3GPP LTE物理层中的Uplink resource grid和Downlink Synchronization signals

Uplink resource grid

一.1个无线帧=2个半帧=10个子帧=10ms=20个时隙=140个符号；  1个RB=7个Symbol*12RE子载波；  

二.下图为 Uplink resource grid：

上图中说明1个RB中有个子载波，个RE（时域*频域）；传输的信号一共有个子载波，有个OFDM符号。一个时隙slot中符号的个数取决于CP的长度，如下表所示。Resource block parametersConfigurationNormal  CP127Extended  CP126下面的程序为不同带宽对应的RB个数、子载波个数、fft点数、CP1和CP2的长度、采样频率的程序：

%% ====== init basewidth, RB number, subcarrier number, fft size,etc... ====== %%SimParam.channel.ulDlFlg = 'downlink';               % 'downlink' or 'uplink': the flag of downlink or uplink for common used files.     SimParam.system.sizeRb  = 12;                        % the number of subcarriers in one RBif strcmp(SimParam.system.cpLen, 'normal')    SimParam.system.numOfdmSymb = 14;                % the number of OFDM symbols in one subframe    if SimParam.system.bandwidth == 1.4        SimParam.system.numAllRb = 6;                % the maximum number of RB which could be scheduled in configured bandwidth        SimParam.system.numSubc  = 72;               % the maximum number subcarriers which could be scheduled in configured bandwidth        SimParam.system.fftSize  = 128;              % the size of FFT/IFFT        SimParam.system.cp1      = 10;               % the CP length in the first OFDM symbol        SimParam.system.cp2      = 9;                % the CP length in the other OFDM symbols        SimParam.system.fs       = 1.92e6;           % Sampling frequency    elseif SimParam.system.bandwidth == 3        SimParam.system.numAllRb = 15;               % the maximum number of RB which could be scheduled in configured bandwidth             SimParam.system.numSubc  = 180;              % the maximum number subcarriers which could be scheduled in configured bandwidth        SimParam.system.fftSize  = 256;              % the size of FFT/IFFT                                                                  SimParam.system.cp1      = 20;               % the CP length in the first OFDM symbol                                                SimParam.system.cp2      = 18;               % the CP length in the other OFDM symbols                                               SimParam.system.fs       = 3.84e6;           % Sampling frequency                                                                elseif SimParam.system.bandwidth == 5        SimParam.system.numAllRb = 25;               % the maximum number of RB which could be scheduled in configured bandwidth             SimParam.system.numSubc  = 300;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth        SimParam.system.fftSize  = 512;              % the size of FFT/IFFT                                                                  SimParam.system.cp1      = 40;               % the CP length in the first OFDM symbol                                                SimParam.system.cp2      = 36;               % the CP length in the other OFDM symbols                                               SimParam.system.fs       = 7.68e6;           % Sampling frequency                                                                elseif SimParam.system.bandwidth == 10        SimParam.system.numAllRb = 50;               % the maximum number of RB which could be scheduled in configured bandwidth             SimParam.system.numSubc  = 600;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth        SimParam.system.fftSize  = 1024;             % the size of FFT/IFFT                                                                  SimParam.system.cp1      = 80;               % the CP length in the first OFDM symbol                                                SimParam.system.cp2      = 72;               % the CP length in the other OFDM symbols                                               SimParam.system.fs       = 15.36e6;          % Sampling frequency                                                                elseif SimParam.system.bandwidth == 15        SimParam.system.numAllRb = 75;               % the maximum number of RB which could be scheduled in configured bandwidth             SimParam.system.numSubc  = 900;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth        SimParam.system.fftSize  = 1536;             % the size of FFT/IFFT                                                                  SimParam.system.cp1      = 120;              % the CP length in the first OFDM symbol                                                SimParam.system.cp2      = 108;              % the CP length in the other OFDM symbols                                               SimParam.system.fs       = 23.04e6;          % Sampling frequency                                                                elseif SimParam.system.bandwidth == 20                   SimParam.system.numAllRb = 100;              % the maximum number of RB which could be scheduled in configured bandwidth             SimParam.system.numSubc  = 1200;             % the maximum numbe subcarriers which could be scheduled in configured bandwidth        SimParam.system.fftSize  = 2048;             % the size of FFT/IFFT                                                                  SimParam.system.cp1      = 160;              % the CP length in the first OFDM symbol                                                SimParam.system.cp2      = 144;              % the CP length in the other OFDM symbols                                               SimParam.system.fs       = 30.72e6;          % Sampling frequency                                                                endelseif strcmp(SimParam.system.cpLen, 'extended')    SimParam.system.numOfdmSymb  = 12;               % the number of OFDM symbols in one subframe    if SimParam.system.bandwidth == 1.4        SimParam.system.numAllRb = 6;                % the maximum number of RB which could be scheduled in configured bandwidth              SimParam.system.numSubc  = 72;               % the maximum numbe subcarriers which could be scheduled in configured bandwidth         SimParam.system.fftSize  = 128;              % the size of FFT/IFFT                                                                   SimParam.system.cp1      = 32;               % the CP length in the first OFDM symbol                                                 SimParam.system.cp2      = 32;               % the CP length in the other OFDM symbols                                                SimParam.system.fs       = 1.92e6;           % Sampling frequency                                                                 elseif SimParam.system.bandwidth == 3                    SimParam.system.numAllRb = 15;               % the maximum number of RB which could be scheduled in configured bandwidth              SimParam.system.numSubc  = 180;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth         SimParam.system.fftSize  = 256;              % the size of FFT/IFFT                                                                   SimParam.system.cp1      = 64;               % the CP length in the first OFDM symbol                                                 SimParam.system.cp2      = 64;               % the CP length in the other OFDM symbols                                                SimParam.system.fs       = 3.84e6;           % Sampling frequency                                                                 elseif SimParam.system.bandwidth == 5                    SimParam.system.numAllRb = 25;               % the maximum number of RB which could be scheduled in configured bandwidth              SimParam.system.numSubc  = 300;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth         SimParam.system.fftSize  = 512;              % the size of FFT/IFFT                                                                   SimParam.system.cp1      = 128;              % the CP length in the first OFDM symbol                                                 SimParam.system.cp2      = 128;              % the CP length in the other OFDM symbols                                                SimParam.system.fs       = 7.68e6;           % Sampling frequency                                                                 elseif SimParam.system.bandwidth == 10                   SimParam.system.numAllRb = 50;               % the maximum number of RB which could be scheduled in configured bandwidth              SimParam.system.numSubc  = 600;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth         SimParam.system.fftSize  = 1024;             % the size of FFT/IFFT                                                                   SimParam.system.cp1      = 256;              % the CP length in the first OFDM symbol                                                 SimParam.system.cp2      = 256;              % the CP length in the other OFDM symbols                                                SimParam.system.fs       = 15.36e6;          % Sampling frequency                                                                 elseif SimParam.system.bandwidth == 15                   SimParam.system.numAllRb = 75;               % the maximum number of RB which could be scheduled in configured bandwidth              SimParam.system.numSubc  = 900;              % the maximum numbe subcarriers which could be scheduled in configured bandwidth         SimParam.system.fftSize  = 1536;             % the size of FFT/IFFT                                                                   SimParam.system.cp1      = 384;              % the CP length in the first OFDM symbol                                                 SimParam.system.cp2      = 384;              % the CP length in the other OFDM symbols                                                SimParam.system.fs       = 23.04e6;          % Sampling frequency                                                                 elseif SimParam.system.bandwidth == 20                   SimParam.system.numAllRb = 100;              % the maximum number of RB which could be scheduled in configured bandwidth              SimParam.system.numSubc  = 1200;             % the maximum numbe subcarriers which could be scheduled in configured bandwidth         SimParam.system.fftSize  = 2048;             % the size of FFT/IFFT                                                                   SimParam.system.cp1      = 512;              % the CP length in the first OFDM symbol                                                 SimParam.system.cp2      = 512;              % the CP length in the other OFDM symbols                                                SimParam.system.fs       = 30.72e6;          % Sampling frequency                                                                 endelse    error('Invalid SimParam.system.cpLen!');end

Downlink Synchronization signals

一.什么是PSS和SSS

PSS的全称是Primary Synchronization Signal，即主同步信号，用于传输组内ID即N(2)_ID值。SSS的全称是Secondary Synchronization Signal，即辅同步信号，用于传输组ID即N(1)_ID值。

二.PSS和SSS的位置

1.时域上的位置

对于LTE-FDD制式，PSS周期的出现在时隙0和时隙10的最后一个OFDM符号上，SSS周期的出现在时隙0和时隙10的倒数第二个符号上。

对于LTE-TDD制式，PSS周期的出现在子帧1、6的第三个OFDM符号上，SSS周期的出现在子帧0、5的最后一个符号上。

如果UE在此之前并不知道当前是FDD还是TDD，那么可以通过这种位置的不同来确定制式。

2.频域上的位置

PSS和SSS映射到整个带宽中间的6个RB中，因为PSS和SSS都是62个点的序列，所以这两种同步信号都被映射到整个带宽（不论带宽是1.4M还是20M）中间的62个子载波（或62个RE）中，即序列的每个点与RE一一对应。

（1）对于LTE-FDD来说，PSS应该被映射到slot0和slot10的最后一个OFDM符号中，在OFDM符号中的位置如下：

下图是1.4M带宽（满带宽6个RB）时，LTE-FDD制式下PSS和SSS的位置：

（2）对于LTE-TDD来说，PSS应该被映射到subframes 1和6的第三个OFDM符号中，在OFDM符号中的位置如下，在这种情况下，62个子载波的两边各有5个子载波，不再映射其他数据：

下图是1.4M带宽（满带宽6个RB）时，LTE-TDD制式下PSS和SSS的位置：

部分转载链接：LTE小区搜索-物理小区ID和同步信号PSS、SSS

部分参考：Physical Channels and Modulation(Release 10)