U.S. patent application number 12/811315 was filed with the patent office on 2011-12-01 for method and system for discontinuous reception operation for long term evolution advanced carrier aggregation.
Invention is credited to Zhijun Cai, Andrew Mark Earnshaw, Mo-Han Fong, Youn Hyoung Heo, Sean McBeath, Yi Yu.
Application Number | 20110294491 12/811315 |
Document ID | / |
Family ID | 42938570 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110294491 |
Kind Code |
A1 |
Fong; Mo-Han ; et
al. |
December 1, 2011 |
Method and System for Discontinuous Reception Operation for Long
Term Evolution Advanced Carrier Aggregation
Abstract
A method for discontinuous reception operation for carrier
aggregation comprising: receiving a first set of discontinuous
reception parameters for a first carrier and a limited or different
set of discontinuous reception parameters for a second carrier; and
configuring discontinuous reception parameters on the first carrier
and second carrier.
Inventors: |
Fong; Mo-Han; (Ottawa,
CA) ; McBeath; Sean; (Keller, TX) ; Cai;
Zhijun; (Euless, TX) ; Earnshaw; Andrew Mark;
(Kanata, CA) ; Heo; Youn Hyoung; (Suwon, KR)
; Yu; Yi; (Irving, TX) |
Family ID: |
42938570 |
Appl. No.: |
12/811315 |
Filed: |
June 15, 2010 |
PCT Filed: |
June 15, 2010 |
PCT NO: |
PCT/US2010/038647 |
371 Date: |
August 16, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61187095 |
Jun 15, 2009 |
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61220886 |
Jun 26, 2009 |
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Current U.S.
Class: |
455/422.1 |
Current CPC
Class: |
H04L 5/0053 20130101;
Y02D 30/70 20200801; H04L 5/0098 20130101; H04W 72/0453 20130101;
H04W 52/0216 20130101; H04L 5/001 20130101; H04W 76/28
20180201 |
Class at
Publication: |
455/422.1 |
International
Class: |
H04W 72/00 20090101
H04W072/00 |
Claims
1. A method for configuring a carrier for a user equipment in a
wireless network, the user equipment supporting multiple carriers,
the method comprising: a. receiving, by the user equipment,
signaling via radio resource signaling, said signaling providing
information for the carrier, wherein the information includes a
logical index for the carrier; b. configuring, by the user
equipment, the carrier according to the received information.
2. The method of claim 1, wherein the information comprises at
least one of: a. frequency of the carrier; b. bandwidth of the
carrier; c. discontinuous reception parameters of the carrier; or
d. control channel support.
3. The method of claim 1, further comprising receiving additional
signaling to enable or disable reception of the carrier.
4. The method of claim 3, wherein the additional signaling includes
information relating to the logical index of the carrier.
5. The method of claim 2, further comprising enabling or disabling
reception of the carrier based on discontinuous reception
parameters configured for the carrier.
6. The method of claim 2, wherein the control channel support
indicates whether control channel reception should be enabled for
the carrier.
7. The method of claim 2, wherein the control channel support
indicates a second carrier, the second carrier contains control
information corresponding to the carrier.
8. The method of claim 7, further comprising disabling, by the user
equipment, reception of the control information corresponding to
the carrier when reception of the carrier is disabled.
9. The method of claim 8, wherein the control information
corresponding to the carrier is transmitted on a different carrier
to the carrier transmitting the packet data.
10. A user equipment comprising: a communications subsystem,
wherein the communications subsystem is configured to perform the
method of claim 1.
11. A method of transmitting control information corresponding to a
carrier among a plurality of carriers, the method comprising:
determining an activation time of the carrier; and transmitting
control information corresponding to the carrier prior to the
activation time.
12. The method of claim 11, wherein the control information
comprises at least one of: a. Channel Quality Indicator (CQI); b.
Precoding Matrix Indicator (PMI); c. Rank Indicator (RI); or d.
Sounding Reference Symbol (SRS).
13. The method of claim 11, wherein the determination of an
activation time of the carrier comprises at least one of: a.
receiving a signaling message to enable reception of the carrier;
and b. a time corresponding to the start of the Active time of the
carrier.
14. The method of claim 11, wherein the plurality of carriers are
determined based on receiving at least one allocation signaling
message.
15. A network element comprising: a communications subsystem,
wherein the communications subsystem is configured to perform the
method of claim 11.
16. A method of operating a user equipment in a wireless network,
the user equipment supporting multiple carriers, the method
comprising: receiving, by the user equipment, a disable command
control element for a carrier; and discontinuing, by the user
equipment, transmission of the control information corresponding to
the carrier after receiving the disable command control
element.
17. The method of claim 16, wherein the reception of the carrier is
disabled based on receiving a signaling message.
18. The method of claim 16, wherein the reception of the carrier is
disabled based on the discontinuous reception operation configured
for the carrier.
19. The method of claim 16, wherein the plurality of carriers are
determined based on receiving an allocation signaling message.
20. A user equipment comprising: a communications subsystem,
wherein the communications subsystem is configured to perform the
method of claim 16.
21. The method of claim 8, wherein disabling, by the user
equipment, reception of the control information comprises stopping,
by the user equipment, monitoring a physical downlink control
channel (PDCCH) associated with the carrier.
22. The method of claim 16, further comprising stopping, by the
user equipment, monitoring a physical downlink control channel
(PDCCH) associated with the carrier when the PDCCH is transmitted
on the carrier after receiving the disable command control
element.
23. The method of claim 16, further comprising stopping, by the
user equipment, monitoring a physical downlink control channel
(PDCCH) associated with the carrier when the PDCCH is transmitted
on another carrier different from the carrier after receiving the
disable command control element.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to long term
evolution-advanced (LTE-A), and in particular to discontinuous
reception when carrier aggregation is utilized in LTE-A.
BACKGROUND
[0002] Discontinuous reception allows a user equipment (UE) to turn
off its radio transceiver during various periods in order to save
battery life on the UE. In the long term evolution (LTE)
specifications, the UE is allowed to proceed into discontinuous
reception (DRX) even when in a connected mode. DRX operation is
defined for single carrier operation in LTE Release 8, in 3GPP TS
36.321, sections 3.1 and 5.7, the contents of which are
incorporated herein by reference.
[0003] In LTE Advanced (LTE-A) it is agreed that carrier
aggregation may be used in order to support a wider transmission
bandwidth for increased potential peak data rates to meet the LTE-A
requirements. In carrier aggregation, multiple component carriers
are aggregated and they can be allocated in a subframe to a UE.
Thus, each component carrier may have a bandwidth of, for example,
20 MHz and a total aggregated system bandwidth of up to 100 MHz.
The UE may receive or transmit on multiple component carriers
depending on its capabilities. Further, carrier aggregation may
occur with carriers located in the same band and/or carriers
located in different bands. For example, one carrier may be located
at 2 GHz and a second aggregated carrier may be located at 800
MHz.
[0004] An issue arises with the translation of DRX operation from a
single carrier LTE Rel-8 system to a multiple carrier LTE-A system.
DRX under LTE Rel-8 may be inoperable or inefficient when multiple
carriers are used. Two approaches have been proposed at the LTE-A
forum.
[0005] In R2-092959, "DRX with Carrier Aggregation in
LTE-Advanced", a proposal is described in which different DRX
parameters are configured independently for different component
carriers and DRX is performed independently for each component
carrier. For example, one component carrier may utilize a short DRX
cycle while another component carrier may utilize only long DRX
cycles; or the DRX cycles configured for the different component
carriers are completely independent of one another. A problem with
this approach is the complexity for the UE to maintain different
states or timers for different carriers. There may also be little
benefit of having completely independent DRX cycles and timers
between carriers. Since upper layer traffic is multiplexed across
multiple carriers, it is the Evolved Node B (eNB) scheduler's
decision to determine on which carrier an encoded packet should be
transmitted.
[0006] In a second approach, outlined in R2-092992, "Consideration
on DRX", DRX operation is only configured on the anchor carrier.
Additional component carriers are allocated on an as needed basis
during the "active time" of the anchor carrier.
[0007] However, the above two proposals do not provide details
regarding the allocation and de-allocation of additional component
carriers. Nor do they explicitly provide details as to the DRX
operation of the various carriers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present disclosure will be better understood with
reference to the drawings in which:
[0009] FIG. 1 is a timing diagram showing DRX operation of a
carrier in LTE Rel. 8;
[0010] FIG. 2 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier has a DRX inactivity timer;
[0011] FIG. 3 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier has no DRX inactivity timer set;
[0012] FIG. 4 is a timing diagram showing DRX operation in LTE-A in
which a first non-designated carrier includes a DRX inactivity
timer and a second non-designated carrier does not have a DRX
inactivity timer;
[0013] FIG. 5 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier is set to activate upon activation
of the associated designated carrier;
[0014] FIG. 6 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier is set to activate upon activation
of the associated designated carrier and further including a DRX
inactivity timer;
[0015] FIG. 7 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier has an On Duration timer value
set;
[0016] FIG. 8 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier has an On Duration timer value set
and where the On Duration timer value is longer than an active time
on the associated designated carrier;
[0017] FIG. 9 is a timing diagram showing DRX operation in LTE-A in
which a non-designated carrier has an On Duration timer value and a
DRX inactivity timer value set;
[0018] FIG. 10 is a timing diagram showing DRX operation in LTE-A
in which a non-designated carrier has a drx-FollowDesignatedTimer
timer value set;
[0019] FIG. 11 is a timing diagram showing a non-designated carrier
configured with a short and long DRX cycle;
[0020] FIG. 12 is a block diagram illustrating a medium access
control (MAC) control element (CE) for enabling or disabling
carrier reception on a non-designated carrier;
[0021] FIG. 13 is a block diagram illustrating a MAC CE to
acknowledge the MAC CE of FIG. 12;
[0022] FIG. 14 is a block diagram illustrating a MAC CE for
enabling or disabling carrier reception on multiple non-designated
downlink carriers;
[0023] FIG. 15 is a block diagram illustrating a MAC CE to
acknowledge the MAC CE of FIG. 14;
[0024] FIG. 16 is a block diagram illustrating a MAC CE configured
to enable or disable multiple downlink and uplink carriers;
[0025] FIG. 17 is a block diagram illustrating a MAC CE to
acknowledge the MAC CE of FIG. 16;
[0026] FIG. 18 is a block diagram of an exemplary mobile device
capable of being used with the embodiments herein;
[0027] FIG. 19 is a data flow diagram showing configuration of
candidate carriers; and
[0028] FIG. 20 is a data flow diagram showing control information
configuration for a carrier and the stopping of transmission from a
disabled carrier.
DETAILED DESCRIPTION
[0029] According to one aspect, there is provided a method for
discontinuous reception operation for carrier aggregation
comprising: receiving a first set of discontinuous reception
parameters for a first carrier and a limited or different set of
discontinuous reception parameters for a second carrier; and
configuring discontinuous reception parameters on the first carrier
and second carrier.
[0030] According to another aspect, there is provided a method for
enabling or disabling carrier reception through medium access
control element signaling comprising: adding a carrier reception
enable or disable command control element; and configuring a
carrier reception enable or disable acknowledgment control
element.
[0031] DRX operation may be used for different purposes. For
example, a UE that is currently experiencing a low level of traffic
activity could be in a DRX state where it wakes up occasionally
from DRX in order to receive traffic. An example of this could be
that the UE is conducting a voice call. Voice packets have a
predictable pattern of occurrence and do not need to be transmitted
in every subframe, so a UE could be configured to spend the time
between successive voice packet transmissions/receptions in DRX.
Another example would be a UE that is currently essentially idle
and has no traffic. The UE needs to wake up temporarily to see if
the eNB has any traffic for the UE.
[0032] DRX could also be used for resource sharing purposes. It is
unlikely that a particular UE would have data transmission and/or
receptions in every subframe on a sustained basis. Thus, for
signaling efficiency reasons, it may be more desirable to
consolidate data into fewer and larger resource allocations if the
additional latency can be tolerated. Such latency would in general
be minimal.
[0033] For instance, it may be more efficient to send a burst of
1000 bytes in one subframe, every 10 subframes, rather than ten 100
byte transmissions across each of those same 10 subframes. Due to
the shared nature of the packet data channels, other UEs could
utilize the data channels during the subframes where the UE in
question is not receiving or transmitting. The UE could therefore
be configured to enter DRX when the eNB knows that it would not
transmit to the UE. The eNB would be transmitting to the other UEs
in those subframes.
[0034] As will be appreciated by those skilled in the art,
different DRX cycle lengths, such as 10 milliseconds for long DRX
cycle and as short as 2, 5, 8 and 10 milliseconds for short DRX
cycles exist, so the use of DRX functionality for this data channel
sharing purpose may be possible. In addition, multiple UEs can be
configured with the same DRX cycle length but with different start
offsets. This would result in different sets of UEs waking up
during different time intervals, thereby facilitating the time
division among multiple UEs.
[0035] Reference is now made to FIG. 1, which shows LTE Rel-8
operation. In FIG. 1, an Active mode 110 is illustrated at a first
level and a DRX mode 112 is illustrated at a second level. During
Active mode 110, the UE monitors the downlink control channel for
possible resource allocation on the downlink or uplink traffic
channels. At a time, illustrated by reference numeral 120, a
boundary of a DRX cycle is encountered. At this point, the mode
changes from DRX mode 112 to Active mode 110. Further, an
OnDuration timer 122 is started. The OnDuration timer 122 signifies
the duration that the UE should remain in Active mode, even if
there is no traffic transmission to/from the UE during this
duration.
[0036] In the example of FIG. 1, within the Active mode, arrow 130
shows the last physical downlink control channel (PDCCH) message is
received indicating a new packet transmission on the physical
downlink shared channel (PDSCH) or uplink grant for new packet
transmission on the physical uplink shared channel (PUSCH). At this
point, a DRX Inactivity timer 132 is started. The DRX inactivity
timer 132 specifies a number of consecutive PDCCH subframes after
the most recent successful decoding of a PDCCH indicating an
initial uplink or downlink user data transmission for the UE. As
will be appreciated by those skilled in the art, in the example of
FIG. 1, the UE remains in an Active mode 110 until the expiration
of a DRX inactivity timer 132. The expiration of the DRX inactivity
timer 132 is shown by arrow 134, at which point the UE transitions
to the DRX mode 112.
[0037] The total duration between the time shown by reference
numeral 120 and arrow 134 is referred to as the Active time 136.
The Active time 136 is related to DRX operation, as defined in sub
clause 5.7 of the LTE Rel-8 DRX specification in 3GPP TS 36.321,
and defines the subframes during which the UE monitors the
PDCCH.
[0038] The last data packet sent, shown by arrow 130, may expect a
hybrid automatic repeat request (HARQ) retransmission. The first
point at which the HARQ retransmission may be expected is shown by
arrow 140. At this point, if an HARQ retransmission is required by
the UE, a DRX retransmission timer 142 is started during which
period the HARQ retransmission may be received. If the HARQ
retransmission is not received, the DRX retransmission timer
expires at 143. When either the DRX inactivity timer is running or
the DRX retransmission timer is running, the UE remains in Active
time.
[0039] As will be appreciated, based on the above, the Active time
136 can therefore potentially be extended by data activity, which
may result in the DRX inactivity timer being reset. Further, if
HARQ retransmission is expected for a previously transmitted PDSCH
packet, the corresponding DRX retransmission timer is started,
causing the Active time 136 to be extended.
[0040] If the UE is configured for a short DRX cycle, a new Active
mode 110 is started at the end of the short DRX cycle, as
illustrated by arrow 150 in FIG. 1. Arrow 150 shows the DRX cycle
which specifies the periodic repetition of the OnDuration, followed
by a period of possible inactivity.
[0041] It is also possible to have a long DRX cycle 152 as shown in
FIG. 1. In general, a long DRX cycle 152 is larger than the short
DRX cycle, and both may be configured by the eNB.
[0042] The UE may be configured by Radio Resource Control (RRC)
with DRX functionality that controls the UE's PDCCH monitoring
activity for the UE's Cell Radio Network Temporary Identifier
(C-RNTI), Transmit Power Control Physical Uplink Control Channel
RNTI (TPC-PUCCH-RNTI), Transmit Power Control Physical Uplink
Shared Channel RNTI (TPC-PUSCH-RNTI) and semi-persistent scheduling
C-RNTI (SPS C-RNTI) (if configured). When in RRC_CONNECTED, if DRX
is configured, the UE is allowed to monitor the PDCCH
discontinuously using the DRX operation specified by sub clause 5.7
of the LTE Rel-8 specification 3GPP TS 36.321. Otherwise the UE
monitors the PDCCH continuously. When using DRX operation, the UE
also monitors the PDCCH according to requirements found in other
sub clauses of the specification. RRC controls DRX operation by
configuring the following: OnDuration timer, DRX-InactivityTimer,
DRX-RetransmissionTimer (one per DL HARQ process except for the
broadcast process), the value of the DRX Start Offset, which is the
subframe where the DRX cycle starts, and optionally the DRX Short
Cycle Timer and Short DRX-Cycle. An HARQ retransmission timer (RTT)
parameter, which specifies the minimum amount of subframes before
downlink HARQ retransmission is expected from the UE, is also
defined per downlink HARQ process.
[0043] Section 5.7 of the LTE Rel. 8 specification 3GPP TR 36.321
provides for the above as:
[0044] When a DRX cycle is configured, the Active Time includes the
time while: [0045] on DurationTimer or drx-InactivityTimer or
drx-Retransmission Timer or mac-ContentionResolutionTimer (as
described in subclause 5.1.5) is running; or [0046] a Scheduling
Request sent on PUCCH is pending (as described in subclause 5.4.4);
or [0047] an uplink grant for a pending HARQ retransmission can
occur and there is data in the corresponding HARQ buffer; or [0048]
a PDCCH indicating a new transmission addressed to the C-RNTI of
the UE has not been received after successful reception of a Random
Access Response for the explicitely signaled preamble (as described
in subclause 5.1.4).
[0049] When DRX is configured, the UE shall for each subframe:
[0050] If the Short DRX Cycle is used and [(SFN*10)+subframe
number]. modulo (shortDRX-Cycle)=(drxStartOffset) modulo
(shortDRX-Cycle); or [0051] if the Long DRX Cycle is used and
[(SFN*10)+subframe number] modulo (LongDRX-Cycle)=drxStartOffset:
[0052] start on DurationTimer. [0053] if a HARQ RTT Timer expires
in this subframe and the data in the soft buffer of the
corresponding HARQ process was not successfully decoded: [0054]
start the drx-RetransmissionTimer for the corresponding HARQ
process. [0055] if a DRX Command MAC control element is received:
[0056] stop on DurationTimer; [0057] stop drx-InactivityTimer.
[0058] if drx-InactivityTimer expires or a DRX Command MAC control
element is received in this subframe: [0059] if the short DRX cycle
is configured: [0060] start or restart drxShortCycleTimer, [0061]
use the Short DRX Cycle. [0062] else: [0063] use the Long DRX
cycle. [0064] if drxShortCycleTimer expires in this subframe:
[0065] use the long DRX cycle. [0066] during the Active Time, for a
PDCCH-subframe except if the subframe is required for uplink
transmission for half-duplex FDD UE operation and except if the
subframe is part of a configured measurement gap: [0067] monitor
the PDCCH; [0068] if the PDCCH indicates a DL transmission or if a
DL assignment has been configured for this subframe: [0069] start
the HARQ RTT Timer for the corresponding HARQ process; [0070] stop
the drx-RetransmissionTimer for the corresponding HARQ process.
[0071] if the PDCCH indicates a new transmission (DL or UL): [0072]
start or restart drx-InactivityTimer. [0073] when not in Active
Time, CQI/PMI/RI on PUCCH and SRS shall not be reported.
[0074] Regardless of whether the UE is monitoring PDCCH or not the
UE receives and transmits HARQ feedback when such is expected.
[0075] NOTE: A UE may optionally choose to not send CQI/PMI/RI
reports on PUCCH and/or SRS transmissions for up to 4 subframes
following a PDCCH indicating a new transmission (UL or DL) received
in the last subframe of active time. The choice not to send
CQI/PMI/RI reports on PUCCH and/or SRS transmissions is not
applicable for subframes where on DurationTimer is running.
[0076] DRX in LTE-A.
[0077] In accordance with the present disclosure, various
embodiments for utilizing DRX in LTE-A to support carrier
aggregation are provided.
[0078] In one embodiment, the UE should have a minimum number of
component carriers for which it needs to turn on signal reception
while meeting traffic demand. Having completely independent DRX
cycles among component carriers assigned to a UE may cause
unnecessary complexity and power consumption at the UE. In one
embodiment it is possible to have coordinated DRX cycles among
component carriers assigned to a UE.
[0079] Various differences between LTE and LTE-A may affect DRX
operation and therefore may need to be addressed by LTE-A DRX
solutions.
[0080] A first difference is that LTE has one downlink and one
uplink carrier. There is a one-to-one mapping between these two
carriers. Conversely, in LTE-A, there may not only be multiple
downlink and/or multiple uplink carriers, but the number of
downlink and the number of uplink carriers may be different. There
may consequently be no direct one-to-one association between
downlink and uplink carriers.
[0081] As will be appreciated, in both LTE and LTE-A HARQ feedback
must always be received and transmitted as expected while the UE is
in DRX operation. In the case of LTE-A with carrier aggregation,
this implies that the corresponding component carriers in the
downlink and uplink must be kept Active in order to receive or
transmit this information.
[0082] In LTE, resource indications on the PDCCH correspond with
either the same downlink carrier or the associated uplink carrier
since there is only one carrier in each link direction. In LTE-A,
PDCCH signaling on one carrier such as the anchor carrier could be
associated with transmissions or receptions on multiple other
uplink or downlink carriers. As will be appreciated by those in the
art, an "anchor carrier" may also be referred to as a "primary
carrier" and a "non-anchor carrier" may also be referred to as a
"secondary carrier".
[0083] A further distinction between the two is that, as a result
of having the PDCCH on one carrier associating with receptions on
multiple other uplink or downlink carriers, a UE expecting HARQ
retransmissions only on one carrier (e.g. non-anchor carrier) may
also need to keep receiving a different carrier (e.g. anchor
carrier) in order to receive PDCCH information about potential HARQ
retransmissions.
[0084] Furthermore, an LTE-A UE with multiple aggregated carriers
will have a large number of HARQ processes. If any of the HARQ
processes potentially expects an HARQ retransmission, the UE can be
in Active time. Due to the large number of HARQ processes, the
probability that the UE will be in Active time and consequently the
proportion of time spent in Active time may be much higher for
LTE-A than for LTE.
[0085] Carrier Configuration
[0086] When the UE is in an RRC_CONNECTED state, it can be assigned
N component carriers, where N is greater than or equal to 1. One or
more of the N component carriers may be assigned as designated
carriers. In one embodiment, a designated carrier is also an
"anchor carrier". The UE enables carrier reception on all the N
component carriers. The term "carrier reception" is defined such
that when the carrier reception of a component carrier is enabled
for a UE, the UE enables the RF reception and/or reception of
downlink physical control channels associated with this component
carrier and downlink physical data channels on this component
carrier. Carrier reception can also be called signal reception or
some other term without deviating from the present disclosure. As
will be appreciated by those in the art, if carrier reception of a
component carrier is disabled for a UE, the UE stops decoding the
PDSCH, the PDCCH and other control channels associated with this
component carrier, regardless of whether the PDCCH is transmitted
on the same carrier as the PDSCH resource allocation or on a
different carrier. The UE may monitor the PDCCH on only one or more
of the designated carriers, on a subset of the N component
carriers, or on all N component carriers. If the UE detects a PDCCH
that assigns a PDSCH resource on a particular component carrier,
the UE performs baseband demodulation and decoding of the assigned
PDSCH resource on that component carrier.
[0087] The eNB can change the set of N component carriers by adding
new component carriers to the set or removing existing component
carriers from the set. The eNB can also change one or more of the
designated carriers.
[0088] The UE can be configured by RRC signaling with DRX
functionality that controls the UE's carrier reception on one or
multiple component carriers. As used herein, the DRX parameters
have similar definitions to those defined in LTE Rel-8, and include
the on DurationTimer, drx-InactivityTimer, drx-RetransmissionTimer
(one per downlink HARQ process, except for the broadcast process),
the long DRX-Cycle, the value of the drxStartOffset and optionally
the drxShortCycleTimer and shortDRX-Cycle. An HARQ retransmission
timer per downlink HARQ process, except for the broadcast process,
is also defined. The above is not meant to be limiting and other
DRX parameters can also be used for various component carriers
including the designated carriers.
[0089] The non-designated carriers could also have various DRX
timers and parameters. In one embodiment, the non-designated
carriers may have timers such as the drx-InactivityTimer,
drx-RetransmissionTimer, and HARQ RTT Timer (with the latter two
timers existing for each downlink HARQ process). The
drx-InactivityTimer may however be omitted in various embodiments
and thus the only parameters used consist of the
drx-RetransmissionTimer and the HARQ RTT Timer expiry time
settings. In other embodiments, there can be a reduced set of DRX
parameters for the non-designated carriers. Different
non-designated carriers may have different reduced sets of DRX
parameters. In yet another embodiment, some non-designated carriers
can be configured with a full set of DRX parameters while other
non-designated carriers are configured with a reduced set of DRX
parameters. In further embodiments, all non-designated carriers may
have the same set of DRX parameters, either full or reduced. In a
further embodiment, the eNB needs only signal one set of parameters
for all non-designated carriers.
[0090] DRX parameters are signaled by the eNB to the UE through RRC
signaling. The eNB can configure the DRX parameters on the
designated carrier(s) and M other non-designated component
carriers, where M is greater than or equal to 0. These designated
carriers and M non-designated component carriers are those for
which the eNB may potentially instruct the UE to enable carrier
reception. In one embodiment, the eNB may instruct the UE to enable
carrier reception on a component carrier which is not within the
set of designated carrier(s) and M non-designated carriers. In
another embodiment, all M non-designated component carriers have
the same DRX configurations, and hence only one common signaling is
needed instead of M individual settings. In a further embodiment,
for a designated carrier or a non-designated carrier on which DRX
parameters are configured, the eNB can explicitly signal the UE to
enable or disable the DRX operation. When DRX operation is enabled
for a carrier, the UE performs DRX operation as specified by the
DRX parameters. When DRX operation is disabled, the UE remains in
Active mode on that carrier if the carrier reception on that
carrier has been previously enabled.
[0091] From the above, the set of N carriers are called the Active
carriers, while the set of designated carriers and M non-designated
carriers on which DRX parameters are configured can be called the
DRX-Configured carriers. The set of DRX-Configured carriers and
Active carriers may or may not overlap. The set of Active carriers
may also be a subset of the set of the DRX-Configured carriers or
vice-versa.
[0092] In addition to the Active carriers and DRX-Configured
carriers, a UE may be pre-allocated additional component carriers
where a logical carrier index is assigned to map to a specific
physical carrier. The set of carriers where a logical carrier index
is assigned is called the candidate carriers. The UE is also
signaled, through unicast or broadcast signaling from the eNB, the
properties of the candidate carriers including carrier frequency,
bandwidth, control channels support, etc. DRX operation can be
configured for one or more carriers within the set of candidate
carriers. UE reception of a carrier within the set of candidate
carriers can be enabled through explicit signaling (e.g., RRC
signaling or MAC CE) from the eNB, or implicitly through the DRX
parameter configuration. This is for example shown in FIG. 19,
where eNB 1910 sends a message 1930 to UE 1920. Message 1930
provides information for carrier configuration, including a carrier
logical index. The carrier can then be configured at UE 1920, as
shown by arrow 1940.
[0093] In one embodiment, non-designated carriers within the set of
M, where M is defined above, are associated with a designated
carrier. One or more non-designated carriers can be associated with
one of the designated carriers. The association is signaled by the
eNB (e.g. through RRC signaling) to the UE. In one embodiment, the
eNB signals the DRX parameters and the association information to
the UE in the same RRC signaling message. In another embodiment,
the association can be implicit through a predefined mapping of the
logical/physical carrier index of a non-designated carrier to a
designated carrier. In yet another embodiment, the association
between a non-designated carrier and a designated carrier can be
signaled by the eNB using broadcast or multicast signaling (e.g.
broadcast or multicast RRC signaling) to multiple UEs in the
cell.
[0094] In one embodiment, for each of the M non-designated
carriers, where M is defined above, the carrier reception on that
carrier can be enabled at the start of the OnDuration of the
associated designated carrier, or it can be enabled during the
Active time of the associated designated carrier. Such enabling may
be through explicit eNB signaling to the UE (for example, PDCCH
enabling signaling), or by some alternative means.
[0095] The two modes can be configured and signaled such as through
RRC signaling or MAC CE by the eNB to the UE for each of the M
non-designated carriers. In the latter mode, during the Active time
on the associated designated carrier, the eNB may instruct the UE
to enable carrier reception on another component carrier through
control signaling. Such control signaling may include, but is not
limited to, RRC signaling, PDCCH signaling, or MAC CE signaling.
The signaling may be sent on the associated designated carrier or
one of the N component carriers, where N is defined above.
[0096] One example of the above is that the UE enables carrier
reception on one of the M non-designated carriers or on a carrier
not within the set of M carriers, if the UE receives a grant or
carrier enabled signaling with C-RNTI successfully in one of the N
component carriers rather than with SPS C-RNTI, SI-RNTI (System
Information RNTI), P-RNTI (Paging RNTI) or TPC RNTI. The action
time to enable the carrier reception on the non-designated carrier
can be implicit, such as x number of subframes after receiving the
corresponding signal from the eNB, or may be explicitly indicated
in the signaling message. In a specific embodiment, x could be
0.
[0097] At the action time, the UE enters Active time on the
non-designated carrier. It is noted that if the carrier reception
of a certain carrier is disabled, the UE can stop monitoring the
PDCCH for this carrier regardless of whether the PDCCH is
transmitted on the same carrier as the PDSCH resource allocation or
on a different carrier. In one embodiment, if the carrier reception
of a certain carrier is disabled, the UE can stop monitoring the
PDCCH associated with this carrier regardless of whether the
associated PDCCH is transmitted on this carrier or on a different
carrier.
[0098] If the UE is indicated to enable carrier reception on a
non-designated carrier, the UE could transmit control information
corresponding to this non-designated carrier such as the Channel
Quality Indicator (CQI), Precoding Matrix Indicator (PMI), Rank
Indicator (RI), and Sounding Reference Symbol (SRS) prior to action
time in a designated uplink carrier or an uplink carrier that is
associated with the downlink non-designated carrier. This is, for
example, shown with reference to FIG. 20, in which eNB 2010
determines an activation time, as shown by arrow 2030, and provides
control information for carrier configuration, as shown by arrow
2040, to UE 2020, prior to activation time.
[0099] Further, when the carrier reception of a certain carrier is
disabled, the UE may stop transmitting the uplink control
information to the eNB corresponding to that particular carrier.
This is, for example, shown in FIG. 20, where carrier reception is
disabled by either signaling, as shown by arrow 2050, or DRX
operation for the carrier, as shown by arrow 2055. Upon the carrier
reception being disable, transmission on the carrier is also
disabled, as shown by arrow 2060. In one embodiment, the uplink
control information corresponding to a non-designated carrier is
only transmitted to the eNB during the Active time of the
non-designated carrier. In a further embodiment, the control
information contains control information for all or a subset of the
N carriers, for example as combined control information. This
control information is only transmitted during the Active time of
any of the designated carrier(s) via the associated uplink carrier
such as a "single report for all".
[0100] The above is demonstrated with regard to various embodiments
below. These embodiments are not meant to be limiting, and can be
used alone, in conjunction with other embodiments or various other
alternatives that would be apparent to those skilled in the art
having regard to the present disclosure are also contemplated.
[0101] 1. Explicit Start, Individual drx-InactivityTimer
[0102] In a first embodiment, the carrier reception on a
non-designated carrier is enabled during the Active time of the
associated designated carrier by eNB signaling. A
drx-InactivityTimer for the non-designated carrier is started at
the action time. The drx-InactivityTimer is restarted whenever a
new PDSCH packet is received on the non-designated carrier. A
drx-RetransmissionTimer is also maintained during the Active time
of the non-designated carrier. The drx-RetransmissionTimer for an
HARQ process is started at the earliest time when a retransmission
may be expected for a previously transmitted packet on the
corresponding HARQ process.
[0103] The drx-RetransmissionTimer for an HARQ process is disabled
when a packet is received correctly for the HARQ process or the
maximum number of retransmissions has been reached.
[0104] The UE remains in Active time on the non-designated carrier
when either the carrier's drx-InactivityTimer or a
drx-RetransmissionTimer is running. At any time during the Active
time on the non-designated carrier, the eNB can instruct the UE,
through signaling, to disable carrier reception on the
non-designated carrier.
[0105] Carrier reception on the carrier is disabled when none of
the drx-InactivityTimer and the drx-RetransmissionTimers are
running.
[0106] Reference is now made to FIG. 2. In FIG. 2, a designated
carrier 200, with which the non-designated carrier 205 is
associated, is shown to have similar properties to the carrier of
FIG. 1. In this regard, similar reference numerals are
utilized.
[0107] Designated carrier 200 has an On Duration 122, which starts
at a time shown as reference numeral 120. The UE then receives its
last PDCCH message corresponding to a new data transmission on the
designated carrier at a time shown by arrow 130, at which point a
drx-InactivityTimer 132 is restarted. Further, after the HARQ
retransmission timer for a downlink HARQ process expires, the
drx-RetransmissionTimer for the same downlink HARQ process 140 is
started. This is the timer during which the UE waits to see whether
an HARQ retransmission is received.
[0108] As shown in FIG. 1, the drx-InactivityTimer 132 expires at a
time shown by arrow 134. This is subsequent to the expiration of
drx-RetransmissionTimer 142. At this point, the designated carrier
200 proceeds to a DRX mode. The Active time during which the UE
monitors the PDCCH on the designated carrier is shown by arrow
136.
[0109] If a short DRX cycle is configured, the designated carrier
200 proceeds back to an Active mode 110 after the short DRX cycle
150 expires. Conversely, if a long DRX cycle is configured then the
designated carrier 200 proceeds back to an Active mode 110 after
the expiration of the long DRX cycle 152.
[0110] At some point the eNB realizes that there is more data to be
sent to the UE and sends a signal to start a second (or subsequent)
component carrier. A non-designated carrier 205 is started as a
result of a message shown at arrow 210 to enable carrier reception
on a component carrier.
[0111] In accordance with the first embodiment, a
drx-InactivityTimer is associated with the component carrier. The
drx-InactivityTimer may have a preconfigured length or the length
of the drx-InactivityTimer may be signaled by the eNB.
[0112] On receipt of the signal (or the corresponding action time)
shown by arrow 210, the non-designated carrier 205 proceeds to an
Active mode, i.e. the UE enables carrier reception on the
non-designated carrier 205. During the Active mode, the last new
PDSCH packet is received on the non-designated carrier, as shown by
arrow 220. At this point the drx-InactivityTimer 222 is restarted.
Also started after the HARQ RTT time is the drx-RetransmissionTimer
224.
[0113] In the example of FIG. 2, an HARQ retransmission is received
and the drx-RetransmissionTimer 224 is stopped.
[0114] Upon the expiration of the drx-InactivityTimer 222 the
non-designated carrier 205 has its reception disabled, as shown by
reference numeral 230. At this point, the eNB can signal through
the associated designated carrier 200 to re-enable reception on the
non-designated carrier 205 at some future point.
[0115] 2. Explicit Signaling, No drx-InactivityTimer
[0116] In a further embodiment, carrier reception on a
non-designated carrier is enabled during the Active time of the
associated designated carrier by eNB signaling. A separate
drx-InactivityTimer is not maintained for a non-designated carrier.
At the action time, the UE enables carrier reception on the
non-designated carrier assigned by the eNB. The UE continues to
enable carrier reception on the non-designated carrier during the
Active time of the designated carrier, unless explicit signaling is
received from the eNB to instruct the UE to disable carrier
reception on the non-designated carrier. Since the HARQ
retransmission process occurs independently between the associated
designated carrier and each of the non-designated carriers, each of
these carriers maintains its own drx-RetransmissionTimer for each
of its downlink HARQ processes. In one embodiment, the designated
carrier shall remain in Active time when the drx-InactivityTimer
for the designated carrier or at least one of the
drx-RetransmissionTimers for the designated carrier or for any
non-designated carriers associated with the designated carriers is
running. In a further embodiment, the designated carrier can go
into DRX even if one or more of the drx-RetransmissionTimers of the
non-designated carriers associated with the designated carriers are
still running.
[0117] Reference is now made to FIG. 3. In FIG. 3, designated
carrier 200 with which the non-designated carrier 305 is
associated, is similar to designated carrier 200 of FIG. 2.
[0118] Non-designated carrier 305 associated with the designated
carrier 200 has only a drx-RetransmissionTimer configured for each
of its downlink HARQ processes.
[0119] As illustrated in FIG. 3, explicit signaling is sent by the
eNB to the UE to indicate to the UE to activate the non-designated
carrier 305. This is shown by arrow 310. The non-designated carrier
then goes into Active time for a period that is determined either
by the Active time 136 of the associated designated carrier 200, or
as indicated above, may be determined by a
drx-RetransmissionTimer.
[0120] Assuming that no drx-RetransmissionTimers are running, at
134, designated carrier 200 moves into DRX. At the same time, the
UE disables reception on the non-designated carrier 305.
[0121] In a second Active period, the UE receives eNB signaling for
the non-designated carrier 305 to enable reception, as shown by
320. The reception is subsequently disabled by explicit eNB
signaling to the UE, as shown by arrow 322.
[0122] 3. Mixing of the Embodiments FIG. 2 and FIG. 3
[0123] Reference is now made to FIG. 4. The DRX operation described
in FIG. 2 and FIG. 3 above can occur at different times for the
same UE, on the same or different non-designated carriers. When the
eNB signals the UE to enable carrier reception for a non-designated
carrier, the eNB can indicate to the UE whether to maintain the
drx-InactivityTimer for that non-designated carrier. In one
embodiment, if the eNB indicates to the UE to maintain the
drx-InactivityTimer, the DRX operation described with regard to
FIG. 2 above follows. Otherwise, DRX operation described with
reference to FIG. 3 above follows. In other embodiments the
signaling could be reversed, and the drx-InactivityTimer could be
used unless explicit signaling indicates otherwise.
[0124] FIG. 4 shows signaling in which two non-designated carriers
are activated. Namely, non-designated carrier 205 is activated with
a message shown by arrow 210. In the message of arrow 210, the eNB
signals that a drx-InactivityTimer should be utilized. Such
signaling can, for example, be indicated with a single bit flag. In
other embodiments, the signaling may include a value for the
drx-InactivityTimer. Other signaling that the drx-InactivityTimer
should be used is possible.
[0125] Based on the message of arrow 210, the non-designated
carrier 205 proceeds as indicated above with regard to FIG. 2. At
the expiration of the drx-InactivityTimer 222, the non-designated
carrier 205 proceeds to disable reception as shown at reference
numeral 230.
[0126] Similarly, non-designated carrier 305 is signaled to
activate, as shown by reference numeral 310. The signaling does not
provide a drx-InactivityTimer or an indication that a
drx-InactivityTimer should be utilized. In this regard, the Active
time of non-designated carrier 305 follows the Active time 136 of
the associated designated carrier 200. An exception may occur if
the drx-RetransmissionTimer is running.
[0127] Similarly, explicit signaling to enable reception on
non-designated carrier 305 may be provided as illustrated by arrow
320 and explicit signaling to disable reception on non-designated
carrier 305 may also be provided, as shown by arrow 322.
[0128] 4. Inherent Activation
[0129] In a further embodiment, at the start of the On Duration on
the designated carrier, the UE enables carrier reception on a
non-designated carrier associated with the designated carrier
assigned by the eNB. The UE continues to enable carrier reception
on the non-designated carrier during the Active time of the
associated designated carrier, unless explicit signaling is
received from the eNB to instruct the UE to disable carrier
reception on the non-designated carrier.
[0130] Since the HARQ retransmission process occurs independently
between the designated carrier and the non-designated carrier, each
of the carriers maintains its own drx-RetransmissionTimers for each
of its HARQ processes. The designated carrier remains in Active
time when the drx-InactivityTimer for the designated carrier or at
least one of the DRX retransmission timers for the designated
carrier or for any non-designated carrier associated with the
designated carrier is running.
[0131] Reference is now made to FIG. 5. In FIG. 5, designated
carrier 200 with which the non-designated carrier 505 is
associated, is similar to designated carrier 200 described above
with reference to FIGS. 2 to 4.
[0132] With regard to non-designated carrier 505, at a time
illustrated by 510, which corresponds with the time illustrated by
reference numeral 120, the active time for non-designated carrier
505 starts. Similarly, when drx-InactivityTimer 132 expires as
shown by arrow 134, the non-designated carrier 505 also proceeds to
DRX, as shown by reference numeral 512.
[0133] Subsequently, at the expiration of the short DRX cycle 150,
both designated carrier 200 and non-designated carrier 505
associated with the designated carrier 200 proceed to Active time,
as shown at reference numeral 520.
[0134] In the example of FIG. 5, explicit signaling from the eNB to
the UE, as provided by arrow 522, causes the UE to disable
reception on the non-designated carrier 505 and proceed to DRX.
However, in one embodiment of FIG. 5, the next Active time cycle on
designated carrier 200 also causes the non-designated carrier 505
associated with the designated carrier 200 to proceed to Active
time.
[0135] As indicated above, the Active time 136 may be extended
based on a drx-RetransmissionTimer running on non-designated
carrier 505.
[0136] 5. Inherent Activation, Inactivity Timer
[0137] In a further embodiment, similar to the embodiment described
above with regard to FIG. 5, at the start of the On Duration of the
designated carrier, the UE enables carrier reception on a
non-designated carrier associated with the designated carrier
assigned by the eNB. In some embodiments carrier reception on
multiple non-designated carriers associated with the designated
carrier may be enabled.
[0138] In addition, a drx-InactivityTimer is maintained for the
non-designated carrier. The drx-InactivityTimer is started when the
carrier reception of the non-designated carrier is enabled at the
start of the On Duration of the associated designated carrier. The
drx-InactivityTimer is restarted whenever a new PDSCH packet is
received on the non-designated carrier. A drx-RetransmissionTimer
is also maintained during Active time of the non-designated
carrier. The drx-RetransmissionTimer for an HARQ process is started
at the earliest time when a retransmission may be expected for a
previously transmitted packet on the corresponding HARQ process.
The drx-RetransmissionTimer for an HARQ process is disabled when a
packet is received correctly for the process or the maximum number
of retransmissions has been reached.
[0139] The non-designated carrier remains in Active time when
either the drx-InactivityTimer or the drx-RetransmissionTimer is
running. At any time during the Active time on the non-designated
carrier, the eNB can instruct the UE through signaling to disable
carrier reception on the non-designated carrier.
[0140] In one embodiment, the designated carrier may delay moving
from an Active time to DRX until all the inactivity timers and DRX
retransmission timers have expired on the non-designated carrier(s)
associated with the designated carrier.
[0141] Referring to FIG. 6, designated carrier 200 with which the
non-designated carrier 605 is associated, is similar to the
designated carriers described above.
[0142] A non-designated carrier 605 is activated at the On Duration
122 of the associated designated carrier 200. Specifically, as
shown at reference numeral 610, the Active time starts at the same
time 120 as the associated designated carrier 200.
[0143] The drx-InactivityTimer 622 for the non-designated carrier
is restarted when the last new PDSCH packet is received on that
non-designated carrier as shown by arrow 620.
[0144] At the expiration of the drx-InactivityTimer 622, the
non-designated carrier 605 proceeds to a DRX period, as shown at
reference numeral 630.
[0145] Subsequently, as shown at reference numeral 640, the
non-designated carrier 605 proceeds to an Active time in
conjunction with the expiration of the short DRX cycle 150 of the
associated designated carrier 200.
[0146] An explicit message 642 is received from the eNB, causing
the non-designated carrier 605 to disable reception. However, in
one embodiment, a subsequent On Duration at the associated
designated carrier 200 causes the non-designated carrier 605 to
proceed to an Active time.
[0147] A drx-RetransmissionTimer 624 may also be utilized to extend
the Active time of non-designated carrier 605.
[0148] 6. Specifying an On Duration Timer for Non-Designated
Carriers
[0149] In a further embodiment, the eNB may signal an On Duration
timer for a non-designated carrier to the UE through RRC signaling
or MAC CE or other signaling methods. The OnDurationTimer is in
addition to the drx-RetransmissionTimers.
[0150] Similar to the embodiment described with reference to FIG. 5
above, at the start of the On Duration on the associated designated
carrier, the UE enables carrier reception on a non-designated
carrier assigned by the eNB. The UE also starts the OnDurationTimer
at this time.
[0151] drx-RetransmissionTimers are also maintained during the
Active time of the non-designated carrier. The
drx-RetransmissionTimer for an HARQ process is started at the
earliest time when a retransmission may be expected for a
previously transmitted packet on the corresponding HARQ process.
The drx-RetransmissionTimer for an HARQ process is disabled when a
packet is received correctly for this HARQ process or the maximum
number of retransmissions has been reached.
[0152] The UE remains in Active time for the non-designated carrier
when the OnDurationTimer is running and when the associated
designated carrier is in Active time or when a
drx-RetransmissionTimer is running for the non-designated carrier.
In another embodiment, the UE remains in Active time for the
non-designated carrier when the OnDurationTimer is running or when
a drx-RetransmissionTimer is running, regardless of whether the
associated designated carrier is in Active time or not.
Furthermore, in one embodiment, the eNB may instruct the UE through
signaling to disable carrier reception on the non-designated
carrier anytime during the Active time of the non-designated
carrier.
[0153] Referring to FIG. 7, designated carrier 200 with which the
non-designated carrier 705 is associated, is similar to the
designated carrier 200 described above.
[0154] A non-designated carrier 705 follows the activation of the
Active time of the associated designated carrier. Thus, as shown at
reference numeral 710, the non-designated carrier 705 proceeds to
an active mode similar to that shown by reference numeral 120 for
associated designated carrier 200.
[0155] In the embodiment of FIG. 7, the OnDurationTimer 720 expires
at a time shown by reference numeral 722. At this point, the UE
disables reception on the non-designated carrier 705.
[0156] Reception is enabled on non-designated carrier 705 at a time
shown by reference numeral 730 which corresponds with the end of
the short DRX cycle 150 when the associated designated carrier 200
proceeds back into an Active mode as shown by reference numeral
110.
[0157] Subsequently, an explicit signal is received to disable the
non-designated carrier 705. The explicit signal is shown by arrow
732, causing non-designated carrier 705 to disable reception.
[0158] Reference is made to FIG. 8. In an alternative embodiment,
the OnDurationTimer 820 in FIG. 8 is set to be for a relatively
long period.
[0159] In the embodiment of FIG. 8, the non-designated carrier 705
proceeds into an Active time at a time 710. This corresponds with
the activation of the associated designated carrier 200 to an
Active time as shown by reference numeral 120.
[0160] However, as opposed to the embodiment of FIG. 7, the
OnDurationTimer 820 does not expire in the embodiment of FIG. 8
prior to the associated designated carrier 200 proceeding back into
a DRX mode at the end of Active time 136. In this case, the UE
disables reception on the non-designated carrier 705 at a time
shown by reference numeral 822 corresponding with the end of the
Active time 136 of the associated designated carrier 200.
[0161] The remaining points of FIG. 8 correspond with those of FIG.
7.
[0162] Thus, in accordance with the embodiments above, the
OnDurationTimer may force the UE to disable reception on the
non-designated carrier 705 prior to the Active time 136 of the
associated designated carrier 200 expiring. Conversely, if the
Active time 136 of the associated designated carrier 200 expires
prior to the expiration of OnDurationTimer 820 of non-designated
carrier 705, this may cause the UE to disable reception on the
non-designated carrier 705.
[0163] 7. Signaling an OnDurationTimer and a
drx-InactivityTimer
[0164] In a further embodiment, the eNB can signal an
OnDurationTimer for the non-designated carrier to the UE through
RRC signaling, a MAC CE or other signaling, in addition to the
drx-RetransmissionTimer and the drx-InactivityTimer. Similar to
FIG. 6 above, at the start of the On Duration on the associated
designated carrier, the UE enables carrier reception on a
non-designated carrier assigned by the eNB. The UE also starts the
OnDurationTimer and the drx-InactivityTimer at this time.
[0165] The drx-InactivityTimer is restarted whenever a new PDSCH
packet is received on the non-designated carrier.
drx-RetransmissionTimers are also maintained during the Active time
of the non-designated carrier. The drx-RetransmissionTimer for an
HARQ process is started at the earliest time when retransmission
may be expected for a previously transmitted packet on the
corresponding HARQ process. The drx-RetransmissionTimer for an HARQ
process is disabled when a packet is received correctly for the
HARQ process or the maximum number of retransmissions has been
reached.
[0166] The UE remains in Active time on the non-designated carrier
when the OnDurationTimer is running and the associated designated
carrier is in Active time, or the drx-Inactivity timer is running
or a drx-RetransmissionTimer is running. In another embodiment, the
UE remains in Active time for the non-designated carrier when the
OnDurationTimer is running or the drx-Inactivity timer is running
or a drx-RetransmissionTimer is running, regardless of whether the
associated designated carrier is in Active time or not.
[0167] At any time during the Active time on the non-designated
carrier, the eNB can instruct the UE through signaling to disable
carrier reception on the non-designated carrier.
[0168] Reference is now made to FIG. 9. In FIG. 9, a designated
carrier 200 with which the non-designated carrier 905 is
associated, is similar to those as described above.
[0169] With regard to non-designated carrier 905, an
OnDurationTimer 912 value is signaled by the eNB to the UE, as well
as a drx-InactivityTimer 922.
[0170] With regard to FIG. 9, in a similar manner to that described
above with regard to FIG. 7, the Active time 910 of non-designated
carrier 905 may be the OnDurationTimer 912 value. In addition, the
Active time 910 may be extended based on the drx-InactivityTimer
922. When the last new PDSCH packet is received as shown by arrow
920 the drx-InactivityTimer restarts and continues running until a
time, as shown by reference numeral 930, the drx-InactivityTimer
expires, at which point the non-designated carrier 905 proceeds to
disable reception.
[0171] In other embodiments, a drx-RetransmissionTimer 924 may
extend the Active time 910.
[0172] The OnDurationTimer 912 is reset and the non-designated
carrier 905 proceeds to an Active time at a time shown by reference
numeral 940, which corresponds with the end of the short DRX cycle
150 for the associated designated carrier 200. Explicit signaling
is provided to the UE to disable non-designated carrier 905, as
depicted by arrow 942.
[0173] In other embodiments, the Active time 136 of FIG. 9 may be
extended if the drx-InactivityTimer 922 or a
drx-RetransmissionTimer 924 on non-designated carrier 905 is still
running. Alternatively, the non-designated carrier 905 may be
forced to disable reception at the end of Active time 136,
regardless of whether drx-InactivityTimer 922 or
drx-RetransmissionTimer 924 has expired.
[0174] In a further alternative embodiment, the Active time 910 of
non-designated carrier 905 may exceed the Active time 136 of the
associated designated carrier 200.
[0175] 8. drx-FollowDesignatedTimer
[0176] In a further embodiment, the eNB may signal a
"drx-FollowDesignatedTimer" for the non-designated carrier to the
UE through RRC signaling or a MAC CE, or other methods of
communication. In addition, the drx-RetransmissionTimer may be
signaled.
[0177] The drx-FollowDesignatedTimer value may be configured
`statically` such as through RRC signaling or dynamically through a
MAC CE. During the Active time on the designated carrier, the eNB
may instruct the UE, through signaling, to enable carrier reception
on the non-designated carrier associated with the designated
carrier at a specific action time. For the case of dynamic
configuration of the drx-FollowDesignatedTimer, the signaling to
enable the carrier reception of the non-designated carrier includes
the drx-FollowDesignatedTimer value. At the action time, the UE
starts the drx-FollowDesignatedTimer.
[0178] drx-RetransmissionTimers are also maintained during the
Active time of the non-designated carrier. The
drx-RetransmissionTimer for an HARQ process is started at the
earliest time when a retransmission may be expected for a
previously transmitted packet on the corresponding HARQ process.
The drx-RetransmissionTimer for an HARQ process is disabled when a
packet is received correctly for the HARQ process or maximum number
of retransmissions has been reached. When the
drx-FollowDesignatedTimer is running, the UE only remains in Active
time on the non-designated carrier when the associated designated
carrier is in Active time or when a drx-Retransmission Timer is
running. When the drx-FollowDesignatedTimer is expired, and if the
drx-Retransmission Timer has also expired, the UE disables the
carrier reception on the non-designated carrier regardless of the
Active time of the associated designated carrier.
[0179] In one specific embodiment, the drx-FollowDesignatedTimer is
of several Long DRX cycles or Short DRX cycles in duration. This
means that the Active time of the non-designated carrier will
follow that of the associated designated carrier for several Long
DRX cycles or Short DRX cycles and then carrier reception on the
non-designated carrier will be disabled.
[0180] Reference is now made to FIG. 10. In FIG. 10, the designated
carrier 200 with which the non-designated carrier 1005 is
associated, is similar to that described above.
[0181] Explicit signaling 1008 provides the start for the
non-designated carrier 1005.
[0182] Non-designated carrier 1005 has a drx-FollowDesignatedTimer
1020 signaled to it. Such signaling may include a pre-configured
value or may have a dynamic value as indicated above.
[0183] The non-designated carrier 1005 follows the associated
designated carrier 200 during the time when the
drx-FollowDesignatedTimer 1020 is Active. Thus, at the time shown
by reference numeral 1010 the non-designated carrier 1005 proceeds
to an Active mode and at a time shown by reference numeral 1022 the
non-designated carrier 1005 proceeds to a DRX mode or where
reception is disabled. This time shown by reference numeral 1022
corresponds with the expiration of the drx-InactivityTimer 132 on
the associated designated carrier 200.
[0184] Similarly, at the expiration of short DRX cycle 150 in the
example of FIG. 10, the non-designated carrier 1005 proceeds back
to an Active time, as shown at reference numeral 1030.
[0185] At the expiration of the drx-FollowDesignatedTimer 1020, the
non-designated carrier 1005 disables reception until further
explicit signaling is received.
[0186] In some embodiments, the drx-FollowDesignatedTimer 1020 may
be used in conjunction with a drx-InactivityTimer.
[0187] The LTE Rel 8 specification, such as 3GPP TS 36.321 may be
supplemented to account for the embodiments described above.
Examples of such specification additions for the designated carrier
may be:
[0188] When a DRX cycle is configured on the designated carrier,
the Active Time includes the time while: [0189] on
DurationTimer.sub.DC or drx-InactivityTimer.sub.DC or
drx-RetransmissionTimer.sub.DC or
mac-ContentionResolutionTimer.sub.DC (as described in subclause
5.1.5) is running; or [0190] a Scheduling Request sent on PUCCH of
any UL carrier assigned to the UE is pending (as described in
subclause 5.4.4); or [0191] an uplink grant/DL ACK/NAK on PHICH for
a pending HARQ retransmission on any UL carrier assigned to the UE
[or a UL carrier whose grant/DL ACK/NAK on PHICH may appear on the
DL designated carrier] can occur and there is data in the
corresponding HARQ buffer; or [0192] a PDCCH indicating a new
transmission addressed to the C-RNTI of the UE has not been
received after successful reception of a Random Access Response for
the explicitely signaled preamble (as described in subclause
5.1.4); or [0193] drx-InactivityTimer.sub.i or
drx-RetransmissionTimer.sub.i is running on at least one of the DL
non-designated carriers associated with the designated carrier; or
an uplink grant/DL ACK/NAK on PHICH for a pending HARQ
retransmission on a UL carrier, whose grant may appear on any of
the DL non-designated carriers associated with the designated
carrier, can occur and there is data in the corresponding HARQ
buffer.
[0194] When DRX is configured on the designated carrier, the UE
shall for each subframe: [0195] If the Short DRX Cycle is used and
[(SFN*10)+subframe number] modulo
(shortDRX-Cycle.sub.DC)=(drxStartOffset.sub.DC) modulo
(shortDRX-Cycle.sub.DC); or [0196] if the Long DRX Cycle is used
and [(SFN*10)+subframe number] modulo
(LongDRX-Cycle.sub.DC)=drxStartOffset.sub.DC: [0197] start on
DurationTimer.sub.DC. [0198] if a HARQ RTT Timer expires in this
subframe and the data in the soft buffer of the corresponding HARQ
process was not successfully decoded: [0199] start the
drx-RetransmissionTimer.sub.DC for the corresponding HARQ process.
[0200] if a DRX Command MAC control element is received: [0201]
stop on DurationTimer.sub.DC; [0202] stop
drx-InactivityTimer.sub.DC. [0203] if drx-InactivityTimer.sub.DC
expires or a DRX Command MAC control element is received in this
subframe: [0204] if the short DRX cycle is configured: [0205] start
or restart drxShortCycleTimer.sub.DC; [0206] use the Short DRX
Cycle.sub.DC. [0207] else: [0208] use the Long DRX cycle.sub.DC.
[0209] if drxShortCycleTimer.sub.DC expires in this subframe:
[0210] use the long DRX cycle.sub.DC. [0211] during the Active
Time, for a PDCCH-subframe except if the subframe is required for
uplink transmission for half-duplex FDD UE operation and except if
the subframe is part of a configured measurement gap: [0212]
monitor the PDCCH; [0213] if the PDCCH indicates a DL transmission
or if a DL assignment has been configured for this subframe: [0214]
start the HARQ RTT Timer for the corresponding HARQ process; [0215]
stop the drx-RetransmissionTimer.sub.DC for the corresponding HARQ
process. [0216] if the PDCCH indicates a new transmission (DL or
UL): [0217] start or restart drx-InactivityTimer.sub.DC. [0218]
when not in Active Time, CQI/PMI/RI on PUCCH and SRS shall not be
reported.
[0219] Regardless of whether the UE is monitoring PDCCH or not the
UE receives and transmits HARQ feedback when such is expected.
[0220] NOTE: A UE may optionally choose to not send CQI/PMI/RI
reports on PUCCH and/or SRS transmissions for up to 4 subframes
following a PDCCH indicating a new transmission (UL or DL) received
in the last subframe of active time. The choice not to send
CQI/PMI/RI reports on PUCCH and/or SRS transmissions is not
applicable for subframes where on DurationTimer is running.
[0221] For the non-designated carrier, building on the embodiments
above, for each of the M non-designated carriers, where M is
defined as above, the carrier reception on that carrier can be
enabled implicitly at the start of the On Duration of the
designated carrier with which the non-designated carrier is
associated, i.e. mode 1; or can be enabled explicitly during the
Active time of the associated designated carrier, through explicit
eNB signaling to the UE, i.e., mode 2. These two modes can be
configured and signaled (e.g. through RRC signaling) by the eNB to
the UE for each of the M non-designated carriers. In mode 2, during
the Active time on the designated carrier, the eNB may instruct the
UE to enable carrier reception on another non-designated component
carrier (e.g. carrier i) associated with the designated carrier,
through control signaling (e.g. RRC signaling, PDCCH, or MAC
control element) sent on the designated carrier or one of the other
N component carriers, where N is defined above.
[0222] The action time to enable the carrier reception on the
component carrier can be implicit (e.g. x subframes after receiving
the corresponding signaling from the eNB) or explicitly indicated
in the signaling message. The signaling message may also indicate
to the UE whether to maintain the drx-InactivityTimer.sub.i during
Active time. If drx-FollowDesignatedTimer.sub.i is configured for a
non-designated carrier, the initial enabling of the non-designated
carrier is using mode 2, i.e. through explicit signaling from the
eNB during the Active time of the associated designated carrier.
The drx-FollowDesignatedTimer is started at the action time. During
the time when drx-FollowDesignatedTimer is running, the
non-designated carrier is subsequently enabled using mode 1, i.e.
at the start of the On Duration of the associated designated
carrier.
[0223] When the carrier reception on carrier i is enabled either at
the start of the On Duration of the associated designated carrier
for mode 1 or at the action time for mode 2, UE starts the
drx-InactivityTimer.sub.i if drx-InactivityTimer, is configured and
the UE is instructed by the eNB to maintain the
drx-InactivityTimer.sub.i during Active time on carrier i.
Otherwise, the UE initializes the activeFlag.sub.i and sets it to
1. For mode 1, the UE also starts the on DurationTimer; if on
DurationTimer; is configured by the eNB. For mode 2, the UE starts
the drx-FollowDesignatedTimer.sub.i at the action time, if
drx-FollowDesignatedTimer.sub.i is configured by the eNB.
[0224] The specification addition for a non-designated carrier may
include:
[0225] When a DRX cycle is configured on a non-designated carrier
i, the Active Time on carrier i includes the time while: [0226]
drx-RetransmissionTimer.sub.i is running; or [0227]
drx-InactivityTimer.sub.i is running; or [0228] the
activeFlag.sub.i is set to 1, and the associated designated carrier
is in Active time; or [0229] on DurationTimer.sub.i is running and
the associated designated carrier is in Active time; or [0230]
drx-FollowDesignatedTimer.sub.i is running and the associated
designated carrier is in Active time; or [0231] an uplink grant/DL
ACK/NAK on PHICH for a pending HARQ retransmission on a UL carrier,
whose grant may appear on carrier i, can occur and there is data in
the corresponding HARQ buffer
[0232] When DRX is configured on a non-designated carrier i, the UE
shall for each subframe: [0233] if a HARQ RTT Timer expires in this
subframe and the data in the soft buffer of the corresponding HARQ
process was not successfully decoded: [0234] start the
drx-RetransmissionTimer.sub.i for the corresponding HARQ process.
[0235] if a signaling from the eNB (e.g. RRC signaling or MAC
control element) is received indicating disabling the carrier
reception on the component carrier i, [0236] stop
drx-InactivityTimer.sub.i if drx-InactivityTimer.sub.i is
configured, stop on DurationTimer.sub.i if on DurationTimer.sub.i
is configured, stop drx-RetransmissionTimer.sub.i, set
activeFlag.sub.i to 0 if activeFlag.sub.i is initialized, stop
drx-FollowDesignatedTimer.sub.i if drx-FollowDesignatedTimer.sub.i
is configured, at the action time indicated in the signaling. The
action time to disable the carrier reception on the component
carrier i can be implicit (e.g. y subframes after receiving the
corresponding signaling from the eNB) or explicitly indicated in
the signaling message. [0237] during the Active Time, except if the
subframe is required for uplink transmission for half-duplex FDD UE
operation and except if the subframe is part of a configured
measurement gap: [0238] enable carrier reception on the component
carrier i; [0239] if a DL transmission or if a DL assignment has
been configured for this subframe: [0240] start the HARQ RTT Timer
for the corresponding HARQ process; [0241] stop the
drx-RetransmissionTimer.sub.i for the corresponding HARQ process.
[0242] if a new transmission is received: [0243] start or restart
drx-InactivityTimer.sub.i. [0244] if
drx-FollowDesignatedTimer.sub.i expires, set activeFlag.sub.i to 0
if activeFlag.sub.i is initialized [0245] when not in Active Time,
CQI/PMI/RI on PUCCH and SRS shall not be reported on carrier i.
[0246] when not in Active Time, on DurationTimer.sub.i shall be
disabled if it has not expired.
[0247] Short and Long DRX Cycles on Both the Designated and
Non-Designated Carriers
[0248] In another embodiment, a full set of DRX parameters may be
configured for both the designated carrier(s) and the
non-designated carrier(s). Intelligent scheduling at the eNB could
enable the potential for efficient use of the Short and Long DRX
cycles on both the designated and non-designated carriers.
[0249] When the Short DRX cycle is also configured, a UE
essentially operates in the Short DRX cycle if it has recently
received resource allocations for new data (only new data, not HARQ
retransmissions). After a certain period of time with no new data
resource allocations having been received, the UE switches to the
Long DRX cycle after drxShortCycleTimer has expired. The UE
continues to use the Long DRX cycle until another new data resource
allocation is received on the PDCCH.
[0250] If each non-designated carrier was configured to operate
with both the Short and Long DRX cycles, then the UE would be able
to adapt to bursty traffic scenarios without the need for any
explicit signalling. A UE receiving a large amount of data would
have all of its carriers (both designated and non-designated)
operating with the Short DRX cycles. If the volume of data
decreased, an intelligent eNB would schedule all of the data for
the UE only on the designated carrier(s). This would cause the
designated carrier(s) to continue to operate with the Short DRX
cycle, while the non-designated carriers would automatically switch
to using the Long DRX cycle after drxShortCycleTimer has expired
(since they would not be receiving any new data resource
allocations). If the traffic activity for the UE then increased,
the non-designated carriers would again start being used by the eNB
during the On Duration and these non-designated carriers would
automatically switch back to the Short DRX cycle mode. The
boundaries of the Short DRX cycle and Long DRX cycle of a
non-designated carrier may align with those of the associated
designated carrier(s).
[0251] A further extension of the above is that a carrier that had
not been used in a certain period of time (e.g. a configured
multiple of the Long DRX cycle length) would be automatically
(implicitly) deactivated by the UE and would need to be re-enabled
by the eNB before being used.
[0252] In a further embodiment, the implicit activation of a
carrier at the UE is possible. If a resource assignment for a
currently-disabled carrier was received by the UE on the associated
PDCCH, then that carrier should be immediately reactivated. As
would be appreciated, the resource assignment that caused the
implicit activation could not be processed, but any future resource
assignments on the carrier in question would be able to be
processed.
[0253] Reference is now made to FIG. 11. In FIG. 11, an designated
carrier 200 operates as described above.
[0254] A non-designated carrier 1105 is configured independently
with a short DRX cycle 1150 and a long DRX cycle 1152. At the start
of data exchange, non-designated carrier 1105 is configured to
utilise the short DRX cycle. Thus, as illustrated in FIG. 11
non-designated carrier 1105 follows designated carrier 200 for the
active time.
[0255] If no data is received on the non-designated carrier 1105
for the short DRX cycle 1150 duration, the non-designated carrier
switches to a long DRX cycle 1152 as illustrated in FIG. 11. In the
example of FIG. 11, long DRX cycle 1152 is twice as long as short
DRX cycle 1150. However, this is not meant to be limiting since the
Long DRX cycle can be any multiple of the Short DRX cycle.
[0256] Signaling
[0257] Signaling DRX Parameters
[0258] As described above, the eNB may configure DRX parameters for
the designated carrier(s) and DRX parameters for a set of M
non-designated carriers for a UE. For each of the M non-designated
carriers, the set of DRX parameters includes
drx-RetransmissionTimer, may include drx-InactivityTimer, may
include on DurationTimer and may include drx-FollowDesignatedTimer.
For each of the M non-designated carriers, the eNB may configure
the designated carrier associated with the non-designated carrier.
For each of the M non-designated carriers, the eNB may indicate
whether the UE should enable carrier reception on that carrier at
the start of the On Duration of the associated designated carrier,
or enable the carrier reception on that carrier only if explicit
activation signaling is received from the eNB.
[0259] In one embodiment, the values of drx-InactivityTimer (if
included), on DurationTimer (if included), drx-RetransmissionTimer
are the same across all the component carriers. In this case, the
RRC signaling used to configure the DRX functionality does not need
to include the drx-InactivityTimer, on DurationTimer and
drx-RetransmissionTimer fields for each of the component carriers.
The values of the full set of DRX parameters can be included in the
RRC signaling for one of the designated carriers, while the values
of the DRX parameters of other designated carriers, and the
drx-InactivityTimer (if included), on DurationTimer (if included)
and drx-RetransmissionTimer of other M non-designated component
carriers are the same as those of the designated carrier. The RRC
signaling also includes the drx-FollowDesignatedTimer for those
non-designated carriers where the drx-FollowDesignatedTimer is
configured.
[0260] In another embodiment, the values of the DRX parameters for
different designated carriers are different. The values of
drx-InactivityTimer (if included), on DurationTimer (if included),
drx-RetransmissionTimer of a non-designated component carrier are
the same as those of the associated designated carrier. In this
case, the RRC signaling includes the full set of DRX parameters for
each of the designated carriers. The drx-InactivityTimer (if
included), on DurationTimer (if included) and
drx-RetransmissionTimer values for each of the M non-designated
component carriers are the same as those of its associated
designated carrier.
[0261] In another embodiment, the values of drx-InactivityTimer (if
included), on DurationTimer (if included), drx-RetransmissionTimer,
and drx-FollowDesignatedTimer (if included for the non-designated
carrier) are different for the different component carriers. In
this case, the RRC signaling includes a full set of DRX parameters
for the designated carrier(s), and a reduced set of DRX parameters,
i.e., drx-InactivityTimer (if included), on DurationTimer (if
included), drx-RetransmissionTimer, and drx-FollowDesignatedTimer
(if included for the non-designated carrier) for each of the M
other component carriers.
[0262] In yet another embodiment, the values of drx-InactivityTimer
(if included), on DurationTimer (if included) and
drx-Retransmission Timer of some of the component carriers are the
same as those of their associated designated carriers while the
values of drx-InactivityTimer (if included), on DurationTimer (if
included) and drx-Retransmission Timer of some other component
carriers are different than those of their designated carriers. In
this case, the RRC signaling includes a full set of DRX parameters
for the designated carriers, a reduced set of DRX parameters, i.e.,
drx-InactivityTimer (if included), on DurationTimer (if included)
and drx-RetransmissionTimer for some of the M component carriers,
and drx-FollowDesignatedTimer for some of the M component carriers
where drx-FollowDesignatedTimer is configured.
[0263] In yet another embodiment, the DRX parameters of all the
non-designated carriers are configured to be the same values. In
this case, the RRC signaling includes a full set of DRX parameters
for the designated carrier(s) and a reduced set of DRX parameters,
i.e., drx-InactivityTimer (if included), on DurationTimer (if
included), drx-Retransmission Timer, and drx-FollowDesignatedTimer
(if included) for all the M other component carriers.
[0264] Table 1 below shows an example of the fields included in the
corresponding RRC signaling that support the different embodiments.
The signaling fields and format shown are not meant to be limiting.
It should be appreciated by those skilled in the art that other
signaling fields and formats are also possible having regard to the
present disclosure are also contemplated.
TABLE-US-00001 TABLE 1 An example of DRX parameters included in the
RRC signalling Fields Definition Number of DRX-configured
designated carrier (D) Number of designated carriers where DRX
parameters are configured For (i=0; i<D; i++) { Designated
carrier index Logical carrier index for the assigned designated
carrier onDurationTimer.sub.DC onDurationTimer of the designated
carrier drx-InactivityTimer.sub.DC drx-InactivityTimer of the
designated carrier drx-RetransmissionTimer.sub.DC
drx-RetransmissionTimer of the designated carrier
longDRX-CycleStartOffset.sub.DC longDRX-Cycle and drxStartOffset of
the designated carrier shortDRX-Cycle.sub.DC shortDRX-Cycle of the
designated carrier (optional) drxShortCycleTimer.sub.DC
drxShortCycleTimer of the designated carrier (optional) } Number of
DRX-configured non-designated Number of non-designated carriers
where carriers (M) DRX parameters are configured for (i=0; i<M;
i++) { Assocated designated carrier Logical/physical carrier index
of the designated carrier with which this non- designated carrier
is associated Implicit/explicit start of Active time A flag to
indicate whether the start of the Active time on the non-designated
carrier i, is aligned to the On Duration of the associated
designated carrier (i.e. implicit); or the start of the Active time
on the non- designated carrier i is explicitly signalled by the eNB
during the Active time of the associated designated carrier.
drx-InactivityTimer.sub.i --configured A flag to indicate whether
drx- InactivityTimer for carrier i is configured. Set to 1 to
indicate that it is configured. Set to 0 to indicate that it is not
configured. If (drx-InactivityTimer.sub.i --configured == 1) {
drx-InactivityTimer.sub.i --value_included A flag to indicate
whether the value of drx- InactivityTimer for carrier i is
included. Set to 1 to indicate the value is included. Set to 0 to
indicate the value is not included and it is the same as that of
the associated designated carrier. If (drx-InactivityTimer.sub.i
--value_included == 1) { drx-InactivityTimer.sub.i Value of
drx-InactivityTimer.sub.i } } drx-RetransmissionTimer.sub.i
--value_included A flag to indicate whether the value of drx-
RetransmissionTimer for carrier i is included. Set to 1 to indicate
the value is included. Set to 0 to indicate the value is not
included since it is the same as that of the associated designated
carrier. If (drx-RetransmissionTimer.sub.i --value included == 1) {
drx-RetransmissionTimer.sub.i Value of
drx-RetransmissionTimer.sub.i } onDurationTimer.sub.i --configured
A flag to indicate whether onDurationTimer for carrier i is
configured. Set to 1 to indicate that it is configured. Set to 0 to
indicate that it is not configured. If (onDurationTimer.sub.i
--configured == 1) { onDurationTimer.sub.i --value_included A flag
to indicate whether the value of onDurationTimer for carrier i is
included. Set to 1 to indicate the value is included. Set to 0 to
indicate the value is not included since it is the same as that of
the associated designated carrier. If (onDurationTimer.sub.i
--value_included == 1) { onDurationTimer.sub.i Value of
onDurationTimer.sub.i } } drx-FollowDesignatedTimer.sub.i
--configured A flag to indicate whether drx- FollowDesignatedTimer
for carrier i is configured. Set to 1 to indicate that it is
configured. Set to 0 to indicate that it is not configured. If
(drx-FollowDesignatedTimer.sub.i --configured == 1) {
drx-FollowDesignatedTimer.sub.i Value of
drx-FollowDesignatedTimer.sub.i } }
[0265] Signaling from the eNB to the UE to Enable/Disable Carrier
Reception
[0266] The eNB can instruct the UE to enable or disable carrier
reception on a component carrier, through RRC signaling or MAC CE
or even via certain Downlink Control Information (DCI) formats on
PDCCH (i.e., Layer 1 signaling). The RRC signaling or MAC CE or
PDDCH can be sent on a designated carrier only or on any of the N
component carriers, where N is defined above. In the signaling
message sent in RRC signaling, MAC CE or PDCCH to enable carrier
reception on a component carrier, a field may be included to
indicate whether the component carrier is a designated carrier or a
non-designated carrier.
[0267] Reference is now made to FIG. 12. FIG. 12 shows an example
of the `carrier reception enable/disable command MAC control
element` 1200 sent by the eNB to the UE to enable/disable the
carrier reception on a carrier, with explicit action time. The new
MAC control element 1200 can use one of the reserved DL LCID
(logical channel ID) values for DL-SCH (downlink shared channel)
shown in Table 6.2.1-1 of 3GPP TS 36.321. `DS` 1205 is a one-bit
field to indicate if the carrier is a designated or a
non-designated carrier. `E/D` 1210 is a one-bit field to indicate
if the command is to enable or disable the carrier reception.
`Carrier Index` 1220 is the physical or logical carrier index of
the carrier on which the carrier reception should be
enabled/disabled. If the `E/D` 1210 is set to disable carrier
reception, the value of `DS` 1205 can be set to a pre-defined value
and is ignored by the UE. Another embodiment is that only the
carrier over which the "carrier reception enable/disable command
MAC control element" 1200 is sent will be impacted by this command.
For example, if a MAC CE disabling the carrier reception is
received on carrier #3, then carrier #3 will disable carrier
reception. The action time for when the carrier reception on the
carrier should be enabled/disabled is defined by the next radio
frame with the 4 least significant bits (LSB) of system frame
number (SFN) equal to `Action time (LSB of SFN)` 1230, and the
subframe within this radio frame with the subframe number equals to
`Action time (subframe offset)` 1240.
[0268] Another alternative for the action time is to define a
relative time offset. Those skilled in the art will appreciate that
in some cases there may be some difficulty determining a fixed
reference timing for the relative time offset since the MAC CE
transmission may involve HARQ retransmissions. One possible way to
establish the fixed reference time is that when the HARQ ACK is
received on the UL, the eNB can derive that the UE receives the
corresponding MAC CE 4 ms earlier, since the HARQ feedback
transmission is, in one embodiment, 4 ms after the corresponding
transport block reception.
[0269] The 4 LSB of SFN allows up to 16 radio frames or 160 ms of
HARQ retransmission attempts for the MAC CE to be successfully
received at the UE and acknowledged back to the eNB. A MAC ACK CE
(called `carrier reception enable/disable ACK MAC control element`)
is defined in the uplink (UL) for the UE to acknowledge reception
of the `carrier reception enable/disable command MAC control
element`. The explicit acknowledgement protocol allows the eNB to
confirm that the UE has successfully received the `carrier
reception enable/disable command MAC control element` 1200 before
sending PDSCH data to the UE on the assigned carrier.
[0270] In general, control signaling is only acknowledged at the
RRC level. However, this particular MAC control signaling has a
potentially long-term consequence and is therefore of sufficient
importance to have some form of acknowledgement. RRC signaling is
possible, but in some embodiments may be too slow for the desired
purpose or may incur too much overhead as compared to the MAC level
signaling, proposed herein.
[0271] A further alternative solution to acknowledge reception of
the `carrier reception enable/disable command MAC control element`
1200 is to use the HARQ feedback. When the transport block
containing the MAC CE is transmitted to the UE, the eNB will
monitor the corresponding UL HARQ feedback. When the corresponding
HARQ ACK is received in the UL, the eNB considers that the `carrier
reception enable/disable command MAC control element` 1200 has been
successfully received by the UE.
[0272] Reference is now made to FIG. 13, which shows an example of
the `carrier reception enable/disable ACK MAC control element`
1300. `Carrier Index` 1310 is the physical or logical carrier index
of the carrier on which the carrier reception enabled/disabled
command is acknowledged. This new MAC CE 1300 can use one of the
reserved UL LCID values for UL-SCH shown in Table 6.2.1-2 of 3GPP
TS 36.321.
[0273] Reference is now made to FIG. 14, which provides another
example format for a MAC control element used to enable or disable
carrier reception on a carrier. Here, binary flags 1410, 1412, 1414
and 1416 are used to selectively enable or disable up to the
maximum of four carriers. The fields 1411, 1413, 1415, 1417 are
used to indicate whether each of the carriers indicated in 1410,
1412, 1414, 1416 respectively, is a designated carrier or a
non-designated carrier. If a CI field is set to disable carrier
reception, the corresponding value of DS field can be set to a
predefined value and is ignored by the UE.
[0274] As will be appreciated, in one embodiment having a
designated carrier and four non-designated carriers, the five
carriers may be aggregated with one UE. One carrier is the
designated carrier which is currently in Active time, leaving the
four non-designated carriers for binary flags 1410, 1412, 1414, and
1416. Further, in one embodiment, the Carrier Indices for any
non-allocated carriers would simply be treated as reserved or
padding bits.
[0275] For example, a value for binary flag 1410 of 0 would
indicate that the corresponding non-designated carrier shall be
disabled, while a value of 1 would indicate that the corresponding
non-designated carrier shall be enabled. Similarly, binary flags
1412, 1414 and 1416 could be set. Any carriers that were to
continue in their present state would simply have their
corresponding binary flags set to the same value as before. For
instance, if carriers 1 and 2, were currently enabled and carriers
3 and 4 were currently disabled, a binary value of 00001010 for the
first byte 1420 of the MAC control element would instruct the UE to
(a) keep carrier 1 enabled, (b) disable carrier 2, (c) enable
carrier 3, and (d) keep carrier 4 disabled. The action time fields
are signaled in the same manner as described above.
[0276] FIG. 15 contains the corresponding example format of an
acknowledgement MAC CE 1500 that would acknowledge reception by the
UE of the carrier enable/disable MAC control element shown in FIG.
14. The values of binary flags 1510, 1512, 1514 and 1516,
corresponding to CI.sub.1, CI.sub.2, CI.sub.3, CI.sub.4 are set to
the same as the corresponding binary flag values 1410, 1412, 1414,
and 1416 previously received in `carrier reception enable/disable
command MAC control element` 1400 of FIG. 14.
[0277] An advantage of the MAC CE format of FIGS. 14 and 15 is that
multiple carriers can be simultaneously enabled and/or disabled by
the same MAC CE, without the need for sending multiple MAC control
elements (thereby representing additional signaling overhead) in
order to achieve the same goal.
[0278] If the ability to enable and disable uplink carriers
selectively is also desired, the MAC CE discussed above could be
extended as shown by MAC control element 1600 in FIG. 16 to handle
up to the maximum of four downlink carriers and four uplink
carriers. The one-bit enable/disable field for each carrier would
function in the same manner as previously discussed. In particular
downlink carrier flags 1610, 1612, 1614 and 1616 control four
downlink carriers and uplink carrier flags 1620, 1622, 1624 and
1626 control activation/deactivation of four uplink carriers.
[0279] FIG. 17 shows the corresponding MAC CE 1700 format for
acknowledging reception by the UE of the carrier enable/disable MAC
CE 1600 shown in FIG. 16. Thus downlink carrier flags 1710, 1712,
1714 and 1716 correspond with downlink carrier flags 1610, 1612,
1614 and 1616 and uplink carrier flags 1720, 1722, 1724 and 1726
correspond with uplink carrier flags 1620, 1622, 1624 and 1626.
[0280] As for the set of MAC CEs proposed in FIGS. 14 and 15, the
contents of the acknowledgement control element in FIG. 17 would
mirror the first payload byte of the enable/disable control element
in FIG. 16.
[0281] As will be appreciated, the above can be implemented on any
UE. One exemplary UE is described below with reference to FIG. 18.
This is not meant to be limiting, but is provided for illustrative
purposes.
[0282] FIG. 18 is a block diagram illustrating a UE capable of
being used with embodiments of the apparatus and method of the
present application. Mobile device 1800 is typically a two-way
wireless communication device having voice or data communication
capabilities. Depending on the exact functionality provided, the
wireless device may be referred to as a data messaging device, a
two-way pager, a wireless e-mail device, a cellular telephone with
data messaging capabilities, a wireless Internet appliance, a
mobile device, or a data communication device, as examples.
[0283] Where UE 1800 is enabled for two-way communication, it
incorporates a communication subsystem 1811, including both a
receiver 1812 and a transmitter 1814, as well as associated
components such as one or more, generally embedded or internal,
antenna elements 1816 and 1818, local oscillators (LOs) 1813, and a
processing module such as a digital signal processor (DSP) 1820. As
will be apparent to those skilled in the field of communications,
the particular design of the communication subsystem 1811 will be
dependent upon the communication network in which the device is
intended to operate.
[0284] Network access requirements will also vary depending upon
the type of network 1819. An LTE UE may require a subscriber
identity module (SIM) card in order to operate on the LTE or LTE-A
network. The SIM interface 1844 is normally similar to a card-slot
into which a SIM card can be inserted and ejected like a diskette
or PCMCIA card. The SIM card may hold key configuration 1851, and
other information 1853 such as identification, and subscriber
related information.
[0285] When required network registration or activation procedures
have been completed, UE 1800 may send and receive communication
signals over the network 1819. As illustrated in FIG. 18, network
1819 can consist of multiple antennas communicating with the UE.
These antennas are in turn connected to an eNB 1870.
[0286] Signals received by antenna 1816 through communication
network 1819 are input to receiver 1812, which may perform such
common receiver functions as signal amplification, frequency down
conversion, filtering, channel selection and the like, and in the
example system shown in FIG. 18, analog to digital (A/D)
conversion. A/D conversion of a received signal allows more complex
communication functions such as demodulation and decoding to be
performed in the DSP 1820. In a similar manner, signals to be
transmitted are processed, including modulation and encoding for
example, by DSP 1820 and input to transmitter 1814 for digital to
analog conversion, frequency up conversion, filtering,
amplification and transmission over the communication network 1819
via antenna 1818. DSP 1820 not only processes communication
signals, but also provides for receiver and transmitter control.
For example, the gains applied to communication signals in receiver
1812 and transmitter 1814 may be adaptively controlled through
automatic gain control algorithms implemented in DSP 1820.
[0287] UE 1800 typically includes a processor 1838 which controls
the overall operation of the device. Communication functions,
including data and voice communications, are performed through
communication subsystem 1811. Processor 1838 also interacts with
further device subsystems such as the display 1822, flash memory
1824, random access memory (RAM) 1826, auxiliary input/output (I/O)
subsystems 1828, serial port 1830, one or more keyboards or keypads
1832, speaker 1834, microphone 1836, other communication subsystem
1840 such as a short-range communications subsystem and any other
device subsystems generally designated as 1842. Serial port 1830
could include a USB port or other port known to those in the
art.
[0288] Some of the subsystems shown in FIG. 18 perform
communication-related functions, whereas other subsystems may
provide "resident" or on-device functions. Notably, some
subsystems, such as keyboard 1832 and display 1822, for example,
may be used for both communication-related functions, such as
entering a text message for transmission over a communication
network, and device-resident functions such as a calculator or task
list.
[0289] Operating system software used by the processor 1838 is
generally stored in a persistent store such as flash memory 1824,
which may instead be a read-only memory (ROM) or similar storage
element (not shown). Those skilled in the art will appreciate that
the operating system, specific device applications, or parts
thereof, may be temporarily loaded into a volatile memory such as
RAM 1826. Received communication signals may also be stored in RAM
1826.
[0290] As shown, flash memory 1824 can be segregated into different
areas for both computer programs 1858 and program data storage
1850, 1852, 1854 and 1856. These different storage types indicate
that each program can allocate a portion of flash memory 1824 for
their own data storage requirements. Processor 1838, in addition to
its operating system functions, may enable execution of software
applications on the UE. A predetermined set of applications that
control basic operations, including data and voice communication
applications for example, will normally be installed on UE 1800
during manufacturing. Other applications could be installed
subsequently or dynamically.
[0291] One software application may be a personal information
manager (PIM) application having the ability to organize and manage
data items relating to the user of the UE such as, but not limited
to, e-mail, calendar events, voice mails, appointments, and task
items. Naturally, one or more memory stores would be available on
the UE to facilitate storage of PIM data items. Such PIM
application would generally have the ability to send and receive
data items, via the wireless network 1819. In one embodiment, the
PIM data items are seamlessly integrated, synchronized and updated,
via the wireless network 1819, with the UE user's corresponding
data items stored or associated with a host computer system.
Further applications may also be loaded onto the UE 1800 through
the network 1819, an auxiliary I/O subsystem 1828, serial port
1830, short-range communications subsystem 1840 or any other
suitable subsystem 1842, and installed by a user in the RAM 1826 or
a non-volatile store (not shown) for execution by the processor
1838. Such flexibility in application installation increases the
functionality of the device and may provide enhanced on-device
functions, communication-related functions, or both. For example,
secure communication applications may enable electronic commerce
functions and other such financial transactions to be performed
using the UE 1800.
[0292] In a data communication mode, a received signal such as a
text message or web page download will be processed by the
communication subsystem 1811 and input to the processor 1838, which
may further process the received signal for element attributes for
output to the display 1822, or alternatively to an auxiliary I/O
device 1828.
[0293] A user of UE 1800 may also compose data items such as email
messages for example, using the keyboard 1832, which may be a
complete alphanumeric keyboard or telephone-type keypad, as
examples, in conjunction with the display 1822 and possibly an
auxiliary I/O device 1828. Such composed items may then be
transmitted over a communication network through the communication
subsystem 1811.
[0294] For voice communications, overall operation of UE 1800 is
similar, except that received signals would typically be output to
a speaker 1834 and signals for transmission would be generated by a
microphone 1836. Alternative voice or audio I/O subsystems, such as
a voice message recording subsystem, may also be implemented on UE
1800. Although voice or audio signal output may be accomplished
primarily through the speaker 1834, display 1822 may also be used
to provide an indication of the identity of a calling party, the
duration of a voice call, or other voice call related information
for example.
[0295] Serial port 1830 in FIG. 18 would normally be implemented in
a personal digital assistant (PDA)-type UE for which
synchronization with a user's desktop computer (not shown) may be
desirable, but is an optional device component. Such a port 1830
would enable a user to set preferences through an external device
or software application and would extend the capabilities of UE
1800 by providing for information or software downloads to UE 1800
other than through a wireless communication network. The alternate
download path may for example be used to load an encryption key
onto the device through a direct and thus reliable and trusted
connection to thereby enable secure device communication. As will
be appreciated by those skilled in the art, serial port 1830 can
further be used to connect the UE to a computer to act as a
modem.
[0296] Other communications subsystems 1840, such as a short-range
communications subsystem, is a further component which may provide
for communication between UE 1800 and different systems or devices,
which need not necessarily be similar devices. For example, the
subsystem 1840 may include an infrared device and associated
circuits and components or a Bluetooth.TM. communication module to
provide for communication with similarly enabled systems and
devices. Subsystem 1840 may also be used for WiFi or WiMAX
communications.
[0297] The processor 1838 and communications subsystem 1811 could
be utilized to implement the procedures and features of FIGS. 1 to
17.
[0298] The embodiments described herein are examples of structures,
systems or methods having elements corresponding to elements of the
techniques of this application. This written description may enable
those skilled in the art to make and use embodiments having
alternative elements that likewise correspond to the elements of
the techniques of this application. The intended scope of the
techniques of this application thus includes other structures,
systems or methods that do not differ from the techniques of this
application as described herein, and further includes other
structures, systems or methods with insubstantial differences from
the techniques of this application as described herein.
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