The basic problems of wireless access are that the available spectrum is too limited and there is great attenuation of energy. These can be solved by frequency reuse and by reducing the maximum distance from the terminal to the nearest base station.
Distributed wireless communication system (DWCS) is a new architecture for a wireless access system with distributed antennas, distributed processors, and distributed controlling. The basic idea is to flatten the tree cellular structure. With distributed antennas, system capacity can be expanded through dense frequency reuse, and transmission power can be greatly decreased. With distributed processors controlling, the system works like software or network radio, so different standards can coexist, and the system capacity can be increased by co processing of signals to and from multiple antennas.
The beyond 3G ie 4G mobile communications is aimed at much larger capacity and coverage requirements. DWCS is a candidate architecture to fulfill these requirements.
INTRODUCTION
With the rapid progress in telecommunications, more and more services are provided on the basis of broadband communications, such as video services and high-speed Internet. With worldwide fundamental construction of a backbone network based on optical fiber providing almost unlimited communications capability, the limited throughput of the subscriber loop becomes one of the most stringent bottlenecks. Compared to the capacity of the backbone network, which is measured by tens of gigabits per second, the throughput of the subscriber loop is much lower, only up to hundreds of megabits
per second for wired systems (including fixed wireless access). However, for mobile access the throughput is even lower, and depends on the mobility of the terminal. For example, the peak data rate is only 2 Mb/s for 3G systems.
Since there will be more and more need for mobile services, the poor throughput of mobile access not only limits user applications based on interconnection, but also wastes the capability of the backbone network. This case is quite similar to the traffic conditions shown in Fig. a, which is an image of an ultra-wide expressway with a few narrow entrances.