Mobile Wireless Networks

Introduction

Mobile Wireless Networks basically are of two types. One called infrastructure wireless network, which requires centalized access point or base station to coordinate the communication among the mobile nodes connected to it through the wireless link. All the base stations (or access points) are connected through wired links so that mobile nodes in the range of one base station can communiacte with the nodes in other base station's range. Cellular Network is an example of Infrastructure Wireless Networks. Second one is called Mobile Ad Hoc Network (MANET). It doesn't require any centralized node to coordinate the communication. All the mobile nodes collectively establish connectivity among themselves. These networks are usually multihop networks as opposed to Infrastructure wireless networks. In infrastructure wireless networks all the mobile nodes are only one hop away from the base station. In MANET if a node wants to send a message to another node which is not in its range the intermediate nodes forward the message to the recipient.

The protocols desinged for Infrastructure Wireless Networks or Wired Networks are not adaptable to MANETs because of its special characteristcs. The special characteristics include the following.

1. Mobile nodes do not rely on any centalized node for communication.
2. Dynamic topology (as the nodes are mobile).
3. Bandwidth is a scarce resource when compared to wired networks.
4. Power-constrained networks as all the mobile nodes rely on batteries.

Objectives

Multimedia communication over network requires some Quality-of-Service (QoS) guarantees. Satisfying the QoS guarantees is difficult in MANETs due to the same special characteristics mentioned above. So protocols which take the special characteristics MANET environment into consideration need to be designed.