TCP is a reliable transport protocol tuned to perform well in traditional wired networks, where most packet losses are due to congestion. In wireless networks, however, packet losses result from wireless link loss in addition to congestion loss. Thus, TCP suffers a significant degradation in performance over wireless networks because it does not distinguish wireless link loss from congestion loss. To overcome this problem, the explicit wireless loss notification (EWLN) scheme is proposed to explicitly inform wireless link loss to the TCP sender. Previous work to deploy EWLN often lacked explicit specification of the interplay between EWLN and link-layer protocols, including error recovery mechanisms. In addition, many systems, being based on computation demanding the functionality of agents at a base station, were designed for the scenario where information is accessed from a mobile station through a wireless-to-wired connection. In this paper, we present an EWLN scheme that deploys the information from the MAC layer and takes into account the interplay with the error recovery mechanism at the link layer. The scheme does not require different implementations for mobile terminals and base stations and hence can support efficient TCP-based data transmission over wired-to-wireless and wireless-to-wired connections as well as ad-hoc networks.

In recent years, the concept of Quality of Service (QoS) has gained attention in the network research community and its extension towards delivering QoS level assurance to sensitive applications has generally been agreed to be crucial for the longevity and usability of the Internet. On the Internet, the Differentiated Services (DiffServ) architecture is a general framework for the differentiated treatment of traffic aggregates in the core network. However, DiffServ does not extend to end-to-end QoS assurance. In this paper, we propose a simple resource-brokering scheme operating over a hierarchically connected internetwork of administratively-independent DiffServ-capable domains that is a simplified model of the Internet. The proposed asynchronous, multi-agent resource-brokering scheme operates locally but avoids conflicts globally. In this way, the traffic control reflects the underlying structure of the internetwork, introduces only a localized complexity thus scaling up well, and permits independent policies between the interconnected domains.