Real-time traffic in Cellular IP network is considered to be important and therefore given priority over non-real-time. Buffer is an important but scarce resource and to optimize Quality of Service by managing buffers of the network is an important and complex problem. Evolutionary Algorithms are quite useful in solving such complex optimization problems, and in this regard, a two-tier model for buffer, Gateway and Base Station, management in Cellular IP network has been proposed. The first tier applies a prioritization algorithm for prioritizing real-time packets in the buffer of the gateway with a specified threshold. Packets which couldn’t be served, after the threshold, is given to the nearest cells of the network to be dealt with in the second tier, while Evolutionary Algorithm (EA) based procedures are applied in order to optimally store these packets in the buffer of the base stations. Experiments have been conducted to observe the performance of the proposed models and a comparative study of the models, GA based and PSO based, has been carried out to depict the advantage and disadvantage of the proposed models.
TopIntroduction
Cellular IP protocol is a solution for mobility management at micro level. Being designed for micro level of mobility, Cellular IP supports frequently moving mobile hosts. It can also efficiently serve rarely moving or even stationary mobile hosts. A Cellular IP network consists of interconnected nodes. These nodes accomplice the tasks to route IP packets inside the Cellular IP network and also communicate with the mobile hosts via wireless interface. Components of Cellular IP network are Cellular IP Base Station which controls and is responsible for the nodes in a cell, Cellular IP Gateway that connects Cellular IP network to Internet and stores the packets intended to be sent through Internet in its buffer, and the Cellular IP Mobile Node which implements the Cellular IP protocol (Valkó, Gomez, Kim, & Campabell, 1999). Many operations such as routing, paging, and handoff etc. take place in Cellular IP network. Quality of Service (QoS) in Cellular IP network depends on number of factors and is insured according to the availability of the resources in the network. Buffer, an important resource should be managed and utilized in an effective manner to achieve better performance in the Cellular IP network.
In wireless communications packets are prone to be dropped, lost, or delayed which results in connection disturbance. Buffer space is a resource which is often in short supply and if handled properly may improve the performance of the network drastically. For the real-time and non real-time traffic there should be good schemes for buffer management that guarantee least packets drop/loss. Also the schemes for buffer management, especially in Cellular IP networks, must be as robust as possible that produce good results in terms of QoS.
In Cellular IP networks, when a packet is sent from a base station to the Gateway connecting the network with Internet, it will be queued for onward transmission to the corresponding node (network). If there is no available buffer space to put the packet in, the packet has to be discarded. To offer good quality of service, buffers can be reserved for real-time flow of packets so that this flow doesn’t have to compete for buffers with other flows. In Cellular IP networks, due to data packet buffering at the air interface of the Gateway, the end-to-end bottleneck is a potential problem. Therefore buffer management is essential to support end-to-end QoS provision. Buffer reservation or buffer management must be done by giving the priority to real-time traffic over non real-time traffic and improve the QoS in the network. QoS can be achieved by increasing the Connection Completion Probability (CCP).
Evolutionary Algorithms (EAs) are often used to solve optimization problems that have no straightforward solutions. EAs maintain a population of structures (usually randomly generated initially) that evolves according to the rules of selection, cross-over, mutation etc. All individuals are evaluated against a fitness function. The fittest individuals are likely to be selected to generate new population in the next generation (Jain, Palade, & Srinivasan, 2007). Buffer management is an important issue to improve QoS in wireless networks especially in Cellular IP networks. With the increase in the number of flows this problem has become a complex one and involves a big search space. EAs can be applied successfully to solve this problem.