单载波二维码分与频分多址系统及其性能分析

Single carrier two dimensional code and frequency division multiple access system and its performance analysis

提出一种单载波二维码分与频分多址(single carrier two dimensional code and frequency division multiple access,SC-2DCFDMA)系统,借助时频二维扩频矩阵解决普通单载波码分与频分多址(single carrier code and frequency division multiple access,SC-CFDMA)系统中扩频因子与子带宽度之间的矛盾;构建了SC-2DCFDMA系统发送端与接收端的数学模型;分析了其在加性高斯白噪声信道和频率选择性信道下的理论误码率。仿真结果表明,理论与仿真误码率曲线吻合;在相同的扩频因子条件下,SC-2DCFDMA系统具有比SC-CFDMA系统更窄的用户子带宽度和更优的误码率性能;在多用户场景下,虽然信道的频率选择性会造成频域扩频码的正交性损失,但这种损失可由时域扩频码的正交性来弥补,从而使得SC-2DCFDMA系统的多用户性能优于SC-CFDMA系统。

A single carrier two dimensional code and frequency division multiple access （SC-2DCFDMA） system is proposed. The contradiction between spreading factor and subband width in common single carrier code and frequency division multiple access （SC-CFDMA） system is resolved by the use of time-frequency two dimensional spreading matrix. The mathematical models of SC-2DCFDMA transmitter and receiver are con- structed. The analytical bit error rate （BER） under additive white Gaussian noise channel and frequency selec- tive channel are analyzed. Simulation results show that the analytical and simulated BER curves coincide with each other. With equal spreading factor, SC-2DCFDMA system has narrower user subband and superior BER performance. In a multi-user scenario, although channel frequency selectivity induces the orthogonality loss of the frequency domain spreading code, this kind of loss could be compensated by the orthogonality of time domain spreading code. Thus multi-user performance of SC-2DCFDMA system is better than SC-CFDMA system.