Broadband Wireless Multimedia Networks

CHAPTER 1

OVERVIEW OF BROADBAND WIRELESS NETWORKS

Mobility and flexibility make wireless networks effective extensions and attractive alternatives to wired networks. Wireless networks provide all the functionality of wired networks, but without the physical constraints of the wire itself. However, the wireless link possesses some unique obstacles that need to be solved. For example, the medium is a scarce resource that must be shared among network users. It can be noisy and unreliable where transmissions from mobile users interfere with each other to varying degrees. The transmitted signal power dissipates in space rapidly and becomes attenuated. Physical obstructions may block or generate multiple copies of the transmitted signal. The received signal strength normally changes slowly with time because of path loss, more quickly with shadow fading and very quickly because of multipath fading. The most distinguishing issues in wireless network design are the constraints placed on bandwidth and power efficiency.

The broadcast nature of wireless transmission offers ubiquity and immediate access for both fixed and mobile users, clearly a vital element of quad-play (voice, video, data, and mobile) services. Moving from one location to another does not lead to disruptive reconnections at the new site. Wireless technology overcomes the need to lay cable, which is difficult, expensive, and time consuming to install, maintain, and especially, modify. Providing wireline connectivity in rural ...