in the data region (e.g., PDCCH).
Next, in step S703 the UE group may look for the downlink control
information (DCI) with the associated G-RNTI by monitoring the
control region (e.g., PDCCH) for each individual sub-frame or only
for each configured sub-frame if the sub-frame pattern used for the
aggregation transmission is pre-configured (e.g., when the
aggregation transmission is configured). Then, in step S705, if the
downlink control information is found by the UE in the PDCCH for
the TTI, then the downlink assignment for the aggregate
transmission can be determined by the UE. Further, in step S707,
the UE looks/searches for another indicator, for example, the New
Data Indicator (NDI) in the DCI information decoded from the PDCCH.
In the present embodiment, the NDI is one of the parameters of the
DCI information. If NDI from the received transmission is found by
the UE to be 0, then the received information is considered to be
the first transmission (S711). If the UE determines that the NDI in
the received information is 1, then the received information is
considered to be a re-transmission (S709).
[0054] In the first embodiment, the parameter included in the DCI
may include parameters such as MCS, HARQ process ID, NDI,
Redundancy Version, and transmission power control (TPC) command.
According to another embodiment with most technical contents
similar to the first embodiment, during a data re-transmission,
UE-specific identifier or UE-specific RNTI such as C-RNTI can be
used instead of the G-RNTI. The reason is that during data
re-transmission, the data does not have to be transmitted to the
entire group, and therefore a re-transmission can be made to a
specific UE identified by an UE-specific RNTI such as C-RNTI. In
this embodiment, the PDCCH may include the same HARQ process ID to
indicate that this downlink assignment is used for
re-transmission.
Second Exemplary Embodiment
[0055] For the second embodiment, PDCCH is used for the first
transmission but not for any subsequent re-transmissions so as to
save control signal overhead. Since PDCCH is also used for the
first transmission of the first embodiment, the steps involved for
the first transmission are identical with the first embodiment.
Essentially, the network assigns a group identity such as G-RNTI to
the aggregated UE group as the aggregate transmission is
configured, and then for each sub-frame or for each configured
sub-frame, the UE group monitors DCIs for the G-RNTI embedded in
the PDCCH. In some embodiments, once the DCI embedded with the
G-RNTI is detected, the transmission may be considered as a first
transmission. In some other embodiments, once the DCI embedded with
the G-RNTI is detected, the NDI information from the DCI is decoded
by the UE. If the UE determines that the NDI indicator is 0, then
the transmission is considered by the UE as a first transmission.
Otherwise, if the NDI is found by the UE to be 1, then the
transmission is considered a re-transmission.
[0056] However, under the second embodiment, the downlink
assignment for re-transmission may be not indicated on the PDCCH
because synchronous HARQ may be used for re-transmission which
renders the sending of PDCCH entirely unnecessary.
[0057] As the synchronous HARQ is used in the second embodiment,
any subsequent re-transmissions would occur at every
fixed/pre-configured period; therefore, resource allocations of
re-transmissions can be found by the UE in predictable locations of
the transmitted sub-frames. An example of the method for data
transmission according to the second embodiment is illustrated in
FIG. 8. In step S801, a downlink assignment is received by the UE
at sub-frame n. In other words, the eNB transmits a downlink
assignment. In S805, the UE may receive and decode the first
transmission received in the corresponding resource block(s) at
sub-frame n. However, if the UE does not successfully receive or
decode the transmission, the UE may assume that the next subsequent
re-transmission would be found at sub-frame n+x where x may be 8 in
a FDD system. In other words, the subsequent re-transmission may be
found at the same resources as the first transmission but shifted
by a predictable period. Then, the next re-transmission may be
found by the UE after yet another same predictable period and so on
and so forth. Therefore, PDCCH is not required in the second
embodiment to be sent in a downlink assignment, and control signal
overhead can be saved. Note that although the downlink assignment
information for the re-transmission may be predicted by the UE, the
eNB may still send the PDCCH for the re-transmission in order to,
for example, re-schedule the downlink resource assignment.
Third Exemplary Embodiment
[0058] For the third embodiment, the PDCCH for the first
transmission may normally be omitted but not for subsequent
re-transmissions. PDCCH is not used for the first transmission
according to the third embodiment except under some exceptions
which will be discussed first. PDCCH would not normally be used for
the third embodiment except when the base station wants to modify
existing configurations or under the circumstance of initial
configuration or de-configuration. For example, when the base
station sends the RRC message to aggregate a group of UEs to
configure the UA group for the first time, a group identity
information such as G-RNTI or SPS C-RNTI which will be embedded
within DCIs in the PDCCH is sent to a group of UEs. Likewise, after
an aggregated UE group (or an UA group) has been configured, the
base station may send release information in the PDCCH to release
or de-configure the UE group, or the base station may decide to
drop or add a member of the group.
[0059] FIG. 9 illustrates an overall process of a method for data
transmission according to the third embodiment. First, in step
S901, the aggregated transmission is configured by the eNB. Next in
S903, for each sub-frame or for each configured sub-frame, the UE
may monitor for the PDCCH. If the PDCCH embedded with the group
identity (e.g., G-RNTI, SPS C-RNTI) is present, this means that
either the upcoming transmission is a re-transmission or the base
station wants to make modification to existing UE group
configurations. Next, in step S905, one of the DCI parameters, NDI,
is read by the UE. If the UE determines that NDI is 1, then the
upcoming transmission is determined to be a re-transmission. In
some other embodiments, the downlink assignment for the
re-transmission may be indicated on the PDCCH by a UE-specific RNTI
such as C-RNTI to signify that only certain UEs in the UA group
need the re-transmission. Normally, the NDI indicator in PDCCH
embedded with the group identity would be 1 and this would mean
that the upcoming transmission is a re-transmission. However, if
the NDI indicator in PDCCH embedded with the group identity is
found by the UE to be 0 under this third embodiment, this means
that the base station wants to make modifications to existing
aggregated transmission configuration. Therefore, in steps
S907-S917, the UE may store the new configuration as the new
configuration will be implemented from this point on.
[0060] On the other hand, if NDI is determined by the UE to be 0,
then in the step S907, the PDCCH content is read to see if the
aggregated transmission is to be released or de-configured. If yes,
then in the step S907, the configured aggregate transmission is to
be cleared and the G-RNTI and SPS-C-RNTI indicator associated with
the UA group may be released. If no, then in step S911, the
downlink assignment may be stored by the UE as a new configuration
which is initiated by the base station. The associated HARQ
information as configured in the downlink assignment will also be
stored by the UE. Next, in the step S913, in the current TTI, the
configured downlink assignment is initialized if the aggregate
transmission is not already active or re-initialized if already
active. For example, the UE may assume that the downlink assignment
recurs in each sub-frame for which (10*SFN+sub-frame)=[(10*SFNstart
time+sub-framestart time)+N*semiPersistSchedIntervalDL] modulo
10240, for all N>0, where SFNstart time and sub-frame start time
are the system frame number (SFN) and Sub-frame respectively, at
the time the configured downlink assignment were initialized or
re-initialized. Next, in step S915, the HARQ process ID is set to
be the HARQ process ID associated with this TTI, or more
specifically, according to following equation (2).
HARQ Process
ID=[floor(Current_TTI/semiPersistSchedIntervalDL)]modulo
numberOfConfSPS-Processes equation (2).
[0061] In the equation (2), floor refers to a flooring function, a
parameter "Current_TTI" refers to a current transmission time
interval (TTI) or a current sub-frame identifier, a parameter
"semiPersistSchedIntervalDL" refers to a SPS scheduling interval
for downlink transmission, modulo refers to a modulo function and a
parameter "numberOfConfSPS-Processes" refers to a number of
configured HARQ processes.
[0062] In step S917, the NDI bit is considered by the UE as zero
which indicates first transmission. Furthermore, the presence of a
configured downlink assignment is indicated and the stored HARQ
information is delivered to the HARQ entity for this TTI.
[0063] Referring back to the step S903 of FIG. 9, if the UE
determined that PDCCH is not present in the sub-frame during the
current TTI, then downlink assignment for this TTI is presumed by
the UE to be already configured. Next, in step S919, the HARQ
process ID is set by the UE to the HARQ process ID associated with
this TTI, and more specifically as following equation (3).
HARQ Process
ID=[floor(CURRENT_TTI/semiPersistSchedIntervalDL)]modulo
numberOFConfSPS-Processes. equation (3).
[0064] In the equation (3), floor refers to a flooring function, a
parameter "Current_TTI" refers to a current transmission time
interval (TTI) or a current sub-frame identifier, a parameter
"semiPersistSchedIntervalDL" refers to a scheduling interval for
downlink transmission, modulo refers to a modulo function and a
parameter "numberOfConfSPS-Processes" refers to a number of
configured HARQ processes.
[0065] Further, in step S921, the NDI bit is considered by the UE
to the first transmission. Under the third embodiment, control
signal overhead is saved as PDCCH is normally not present during
the first transmission of data except in relatively rare
circumstances as described previously.
Fourth Exemplary Embodiment
[0066] For the fourth embodiment, PDCCH may be not used in neither
the first transmission nor subsequent re-transmissions. The lack of
PDCCH for upcoming transmissions would be communicated to the UE in
the initial RRC message as well as all information required for any
first transmission and re-transmissions. In this fourth embodiment,
the downlink resource for the aggregated transmission including the
first and/or re-transmissions may appear or recur at a
pre-configured resource location. For example, in some embodiments,
the whole sub-frame in the pre-configured sub-frame can be used for
the first transmission and/or re-transmission for the aggregated
transmission. In some other embodiments, certain pre-defined
resource blocks in the pre-configured sub-frame may be used for the
aggregated transmission. For each configured sub-frame, the UE may
set the HARQ Process ID to the HARQ Process ID associated with this
TTI according to following equation (4).
HARQ Process
ID=[floor(CURRENT_TTI/semiPersistSchedIntervalDL)]modulo
numberOFConfSPS-Processes equation (4).
[0067] In the equation (4), In the equation (3), floor refers to a
flooring function, a parameter "Current_TTI" refers to a current
transmission time interval (TTI) or a current sub-frame identifier,
a parameter "semiPersistSchedIntervalDL" refers to a SPS scheduling
interval for downlink transmission, modulo refers to a modulo
function and a parameter "numberOfConfSPS-Processes" refers to a
number of configured HARQ processes.
[0068] In the fourth embodiment, control region (e.g., PDCCH) is
not used for the first transmission or the subsequent
re-transmission(s) as the UE directly looks for its resource
allocation assignment in the data region by following
pre-configured resource location of control signaling information
delivered by the previous RRC message. As such, control signaling
overhead is also reduced.
[0069] Referring back to FIG. 2, as the eNB sends an aggregated
data transmission for the first time transmission or any subsequent
re-transmissions, the UA group in the step S205 may respond with
aggregated ACK/NACK feedbacks in order to indicate to the eNB
whether the transmitted data has been successfully received and
decoded. There may be two options for a UA group of UEs to
accomplish aggregated ACK/NACK response. The first option is to use
a shared ACK/NACK resource which is common for the entire UA group.
The second option is to use a dedicated ACK/NACK response for each
individual UE to respond to the eNB. In other words, the response
is either an aggregate response or a dedicated response for an
individual of the aggregate transmission.
[0070] For the first option, the UE group may be configured with
the ACK/NACK resources which are shared by the UA group of UEs
involved in the aggregate transmission. Under this first option, if
the transmitted data in the soft buffer of the UE is not
successfully decoded by the UA group, then the UA may send a NACK
in the shared resource to the eNB in order for the eNB to
re-transmit the data. If the UE has successfully received and
decoded the transmission, then ACK may not be required to be sent
from the UE. The resource to send ACK/NACK may be implicitly
indicated by the downlink assignment such as the resource block
index and/or demodulation reference signal (DMRS). Based on the
detection of ACK feedback(s), the eNB may determine to re-transmit
the aggregate data for the aggregate transmission.
[0071] For the second option, each of the UEs may be configured
with dedicated ACK/NACK resources for the aggregate transmission.
If the transmitted data in the soft buffer of the UE is
successfully decoded, then each UE may send a ACK in the
corresponding ACK/NACK resource to the eNB of the wireless
communication network. Otherwise, if the data is not successfully
decoded by the UE, each individual UE may send a NACK in the
ACK/NACK resource to the eNB of the wireless communication network.
Based on the detection of ACK/NACK feedback(s) from individual
UE(s), the eNB may determine to re-transmit the aggregate data for
the aggregate transmission, and/or the eNB may determine to
re-transmit an individual data for the individual UE.
[0072] Referring back to FIG. 2, the process of the steps S201-S207
is repeated as there is more data to be transmitted. Otherwise, in
the step S209, if there is no more data to be transmitted or if the
base station decides that the aggregate transmission will not
continue, in the step S211 the aggregate transmission will be
de-configured. There may be two methods to de-configure the
aggregate transmission. The first method is by explicit signaling,
and the second method is by implicit.
[0073] For the first method of de-configuring the aggregate
transmission, the wireless communication network may explicitly
send a message by the eNB such as a release indicator in PDCCH or
the same indicator in RRC message to release the aggregate
transmission or to release a single UE from the UA group. (wherein
the RRC message is a control message. In other words, since the RRC
message is another control message, a release may be accomplished
by sending another RRC message).
[0074] For the second method of de-configuring the aggregate
transmission, the wireless communication network and/or UE may
autonomously release the related configuration such as when the
corresponding timer expires. In some embodiments, the network
and/or UE may start or re-start a timer, for example, when the
aggregation transmission is started or is configured. The length of
the timer may be configured by the network by using the RRC message
(400). Once the timer expires, the network and/or UE may
autonomously release the configuration of the aggregate
transmission. In some embodiments, when a timer such as a
timea-lighmenttimer expires, the UE may notify RRC entity in the
wireless communication network to release the configuration for the
aggregate transmission and/or may clear the configured downlink
assignments. The UE may notify the RRC entity to release the PUCCH
resource for the ACK/NACK feedbacks and/or flush the corresponding
HARQ buffers of its processing circuit.
[0075] In view of the aforementioned descriptions, the present
disclosure is suitable for being used in a wireless communication
system and is able to enhance data transmission by reducing the
control signal overhead through user aggregation. Accordingly,
overall control signaling space may be utilized in a more efficient
manner to serve more user equipments, or overall system
transmission efficiency as well as spectrum efficiency are
improved.
[0076] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
disclosed embodiments without departing from the scope or spirit of
the disclosure. In view of the foregoing, it is intended that the
disclosure cover modifications and variations of this disclosure
provided they fall within the scope of the following claims and
their equivalents.
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