(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2011/0267957 A1
` Du et al. (43) Pub. Date: NOV. 3, 2011
`
`
`
`US 20110267957A1
`
`(54) DISCONTINUOUS RECEPTION IN CARRIER
`AGGREGATION WIRELESS
`COMMUNICATION SYSTEMS
`
`(76)
`
`Inventors:
`
`Lei Du, Beijing (CN); Min Huang,
`Beijing (CN); Yong Teng, Beijing
`(CN)
`
`(21) Appl. No.:
`
`13/143,464
`
`(22) PCT Filed:
`
`Jan. 73 2009
`
`(86) PCT N05
`
`PCT/EP2009/050134
`
`§ 371 (0)0 )5
`(2), (4) Date:
`
`Jul. 6’ 2011
`
`Publication Class1ficat10n
`
`(51)
`
`Int. Cl.
`H04W 52/02
`H04 W 24/00
`H04 W 72/04
`
`(200901)
`(200901)
`(2009.01)
`
`(52) US. Cl. .......................... 370/241; 370/329; 370/311
`
`(57)
`
`ABSTRACT
`
`A communication system is presented, which is capable of
`sending a transmission over an interface having at least two
`aggregated component carriers including a primary compo-
`nent carrier and at least one secondary component carrier,
`wherein the primary component carrier has a physical down-
`link control channel (PDCCH) associated therewith and
`wherein the PDCCH is capable of signaling allocations for
`the primary component carrier and the at least one secondary
`component carrier. A method of operating a network element
`including sending to a user equipment a transmission indica-
`tion indicative of the transmission in the PDCCH of the
`primary component carrier. A method of operating a user
`equipment includes monitoring downlink control signaling
`for a transmission indication indicative of a transmission to
`the user equipment only on the PDCCH of the primary com-
`ponent carrier.
`
`
`
`
`
`
`
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`Patent Application Publication
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`Nov. 3, 2011 Sheet 1 0f 4
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`US 2011/0267957 A1
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`Patent Application Publication
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`Nov. 3, 2011 Sheet 3 0f4
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`Patent Application Publication
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`US 2011/0267957 A1
`
`Nov. 3, 2011
`
`DISCONTINUOUS RECEPTION IN CARRIER
`AGGREGATION WIRELESS
`COMMUNICATION SYSTEMS
`
`FIELD OF INVENTION
`
`[0001] The present invention relates to the field of wireless
`communication and in particular to the field of carrier aggre-
`gation in wireless communication.
`
`ART BACKGROUND
`
`In order to achieve higherpeak data rates, it has been
`[0002]
`proposed operate in spectrum allocations of different sizes
`including wider spectrum allocations than e.g.
`those of
`Release 8 LTE (LTE:Long Term Evolution), e.g. up to 100
`MHZ, e.g. to achieve the peak data rate of 100 Mbit/s for high
`mobility and 1 Gbit/s for low mobility. Moreover, backward
`compatibility is desirable.
`[0003] A possible measure for achieving wider spectrum
`allocations is carrier aggregation, where two or more compo-
`nent carriers are aggregated, as it is considered for LTE-
`Advanced in order to support downlink transmission band-
`widths larger than 20 MHZ.
`[0004] A user equipment (UE), e.g. a terminal, may simul-
`taneously receive one or multiple component carriers depend-
`ing on its capabilities:
`[0005] An LTE-Advanced terminal with reception capa-
`bility beyond 20 MHZ can simultaneously receive trans-
`missions on multiple component carriers.
`[0006] An LTE Rel-8 terminal can receive transmissions
`on a single component carrier only, provided that the
`structure of the component carrier follows the Rel-8
`specifications.
`[0007]
`FIG. 1 gives an example ofthe carrier aggregation of
`an LTE Advanced System. M Re18 bandwidth “chunks”, or
`component carriers 2, indicated with C1, C2, C3, C4 and C5
`over frequency f in FIG. 1, are combined together to form
`M><Re18 Bandwidth 4, e.g. 5x20 MHZ:100 MHZ, given M:5,
`for the system illustrated in FIG. 1. In the illustrated example,
`Rel’8 terminals receive/transmit on one component carrier,
`whereas LTE-Advanced terminals may receive/transmit on
`multiple component carriers simultaneously to reach the
`higher bandwidths, e.g. an LTE Advanced maximum band-
`width 4 of 100 MHZ, as shown in FIG. 1.
`[0008] On the other hand, besides higher peak data rates,
`power consumption is an important issue.
`[0009]
`In view ofthe above-described situation, there exists
`a need for an improved technique that enables carrier aggre-
`gation, while substantially avoiding or at least reducing one or
`more of the above-identified problems.
`
`SUMMARY OF THE INVENTION
`
`[0010] This need may be met by the subject matter accord-
`ing to the independent claims. Advantageous embodiments
`are described by the dependent claims.
`[0011] Aspects of the herein disclosed subject matter are
`based on the idea to implement a concept of discontinuous
`reception DRX on a system capable of carrier aggregation. In
`order to reduce power consumption, it is proposed to intro-
`duce to carrier aggregation system a concept ofdiscontinuous
`reception wherein the user equipment and a network element
`negotiate time intervals in which data transfer happens. Out-
`side these time intervals, the user equipment turns its receiver
`off and enters a low power state.
`
`[0012] According to a first aspect of the herein disclosed
`subject matter there is provided a method of operating a
`network element capable of sending a transmission over an
`interface having at least two aggregated component carriers
`including a primary component carrier and at least one sec-
`ondary component carrier, the primary component carrier
`having a physical downlink control channel (PDCCH) asso-
`ciated therewith, wherein the PDCCH is capable of signaling
`allocations for the primary component carrier and the at least
`one secondary component carrier.
`[0013] Examples of a user equipment (referred to as UE
`hereinafter) include but are not limited to a mobile phone, a
`mobile computer, etc. Examples of a network element include
`but are not limited to a base station of a wireless communi-
`
`cations network, e.g. an e-nodeB.
`[0014] According to an embodiment, the method according
`to the first aspect comprises sending to a UE a transmission
`indication indicative ofthe transmission in the PDCCH ofthe
`
`primary component carrier.
`[0015] According to a further embodiment, an on-duration
`timer is configured only on the primary component carrier,
`e.g. by respective signaling ofthe network element to the user
`equipment. The on-duration indicating the time duration the
`user equipment monitors the PDCCH for allocations.
`According to a further embodiment the offsets of the on-
`duration are configured by radio resource control (RRC) sig-
`naling. Thus the power consumption can be decreased.
`[0016] According to a further embodiment the PDCCH on
`primary component carrier is capable of configuring the
`transmission in the following subframes, i.e. the subframes
`which follow the subframe wherein the PDCCH is transmit-
`
`ted. The method according to the first aspect may be config-
`ured accordingly. For example, according to a further
`embodiment, the method according to the first aspect may
`further comprise defining a timing gap between, in the UE,
`successful decoding of the transmission indication and start-
`ing of an inactivity timer on a secondary component carrier,
`the inactivity timer indicating the time duration the UE at
`least waits until deactivating reception on the component
`carrier associated with the inactivity timer. According to an
`embodiment, defining such a timing gap is performed by
`sending to a UE a timing gap message for configuring the UE
`to impose the timing gap between the successful decoding of
`the transmission indication and the starting of an inactivity
`timer on a secondary component carrier.
`[0017] Herein, a subframe is a basic timing unit of radio
`resource, e.g. of radio resource in LTE frame structure. For
`example, according to an illustrative embodiment, downlink
`and uplink transmissions are organized into radio frames with
`a predefined duration, e.g. with 10 ms duration as defined in
`3GPP TS 36.300 V8.6.0 (September 2008). Each radio frame
`is divided into a predefined number of equally sized sub-
`frames. Each subframe may consist of a further predefined
`number of equally sized slots. For example, according to TS
`36.300 V8.6.0, for frequency division duplexing (FDD), 10
`subframes are available for downlink transmission and 10
`
`subframes are available for uplink transmissions in each 10
`ms interval and each subframe consists of two slots. Uplink
`and downlink transmissions are separated in the frequency
`domain. According to other embodiments, e.g. where the UE
`has a preconfigured timing gap between the successful decod-
`ing of the transmission indication and the starting of an inac-
`tivity timer on a secondary component carrier, no such timing
`gap message is sent by the network element to the UE.
`
`6
`
`

`

`US 2011/0267957 A1
`
`Nov. 3, 2011
`
`[0018] According to a further embodiment the PDCCH on
`primary component carrier is not capable of configuring the
`transmission in the following subframes. For example, the
`PDCCH on the primary component carrier may be capable of
`configuring the transmission only in subframe ofthe PDCCH.
`The method according to the first aspect may be configured
`accordingly. For example, according to a further embodiment
`the method further comprises (a) sending to a UE a reception
`preparation message indicating the requirement of preparing
`at least one secondary component carrier for signal reception
`thereon; and (b) sending the transmission indication on the
`primary component carrier and starting the inactivity timer on
`the secondary component carrier. Hence, according to an
`embodiment wherein the PDCCH on the primary component
`carrier can only configure the transmission in the same sub-
`frame, a two-step signaling from the network element to the
`user equipment is executed, i.e. steps (a) and (b) are carried
`out in two sequent subframes.
`[0019] According to a further embodiment, on—duration is
`configured on at least one secondary component carrier. The
`on-duration indicating the time duration the user equipment
`monitors the PDCCH for allocations or stays awake for pos-
`sible downlink data transmission. For example, on-duration
`may be configured on every secondary component carrier.
`Hence, according to these embodiments, no timing gap
`between PDCCH indication and data transmission is needed.
`
`For example, according to a still further embodi-
`[0020]
`ment of the first aspect, the method further comprises signal-
`ing to the UE offsets ofon-duration ofthe primary component
`carrier and the at least one second component carrier.
`[0021] According to a second aspect ofthe herein disclosed
`subject matter, a network element is configured for carrying
`out the method according to one or more of the embodiments
`of the first aspect.
`[0022] According to a third aspect of the herein disclosed
`subject matter there is provided a method of operating a user
`equipment capable of receiving a transmission over an inter-
`face having at least two aggregated component carriers of
`which a primary component carrier has a physical downlink
`control channel (PDCCH) associated therewith, the PDCCH
`capable of signaling allocations for the primary component
`carrier and at least one secondary component carrier.
`[0023] According to an embodiment ofthe third aspect, the
`method comprises monitoring downlink control signaling for
`a transmission indication indicative of a transmission to the
`
`user equipment only on the PDCCH of the primary compo-
`nent carrier.
`
`[0024] According to a further embodiment of the third
`aspect, the user equipment is capable of receiving the trans-
`mission on at least one secondary component carrier in a
`following subframe which follows a subframe in which the
`transmission indication was sent (subframe of the PDCCH).
`According to a further embodiment, the method of the third
`aspect is configured accordingly. For example, according to a
`further embodiment, the method further comprises imposing
`a timing gap between successful decoding ofthe transmission
`indication and starting of an inactivity timer, the inactivity
`timer indicating the duration that the UE at least waits until
`deactivating reception on the component carrier associated
`with the inactivity timer.
`[0025] According to a further embodiment, the timing gap
`is defined by a timing gap message transmitted by a network
`element.
`
`[0026] According to a further embodiment, the timing gap
`is defined by a timing gap duration value stored in the user
`equipment.
`[0027] According to a further embodiment, the method
`according to the third aspect comprises (a) receiving on the
`primary component carrier a message indicating the prepara-
`tion of signal reception on at least one of the at least one
`secondary component carrier; and (b) receiving the transmis-
`sion indication on the primary component carrier, e.g. on the
`PHCCH of the primary component carrier.
`[0028] According to a further embodiment, only the pri-
`mary component carrier is configured with an on-duration
`timer defining a time duration during which the user equip-
`ment monitors the PDCCH for allocations.
`
`[0029] According to a still further embodiment, the pri-
`mary component carrier and at least one of the at least one
`secondary component carrier is configured with an on-dura-
`tion timer. According to an embodiment, the on-duration
`timer defines a time duration during which the user equip-
`ment monitors the PDCCH for allocations or stays awake for
`possible downlink data transmission. According to a further
`embodiment, the range of on-duration on the primary com-
`ponent carrier covers all on-duration ranges of on—duration on
`the at least one secondary component carrier.
`[0030] According to a still further embodiment, the method
`according to the third aspect further comprises starting an
`inactivity timer on a secondary component carrier only within
`an active time on the secondary component carrier, wherein
`the inactivity timer indicates the time duration the UE at least
`waits until deactivating reception on the component carrier
`associated with the inactivity timer.
`[0031] According to a still further embodiment, the active
`time indicates the time duration which includes on-duration
`
`and inactivity timer. For example, according to an embodi-
`ment the active time indicates the time duration wherein
`
`either the on-duration timer or the inactivity timer is running.
`[0032] According to a fourth aspect of the herein disclosed
`subject matter, a user equipment (UE) is provided which is
`configured to carry out the method according to the third
`aspect or an embodiment thereof.
`[0033] According to a fifth aspect, a computer program is
`provided which, when being executed by a data processor, is
`adapted for controlling a method according to the first aspect
`or an embodiment thereof.
`
`[0034] According to a sixth aspect, a computer program is
`provided which, when being executed by a data processor, is
`adapted for controlling a method according to the third aspect
`or an embodiment thereof.
`
`In the following there will be described exemplary
`[0035]
`embodiments of the subject matter disclosed herein with ref-
`erence to a method for operating a user equipment and a
`method for operating a network element. It has to be pointed
`out that of course any combination of features relating to
`different aspects of the herein disclosed subject matter is also
`possible. In particular, some embodiments are described with
`reference to apparatus type claims whereas other embodi-
`ments are described with reference to method type claims.
`However, a person skilled in the art will gather from the above
`and the following description that, unless other notified, in
`addition to any combination of features belonging to one
`aspect also any combination between features relating to
`different aspects or embodiments, for example even between
`
`7
`
`

`

`US 2011/0267957 A1
`
`Nov. 3, 2011
`
`features of the apparatus type claims and features of the
`method type claims is considered to be disclosed with this
`application.
`[0036]
`Further, a person skilled in the art will gather from
`the above and the following description that, unless other
`notified, in addition to any combination of features belonging
`to one aspect also any combination between features relating
`to different aspects or embodiments,
`for example even
`between features relating to a network element and features
`relating to a user equipment is considered to be disclosed with
`this application. In particular the skilled person will gather
`from the herein disclosed subject matter that e.g. settings in
`the UE may be configured by respective signaling of the
`network element to the UE. Herein, the wording “starting a
`timer” includes “starting a timer for the first time” as well as
`“restarting a timer”.
`[0037] The aspects defined above and further aspects are
`apparent from the examples of embodiment to be described
`hereinafter and are explained with reference to the examples
`of embodiment. The herein disclosed subject matter will be
`described in more detail hereinafter with reference to
`
`examples of embodiment given in the detailed description but
`to which the herein disclosed subject matter is not limited.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates carrier aggregation in a long-term
`[0038]
`evolution advanced (LTE-A) system.
`[0039]
`FIG. 2 illustrates on-duration and inactivity timer in
`a LTE system.
`[0040]
`FIG. 3 shows three component carriers including
`primary component carrier having a joint physical downlink
`control channel (PDCCH).
`[0041]
`FIG. 4 shows an exemplary illustration of a proce-
`dure of dynamic DRX design.
`[0042]
`FIG. 5 shows an exemplary illustration of a proce-
`dure of semi-persistent DRX design.
`
`DETAILED DESCRIPTION
`
`[0043] The illustration in the drawings is schematic. It is
`noted that in different figures, similar or identical elements
`are provided with the same reference signs or with reference
`signs, which are different from the corresponding reference
`signs only within the first digit or within an appendix starting
`with a character.
`
`[0044] One aspect of the herein disclosed subject matter is
`to implement a concept of discontinuous reception DRX on a
`system capable of carrier aggregation. For an LTE (Long
`Term Evolution) system an example of a DRX scheme has
`been proposed by the third generation partnership project
`(3GPP) in TS 36.300 V8.6.0 (September 2008).
`[0045]
`FIG. 2 shows an illustration of on-duration and inac-
`tivity timer in a known LTE system.
`[0046] As illustrated in 3GPP TS 36.300 [2], in the discon-
`tinuous reception (DRX) procedure, “when a DRX cycle is
`configured, the active time includes the time while the on
`duration timer or the DRX inactivity timer or a DRX retrans-
`mission timer or the contention resolution timer is running.”
`In this document, on-duration (on-duration timer), inactivity-
`timer (DRX inactivity timer) and active-time are the basic
`concepts in DRX procedures, as defined below. These defi-
`nitions are also valid for an illustrative embodiment of the
`
`herein disclosed subject matter, without being limited to the
`framework of LTE:
`
`[0047] On-duration: duration, e.g. in downlink subframes,
`that the UE waits for, after waking up from DRX, to receive
`physical downlink control channels
`(PDCCHs) which
`informs the UE about resource allocation. If the UE success-
`fully decodes a PDCCH, the UE stays awake and starts the
`inactivity timer.
`in downlink sub-
`[0048]
`Inactivity-timer: duration, e.g.
`frames, that the UE waits to successfully decode a PDCCH,
`from the last successful decoding of a PDCCH, failing which
`it re-enters DRX. The UE shall restart the inactivity timer
`following a single successful decoding of a PDCCH for a first
`transmission only (i.e. not for retransmissions).
`[0049] Active-time: 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 continu-
`ous reception while waiting for a downlink (DL) retransmis-
`sion after one HARQ RTT (Hybrid Automatic Repeat
`reQuest Round Trip Time). Based on the above the minimum
`active time is of length equal to on-duration, and the maxi-
`mum is undefined (infinite).
`[0050] According to an embodiment, the entities of on-
`duration timer and DRX inactivity timer are given as follows:
`[0051] On-duration timer: Specifies the number of con-
`secutive PDCCH-subframe(s) at the beginning of a DRX
`Cycle.
`[0052] DRX inactivity timer: Specifies the number of con-
`secutive PDCCH-subframe(s) after successfully decoding a
`PDCCH indicating an initial uplink (UL) or downlink (DL)
`user data transmission for this UE.
`
`[0053] These definitions correspond to the definitions in
`3GPP TS 36.321, without being limited to the framework
`thereof.
`
`FIG. 2 exemplarily illustrates a timing diagram over
`[0054]
`time t for an on-duration timer 6, defining an on-duration 8, as
`well as two inactivity timers 10a, 10b defining inactivity time
`durations 12a, 12b, respectively. Together the on-duration
`timer 6 and inactivity timers 10a, 10b define the active time
`14. In the timing diagram of FIG. 2, the upper level 16 indi-
`cates that the UE shall monitor the PDCCH (awake state),
`whereas the lower level 18 indicates that the UE shall not
`
`monitor the PDCCH (sleep state). The beginning of the on-
`duration 8, indicated at 20 in FIG. 2, is referred to as DRX
`timeout. The beginnings of the inactivity time durations (in-
`activity timer active), indicated at 22 in FIG. 2, is referred to
`as “UE being scheduled” for UL or DL user data transmis-
`s10n.
`
`[0055] The concept of on-duration means the period when
`on-duration timer is running, and the concept of inactivity-
`timer means the period when DRX inactivity timer is running.
`Further, the joint operation of on-duration timer and DRX
`inactivity timer in case a new transmission occurs in on-
`duration or when DRX inactivity timer is running is given
`(similar to 3GPP TS 36.321):
`[0056] According to an embodiment, when DRX is config-
`ured, the UE shall for each subframe (wherein SFN is the cell
`system frame number):
`[0057]
`If the short DRX cycle is used and [(SFN*10)+
`subframe number] modulo (Short DRX Cycle):DRX
`Start Offset;
`[0058]
`or
`if the long DRX cycle is used and [(SFN*10)+
`[0059]
`subframe number] modulo (long DRX cycle):DRX
`start offset:
`
`[0060]
`
`start the on-duration timer.
`
`8
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`

`US 2011/0267957 A1
`
`Nov. 3, 2011
`
`if the DRX inactivity timer expires or a DRX
`[0061]
`Command MAC control element is received in this sub-
`frame:
`[0062]
`if the short DRX cycle is configured:
`[0063]
`start or restart the DRX short cycle timer;
`[0064]
`use the short DRX cycle.
`else:
`[0065]
`use the long DRX cycle.
`[0066]
`[0067]
`during the active time, for a PDCCH-subframe
`except if the subframe is required for uplink transmis-
`sion for half-duplex FDD UE operation and except if the
`subframe is part of a configured measurement gap:
`[0068] monitor the PDCCH;
`[0069]
`if the PDCCH indicates a new transmission (DL
`or UL):
`start or restart the DRX inactivity timer.
`[0070]
`[0071] Now referring to a system with aggregated carriers
`according to an illustrative embodiment of the herein dis-
`closed subject matter, one PDCCH is provided for signaling
`the allocations for all component carriers jointly, where the
`component carrier containing PDCCH is herein referred to as
`“primary component carrier” and the other component carri-
`ers without PDCCH are referred to as “secondary component
`carrier”.
`
`three
`FIG. 3 shows one joint PDCCH for all
`[0072]
`depicted component carriers 2. It should be understood that
`the number of component carriers 2 shown in FIG. 3 is only
`for illustrative purposes can widely vary. In FIG. 3 one pri-
`mary component carrier 2a and two secondary component
`carriers 2b are shown. Per definition, the primary component
`carrier 2a has associated therewith a PDCCH 24 for signaling
`the allocations for all aggregated component carriers, the
`signaling being indicated at 26 in FIG. 3. Arrows 28a, 28b
`indicate the component carrier bandwidth (BW) of primary
`and secondary component carriers 2a, 2b, respectively. Allo-
`cated resources are indicated at 30 in FIG. 3.
`
`[0073] According to an illustrative embodiment, generally,
`on-duration as defined above is configured for the primary
`component carrier, while the inactivity timer as defined above
`is configured for both the primary and the secondary compo-
`nent carriers.
`
`In this case, because there is no on-duration on
`[0074]
`secondary component carrier in this embodiment, the defini-
`tions of on-duration and inactivity-timer given above should
`be adapted as follows to be compatible for both primary and
`secondary component carriers.
`[0075] On-duration: duration, e.g. in downlink subframes,
`that the UE waits for, after waking up from DRX, to receive
`PDCCHs if configured otherwise to receive downlink data. If
`the UE successfully decodes a PDCCH, the UE stays awake
`and starts the inactivity timer on the component carrier(s)
`where the PDCCH is located and the component carrier(s)
`where the indicated DL or UL transmission is configured.
`[0076]
`Inactivity-timer: duration, e. g.
`in downlink sub-
`frames, that the UE waits to successfully decode a PDCCH,
`from the last successful decoding of a PDCCH, failing which
`it re-enters DRX. The UE shall restart the inactivity timer
`following a single successful decoding of a PDCCH for a first
`transmission only (i.e. not for retransmissions). These proce-
`dures are valid only on the component carrier(s) where the
`PDCCH is located and the component carrier(s) where the
`indicated DL or UL transmission is configured.
`[0077] However, it should be noted that according to other
`embodiments, other timer configurations are possible.
`
`In the following, two exemplary approaches will be
`[0078]
`described, each of which embodies various embodiments of
`the herein disclosed subject matter. Although in each
`approach a
`specific
`combination of embodiments
`is
`described, those skilled in the art will readily recognize that
`other combinations of features are also possible and are real-
`izable within the scope of the appended claims.
`[0079] A first approach described hereinafter is referred to
`as “dynamic DRX”. Within this approach, it is defined that:
`[0080]
`1.1 On—duration exists only on primary component
`carrier; and
`[0081]
`1.2: Inactivity-timer can be started or restarted on a
`secondary component carrier upon the indication of new
`transmission in primary component carrier’s PDCCH, only
`within active-time (when either on-duration timer or DRX
`inactivity timer is running) on the primary component carrier.
`[0082] The detailed rules for an exemplary implementation
`of the first approach are as follows:
`[0083] Rule 1.1: On-duration is configured only on primary
`component carrier 2a but not on any secondary component
`carriers 2b. During on-duration, UE is awake monitoring
`PDCCH on primary component carrier and is sleeping on
`secondary component carriers.
`[0084] Rule 1.2: When UE is monitoring PDCCH, if a new
`transmission is configured on primary component carrier,
`eNB shall send an indication in the primary component car-
`rier’s PDCCH and UE starts or restarts DRX inactivity timer
`on primary component carrier upon successfully decoding
`the PDCCH.
`
`[0085] Rule 1.3: When UE is monitoring PDCCH, if a new
`transmission is configured on secondary component carriers,
`then two options are followed:
`[0086]
`If PDCCH on primary component carrier can
`configure the transmission in the following subframes
`far away enough to awaken secondary component car-
`rier,
`new transmission can be indicated directly by
`[0087]
`PDCCH at eNB, and UE starts or restarts DRX inac-
`tivity timer on both primary and secondary compo-
`nent carriers a gap after successfully decoding the
`PDCCH, i.e. from the subframe when the data trans-
`mission happens.
`[0088] A gap between PDCCH indication and data
`transmission needs to be configured by RRC signal-
`ing explicitly or used by UE itself implicitly.
`[0089] Otherwise, if PDCCH on primary component
`carrier can only configure the transmission in the same
`subframe,
`[0090]
`first, a message (e.g., by MAC control element
`(CE) or RRC message) is sent by eNB to make UE
`start the reception on the corresponding secondary
`component carrier;
`[0091]
`secondly, an indication of new transmission in
`PDCCH is sent a gap after sending the MAC CE/RRC
`message from eNB, and UE starts or restarts DRX
`inactivity timer on both primary and secondary com-
`ponent
`carriers
`immediately upon successfully
`decoding the PDCCH.
`FIG. 4 shows an exemplary procedure of dynamic
`[0092]
`DRX design. Three cases are considered therein which cor-
`respond to the rules 1.1, 1.2 and 1.3 above. In FIG. 4, a DRX
`cycle is indicated at 101.
`
`9
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`9
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`

`

`US 2011/0267957 A1
`
`Nov. 3, 2011
`
`[0093] Case 1: If a new transmission happens on primary
`component carrier then the following steps are performed:
`[0094]
`Step 1: for eNB, new transmission indication is
`sent in primary component carrier’s PDCCH 124a, indi-
`cating the transmission on primary component carrier
`102a; and
`[0095]
`Step 2: for UE, during active-time on primary
`component carrier 10211, if a PDCCH indication for
`primary component carrier is received, DRX inactivity
`timer is started on primary component carrier in the
`same subframe. In FIG. 4, the active-time on primary
`component carrier is not explicitly indicated, but given
`by the time duration where at least one ofthe on-duration
`timer 108 and the inactivity timer 11211 is active (respec-
`tive high levels in FIG. 4).
`[0096] According to illustrative embodiments of case 1,
`indicated at d-CSl in FIG. 4, if a new transmission happens at
`primary component carrier 102a, then DRX inactivity timer
`is started in the same subframe.
`
`[0097] Case 2: If a new transmission happens on a first
`secondary component carrier 102b-1 then the following steps
`are performed:
`[0098]
`Step 1: For eNB, a new transmission indication is
`sent in primary component carrier’s PDCCH 124b, indi-
`cating the transmission on secondary component carrier
`102b-1;
`[0099]
`Step 2: for UE, during active-time on primary
`component carrier 10211, if a PDCCH 124b indication
`for secondary component carrier 102b-1 is received, a
`timing gap 132 is used until the reception on secondary
`component carrier 1 is available (according to an
`embodiment shown in FIG. 4, the timing gap 132 is
`between PDCCH indication and data transmission);
`[0100]
`Step 3: DRX inactivity timer 112b-1, 112b-2 is
`started or restarted on both primary component carrier
`102a and secondary component carrier 102b-1, respec-
`tively.
`[0101] According to illustrative embodiments of case 2,
`indicated at d-CS2 in FIG. 4, if a new transmission happens at
`the first secondary component carrier 102b-1, then a timing
`gap is needed to guarantee secondary component carrier
`awake when transmission begins and DRX inactivity timer is
`started or restarted on both primary and secondary compo-
`nent carriers 102a, 102b-1.
`[0102] Case 3: If a new transmission happens on a second
`secondary component carrier 102b-2 then the following steps
`are performed:
`[0103]
`Step 1: for eNB, a MAC CE or RRC message 134
`(i.e. a MAC control element) is sent on primary compo-
`nent carrier 102a indicating signal reception on second-
`ary component carrier 10219-2;
`[0104]
`Step 2: for eNB, new transmission indication
`1240 is sent in primary component carrier’s PDCCH,
`indicating transmission on secondary component carrier
`102b-2, after a timing gap 138 (i.e. according to an
`illustrative embodiment, the timing gap 138 extends
`between the message indicating signal reception on sec-
`ondary component carrier 102b-2 and the PDCCH indi-
`cation);
`[0105]
`Step 3: for UE, during active-time on primary
`component carrier 10211, ifa PDCCH indication 124c for
`a secondary component carrier 102b-2 is received, a
`
`DRX inactivity timer 1120-1, 1120-2 is started or
`restarted on both primary and secondary component
`carriers 102a, 102b-2.
`[0106] According to illustrative embodiments of case 3,
`indicated at d-Cs3 in FIG. 4, if a new transmission happens at
`secondary component carrier 102b-2, then
`[0107]
`1) a MAC/RRC message is sent at primary com-
`ponent carrier to awaken secondary component carrier,
`indicated at 1) in FIGS. 4, and
`in
`[0108]
`2) a new transmission indication is sent
`PDCCH for a transmission to begin, and DRX inactivity
`timer is started or restarted at both primary and second-
`ary component carriers 102a, 102b-2, indicated at 2) in
`FIG. 4.
`
`If transmission on multiple secondary component
`[0109]
`carriers needs to be scheduled, eNB can send indications in
`PDCCH to start or restart DR