Preface.1. Introduction.2. PLC in the Telecommunications Access Area.3. PLC Network Characteristics.4. Realization of PLC Access Systems.5. PLC MAC Layer.6. Performance Evaluation of Reservation MAC Protocols.Appendix A.References.Index.

Broadband powerline communications networks : network design

Testimonies of "wireless catching up with wireline" have begun. An information superhighway system is envisioned to fulfill the plethora of demand for wireless communications and the need for multimedia networks with multiservice requirements. The revolution in this technology will eventually free us, as communication users, from being tied down to a particular fixed location in a telephone network to person-to-person communications, via pocket-sized terminals, at an affordable price. This article briefly surveys the state of the art, standards, and technological growth experienced in mobile cellular (terrestrial and satellite) communications since the days of the ingenious inventions of Alexander Graham Bell and Guglielmo Marconi, over a century ago. Subsequently, we describe some emerging technological trends that can improve the capacity of third-generation systems and future outlooks for PCS networks in the next millennium.

Recent advances in cellular wireless communications

Driven by the twin forces of industry-wide deregulation and the explosive demand for Internet access and bandwidth-intensive multimedia services, broadband local access has emerged as one of the key issues in modern telecommunications. We describe a broadband local access network consisting of small, densely spaced packet-switching nodes interconnected by focused free-space optical links in a multihop mesh arrangement. Each switch serves a client, which may be an office building (containing, for example, conventional PBXs and LANs), a picocellular base station, or both. It is the responsibility of our local access network to economically and reliably extend broadband local access service (perhaps OC-3 or OC-12 for building LANs and PBXs; perhaps several tens of megabits per second to base stations) from an infrastructure end office or fiber ring add/drop multiplexer without requiring the installation of new buried optical cabling. Computed is the capacity of the multihop mesh, defined to be the maximum number of virtual connections which can be delivered to the infrastructure access point such that, independent of the traffic distribution among clients, all quality of service guarantees are maintained.

A broadband wireless access network based on mesh-connected free-space optical links

A communication system having a wireless trunk for connecting multiple phone lines over wireless communication links to a cellular network comprises a central telephone switch, such as a private branch exchange or key system, connected through one or more trunk lines to a wireless access communication unit. The wireless access communication unit preferably comprises a separate subscriber interface for each trunk line from the central telephone switch. The wireless access communication unit collects data from each of the subscriber interfaces, formats the data into a format compatible with an over-the-air protocol, and transmits the information over one or more wireless channels to a cellular base station. The wireless access communication unit thereby connects calls received from the central telephone switch's trunk lines over a wireless trunk to a network. A controller within the wireless access communication unit interfaces the subscriber interfaces with a radio transceiver, and assists in the conversion of data from a format suitable for wireless transmission. Authentication is carried out separately for each of the subscriber interfaces, thereby allowing the wireless access communication unit to represent itself as multiple individual subscribers to the network. Upon each initial registration, each subscriber interface derives its own ciphering key from a stored user key and uses it thereafter for encryption and decryption.

Authentication and security in wireless communication system

Given the user distribution in a cell, we investigate the two problems of how to appropriately sectorize the cell such that we minimize the total received power and the total transmit power of all the users, while giving each user acceptable quality of service in both cases. For the received power optimization problem, we show that the optimum arrangement equalizes the number of users in each sector. The transmit power optimization is formulated as a graph partitioning problem that is polynomially solvable. We provide an algorithm that finds the best sectorization assignment as well as the optimal transmit powers for all the users. The computational complexity of the algorithm is polynomial in the number of users and sectors. For both the received power optimization and the transmit power optimization, under nonuniform traffic conditions, we show that the optimum arrangement can be quite different from uniform cell sectorization (equal width sectors). We also formulate and solve the transmit power optimization and cell sectorization problem in a multicell scenario that would improve the capacity of a hot spot in the network. We observe that, with adaptive sectorization, where the sector boundaries are determined in response to users' locations, received and transmit power savings are achieved, and the number of users served by the system (system capacity) is increased compared to uniform sectorization of the cell.

/pdf/adaptive-cell-sectorization-for-cdma-systems-2mr0fxcqbf.pdf

Adaptive cell sectorization for CDMA systems

The digital access technologies for the wireless local loop (WLL) or fixed wireless system are discussed. WLL is an important means of providing telephone services more cheaply and quickly in the developing countries than through a wireline system. Capacities of a WLL system based on the IS-54 (now IS-136) TDMA, IS-95A CDMA, and ETSI GSM technologies are developed and compared.

V.K. Garg

Papers

Digital wireless local loop system