一、加扰
最多可以传输两个码字 \(q \in\{0,1\}\) 。在单码字传输的情况下,\(q=0\) 。
对于每个码字 \(q\) ,UE应假设比特块 \(b^{(q)}(0), \ldots, b^{(q)}\left(M_{\mathrm{bit}}^{(q)}-1\right)\) 在调制之前被加扰,\(M_{\mathrm{bit}}^{(q)}\) 是在物理信道中传输的码字 \(q\) 的比特数量,根据如下公式产生一个加扰比特块 \(\tilde{b}^{(q)}(0), \ldots, \tilde{b}^{(q)}\left(M_{\mathrm{bit}}^{(q)}-1\right)\) :
\[
\widetilde{b}^{(q)}(i)=\left(b^{(q)}(i)+c^{(q)}(i)\right) \bmod 2
\]
式中,加扰序列 \(c^{(q)}(i)\) 由5.2.1节给出。加扰序列生成器应按照如下公式初始化:\[ c_{\text {init }}=n_{\mathrm{RNTI}} \cdot 2^{15}+q \cdot 2^{14}+n_{\mathrm{ID}} \]
式中,
- \(n_{\mathrm{ID}} \in\{0,1, \ldots, 1023\}\) 等于高层参数dataScramblingIdentityPDSCH(如果配置),并且RNTI等于C-RNTI、MCS-C-RNTI或CS-RNTI,并且在公共搜索空间中不使用DCI格式1_0调度传输,
- 否则,\(n_{\mathrm{ID}}=N_{\mathrm{ID}}^{\mathrm{cell}}\)
二、调制
对于每个码字 \(q\) ,UE应假设加扰比特块 \(\tilde{b}^{(q)}(0), \ldots, \tilde{b}^{(q)}\left(M_{\mathrm{bit}}^{(q)}-1\right)\) 使用表2-1中的一种调制格式,按5.1节所述进行调制,产生一个复数值调制符号块 \(d^{(q)}(0), \ldots, d^{(q)}\left(M_{\mathrm{symb}}^{(q)}-1\right)\) 。
调制格式 | 阶数 |
---|---|
QPSK | 2 |
16QAM | 4 |
64QAM | 6 |
256QAM | 8 |
三、层映射
UE应假设根据表3-1将要发送的每个码字的复数值调制符号映射到一个或多个层上。码字 \(q\) 的复数值调制符号 \(d^{(q)}(0), \ldots, d^{(q)}\left(M_{\mathrm{symb}}^{(q)}-1\right)\) 应映射到层 \(x(i)=\left[\begin{array}{lll}{x^{(0)}(i)} & {\dots} & {x^{(\nu-1)}(i)}\end{array}\right]^{T}\) 上,\(i=0,1, \ldots, M_{\mathrm{symb}}^{\mathrm{layer}}-1\),式中 \(v\) 是层数,\(M_{\mathrm{symb}}^{\mathrm{layer}}\) 是每层调制符号数。
层数 | 码字数 | 码字-层映射\[i=0,1, \ldots, M_{\mathrm{symb}}^{\mathrm{layer}}-1\] |
---|---|---|
1 | 1 | \(x^{(0)}(i)=d^{(0)}(i)\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)}\) |
2 | 1 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(2 i)} \\ {x^{(1)}(i)=d^{(0)}(2 i+1)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 2\) |
3 | 1 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(3 i)} \\ {x^{(1)}(i)=d^{(0)}(3 i+1)} \\ {x^{(2)}(i)=d^{(0)}(3 i+2)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 3\) |
4 | 1 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(4 i)} \\ {x^{(1)}(i)=d^{(0)}(4 i+1)} \\ {x^{(2)}(i)=d^{(0)}(4 i+2)} \\ {x^{(3)}(i)=d^{(0)}(4 i+3)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 4\) |
5 | 2 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(2 i)} \\ {x^{(1)}(i)=d^{(0)}(2 i+1)} \\ {x^{(2)}(i)=d^{(1)}(3 i)} \\ {x^{(3)}(i)=d^{(1)}(3 i+1)} \\ {x^{(4)}(i)=d^{(1)}(3 i+2)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 2=M_{\mathrm{symb}}^{(1)} / 3\) |
6 | 2 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(3 i)} \\ {x^{(1)}(i)=d^{(0)}(3 i+1)} \\ {x^{(2)}(i)=d^{(0)}(3 i+2)} \\ {x^{(3)}(i)=d^{(1)}(3 i)} \\ {x^{(4)}(i)=d^{(1)}(3 i+1)} \\ {x^{(5)}(i)=d^{(1)}(3 i+2)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 3=M_{\mathrm{symb}}^{(1)} / 3\) |
7 | 2 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(3 i)} \\ {x^{(1)}(i)=d^{(0)}(3 i+1)} \\ {x^{(2)}(i)=d^{(0)}(3 i+2)} \\ {x^{(3)}(i)=d^{(1)}(4 i)} \\ {x^{(4)}(i)=d^{(1)}(4 i+1)} \\ {x^{(5)}(i)=d^{(1)}(4 i+2)} \\ {x^{(6)}(i)=d^{(1)}(4 i+3)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 3=M_{\mathrm{symb}}^{(1)} / 4\) |
8 | 2 | \(\begin{array}{l}{x^{(0)}(i)=d^{(0)}(4 i)} \\ {x^{(1)}(i)=d^{(0)}(4 i+1)} \\ {x^{(2)}(i)=d^{(0)}(4 i+2)} \\ {x^{(3)}(i)=d^{(0)}(4 i+3)} \\ {x^{(3)}(i)=d^{(0)}(4 i)} \\ {x^{(4)}(i)=d^{(1)}(4 i+1)} \\ {x^{(6)}(i)=d^{(1)}(4 i+2)} \\ {x^{(7)}(i)=d^{(1)}(4 i+3)}\end{array}\),\(M_{\mathrm{symb}}^{\mathrm{layer}}=M_{\mathrm{symb}}^{(0)} / 4=M_{\mathrm{symb}}^{(1)} / 4\) |