R-PDCCHonCarrierAggregation.docVIP

3GPP TSG RAN WG1 meeting #54bis R1-083705 Prague, Czech Republic, Sept 29th – Oct 3rd 2008 Agenda Item: 11 Source: Huawei Title: PDCCH on Carrier Aggregation Document for: Discussion Introduction Carrier aggregation has become the agreed technology to extend the bandwidth beyond 20 MHz for LTE-Advanced, and its potential issues and possible solutions have been presented by lots of contributions in RAN1#54 [1][2][3][4][5]. In this contribution, the aggregation levels for MAC/PHY and the related PDCCH signaling are discussed. Furthermore, the method of selecting the downlink anchor carrier is presented, and the related considerations are described [6]. Aggregation levels for MAC/PHY and PDCCH signaling The aggregation levels for MAC/PHY have been mentioned in [3][4][5][6]. Here further property analysis and PDCCH signaling design of the two possible alternatives are described. Aggregation Levels Alternative 1: Aggregation of data packets at the MAC layer Advantages: Transport block will adapt to the carrier at the aspects of MCS, rank selection, etc. Disadvantages: The signaling overhead may increase more compared to LTE Rel-8, Alternative 2: Aggregation of data packets at the physical layer One transport block (two transport blocks in case of spatial multiplexing) is transmitted. Advantages: Less signaling overhead is needed compared to alternative 1; Disadvantages: Transport block will not adapt to each component carrier; In LTE, the maximum code block size is 6144. Transport Blocks larger than 6144 will be segmented; however, only one ACK/NACK is fed back for the whole data packet, and the coarse BLER of the large block is [1- ]. PDCCH The PDCCH signaling can probably be done in two ways. Option 1 is that there are multiple PDCCHs, one per component carrier, sent on the same component carrier as the corresponding PDSCH. Option 1 is possible for alternative 1. Advantages: Maintains the Rel-8 physical layer design for each component carrier, for ex