CPC-DTX/DRXThis section describes the WRFD-010686 CPC-DTX / DRX feature.OverviewDTX-DRX consists of the DTX (Discontinuous Transmission of the uplink DPCCH) and the DRX (Discontinuous Reception of the downlink HS-SCCH). The feature of DTX-DRX allows a UE to shut down its receiver and transmitter at a specific time and thus reduces the uplink interference and UE power consumption.The requirements of DTX-DRX are listed in Table 4-6.Table 4-6 Requirements of DTX-DRX for NEs ItemRequirement

CNNone

RNCThe RNC also needs to control the use of DTX-DRX during RB setup, reconfiguration, and handover.The RNC needs to support the configuration of the DTX-DRX transmission pattern.

NodeBThe NodeB can configure, reconfigure, activate, and deactivate DTX or DRX.

UEUEs must support CPC-DTX/DRX.

Basic PrincipleUplink DTXThe uplink DTX function allows a UE to stop transmission on the uplink DPCCH when there is no data for transmission. As a result, uplink interference is reduced.Uplink DTX is of importance for services such as VoIP and web browsing, with intermittent data transmission.Figure 4-7 shows the impact of uplink DTX.Figure 4-7 Impact of uplink DTX

The basic principle of uplink DTX is that the UE automatically stops transmitting the DPCCH to reduce the interference from the DPCCH when there is no data transmitted on the E-DCH. Then, the UE regularly transmits a DPCCH burst in a UE DTX cycle to maintain power control signaling and link synchronization.Note that if the E-DCH data is transmitted continuously, the DPCCH has to be transmitted and DTX becomes unavailable.Downlink DRXThe UE in connected mode needs to listen to the control channel (HS-SCCH) continuously and therefore power consumption is high. If downlink DRX is used, the UE needs to receive the HS-SCCH only at some time points. Figure 4-8 shows the impact of downlink DRX.Figure 4-8 Impact of downlink DRX

Downlink DRX depends on uplink DTX. Therefore, downlink DRX can be activated only after uplink DTX is activated. Downlink DRX, together with uplink DTX, allows the UE to periodically shut down the TX and RX function in the UE, lowering the UE battery consumption and prolonging the UE battery life.HS-SCCH OrderIn 3GPP release 7, HS-SCCH order is introduced and carried on HS-SCCH type 1 (non-MIMO UEs) and HS-SCCH type 3 (MIMO UEs). Bit fields on HS-SCCH are fixed to a value to indicate a specific HS-SCCH function.After the RNC configure a UE with DTX-DRX, the NodeB can activate/deactivate DTX or DRX respectively by sending HS-SCCH order to this UE. Radio BearersCPC DTX-DRX is an optional feature. A prerequisite for using CPC is that HSDPA, HSUPA, and SRB over HSPA are activated. The DCH is not configured in the uplink and downlink. The E-DCH is configured in the uplink, and the HS-DSCH and F-DPCH are configured in the downlink. Signaling and data are carried on HSPA channels. Therefore, CPC is dependent on SRB over HSDPA and SRB over HSUPA.DTX/DRX can be selected if the following conditions are met: DTX/DRX is supported by the network and the UE, and it is activated. To activate DTX/DRX, select DTX_DRX of the HspaPlusSwitch(BSC6900,BSC6910) parameter, and CFG_HSPA_DTX_DRX_SWITCH of the CfgSwitch(BSC6900,BSC6910) parameter. The SRB is carried on HS-DSCH for the downlink and E-DCH for the uplink. For details, see Radio Bearers Feature Parameter Description. The service type is CS voice over HSPA service, PS voice service, PS streaming service, or PS BE service. The downlink HS-DSCH and uplink E-DCH are selected as transport channels.Transmission PatternFor details of the transmission pattern, see 3GPP TS 25.214.There are two UE DTX cycles, namely cycle 1 and cycle 2. Generally, the UE uses cycle 1 for uplink DTX. If the UE has no data to transmit for a long time, the UE uses cycle 2 for uplink DTX. At the beginning of each cycle, the UE sends a DPCCH burst. One burst may consist of one, two, or five subframes.Figure 4-9 Switching between cycle 1 and cycle 2

Figure 4-9 shows the switching between the two UE DTX cycles. The operator can set cycle-related information by using the SET UDTXDRXPARA command for different services to increase the system capacity while ensuring QoS. The parameters are listed as follows: DtxCycle1(BSC6900,BSC6910) DtxCycle2(BSC6900,BSC6910) MacDtxCycle(BSC6900,BSC6910) InactThsForCycle2(BSC6900,BSC6910) DtxLongPreamble(BSC6900,BSC6910) MacInactiveThreshold(BSC6900,BSC6910) DpcchBurst1(BSC6900,BSC6910) DpcchBurst2(BSC6900,BSC6910)The operator can adjust the DRX cycles by running the SET UDTXDRXPARA command to meet the requirements of the UE. The parameters are listed as follows: Drxvalid(BSC6900,BSC6910) DrxCycle(BSC6900,BSC6910) InactThsForDrxCycle(BSC6900,BSC6910) CQIFbCkinInDTXDRXmode(BSC6900,BSC6910)State TransitionState transition from CELL_DCH (CPC) to CELL_FACH or enhanced CELL_FACH and state transition from CELL_DCH (without CPC) to CELL_FACH use the same scheme. The only difference lies in parameter settings.For details about state transition from CELL_DCH (CPC) to CELL_FACH and from CELL_DCH (CPC) to enhanced CELL_FACH, see State Transition Feature Parameter Description.Mobility ManagementA UE initiating a handover procedure supports DTX-DRX only when all cells in the active set for the UE support DTX. When a cell in the active set does not support DTX-DRX, the UE does not support DTX-DRX either.Power ControlDTX affects power control on the network side. When the network side does not detect signals from a DTX UE on the uplink DPCCH, the network side suspends power control on the DTX UE. Network KPIs are not affected because UEs periodically send signals on the uplink DPCCH and power control can be performed on these UEs.Load ControlFor a UE using DTX-DRX, the RNC performs admission on cells that are to be added to the active set for the UE. For a UE that starts to use DTX-DRX, the RNC performs admission on all cells in the active set for the UE. In the uplink, the admission is performed on the E-DCH, not on the DPCCH. In the downlink, the admission is performed on the HS-DSCH. The admission policies for the E-DCH and HS-DSCH are the same as those before CPC - DTX / DRX is enabled.HSDPA Scheduling AlgorithmFor a UE using DRX, scheduling can be performed for the UE at the HS-SCCH reception pattern or during n subframes after HSDPA scheduling is complete. The value of n is specified by InactThsForDrxCycle(BSC6900,BSC6910).Automatic Activation and Deactivation on NodeBsDRX is activated or deactivated based on the QoS. QoS specifications for DRX UEs are monitored. When data to be transmitted in the MAC-ehs queue waits for a long period and the QoS cannot be guaranteed, DRX is deactivated. When data to be transmitted in the MAC-ehs queue waits for a short period and the QoS can be guaranteed, DRX is activated.DTX is activated or deactivated based on the uplink throughput. DTX is activated or deactivated based on the uplink throughput. When a UE's uplink throughput is larger than 400 kbit/s, continuous transmission is required in the uplink E-DCH and DPCCH at the same time. In this case, DTX needs to be deactivated. When a UE's uplink throughput is less than 200 kbit/s, DTX can be used to reduces the uplink interference. In this case, DTX needs to be activated.The activation and deactivation functions have no control switch and they are enabled by default. In addition, the QoS and uplink throughput thresholds are unconfigurable