tailieunhanh - Wireless địa phương vòng - lý thuyết và ứng dụng P7

The focus of interest is the multiple access technology that will be employed in Wireless Local Loop (WLL) systems, here referred to as Fixed Wireless Access (FWA) networks. The discussion of whether to employ Code Division Multiple Access (CDMA) or Time Division Multiple Access (TDMA) has gone on for a long time with no result to be expected in the near future. In this chapter, a capacity comparison for FWA based on two access technologies is performed. The TDMA system is analysed with the help of a simulator in chapter by S. V. Krishnamurthy et al. [8] | Wireless Local Loops Theory and Applications Peter Stavroulakis Copyright 2001 John Wiley Sons Ltd ISBNs 0-471-49846-7 Hardback 0-470-84187-7 Electronic 7 Traffic Considerations in Comparing Access Techniques for WLL Stefan Mangold Ingo Forkel Roger Easo and Bernhard Walke Introduction The focus of interest is the multiple access technology that will be employed in Wireless Local Loop WLL systems here referred to as Fixed Wireless Access FWA networks. The discussion of whether to employ Code Division Multiple Access CDMA or Time Division Multiple Access TDMA has gone on for a long time with no result to be expected in the near future. In this chapter a capacity comparison for FWA based on two access technologies is performed. The TDMA system is analysed with the help of a simulator in chapter by S. V. Krishnamurthy et al. 8 . With this approach it is possible to adjust different scenarios and system parameters in order to find the best capacity utilization of the system. The CDMA system is investigated analytically in this chapter. It is clear that in performing an analytical calculation certain simplifications and assumptions will need to be made. The structure of this chapter is as follows. In the next section the FWA network is explained in more detail. Apart from the technological description of this access scheme the section will also examine the economic viability. The impact of the FWA network in developed and developing countries is investigated and a prognosis is made on the future market possibilities of FWA networks. Following is a brief overview of multiple access schemes. A derivation for capacity equations of a CDMA system is contained in the following section. An analysis is performed for a single cell scenario offering only one service class. The approach is then adopted for a single radio cell with multiple service classes and finally for a multiple radio cell environment with multiple service classes. A comparison of the capacity result for .