6.7 Modulation for the 1.28 Mcps option

25.2233GPPRelease 17Spreading and modulation (TDD)TS

The complex-valued chip sequence in uplink or downlink on one carrier within one timeslot is modulated as shown in figure 6.

Figure 6: Modulation of complex valued chip sequences

The pulse-shaping characteristics are described in [9] and [10].

6.7.1 Combination of physical channels in uplink

The principle of combination of two different physical uplink channels within one timeslot is the same as in the 3.84 Mcps TDD cf. [6.6.1 Combination of physical channels in uplink] In the case of E-PUCH, the procedures of subclause 6.7.1a shall instead apply).

6.7.1a Physical channel transmission for E-PUCH

Figure 6a illustrates the principle of E-PUCH transmission when one uplink physical channel is transmitted.

The amplitude of the E-PUCH is adjusted in accordance with the E-PUCH UL power control procedure described in [12]. The power setting procedure of [12] includes appropriate power adjustment factors for the E-PUCH spreading factor and for the E-TFC selected by higher layers [13]. Quantisation of the gain factor used to set the E-PUCH power is not specified.

Figure 6a: Combination of different physical channels in uplink

6.7.2 Combination of physical channels in downlink

Figure 7 illustrates how different physical downlink channels are combined within one timeslot. Each spread channel is separately weighted by a weight factor G_i.. All downlink physical channels are then combined using complex addition.

Figure 7: Combination of different physical channels in downlink

6.7.3 Combination of signature sequences for Scheduled E-HICH

For Scheduled E-HICH, every scheduled user is assigned one signature sequence which is related to the E-DCH resources allocated by Node-B to indicate ACK/NACK. But for the user configured in MU-MIMO mode by higher layers, in case the special default midamble allocation scheme is taken, the signature sequence allocated to the user is related to both the E-DCH resources allocated by Node-B and the variable "offset" which is determined by the special default midamble pattern indicator [7] signalled on E-AGCH. Multiple users’ HARQ acknowledgement indicator signature sequences may be mapped onto the same channelisation code. Each signature sequence (described in [8]) is first subjected to QPSK modulation as described in subclause 5.2.1.1 to form the output sequence for the h^th indicator sequence, where n=1,2,…,N_k and i=1,2. Code k is the same value for all signature sequences mapped to the same channelisation code.

When multiple signature sequences are to be transmitted on the same channelisation code, the following procedure shall be applied prior to spreading.

Each QPSK-modulated stream is amplitude-weighted by a factor g_h according to the desired signature sequence power. Each E-HICH physical channel may carry ACK/NACK signature sequence(s) for one UE or multiple UEs decided by Node-B. A summation is then performed across M signature sequences mapped to the same channelisation code as shown in figure 8. The output of the summation block is the sequence:

(n = 1,2,…,N_k) and (i=1,2) (9)

Figure 8: Combination of HARQ acknowledgement indicator sequences prior to spreading for Scheduled E-HICH

The sequence is mapped to a single channelisation code and subject to spreading at SF=16 in accordance with the general method of subclause 6.

6.7.3a Combination of signature sequences for Non-Scheduled E-HICH

For Non-Scheduled E-HICH, the 80 signature sequences are divided into 20 groups while each group includes 4 sequences. Every non-scheduled user is assigned one group by higher layer, from that two sequences are selected to indicate ACK/NACK and TPC/SS command. Multiple users’ signature sequences may be mapped onto the same channelisation code. Each user’s two signature sequences (described in [8]) are first subjected to QPSK modulation as described in subclause 5.2.1.1 to form the two output sequences and for the h^th user, where n=1,2,…,N_k and i=1,2. Code k is the same value for all signature sequences mapped to the same channelisation code.

When multiple users’ signature sequences are to be transmitted on the same channelisation code, the following procedure shall be applied prior to spreading.

Firstly, each user’s QPSK-modulated stream corresponding to TPC/SS signature sequence is amplitude-weighted by a factor f_h and added to the QPSK-modulated stream corresponding to ACK/NACK signature sequence; Secondly, each user’s combined stream is amplitude-weighted by a factor g_h according to the desired user power. A summation is then performed across M users’ signature sequences mapped to the same channelisation code as shown in figure 8a. The output of the summation block is the sequence:

(n = 1,2,…,N_k) and (i=1,2) (9a)

Figure 8a: Combination of ACK/NACK and TPC/SS sequences prior to spreading for Non-Scheduled E-HICH

The sequence is mapped to a single channelisation code and subject to spreading at SF=16 in accordance with the general method of subclause 6.