Low cost high performance CDMA system for US PCS

The goal of the future personal communication systems (PCS) is to augment the wireline phone system with a tetherless system providing ubiquitous coverage. The authors propose a two tier PCS system. The low tier (local service or PCS/LS) system is based on a low power, low cost TDM/TDMA access method using a microcell structure with a 25 cell reuse pattern designed for pedestrian usage. The high tier (enhanced service or PCS/ES) system, on the other hand, is a high capacity system designed for a cellular type coverage with a 1-cell reuse pattern. Major emphasis is placed on the enhanced system design. This system is based on a combination of slow frequency hopping CDMA (SFH-CDMA) with TDMA structure. Careful design of TDMA slots allow for a slow synthesizer requirement. Also, use of short constraint length convolutional codes combined with MLSE equalization provides a high coding gain even at long delay spreads. These functions, due to their highly parallel structure can be efficiently integrated using custom ICs for low cost design. The modem performance of PCS/ES system in a cellular environment is investigated for both max-ratio and selection diversity. Based on the modem performance, system capacity is derived and then compared with AMPS cellular system