QoS management in packet cellular networks

This study is a comprehensive look at our work on providing reliable and sustained QoS in wireless mobile networking environments.; Implementing end-to-end TCP in wireless networks faces two problems. First, TCP cannot distinguish packet losses caused by link failures from those caused by network congestion. Second, the TCP congestion control mechanism does not deal effectively with large numbers of out-of-order packet retransmissions. We present a Link-Layer Protection (LHP) protocol which implements Explicit Loss Notification (ELN) in a simple, scalable manner, addressing the first problem. We also modify the congestion control mechanism to incorporate knowledge of ELN and packet loss patterns into retransmission decisions, solving the second problem.; The goodput of a multimedia stream depends on answering not only the question “At what rate should a sender transmit data under current network conditions?” but also the question “Which packets should the sender transmit given its current transmission rate?” We present an objective definition of goodput at the QoS-aware middleware and present a set of simple online packet dropping algorithms that can be used at the sender side to improve the application level reception quality for the flow.; We identify the influence on the application-layer valid bandwidth of link-layer error correction mechanisms in a wireless network because of the network's use of redundancy bits. We propose our framework of utility-based wireless fair scheduling to integrate the different wireless scheduling mechanisms, error correction mechanisms, and application-layer fairness together to provide QoS guarantee to the application layer.; We identify the unique characteristics of shared wireless channels and investigate the fairness properties that can be achieved by the class of multiple access wireless MAC protocols in shared-channel wireless networks in general, and ad hoc networks in particular. We propose our general mechanism for translating a given fairness model into a corresponding backoff-based collision resolution algorithm that probabilistically achieves the fairness objective.