The proliferation of wireless and mobile computing and networking that creates the bases for global nomadicity, which is the ability to communicate from everywhere to anywhere by everyone, has experienced exponential growth. The advent of mobile-centric and wireless devices and the need to preserve and apply the ubiquitous Internet technology, which was originally conceived when mobility was not an issue, has posited the need to create augmented and modified models of communication that attempt to preserve the semantic integrity and transparency independent of the underlying communication infrastructure. Moreover, the number, the power and the richness of the applications developed for mobile and wireless products include multimedia capabilities whose proper execution depends on the essential network attributes such as bandwidth, delay and reliability. These attributes are also the components of the Quality of Service (QoS). Some of the problems in a heterogeneous wireless networks that either directly or indirectly influence the QoS are well known. These include but are not limited to reliable transport services, where reliability due to the infrastructure might prove to be liability rather then an asset, then asymmetrical nature of the traffic, and finally the problem of handoffs. These problems have been one of the principal areas of research in communication networks in the last several years. In the paper, that is a report on an ongoing research, we propose an architecture that addresses the problems of the Internet technology deployment in wireless heterogeneous networks through a unified conceptual model. The diversity of this model and the basic architectural components, once sufficiently explored and well defined, should enable to achieve a desirable QoS for 4G networking.
Both streaming techniques and wireless heterogeneous networks have recently become more widely deployed. As the current streaming techniques are primarily designed for homogenous wired networks, streaming multimedia applications in heterogeneous networks can perform poorly due to wireless networks conditions and vertical handover. These problems can significantly degrade the performance of streaming multimedia applications. Effects of the degradation are delay, jitter and packet loss resulting in lower multimedia quality. The use of some congestion recovery algorithms are detrimental factors to QoS. One approach used to control congestion in the network layer is Active Queue Management (AQM). This dissertation presents an evaluation and comparison of AQM mechanisms in heterogeneous networks. Based of the results of this research a new AQM algorithm, named the Adaptive AQM (AAQM) is proposed. The AAQM uses control law and link utilization in order to manage congestion. The action of the control law is to mark incoming packets in order to maintain the quotient between arriving and departing packets as low as possible. The AAQM enhances performance with respect to the queue length and packet loss as well as buffer space requirements. AAQM outperforms the other AQM algorithms in terms of multimedia packet loss and buffer delay.