U.S. patent application number 14/413191 was filed with the patent office on 2015-06-11 for method and apparatus for changing discontinuous reception cycle in wireless communication system.
The applicant listed for this patent is LG Electronics Inc.. Invention is credited to Sunghoon Jung, Sunyoung Lee, Youngdae Lee, Sungjun Park, Seungjune yi.
Application Number | 20150163740 14/413191 |
Document ID | / |
Family ID | 49916287 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150163740 |
Kind Code |
A1 |
Lee; Sunyoung ; et
al. |
June 11, 2015 |
METHOD AND APPARATUS FOR CHANGING DISCONTINUOUS RECEPTION CYCLE IN
WIRELESS COMMUNICATION SYSTEM
Abstract
A method and apparatus for changing a Discontinuous Reception
(DRX) cycle in a wireless communication system is provided. A
wireless device configures a short DRX cycle and a long DRX cycle.
When the wireless device receives a PDCCH indicating a new data
transmission, it determines that the short DRX cycle is used and a
running drxShortCycleTimer is stopped for the DRX operation.
Discontinuous reception (DRX) cycle can be configured flexibly
according to the new data transmission and a CSI report between the
UE and the eNB can be complied with accurately and frequently.
Inventors: |
Lee; Sunyoung; (Seoul,
KR) ; Lee; Youngdae; (Seoul, KR) ; Park;
Sungjun; (Seoul, KR) ; yi; Seungjune; (Seoul,
KR) ; Jung; Sunghoon; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
|
KR |
|
|
Family ID: |
49916287 |
Appl. No.: |
14/413191 |
Filed: |
July 8, 2013 |
PCT Filed: |
July 8, 2013 |
PCT NO: |
PCT/KR2013/006065 |
371 Date: |
January 6, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61670137 |
Jul 11, 2012 |
|
|
|
Current U.S.
Class: |
370/311 |
Current CPC
Class: |
Y02D 70/23 20180101;
H04W 72/0413 20130101; H04W 52/0216 20130101; Y02D 70/21 20180101;
Y02D 30/70 20200801; H04W 52/0229 20130101; Y02D 70/24 20180101;
H04W 76/28 20180201; H04W 72/042 20130101; Y02D 70/1264 20180101;
H04W 72/048 20130101; Y02D 70/1262 20180101; Y02D 70/1242
20180101 |
International
Class: |
H04W 52/02 20060101
H04W052/02; H04W 72/04 20060101 H04W072/04 |
Claims
1. A method for changing a Discontinuous Reception (DRX) cycle in a
wireless communication system, performed by a wireless device, the
method comprising: configuring a short DRX cycle and a long DRX
cycle; receiving a physical downlink control channel (PDCCH)
indicating a new data transmission; and using the short DRX cycle
if the received PDCCH indicates the new data transmission.
2. The method of claim 1, further comprising: stopping a
drxShortCycleTimer if the drxShortCycleTimer is running.
3. The method of claim 1, wherein the using further comprising:
choosing that at least one of a Channel Quality Indicator (CQI), a
Precoding Matrix Index (PMI), a Rank Indicator (RI) and a Precoding
Type Indicator (PTI) on a Physical Uplink Control Channel (PUCCH)
is reported at an On Duration predetermined with the short DRX
cycle.
4. The method of claim 1, wherein the receiving further comprising:
checking whether a new data indicator in the PDCCH is a bit setup
for a new data transmission or not.
5. The method of claim 1, wherein the receiving comprising:
monitoring the PDCCH at an On Duration predetermined with the short
cycle.
6. A wireless device configured for changing a Discontinuous
Reception (DRX) cycle in a wireless communication system,
comprising: a radio frequency unit configured to receive a radio
signal; and a processor operatively coupled with the radio
frequency unit and configured to: configure a short DRX cycle and a
long DRX cycle; receive a physical downlink control channel (PDCCH)
indicating a new data transmission; use the short DRX cycle if the
received PDCCH indicates the new data transmission.
7. The wireless device of claim 6, wherein the processor is
configured to: stop a drxShortCycleTimer if the drxShortCycleTimer
is running.
8. The wireless device of claim 6, the processor is configured to:
choose that at least one of a Channel Quality Indicator (CQI), a
Precoding Matrix Index (PMI), a Rank Indicator (RI) and a Precoding
Type Indicator (PTI) on a Physical Uplink Control Channel (PUCCH)
is reported at an On Duration predetermined with the short DRX
cycle.
9. The wireless device of claim 6, the processor is configured to:
check whether a new data indicator in the PDCCH is a bit setup for
a new data transmission or not.
10. The wireless device of claim 6, the processor is configured to:
monitor the PDCCH at an On Duration predetermined with the short
cycle.
Description
TECHNICAL FIELD
[0001] The present invention relates to wireless communications,
and more particularly, to a method and apparatus for changing a DRX
cycle in a wireless communication system.
BACKGROUND ART
[0002] 3rd generation partnership project (3GPP) long term
evolution (LTE) is an improved version of a universal mobile
telecommunication system (UMTS) and a 3GPP release 8. The 3GPP LTE
uses orthogonal frequency division multiple access (OFDMA) in a
downlink, and uses single carrier-frequency division multiple
access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input
multiple output (MIMO) having up to four antennas. In recent years,
there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is
an evolution of the 3GPP LTE.
[0003] Discontinuous reception (DRX) is a method for reducing
battery consumption by allowing a user equipment (UE) to
discontinuously monitor a downlink channel. When the DRX is
configured, the UE discontinuously monitors the downlink channel.
Otherwise, the UE continuously monitors the downlink channel.
[0004] Recently, many applications require an always-on
characteristic. Always-on is a characteristic in which the UE is
always connected to a network so as to directly transmit data
whenever necessary.
[0005] However, since battery consumption is great when the UE
continuously maintains the network connection, a proper DRX is
configured in a corresponding application to guarantee the
always-on characteristic while reducing battery consumption.
[0006] Recently, several various applications are running in
parallel in one UE, and thus it is not easy to configure one DRX
suitable for all of the applications. This is because, even if an
optimal DRX is configured for a specific application, it may be a
not proper DRX configuration with respect to other applications
which are running in parallel.
[0007] There is a need for a method for operating the DRX in a more
flexible manner.
DISCLOSURE
Technical Problem
[0008] The present invention provides a method and apparatus for
changing a DRX cycle in a wireless communication system.
[0009] The present invention also provides a method and apparatus
for changing a DRX cycle in consideration of a new data
transmission in a wireless communication system.
[0010] The present invention also provides a method and apparatus
for controlling to not use a long DRX cycle with restriction on DRX
operation in a wireless communication system.
Technical Solution
[0011] In an aspect, a method for changing a DRX (Discontinuous
Reception) cycle in a wireless communication system is provided.
The method includes configuring a short DRX cycle and a long DRX
cycle; receiving a physical downlink control channel (PDCCH)
indicating a new data transmission; and using the short DRX cycle
if the received PDCCH indicates the new data transmission.
[0012] The method may further include stopping a drxShortCycleTimer
if the drxShortCycleTimer is running.
[0013] The method may further include using the long DRX cycle if
the received PDCCH does not indicate the new data
transmission..
[0014] In another aspect, a wireless device for changing DRX
(Discontinuous Reception) cycle in a wireless communication system
is provided. The wireless device includes a radio frequency unit
for receiving a radio signal; and a processor, operatively coupled
with the radio frequency unit, configured to configure a short DRX
cycle and a long DRX cycle, receive a physical downlink control
channel (PDCCH) indicating a new data transmission, and use the
short DRX cycle if the received PDCCH indicates the new data
transmission.
Advantageous Effects
[0015] Discontinuous reception (DRX) cycle can be configured
flexibly and a changing a DRX cycle in consideration of a new data
transmission between the UE and the eNB can be complied with
accurately. More details, the UE may not use a long DRX cycle when
the new data transmission is expected. It can be advantaged that a
CSI reporting can performed in consideration of data traffic when a
DRX operation is configured for the UE.
DESCRIPTION OF DRAWINGS
[0016] FIG. 1 shows a wireless communication system to which the
present invention is applied.
[0017] FIG. 2 is a diagram showing a radio protocol architecture
for a user plane to which the present invention is applied.
[0018] FIG. 3 is a diagram showing a radio protocol architecture
for a control plane to which the present invention is applied to
which the present invention is applied
[0019] FIG. 4 shows a DRX cycle to which the present invention is
applied.
[0020] FIG. 5 shows active time for DRX operation to which the
present invention is applied.
[0021] FIG. 6 shows an example of a transition of a DRX cycle to
which the present invention is applied.
[0022] FIG. 7 shows an example of DRX operation with a Long DRX
cycle which the wireless communication system is applied.
[0023] FIG. 8 shows an example of DRX operation with a short DRX
cycle according to an exemplary embodiment of the present
invention.
[0024] FIG. 9 shows a flowchart for changing a DRX cycle according
to an exemplary embodiment of the present invention.
[0025] FIG. 10 shows a block diagram showing a wireless
communication system according to an exemplary embodiment of the
present invention.
MODE FOR INVENTION
[0026] FIG. 1 shows a wireless communication system to which the
present invention is applied. The wireless communication system may
also be referred to as an evolved-UMTS terrestrial radio access
network (E-UTRAN) or a long term evolution (LTE)/LTE-A system.
[0027] The E-UTRAN includes at least one base station (BS) 20 which
provides a control plane and a user plane to a user equipment (UE)
10. The UE 10 may be fixed or mobile, and may be referred to as
another terminology, such as a mobile station (MS), a user terminal
(UT), a subscriber station (SS), a mobile terminal (MT), a wireless
device, etc. The BS 20 is generally a fixed station that
communicates with the UE 10 and may be referred to as another
terminology, such as an evolved node-B (eNB), a base transceiver
system (BTS), an access point, etc.
[0028] The BSs 20 are interconnected by means of an X2 interface.
The BSs 20 are also connected by means of an Si interface to an
evolved packet core (EPC) 30, more specifically, to a mobility
management entity (MME) through S1-MME and to a serving gateway
(S-GW) through S1-U.
[0029] The EPC 30 includes an MME, an S-GW, and a packet data
network-gateway (P-GW). The MME has access information of the UE or
capability information of the UE, and such information is generally
used for mobility management of the UE. The S-GW is a gateway
having an E-UTRAN as an end point. The P-GW is a gateway having a
PDN as an end point.
[0030] Layers of a radio interface protocol between the UE and the
network can be classified into a first layer (L1), a second layer
(L2), and a third layer (L3) based on the lower three layers of the
open system interconnection (OSI) model that is well-known in the
communication system. Among them, a physical (PHY) layer belonging
to the first layer provides an information transfer service by
using a physical channel, and a radio resource control (RRC) layer
belonging to the third layer serves to control a radio resource
between the UE and the network. For this, the RRC layer exchanges
an RRC message between the UE and the BS.
[0031] FIG. 2 is a diagram showing a radio protocol architecture
for a user plane. FIG. 3 is a diagram showing a radio protocol
architecture for a control plane. The user plane is a protocol
stack for user data transmission. The control plane is a protocol
stack for control signal transmission.
[0032] Referring to FIGS. 2 and 3, a PHY layer provides an upper
layer with an information transfer service through a physical
channel. The PHY layer is connected to a medium access control
(MAC) layer which is an upper layer of the PHY layer through a
transport channel. Data is transferred between the MAC layer and
the PHY layer through the transport channel. The transport channel
is classified according to how and with what characteristics data
is transferred through a radio interface.
[0033] Between different PHY layers, i.e., a PHY layer of a
transmitter and a PHY layer of a receiver, data is transferred
through the physical channel. The physical channel may be modulated
using an orthogonal frequency division multiplexing (OFDM) scheme,
and may utilize time and frequency as a radio resource.
[0034] Functions of the MAC layer include mapping between a logical
channel and a transport channel and multiplexing/de-multiplexing on
a transport block provided to a physical channel over a transport
channel of a MAC service data unit (SDU) belonging to the logical
channel. The MAC layer provides a service to a radio link control
(RLC) layer through the logical channel.
[0035] Functions of the RLC layer include RLC SDU concatenation,
segmentation, and reassembly. To ensure a variety of quality of
service (QoS) required by a radio bearer (RB), the RLC layer
provides three operation modes, i.e., a transparent mode (TM), an
unacknowledged mode (UM), and an acknowledged mode (AM). The AM RLC
provides error correction by using an automatic repeat request
(ARQ).
[0036] Functions of a packet data convergence protocol (PDCP) layer
in the user plane include user data delivery, header compression,
and ciphering. Functions of a PDCP layer in the control plane
include control-plane data delivery and ciphering/integrity
protection.
[0037] A radio resource control (RRC) layer is defined only in the
control plane. The RRC layer serves to control the logical channel,
the transport channel, and the physical channel in association with
configuration, reconfiguration and release of radio bearers (RBs).
An RB is a logical path provided by the first layer (i.e., the PHY
layer) and the second layer (i.e., the MAC layer, the RLC layer,
and the PDCP layer) for data delivery between the UE and the
network.
[0038] The setup of the RB implies a process for specifying a radio
protocol layer and channel properties to provide a particular
service and for determining respective detailed parameters and
operations. The RB can be classified into two types, i.e., a
signaling RB (SRB) and a data RB (DRB). The SRB is used as a path
for transmitting an RRC message in the control plane. The DRB is
used as a path for transmitting user data in the user plane.
[0039] When an RRC connection is established between an RRC layer
of the UE and an RRC layer of the network, the UE is in an RRC
connected state (also may be referred to as an RRC connected mode),
and otherwise the UE is in an RRC idle state (also may be referred
to as an RRC idle mode).
[0040] Data is transmitted from the network to the UE through a
downlink transport channel. Examples of the downlink transport
channel include a broadcast channel (BCH) for transmitting system
information and a downlink-shared channel (SCH) for transmitting
user traffic or control messages. The user traffic of downlink
multicast or broadcast services or the control messages can be
transmitted on the downlink-SCH or an additional downlink multicast
channel (MCH). Data is transmitted from the UE to the network
through an uplink transport channel. Examples of the uplink
transport channel include a random access channel (RACH) for
transmitting an initial control message and an uplink SCH for
transmitting user traffic or control messages.
[0041] Examples of logical channels belonging to a higher channel
of the transport channel and mapped onto the transport channels
include a broadcast channel (BCCH), a paging control channel
(PCCH), a common control channel (CCCH), a multicast control
channel (MCCH), a multicast traffic channel (MTCH), etc.
[0042] The physical channel includes several OFDM symbols in a time
domain and several subcarriers in a frequency domain. One subframe
includes a plurality of OFDM symbols in the time domain. A resource
block is a resource allocation unit, and includes a plurality of
OFDM symbols and a plurality of subcarriers. Further, each subframe
may use particular subcarriers of particular OFDM symbols (e.g., a
first OFDM symbol) of a corresponding subframe for a physical
downlink control channel (PDCCH), i.e., an L1/L2 control channel. A
transmission time interval (TTI) is a unit time of subframe
transmission.
[0043] The 3GPP LTE classifies a physical channel into a data
channel, i.e., a physical downlink shared channel (PDSCH) and a
physical uplink shared channel (PUSCH), and a control channel,
i.e., a physical downlink control channel (PDCCH), a physical
control format indicator channel (PCFICH) and a physical hybrid-ARQ
indicator channel (PHICH), and a physical uplink control channel
(PUCCH).
[0044] The PCFICH transmitted in a 1st OFDM symbol of the subframe
carries a control format indicator (CFI) regarding the number of
OFDM symbols (i.e., a size of the control region) used for
transmission of control channels in the subframe. The UE first
receives the CFI on the PCFICH, and thereafter monitors the
PDCCH.
[0045] The PDCCH is a downlink control channel, and is also called
a scheduling channel in a sense that it carries scheduling
information. Control information transmitted through the PDCCH is
referred to as downlink control information (DCI). The DCI may
include resource allocation of the PDSCH (this is referred to as a
downlink (DL) grant), resource allocation of a PUSCH (this is
referred to as an uplink (UL) grant), a set of transmit power
control commands for individual UEs in any UE group and/or
activation of a voice over Internet protocol (VoIP).
[0046] The wireless communication system as 3GPP LTE of the present
invention uses blind decoding for PDCCH detection. The blind
decoding is a scheme in which a desired identifier is de-masked
from a CRC of a PDCCH (referred to as a candidate PDCCH) to
determine whether the PDCCH is its own channel by performing CRC
error checking.
[0047] A BS determines a PDCCH format according to DCI to be
transmitted to a UE. Thereafter, the BS attaches a cyclic
redundancy check (CRC) to the DCI, and masks a unique identifier
(referred to as a radio network temporary identifier (RNTI)) to the
CRC according to an owner or usage of the PDCCH.
[0048] Now, discontinuous reception (DRX) in a wireless
communication system, as example, 3GPP LTE will be described.
[0049] The DRX is a method for reducing battery consumption of a UE
by allowing the UE to discontinuously monitor a downlink
channel.
[0050] FIG. 4 shows a DRX cycle to which the present invention is
applied.
[0051] A DRX cycle specifies the periodic repetition of the
on-duration followed by a possible period of inactivity. The DRX
cyclic includes an on-duration and an off-duration. The on-duration
is a duration in which a UE monitors a PDCCH within the DRX cycle.
The DRX cycle has two types, i.e., a long DRX cycle and a short DRX
cycle. The long DRX cycle which has a long period can minimize
battery consumption of the UE. The short DRX cyclic which has a
short period can minimize a data transmission delay.
[0052] When the DRX is configured, the UE may monitor the PDCCH
only in the on-duration and may not monitor the PDCCH in the
off-duration.
[0053] An onDuration timer is used to define the on-duration. The
on-duration can be defined as a duration in which the onDuration
timer is running. The onDuration timer may specify the number of
consecutive PDCCH-subframe(s) at the beginning of a DRX Cycle. The
PDCCH-subframe specifies a subframe in which the PDCCH is
monitored.
[0054] In addition to the DRX cycle, a duration in which the PDCCH
is monitored can be further defined. A duration in which the PDCCH
is monitored is collectively referred to as an active time.
[0055] A drx-Inactivity timer deactivates the DRX. If the
drx-Inactivity timer is running, the UE continuously monitors the
PDCCH irrespective of the DRX cycle. The drx-Inactivity timer
starts upon receiving an initial UL grant or DL grant on the PDCCH.
The drx-Inactivity timer may specify the number of consecutive
PDCCH-subframe(s) after successfully decoding a PDCCH indicating an
initial UL or DL user data transmission for this UE.
[0056] A HARQ RTT timer defines a minimum duration in which the UE
expects HARQ retransmission. The HARQ RTT timer may specify the
minimum amount of subframe(s) before a DL HARQ retransmission is
expected by the UE.
[0057] A drx-Retransmission timer defines a duration in which the
UE monitors the PDCCH while expecting DL retransmission. The
drx-Retransmission timer may specify the maximum number of
consecutive PDCCH-subframe(s) for as soon as a DL retransmission is
expected by the UE. After initial DL transmission, the UE starts
the HARQ RTT timer. When an error is detected for the initial DL
transmission, the UE transmits NACK to a BS, stops the HARQ RTT
timer, and runs the drx-Retransmission timer. The UE monitors the
PDCCH for DL retransmission from the BS while the
drx-Retransmission timer is running.
[0058] An Active Time can include an on-duration in which the PDCCH
is periodically monitored and a duration in which the PDCCH is
monitored due to an event occurrence.
[0059] When a DRX cycle is configured, the Active Time includes the
time while: [0060] onDuration timer or drx-Inactivity timer or
drx-Retransmission timer or mac-ContentionResolution timer is
running; or [0061] a Scheduling Request is sent on PUCCH and is
pending; or [0062] an uplink grant for a pending HARQ
retransmission can occur and there is data in the corresponding
HARQ buffer; or [0063] 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 preamble
not selected by the UE.
[0064] FIG. 5 shows active time for DRX operation to which the
present invention is applied.
[0065] When DRX is configured, the UE shall for each subframe:
[0066] if a HARQ RTT Timer expires in this subframe and the data of
the corresponding HARQ process was not successfully decoded: [0067]
start the drx-Retransmission timer for the corresponding HARQ
process. [0068] if a DRX Command MAC CE (control element) is
received: [0069] stop onDuration timer and drx-Inactivity timer.
[0070] if drx-InactivityTimer expires or a DRX Command MAC CE is
received in this subframe: [0071] if the Short DRX cycle is
configured: [0072] start or restart drx-ShortCycle timer and use
the Short DRX Cycle. [0073] else: [0074] use the Long DRX cycle.
[0075] if drx-ShortCycle timer expires in this subframe: [0076] use
the Long DRX cycle. [0077] If the Short DRX Cycle is used and
[(SFN*10)+subframe number] modulo (shortDRX-Cycle)=(drxStartOffset)
modulo (shortDRX-Cycle); or [0078] if the Long DRX Cycle is used
and [(SFN*10)+subframe number] modulo
(longDRX-Cycle)=drxStartOffset: [0079] start onDuration timer.
[0080] during the Active Time, for a PDCCH-subframe, if the
subframe is not required for uplink transmission for half-duplex
FDD UE operation and if the subframe is not part of a configured
measurement gap: [0081] monitor the PDCCH; [0082] if the PDCCH
indicates a DL transmission or if a DL assignment has been
configured for this subframe: [0083] start the HARQ RTT timer for
the corresponding HARQ process; [0084] stop the drx-Retransmission
timer for the corresponding HARQ process. [0085] if the PDCCH
indicates a new transmission (DL or UL): [0086] start or restart
drx-Inactivity timer. [0087] when not in Active Time,
type-0-triggered SRS shall not be reported. [0088] if CQI masking
(cqi-Mask) is setup by upper layers: [0089] when onDurationTimer is
not running, CQI/PMI/RI/PTI on PUCCH shall not be reported. [0090]
else: [0091] when not in Active Time, CQI/PMI/RI/PTI on PUCCH shall
not be reported.
[0092] As mentioned, the active-time is defined a total duration
that the UE is awake. This includes the on-duration of the DRX
cycle, the time UE is performing continuous reception while the
inactivity timer has not expired and the time UE is performing
continuous reception while waiting for a DL retransmission after
one HARQ RTT. Based on the above the minimum active time is of
length equal to on-duration, and the maximum is undefined
(infinite).
[0093] FIG. 6 shows an example of a transition of a DRX cycle to
which the present invention is applied.
[0094] Upon receiving initial transmission from an eNB, a
drx-Inactivity timer (also referred to as a first timer or an
inactivity timer) starts (step S610). A UE continuously monitors a
PDCCH while the drx-Inactivity timer is running.
[0095] If the drx-Inactivity timer expires or if a DRX command is
received from the eNB, the UE transitions to a short DRX cycle
(step S620). Then, the drx-ShortCycle timer (also referred to as a
second timer or a DRX cycle timer) starts.
[0096] The DRX command can be transmitted as a MAC CE, and can be
called a DRX indicator that indicates a transition to the DRX. The
DRX command MAC CE is identified through a long channel ID (LCID)
of a MAC PDU subheader.
[0097] While the drx-ShortCycle timer is running, the UE operates
in the short DRX cycle. If the drx-ShortCycle timer expires, the UE
transitions to a long DRX cycle.
[0098] If the short DRX cyclic is pre-set, the UE transitions to
the short DRX cycle. If the short DRX cyclic is not pre-set, the UE
can transition to the long DRX cycle.
[0099] A value of HARQ RTT timer is fixed to 8 ms (or 8 subframes).
Other timer values (i.e., an onDuration timer, a drx-Inactivity
timer, a drx-Retransmission timer, a mac-ContentionResolution
timer, etc.) can be determined by the eNB through an RRC message.
The eNB can configure the long DRX cycle and the short DRX cycle
through the RRC message.
[0100] FIG. 7 shows a situation of DRX operation to which a
wireless communication system is applied, i.e., the situation where
the UE uses the long DRX cycle while receiving at least one PDCCH
including information on radio resource allocation from the BS.
[0101] Referring to FIG.7, the UE with DRX operation can be
configured to transmit CSI report and periodical SRS to the BS
according to a CSI configuration of the BS.
[0102] This means that the UE is configured to preform CSI and SRS
transmission only at the subframe corresponding to the On Duration
of the DRX cycle according to the DRX and CSI configuration of the
BS. At this step, the BS transmits a RRC signal to set the UE to
the configuration for a DRX operation and the configuration for
CSI/SRS transmission. Also, the CSI transmission and SRS
transmission are set by the BS, which are limited to the operation
of the UE related to the CSI transmission with CQI masking
(cqi-Mask) scheme and periodic SRS transmission. The CSI
transmission includes a transmission of CQI/PMI/RI/PTI on a PUCCH,
which is the configuration sets to transmit at On Duration of the
DRX cycle. Also, the UE provides a uplink state by periodically
sending a Sounding Reference Signal (SRS), and this periodic SRS
transmission is called a type-0-triggered SRS. The SRS transmission
according to the present invention includes the limitation to
type-0-triggered SRS.
[0103] When the UE is configured to use both Short DRX Cycle (700)
and Long DRX cycle(760) for the DRX operation, the UE starts a
drx-shortCycle timer(720) when a drx-Inactivity timer expires(730),
and the UE starts using the Long DRX cycle(760) if the
drx-ShortCycle timer expires(720).
[0104] When the drx-ShortCycle timer is running, the UE will
continuously resume the drx-Inactivity timer if the UE which uses
the Short DRX cycle continuously receives at least one PDCCH
including information on new radio resource allocation from the BS
at the subframe in which the drx-Inactivity timer is running.
However, since the drx-Inactivity timer does not expire because of
the receiving at least one PDCCH continuously, the running the
drx-ShortCycle timer expires after predetermined time, and the UE
finally transits from a Short DRX cycle to the long DRX cycle.
[0105] As a result, the UE transits the short DRX cycle to Long DRX
cycle and uses the Long DRX cycle although it has to perform data
transmission/reception by receiving radio resource allocation
information continuously from the BS, it is caused the problem of
not being able to perform the CSI transmission with sufficient
frequency even if the UE is configured to transmit the CSI and SRS
reports at the subframe corresponding to On Duration.
[0106] In addition, this problem causes difficulties with
allocating radio resources correctly for the UE and making a low
system performance in view of the BS. Therefore, this operation of
the DRX is not proper and the DRX operation needs to be
modified.
[0107] In consideration of this problem and in order to perform the
CSI report and the SRS transmission with sufficient and correct
frequency, the present invention is disclosed a solution for
controlling to not use the Long DRX cycle by stopping the running
the drx-ShortCycle timer when new data transmissions on at least
one PDCCH are expected. In other words, the present invention
discloses a controlling scheme about a change of DRX cycle by
stopping the drxShortCycle timer.FIG. 8 shows an example of change
DRX cycle according to an exemplary embodiment of the present
invention. For example, the present invention includes a use of the
Long DRX cycle is prohibited especially when a PDCCH indicating
transmission of new data is received from the BS.
[0108] Referring to FIG. 8, the UE is configured to use both the
Short DRX Cycle and the long DRX cycle. If the UE which uses the
Short DRX cycle continuously receives at least one PDCCH including
information on a new radio resource allocation from the BS, herein
the PDCCH includes a new data transmission, at the subframe in
which a drx-Inactivity timer is running while the drx-ShortCycle
timer is running, the UE continuously resumes the drx-Inactivity
timer, and the UE starts to use the Short DRX cycle (800).
[0109] If the drxShortCycle timer is running at this step, the UE
controls that the running drxShortCycle timer is stopped (825).
[0110] In other words, in the present invention, if the UE using
the Short DRX cycle determines to continuously perform the new data
transmission with the BS, the UE determines to use the Short DRX
cycle by not applying the Long DRX cycle with restriction. The DRX
cycle change is restricted by stopping of the drxShortCycle timer,
in order to bar the conventional DRX operation of changing the Long
DRX cycle when the drxShortCycle timer expired.
[0111] In relation to this situation, the operation of changing a
DRX cycle will be described with reference to FIG. 9.
[0112] FIG. 9 shows an example on the operation process of the UE
according to the present invention, in which the DRX cycle is
changed in consideration of the stop of drxShortCycle timer when
the UE operates to be expected to receive the new data
transmission.
[0113] Referring to FIG. 9, the UE sets configurations related to a
DRX configuration and a CSI reporting transmission. At this step,
the UE can be configured to use the Short DRX cycle and the long
DRX cycle with the DRX configuration (910). In order to set these
configurations related to the DRX configuration and CSI
transmission, the UE can receive a RRC signaling from the BS. In
other words, the BS transmits the RRC signal to the UE in order to
configure to use two types of DRX cycles such as the Short DRX
cycle and the Long DRX cycle.
[0114] At this step, the UE can receive information on radio
resource allocation from the BS through the PDCCH during the On
Duration predetermined according to the DRX configuration (920).
Herein the PDCCH includes a new data transmission. At this step,
the UE receives, from the base station, the PDCCH indicating a new
data transmission (920). The reception of the PDCCH includes
monitoring of the PDCCH at On Duration predetermined with the Short
DRX cycle. The UE determines whether the new data transmission is
existed or not by checking a New Data Indicator (NDI) in the
received PDCCH.
[0115] For example, if initial transmission(new data transmission)
is set, the UE can receive a PDCCH including the NDI with 0 of
value(bit) for indicating the initial transmission(or new data
transmission), so the UE determines the data transmission is new or
retransmitted by the NDI value(bit). Herein the data transmission
includes uplink from the UE to BS, and downlink from the BS to the
UE. This invention includes the NDI is applied for the uplink data
transmission or the downlink data transmission.
[0116] Then, the UE starts or resumes the drx-Inactivity timer is
operated with a predetermined length of subframe by receiving the
PDCCH. At the same time, the UE starts to use the Short DRX cycle,
and stops the running the drxShortCycle timer if the drxShortCycle
timer is running (930). That is the UE controls to not use the Long
DRX cycle when the UE determines that the PDCCH including the new
data transmission is received. Therefore, the UE can bar a
transition to the Long DRX cycle when the PDCCH indicating NDI is
existed from the BS.
[0117] The present invention, as described above, provides the
advantages of using the Short DRX cycle by not using the change to
the Long DRX cycle when the UE performing DRX operation
continuously performs data transmission with the BS. It is the
advantage of performing CSI transmission and SRS transmission at
the subframe corresponding to predetermined On Duration with
sufficient frequency by performing DRX operation according to Short
DRX cycle. Therefore, the present invention allows the BS to
correctly acquire the information for performing radio resource
allocation, thereby enhancing the performance of the entire
system.
[0118] Although the aforementioned embodiment shows the DRX
operation of the UE for example, the proposed invention is
applicable to a DRX operation of a machine to machine (M2M) device
or a machine-type communication (MTC) device. MTC is one type of
data communication including one or more entities not requiring
human interactions. That is, the MTC refers to the concept of
communication performed by a machine device, not a terminal used by
a human user, by using the existing wireless communication network.
The machine device used in the MTC can be called an MTC device.
There are various MTC devices such as a vending machine, a machine
of measuring a water level at a dam, etc.
[0119] FIG. 10 is a block diagram showing a wireless communication
system according to an embodiment of the present invention.
[0120] A BS 1050 includes a processor 1051, a memory 1052, and a
radio frequency (RF) unit 1053. The memory 1052 is coupled to the
processor 1051, and stores a variety of information for driving the
processor 1051. The RF unit 1053 is coupled to the processor 51,
and transmits and/or receives a radio signal. The processor 1051
implements the proposed functions, procedures, and/or methods. In
the embodiments of FIG. 8 to FIG. 10, the operation of the BS can
be implemented by the processor 51.
[0121] Especially, the processor 1051 configures and sets the DRX
configuration and CSI transmission configuration with CQI masking
on the UE. Herein, the DRX configuration is included to set to UE
with both the Short DRX cycle and the Long DRX cycle. This
processor 1051 controls CSI transmission configuration to UE in
order to correctly perform CSI report at specific subframe during
On Duration configured for the CSI transmission configuration with
CQI masking under the environment of performing the DRX
operation,
[0122] The processor 1051 also estimates that the UE performs the
DRX cycle using with the Short cycle not to use of the Long DRX
cycle by stopping the drx-ShortCycle timer of the UE while the new
transmission/reception is occurred, so that the processor 1051 also
estimates the CSI report at the specific subframe On Duration with
the DRX cycle estimated in consideration of the data transmission
of the initial transmission or retransmission. In addition to, the
processor 1051 configures the PDCCH with NDI set to indicate the
initial data transmission. Therefore, more proper and clear DRX
operation is suggested in consideration of the data transmission
between the UE and BS,
[0123] A wireless device 1060 includes a processor 1061, a memory
1062, and an RF unit 1063. The memory 1062 is coupled to the
processor 1061, and stores a variety of information for driving the
processor 1061. The RF unit 1063 is coupled to the processor 1061,
and transmits and/or receives a radio signal. The processor 1061
implements the proposed functions, procedures, and/or methods. In
the embodiments of the FIG. 8 to FIG. 10, the operation of the UE
can be implemented by the processor 1061.
[0124] Especially, the processor 1061 configures the DRX
configuration and the CSI transmission configuration by checking a
RRC signaling received by the RF unit 1063. Herein, the DRX
configuration is included the state where both the Short DRX cycle
and the Long DRX cycle are configured. This processor 1061, in
order to correctly perform CSI report at On Duration configured for
transmission under the environment of performing the DRX operation,
i.e., configured with CQI masking, can selectively control
transition of DRX cycle in consideration that the drx-Inactivity
timer is running or not if the drx-ShortCycle timer which has been
running by using the Short DRX cycle expires.
[0125] The processor 1051 controls to use the Short DRX cycle, not
to use the Long DRX cycle by checking that the PDCCH indicating the
new data transmission from the BS is received, and the PDCCH is
checked to indicate the new data transmission. The processor 1061
checks the NDI in the PDCCH is set to indicate 0 of value(bit) for
indicating the initial transmission(or new data transmission).
[0126] The processor 1061 controls a change of the DRX cycle
selectively for more clear DRX operation by stopping of the
drx-ShortCycle timer in order to not to use the Long DRX cycle when
the drx-ShortCycle timer expires, and checking the NDI in the
PDCCH. Meanwhile, the processor 1061 determines to keep the use the
Short DRX cycle if radio resource allocation information for the
new data transmission via at least one PDCCH from the BS is
received, and restriction of the use to the Long DRX cycle is
made.
[0127] The processor 1061 also determines to CSI report at the
specific subframe On Duration determined according to the
maintained DRX cycle. Therefore, the processor 1061 controls to
perform CSI transmission at the On Duration interval determined
with the Short DRX cycle in order to provide channel state reports
to the BS to when it is need to receive radio resource allocation
information for the new data transmission/reception with
effect.
[0128] Therefore, more clear and correct DRX operation in
consideration of the new data traffic is provided, in addition to
more frequent CSI reports to be allocated radio resource allocation
information with more proper.
[0129] The technical concept of the present invention is based on
provisional documents as described in the below.
[0130] <Start of Priority Document>
[0131] In this invention, to send sufficiently frequent
CQI/PMI/PTI/RI reports during the drx-Inactivity timer is running,
the UE forbids the DRX Cycle transition from the Short DRX Cycle to
the Long DRX Cycle when there is on-going data transmission.
[0132] Invention 3.1: Selective DRX Cycle change.
[0133] The eNB configures to the UE, [0134] the DRX functionality
including the Short DRX cycle and the Long DRX Cycle, [0135] CQI
reports including CQI masking
[0136] When the UE is configured with the DRX functionality, [0137]
The UE uses the short DRX cycle; [0138] The UE starts
drx-ShortCycle timer. [0139] The UE uses the long DRX cycle at the
expiry of drx-ShortCycle timer.
[0140] If the UE receives the PDCCH indicating a new transmission
in UL or DL, [0141] The UE starts or restarts drx-Inactivity timer.
[0142] When drx-ShortCycle timer expires, [0143] The UE checks if
drx-Inactivity timer is running [0144] If drx-Inactivity timer is
running, the UE uses the Short DRX Cycle [0145] Else, the UE uses
the Long DRX Cycle. [0146] The UE applies the CQI masking
configuration. [0147] The UE applies the CQI masking and reports
CQI/PMI/RI/PTI on PUCCH when onDurationTimer is running. [0148]
When the drx-Inactivity timer expires, [0149] The UE starts
drx-ShortCycle timer. [0150] The UE uses Short DRX Cycle. [0151]
Then, when drx-ShortCycle timer expires, the UE uses the Long DRX
Cycle.
[0152] Invention 3.2: The UE stops drx-ShortCycle timer.
[0153] The eNB configures to the UE, [0154] the DRX functionality
including the Short DRX cycle and the Long DRX Cycle, [0155] CQI
reports including CQI masking
[0156] When the UE is configured with the DRX functionality, [0157]
The UE uses the short DRX cycle; [0158] The UE starts
drx-ShortCycle timer. [0159] The UE uses the long DRX cycle at the
expiry of drx-ShortCycle timer.
[0160] If the UE receives the PDCCH indicating a new transmission
in UL or DL, [0161] The UE starts or restarts drx-Inactivity timer.
[0162] The UE uses the Short DRX Cycle. [0163] The UE stops
drx-ShortCycle timer, if running; [0164] The UE applies the CQI
masking configuration. [0165] The UE applies the CQI masking and
reports CQI/PMI/RI/PTI on PUCCH when onDurationTimer is running.
[0166] When the drx-Inactivity timer expires, [0167] The UE uses
Short DRX Cycle. [0168] The UE starts drx-ShortCycle timer. [0169]
Then, when drx-ShortCycle timer expires, the UE uses the Long DRX
Cycle.
[0170] Text Proposal: TS36.321
[0171] For invention 1:
[0172] When DRX is configured, the UE shall for each subframe:
[0173] if a HARQ RTT Timer expires in this subframe and the data of
the corresponding HARQ process was not successfully decoded: [0174]
start the drx-RetransmissionTimer for the corresponding HARQ
process. [0175] if a DRX Command MAC control element is received:
[0176] stop onDurationTimer; [0177] stop drx-Inactivity timer.
[0178] if drx-Inactivity timer expires or a DRX Command MAC control
element is received in this subframe: [0179] if the Short DRX cycle
is configured: [0180] start or restart drx-ShortCycle timer ;
[0181] use the Short DRX Cycle. [0182] else: [0183] use the Long
DRX cycle. [0184] if drx-ShortCycle timer expires in this subframe
and if the drx-Inactivity timer is not running: [0185] use the Long
DRX cycle. [0186] If the Short DRX Cycle is used and
[(SFN*10)+subframe number] modulo (shortDRX-Cycle)=(drxStartOffset)
modulo (shortDRX-Cycle); or [0187] if the Long DRX Cycle is used
and [(SFN*10)+subframe number] modulo
(longDRX-Cycle)=drxStartOffset: [0188] start onDurationTimer.
[0189] during the Active Time, for a PDCCH-subframe, if the
subframe is not required for uplink transmission for half-duplex
FDD UE operation and if the subframe is not part of a configured
measurement gap: [0190] monitor the PDCCH; [0191] if the PDCCH
indicates a DL transmission or if a DL assignment has been
configured for this subframe: [0192] start the HARQ RTT Timer for
the corresponding HARQ process; [0193] stop the
drx-RetransmissionTimer for the corresponding HARQ process. [0194]
if the PDCCH indicates a new transmission (DL or UL): [0195] start
or restart drx-Inactivity timer. [0196] when not in Active Time,
type-0-triggered SRS [2] shall not be reported. [0197] if CQI
masking (cqi-Mask) is setup by upper layers: [0198] when
onDurationTimer is not running, CQI/PMI/RI/PTI on PUCCH shall not
be reported. [0199] else: [0200] when not in Active Time,
CQI/PMI/RI/PTI on PUCCH shall not be reported.
[0201] For invention 2:
[0202] When DRX is configured, the UE shall for each subframe:
[0203] if a HARQ RTT Timer expires in this subframe and the data of
the corresponding HARQ process was not successfully decoded: [0204]
start the drx-RetransmissionTimer for the corresponding HARQ
process. [0205] if a DRX Command MAC control element is received:
[0206] stop onDurationTimer; [0207] stop drx-Inactivity timer.
[0208] if drx-Inactivity timer expires or a DRX Command MAC control
element is received in this subframe: [0209] if the Short DRX cycle
is configured: [0210] start or restart drx-ShortCycle timer; [0211]
use the Short DRX Cycle. [0212] else: [0213] use the Long DRX
cycle. [0214] if drx-ShortCycle timer expires in this subframe:
[0215] use the Long DRX cycle. [0216] If the Short DRX Cycle is
used and [(SFN*10)+subframe number] modulo
(shortDRX-Cycle)=(drxStartOffset) modulo (shortDRX-Cycle); or
[0217] if the Long DRX Cycle is used and [(SFN*10)+subframe number]
modulo (longDRX-Cycle)=drxStartOffset: [0218] start
onDurationTimer. [0219] during the Active Time, for a
PDCCH-subframe, if the subframe is not required for uplink
transmission for half-duplex FDD UE operation and if the subframe
is not part of a configured measurement gap: [0220] monitor the
PDCCH; [0221] if the PDCCH indicates a DL transmission or if a DL
assignment has been configured for this subframe: [0222] start the
HARQ RTT Timer for the corresponding HARQ process; [0223] stop the
drx-RetransmissionTimer for the corresponding HARQ process. [0224]
if the PDCCH indicates a new transmission (DL or UL): [0225] start
or restart drx-Inactivity timer. [0226] use the Short DRX Cycle.
[0227] stop drx-ShortCycle timer. [0228] when not in Active Time,
type-0-triggered SRS [2] shall not be reported. [0229] if CQI
masking (cqi-Mask) is setup by upper layers: [0230] when
onDurationTimer is not running, CQI/PMI/RI/PTI on PUCCH shall not
be reported. [0231] else: [0232] when not in Active Time,
CQI/PMI/RI/PTI on PUCCH shall not be reported.
[0233] <End of Priority Document>
[0234] The processor may include application-specific integrated
circuit (ASIC), other chipset, logic circuit and/or data processing
device. The memory may include read-only memory (ROM), random
access memory (RAM), flash memory, memory card, storage medium
and/or other storage device. The RF unit may include baseband
circuitry to process radio frequency signals. When the embodiments
are implemented in software, the techniques described herein can be
implemented with modules (e.g., procedures, functions, and so on)
that perform the functions described herein. The modules can be
stored in memory and executed by processor. The memory can be
implemented within the processor or external to the processor in
which case those can be communicatively coupled to the processor
via various means as is known in the art.
[0235] In view of the exemplary systems described herein,
methodologies that may be implemented in accordance with the
disclosed subject matter have been described with reference to
several flow diagrams. While for purposed of simplicity, the
methodologies are shown and described as a series of steps or
blocks, it is to be understood and appreciated that the claimed
subject matter is not limited by the order of the steps or blocks,
as some steps may occur in different orders or concurrently with
other steps from what is depicted and described herein. Moreover,
one skilled in the art would understand that the steps illustrated
in the flow diagram are not exclusive and other steps may be
included or one or more of the steps in the example flow diagram
may be deleted without affecting the scope and spirit of the
present disclosure.
* * * * *