Wireless Transceiver Architecture

9 Algorithms for Transceivers

In this final chapter, we show how to improve the performance of a given architecture by using a dedicated algorithm. The approach is either to compensate for the distortion experienced by the wanted signal when going through a non-ideal device (e.g. with a predistortion system on the transmit side), or to optimize the usage of the hardware available in the line-up under operating conditions (e.g. with an AGC scheme on the receive side). Such an approach is of interest from the perspective of implementing a line-up using a technology that allows for a high level of digital integration. We examine some of the algorithms classically encountered in wireless transceivers. In keeping with the transceiver architecture point of view, we stay at a system level rather than discussing the design and implementation of the algorithms themselves.

9.1 Transmit Side

Let us begin with algorithms typical of those encountered on the transmit side. We recall a simple fact that drives most of the trade-off involved in the implementation of such algorithms, at least when dealing with the compensation of a default in the line-up. When considering a transmitter as such, unless something special is done, we do not have access to the transmitted signal as effectively recovered at the output of the line-up. This is obviously an important difference compared to a receiver that, by definition, gives access to the received wanted signal. On the transmit side, we thus cannot ...