Sum Rate Characterization of Joint Multiple Cell-Site Processing

• Published in: IEEE transactions on information theory 2007-12, Vol.53 (12), p.4473-4497
• Main Authors: Somekh, O., Zaidel, B.M., Shamai, S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Arrays; Bandwidth; Boundaries; Cellular telephones; Channels; Coding, codes; Constraining; Distributed antenna array; Downlink; Electrical engineering; Equipments and installations; Exact sciences and technology; Exact solutions; fading; Information theory; Information, signal and communications theory; Lagrangian functions; Mathematical analysis; Mathematical models; Mobile communications networks; Mobile radiocommunication systems; multicell processing; Multiuser detection; multiuser diversity; Performance analysis; Radiocommunications; Shannon theory; Signal and communications theory; Signal processing; System performance; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Time division multiple access; Transmission and modulation (techniques and equipments); Transmitters; Wideband; Wireless communication; Wyner's cellular model
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2007.909170

The sum-rate capacity of a cellular system model is analyzed, considering the uplink and downlink channels, while addressing both nonfading and flat-fading channels. The focus is on a simple Wyner-like multicell model, where the system cells are arranged on a circle, and the cell sites are located at the boundaries of the cells. For the uplink channel, analytical expressions of the sum-rate capacities are derived for intra-cell time-division multiple-access (TDMA) scheduling, and a "wideband" (WB) scheme (where all users are active simultaneously utilizing all bandwidths for coding). Assuming individual equal per-cell power constraints, and using the Lagrangian uplink-downlink duality principle, an analytical expression for the sum-rate capacity of the downlink channel is derived for nonfading channels, and shown to coincide with the corresponding uplink result. Introducing flat-fading, lower and upper bounds on the average per-cell ergodic sum-rate capacity are derived. The bounds exhibit an O(loge K) multiuser diversity factor for a number of users per cell K Gt 1, in addition to the array diversity gain. Joint multicell processing is shown to eliminate out-of-cell interference, which is traditionally considered to be a limiting factor in high-rate reliable communications.