tailieunhanh - Wireless địa phương vòng - lý thuyết và ứng dụng P8

The need for providing telecommunication services is growing faster than ever. For this purpose Wireless Local Loop (WLL) also known as Fixed Wireless Access (FWA) Networks is an effective alternative to the problematic wired system. Compared to mobile systems, FWA networks provide two-way communication services to near-stationary users within a small area [8]. The next section presents an overview of multiple access schemes. Channel allocation strategies are described in the second part of the section. The emphasis here is on fixed and dynamic channel allocation schemes | Wireless Local Loops Theory and Applications Peter Stavroulakis Copyright 2001 John Wiley Ltd ISBNs 0-471-49846-7 Hardback 0-470-84187-7 Electronic 8 Traffic based Dynamic Channel Allocation Schemes for WLL Ingo Forkel Stefan Mangold Roger Easo and Bernhard Walke Introduction The need for providing telecommunication services is growing faster than ever. For this purpose Wireless Local Loop WLL also known as Fixed Wireless Access FWA Networks is an effective alternative to the problematic wired system. Compared to mobile systems FWA networks provide two-way communication services to near-stationary users within a small area 8 . The next section presents an overview of multiple access schemes. Channel allocation strategies are described in the second part of the section. The emphasis here is on fixed and dynamic channel allocation schemes. A unique Dynamic Channel Allocation DCA technique for a Wireless Asynchronous Transfer Mode WATM system based on the Carrier to Interference ratio C I measuring is presented. This technique is explained in detail as it provides the concept for the simulator which is used for the analysis of the broadband FWA network. The FWA network scenario and its parameters are presented in the following section. The parameters of the radio channel are explained as well as the traffic models and the system parameters such as its geometrical setting and radio characteristics. Simulation results of Time Division Multiple Access TDMA with DCA are presented. The effects of different capacity enhancing schemes suitable in WLL scenarios for the proposed algorithm are investigated and evaluated. Access and Allocation Technologies Presented in this section is a description of multiple access technologies and an overview of existing channel allocation schemes. An extended version with some examples explained in more detail is given in 5 . Multiple Access Technology A defined radio bandwidth can be divided into a set of defined radio .