穿戴式超宽带接收机误码率性能分析

Bit Error Rate Performance Analysis of On-body Ultra Wideband Receiver for Wireless Body Area Networks

为研究不同接收机的架构、收发天线的角度和判决方式对穿戴式超宽带（UWB）信道RAKE接收机误码率（BER）的影响,利用数字抽样示波器获取时域接收信号,使用CLEAN算法去卷积,得到体表-体表和体表-体外环境下人体信道冲激响应;并采用不同结构不同分支数的RAKE接收机对含有加性高斯噪声的跳时信号进行接收,以分析其对BER的影响.仿真结果表明,包含所有分支的RAKE接收机BER最低但结构复杂;在相同分支数下,包含部分分支的RAKE接收机的BER损失要比选择性RAKE接收机高3dB,但复杂度较低.对收发天线不同角度的研究表明,收发天线应避免垂直,否则体表反射作用带来的多径分量增多,容易出现码间干扰,从而增加BER.在重复编码情况下,软判决的BER性能要优于硬判决0.2-0.4dB.该信道模型和误码率分析研究可对穿戴式UWB收发机的架构设计和性能研究提供参考.

A method of analyzing bit error rate（BER）based on channel model of on-body Ultra Wideband （UWB） networks is proposed with consideration of various structures of RAKE receiver,the angle between transmitter忆s antenna and receiver忆s antenna and the way of signals忆decision. Digital storage oscilloscope is adopted to acquire received signal of time domain and CLEAN deconvolution algorithm is used to get the impulse response of body channel in the line-of-sight condition of body surface to body surface and body surface to external. Various structures and branch number of RAKE receivers are applied to receive the time-hopping signal accompanied with additive white Gaussian noise and so BER can be analyzed. The simulation results show that absolute RAKE receiver has best BER performance while it has the most com-plex structure. For the same branch number,partial RAKE receiver忆s BER is nearly 3 dB degraded than se-lective RAKE忆s but it has lower complex structure. In order to reduce multipath components due to body re-flection and get better BER and inter-symbol interference（ISI）,results show that vertical angle between transmitter＇s antenna and receiver忆s antenna should be avoided. For repetition code,the BER performance of soft decision is 0. 2 -0. 4 dB better than hard decision. The channel model and BER performance analy-sis provide references for UWB transceivers design and performance evaluation.