T Busby

A comparison of CDMA techniques for third generation mobile radio systems

A comparison is made between both direct sequence (DS) and frequency hopping (FH) spreading techniques in code division multiple access (CDMA) based upon the stringent requirements of proposed third generation mobile radio systems in Europe. Given the many criteria against which this comparison is made, the outcome is slightly in favour of DS-CDMA.

The application of frequency hopping CDMA for future universal Personal Communications Systems

The future of mobile telephony is moving towards a universal standard to replace the mixture of technologies that exist in the market place today. In North America, Personal Communications Systems (PCS) have become synonymous with this goal and candidates for the air interface include both CDMA and TDMA. CDMA technology has been dominated by a technique exploiting direct sequence (DS) spread spectrum. An alternative approach employs frequency hopping (FH) spread spectrum, and recent work has shown that the claimed advantages of DS also apply to FH. In this contribution, these claims are investigated and an alternative FH-CDMA architecture proposed to rival current DS-CDMA systems.

The UK LINK personal communications programme: downlink synchronisation for a DS-CDMA field trial system

DS-CDMA is recognised as one of the foremost radio access techniques today. However, to date, there has been relatively scant information on the system implementation and the many problems facing radio engineers. A DS-CDMA field trial demonstration system is described briefly, before discussing in detail the vital process of acquisition and synchronisation at the mobile and its practical implementation.