Wireless Technology Essay -- Network Congestion,

Wireless is a new technology that allows users to access information and services regardless of the geographic position. People can utilize and surf the Internet with computers (e.g., laptop, palmtop, smart phone and PDA) whenever and wherever possible. In general, wireless network can be classified into two types: infrastructure network and ad hoc network. Mobile ad hoc network (MANET) is an autonomous group of mobile users who communicate through relatively bandwidth constrained wireless links. Since the hosts are mobile, the network topology may change rapidly and unpredictably over time [3]. Congestion in a network may occur if the load on the network (the numbers of packets send to the network) is greater than the capacity of the network (the number of packets a network can handle). Thus network congestion can severely increase delay and packet loss and reduced network throughput. Congestion control refers to techniques and mechanisms that can either prevent congestion before it happens, or remove congestion after it happened. The main objective of congestion control is to limit the delay and buffer overflow caused by network congestion and provide better performance of the network [6]. In wire line networks, congestion control is implemented at the transport layer and is often designed separately from functions of other layers [20]. However, these congestion control techniques do not apply directly to adhoc networks because the ad hoc network is challenged by limited wireless bandwidth, power constraints, route failures due to node mobility and limited buffer size. The final result is high packet-loss rate, re-routing instability, loss of energy, bandwidth and retransmission of lost packets, which means that even mo... ...ne ( warn_line= queue_size/2), then the node’s congestion status becomes Zone I (safe zone). The average queue length greater than Minth and less than Maxth, then the node’s congestion status becomes Zone-II (likely to be congested zone) and initiates alternate path discovery mechanism. In mean time, the instant queue size is greater than Maxth due to heaviness of incoming traffic and the status of alternate path discovery becomes false. In this situation our algorithm introduce queue utilization parameter consists of three ranges {85%queuesize, 87.5%queuesize, 90%queuesize} which will help to change Maxth values dynamically until alternate path discovery becomes true. Finally average queue length is greater than Maxth, then the node’s congestion status becomes Zone –III(congested zone). The algorithm of dynamic congestion detection algorithm is shown in Fig.1. Wireless Technology Essay -- Network Congestion, Wireless is a new technology that allows users to access information and services regardless of the geographic position. People can utilize and surf the Internet with computers (e.g., laptop, palmtop, smart phone and PDA) whenever and wherever possible. In general, wireless network can be classified into two types: infrastructure network and ad hoc network. Mobile ad hoc network (MANET) is an autonomous group of mobile users who communicate through relatively bandwidth constrained wireless links. Since the hosts are mobile, the network topology may change rapidly and unpredictably over time [3]. Congestion in a network may occur if the load on the network (the numbers of packets send to the network) is greater than the capacity of the network (the number of packets a network can handle). Thus network congestion can severely increase delay and packet loss and reduced network throughput. Congestion control refers to techniques and mechanisms that can either prevent congestion before it happens, or remove congestion after it happened. The main objective of congestion control is to limit the delay and buffer overflow caused by network congestion and provide better performance of the network [6]. In wire line networks, congestion control is implemented at the transport layer and is often designed separately from functions of other layers [20]. However, these congestion control techniques do not apply directly to adhoc networks because the ad hoc network is challenged by limited wireless bandwidth, power constraints, route failures due to node mobility and limited buffer size. The final result is high packet-loss rate, re-routing instability, loss of energy, bandwidth and retransmission of lost packets, which means that even mo... ...ne ( warn_line= queue_size/2), then the node’s congestion status becomes Zone I (safe zone). The average queue length greater than Minth and less than Maxth, then the node’s congestion status becomes Zone-II (likely to be congested zone) and initiates alternate path discovery mechanism. In mean time, the instant queue size is greater than Maxth due to heaviness of incoming traffic and the status of alternate path discovery becomes false. In this situation our algorithm introduce queue utilization parameter consists of three ranges {85%queuesize, 87.5%queuesize, 90%queuesize} which will help to change Maxth values dynamically until alternate path discovery becomes true. Finally average queue length is greater than Maxth, then the node’s congestion status becomes Zone –III(congested zone). The algorithm of dynamic congestion detection algorithm is shown in Fig.1.