Field test measurement of DS-CDMA RAKE receiver with TWCL in an urban area

This paper presents field test measurement results from a postdetection RAKE receiver system using a time-window control loop (TWCL). TWCL is a code synchronization scheme, and its performance with delay paths is better than the performance, in terms of acquisition and tracking, without delay paths because of the path-diversity effect. This receiver is suitable for systems that use short spreading codes such as wireless local area networks because it employs a matched filter for despreading. The RAKE method is a simple integral demodulation method used to combine correlation peaks including delay paths in a time window, and two-branch-antenna combining diversity is available. A field test is implemented while walking in an urban area, including the no-line-of-sight situation, taking into consideration microcellular systems. The results show that when the bit error rate is 10^-3 and the spreading-chip rate is 4.096 Mchip/s, path-diversity gain from the theoretical differential quadrature phase-shift keying value is more than 12 dB without antenna diversity. This path-diversity gain value corresponds to a path-diversity reception gain of between two and three. Using two-branch-antenna diversity, the total of path- and antenna-diversity gain is up to 18 dB in the no-line-of-sight situation. From the above results, it is clear that this RAKE receiver is effective even in the no-line-of-sight situation and that TWCL provides good performance under the given field conditions