Signal Processing Requirements of the TDD Terminal

Abstract

This paper considers the signal processing requirements of 3GPP-TDD terminal and examines the technology requirements for the implementation of the 3GPP-TDD mode, this is followed by a discussion of how the terminal complexity of the TDD mode compares to that of the FDD mode. The first part of the paper begins with a short explanation of how the 3GPP TDD mode fits into the ITU family of standards, the specification of the TDD mode covering the frequency bands, the synchronous nature, and the physical channel structure. The differences in the inner receiver implementation between the TDD mode and the FDD mode are highlighted.

The second part of the paper identifies the key signal processing complexity issues that determine the TDD terminal architecture. This section explains the requirement for terminal synchronisation to the network in the synchronous TDD mode and asynchronous FDD mode. The baseband implementation section briefly covers the inner receiver functions of the TDD mode: channel estimation, active code detection and multi-user detection. The latter is basically examined from the joint detection point of view; nevertheless other techniques are presented with particular interest in the single detection algorithms. This leads to a brief comparison of the terminal architectures for the FDD and TDD modes, in particular the suitability of the air interface to flexible implementation on a DSP.