Performance of diversity combining scheme using simplified weighting factor

In land mobile communication, a signal transmission is affected by fading. A received signal suffers from extreme fluctuation in both its envelope and phase, causing performance degradation of the receiver. In order to reduce this degradation, there is a variety of diversity combining techniques. Maximal-ratio combining (MRC), which maximizes the carrier to noise ratio (CNR) of the combined signal, generally requires envelope detection and multiplication having a linear characteristic over a wide dynamic range to generate a weighting factor for each branch. We propose a simplified diversity combining scheme without linear envelope detection. The proposed scheme, called "level comparison weighted combining (LCWC)", is simplified in a manner that its weighting factor for each branch is generated from hard-decision results of comparing signal envelopes among the branches. The performance of LCWC is evaluated by computer simulation and laboratory experiment, which shows that its diversity gain is very close to that of MRC.