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© NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Downlink Shared Channel - DSCH DSCH associated with a dedicated channel (DCH) Downlink.

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Presentation on theme: "© NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Downlink Shared Channel - DSCH DSCH associated with a dedicated channel (DCH) Downlink."— Presentation transcript:

1 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Downlink Shared Channel - DSCH DSCH associated with a dedicated channel (DCH) Downlink Shared Channel - DSCH DSCH associated with a dedicated channel (DCH) 3GPP TSG RAN WG1 Meeting No. 2Tdoc R Yokohama, Japan, Jan Source: Nokia

2 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Outline DSCH options introduction DSCH associated with DCH - Description DSCH interaction with layer 2/3 Benefits Downlink code resource usage Operational aspects Performance UE Complexity with DSCH DSCH Layer 1 signaling needs DSCH operation in handover DSCH Conclusions

3 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH options ETSI documentation covers two options for DSCH operation 1. DSCH associated with a dedicated channel (DCH) 2. DSCH associated with a DSCH control channel Additionally so called MAC multiplexing was proposed for DSCH, but this was rejected in ETSI due mainly performance and complexity reasons In MAC multiplexing several users were sharing the same 10 ms radio frame In this slide set, the option 1, operation with DSCH with a dedicated channel (DCH) is presented in more detail and benefits to non- DSCH case are given.

4 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH associated with a DCH ( from UMTS XX.03, UTRA FDD; Transport channels and physical channels ) PDSCH = Physical Downlink Shared CHannel

5 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH interaction with Layer 2/3 (MAC) All the MAC PDUs belonging to the service to use DSCH are coded independently of DCH and sent on DSCH. Layer 2/3 controls the DSCH resource division, being indicated with TFCI or higher layer signalling

6 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Downlink code resource usage (1) Downlink code resource usage with dedicated channel (DCH) only: 384 kbits/s packet data with dedicated channel, 3 users Activity cycle 1/10, needed spreading ratio 8 (DCH) Resulting code usage is: with 3/8 of the total downlink code space occupied

7 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Downlink code resource usage (2) Downlink code resource usage with DSCH 384 kbits/s packet data with dedicated channel, 3 users Activity Cycle 1/10, needed spreading ratio 8 (DSCH), DCH spreading ratio 256 Resulting code usage is: with 1/8 + 3/256 of the total downlink code space occupied

8 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Downlink code resource usage (3) From the example case, with DSCH it is possible to support 3 times more users on a given packet data rate that providing the same via a dedicated channel before running out of downlink code resource. Dedicated channel (DCH) impact to the code resource usage is small with DSCH since DCH spreading factor can be kept at 256. DCH spreading ratio 512 also usable (In ARIB) In a comparison one has to note that there needs to be capability to provide not only layer 1 control (TPC, pilots & TFCI) on DPCCH but also to accommodate needs for higher layer control information for handover etc. purposes on DPDCH on the downlink.

9 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 Operation Aspects with DSCH (1) Terminals with different capabilities can share one DSCH Terminal with 384 kbits/s can co-exists sharing the same DSCH with a 144 kbits/s terminal. With 144 kbits/s two terminals can receive data simultaneously with code multiplexing. (Example) DSCH can be controlled alternatively with higher layer signaling when activity cycle (or idle times) is relatively long and frame by frame operation is not needed

10 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH Operational Aspects (2) Operational coverage: Code multiplexing provides possibility for adapting the data rate of DSCH according to the needed range, thus DSCH can reach the whole cell. BS power budget can be taken into account when allocating data to DSCH BS1 M2 512 kbits/s 64 kbits/s

11 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH Performance DSCH when associated with DCH can use: Fast power control Beam forming Code multiplexing principles allow to reduce variations in the interference level (More constant TX power level) Range is larger than with a fixed rate downlink channel, example: Example: DSCH data 512, 144 & 64 kbits/s Ranges equal to 512, 144 & 64 kbits/s can be achieved  The coverage area for DSCH variable rate 3 times bigger compared to the fixed rate DSCH (with 512 kbits/s)  (9 dB difference due data rates gives about 70 % more range or 3 times larger coverage area. (Pathloss exponent 3.6)

12 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 UE Complexity with DSCH Example; Terminal with 384 kbits/s receiving capability with and without DSCH Despreading: Despreading functionality added only with the capability to receive a parallel code channel with spreading ratio of 256. Compared to receiver with 384 kbits/s capability, the added complexity is very small. Buffering: Buffering is basically the same, difference is added from the possible time offset between a DCH and a DSCH (assumed to be within one slot), thus extra (2560/smallest spreading ratio) samples to buffer, less than 300 samples extra buffer, small with respect to turbo interleaver of up to 8192 samples) Other functions: TFCI decoding, power control and channel estimation: No impact (All done based on DCH)

13 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH Layer 1 Signaling needs The TFCI signalling on DPCCH is used to indicate the data rate for all services being provided to the mobile, including DSCH, (similar to code multiplexing.) Case A) The shared channel can use only one data rate for a given user, the TFCI usage is identical with the packet data on a dedicated channel.  Case B) Packet data on dedicated channel would have more than single data rate, those rates are mapped on DSCH different spreading codes, with different spreading factors, again identical TFCI usage with and without DSCH.  Case C) When TFCI combinations allow, alternative spreading codes under the code tree are used for one data rate. Example would be to have peak rate mapped to one code and then lower rate mapped to two alternative codes.

14 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH operation in handover DSCH is not operated in soft handover, hard handover is used If the associated DCH contains e.g. speech, it can be operated in soft handover. Power control for DSCH is not necessary optimal in this case, but situation is similar to the case of high bit rate packet on dedicated channel as well (which has not been assumed to be in soft handover either in RTT simulations) If DCH is in soft handover, hard handover for DSCH is very fast as synchronisation exists already (depends only on the network side) With multi-service case and DCH in soft handover it is possible to use either TFCI or higher layer signalling to indicate data on DSCH, depending on network capability. During slotted/compressed frames UE would not have data on DSCH

15 © NOKIAProduced as informative material for 3GPP RAN WG1 meeting No. 2 DSCH conclusions DSCH is improvement for UTRA packet data capabilities, since Helps to avoid downlink code shortage Can cope with future enhancements, such as adaptive antennas Provides fast power control Impact to terminal complexity is small Fast resource sharing, good end user quality Existing TFCI signaling can be used DSCH is recommended to be part of the combined 3GPP specification Note: This slide set focuses on DSCH associated with DCH, the concept of DSCH operated with a specific DSCH control channel is not covered by this presentation.


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