With advances in wireless communication technologies, users can have rich contents not only via wired networks but also via wireless networks such as Cellular, WiFi, and WiMAX. On the other hand, however, lack of spectrum resources becomes an important problem for future wireless networks. To overcome this problem, dynamic spectrum access technology receives much attention. In this paper, we pr...

Currently, mobile phones are the primary method of navigation. However, indoor positioning and navigation poses a unique problem because the Global Positioning System (GPS) satellites normally used to navigate oudoors have limited use indoors. One solution is using Wifi access points as anchors, measuring the signal strength and calulating position using trilateration. Indeed, there are tools t...

In a Wireless Fidelity (WiFi) network it is well known that large periods of contention, the intermittent disruptions of the service and limited bandwidth represent a handicap for interactive realtime multimedia applications since they demand high troughput and real time constraints, e.g. Video on Demand (VoD) or Voice over Internet Protocol (VoIP). Nevertheless, it is very common to use WiFi n...

Extensive work has been done in wireless multihop routing with several ideas based on shortest path or load balancing routing algorithms, that aim at minimizing end-to-end delay or maximizing throughput respectively. Backpressure is a throughput-optimal scheme for multihop routing and scheduling, while Enhanced-Backpressure is an incremental work that reduces end-to-end delay without sacrificin...

Integrity checking is ubiquitous in data networks, but not all network traffic needs integrity protection. Many applications can tolerate slightly damaged data while still working acceptably, trading accuracy versus efficiency to save time and energy. Such applications should be able to receive damaged data if they so desire. In today’s network stacks, lower-layer integrity checks discard damag...

This paper describes a Session Initiation Protocol (SIP) based solution for mobility management that provides seamless mobile multimedia services in a heterogeneous scenariowhere different radio access technologies are used (802.11/ WiFi, Bluetooth, 2.5G/3G networks). The solution relies on the so called “Session Border Controllers” which are now widely used in many commercial SIP telephony sol...

requirements on the network traffic compared to the traditional interactive and background applications. IEEE standard 802.11e addresses these QoS requirements in a WiFi based WLAN. It provides enhancements to the MAC layer protocol for supporting both prioritized and parameterized traffic between a QSTA and a QAP. To address the end-to-end QoS needs, the link level QoS supported by 802.11e sta...