Cochannel performance of 16-level QAM with phase-locked TTIB/FFSR processing

Transparent tone in band (TTIB) is a reference based channel sounding technique which can facilitate the transmission of data with coherent demodulation. By exploiting the power and bandwidth efficiency of multi-level modulation schemes such as 16-level quadrature amplitude modulation (QAM), high data rate transmission can be achieved over frequency congested mobile links. With the use of feed forward signal regeneration (FFSR), the channel can be sounded and the undesirable propagation effects, such as fading, can be reduced. Two important factors used in defining modulation efficiency are tolerance to adjacent and cochannel interference. Although TTIB offers a much reduced channel spacing over existing cellular schemes such as the Total Access Communication System (TACS) and digital Time Division Multiple Access (TDMA) system, this must be equated with the protection ratio associated with each modulation scheme. Simulation results of the cochannel performance of 16-level QAM/TTIB subject to fading conditions as would be experienced in land mobile channels are presented