We consider the problem of maintaining end-to-end security in the presence of intelligent proxies that may adaptively modify data being transmitted across a network. The video coding community considers this problem in the context of transcoding media streams, but their approaches either fail to address authentication or fail to provide meaningful security guarantees. We present two provably-secure schemes, LISSA and TRESSA, that allow an intelligent network intermediary to intercept a stream signed by a content provider, and adapt it dynamically, while preserving the ultimate receiver's ability to securely verify the content provider's signature (and, hence, authenticity and integrity of the data received). Our schemes allow the intermediary to selectively remove portions of the stream and, thus, permit common media transcoding techniques such as scalable compression and multiple file switching. Moreover, a content provider only has to encode and sign its entire data stream once, as opposed to nondynamically encoding and signing different versions for each anticipated combination of device, network configuration, and channel condition. Our implementation results demonstrate efficiency.

We present a technique called Dynamic Distributed Service Coordination Protocol (DDSCP) that enables dynamic and distributed coordination for composed services and applications in telecommunication networks. Individual service components are modeled as Web services and DDSCP facilitates coordination among these components by dispatching executable processes to the service components that specify different steps that the service component must follow in response to (receipt of) specific messages and events. The collective and concurrent execution of these processes at different service components achieves overall goals of the service. The planning and creation of these processes is not our focus in this paper. We describe the structure and processing of different messages DDSCP, and describe how this protocol can work. Our model has several advantages over the existing service platforms for 3rd Generation Mobile Networks, such as Parlay/OSA, and the Web-service composition models. These advantages include introduction of flexibility among network components at finest level, ease of creation of highly customized services, easy integration with foreign components, reduced application complexity, increased reuse of application components, and possibility of increased user participation in managing her services, and thus reducing load on the network.

We present algorithms for estimating the location of stationary and mobile users based on heterogeneous indoor RF technologies. We propose two location algorithms, selective fusion location estimation (SELFLOC) and region of confidence (RoC), which can be used in conjunction with classical location algorithms such as triangulation, or with third-party commercial location estimation systems. The SELFLOC algorithm infers the user location by selectively fusing location information from multiple wireless technologies and/or multiple classical location algorithms in a theoretically optimal manner. The RoC algorithm attempts to overcome the problem of aliasing in the signal domain, where different physical locations have similar RF characteristics, which is particularly acute when users are mobile. We have empirically validated the proposed algorithms using wireless LAN and Bluetooth technology. Our experimental results show that applying SELFLOC for stationary users when using multiple wireless technologies and multiple classical location algorithms can improve location accuracy significantly, with mean distance errors as low as 1.6 m. For mobile users we find that using RoC can allow us to obtain mean errors as low as 3.7 m. Both algorithms can be used in conjunction with a commercial location estimation system and improve its accuracy further.

Most development of cellular communications technology has been focused on providing services to the wealthiest 20% of the world's population - the top of the economic pyramid. We discuss the motivation for serving the bottom of the pyramid (BoP), loosely defined as the 4 billion people earning less that US$2000/year. We consider the design requirements for a rural wireless telecommunications system for the BoP, and how they differ from traditional cellular system and WLL requirements. We discuss alternative technologies and architectures for meeting these requirements, ranging from satellite to WLAN systems. We then present our initial link analysis showing that cellular systems based on WCDMA or OFDM meet the requirements with small modifications. We end with some discussion of open problems and further work.

During the recent years, research efforts have been made to study how to deploy the WLAN in a multi-hop manner. One of the many challenges to deploy a multi-hop network is how to provide delay-sensitive application support. Research have been done to study how to use DCF mode in a multi-hop network to provide delay-sensitive application support. However, few research have been made to study how to use PCF mode in a multi-hop network. In this paper, we first propose a CFP leasing scheme based on the PCF mode of 802.11 and a conservative scheduling scheme to enable voice service in a multi-hop network. Then we theoretically and numerically evaluate the performance of proposed scheme. Results show that with the proposed scheme, we can provide real-time application support for a small scale multi-hop network.

Mobile IP protocol has been proven to be problematic when it is used to support global-wide roaming due to the end-to-end signalling scheme used during the handover process which might lead to significant packet loss and generates a large amount of signaling messages. In order to solve these problems, micromobility protocols have been proposed which limit the signalling messages within a domain, i.e. a micromobility domain. The structure of the micromobility domain is directly related to the performance of the micromobility protocols. In this paper, we propose a dynamic micromobility domain construction scheme which dynamically constructs each micromobility domain according to the aggregated traffic information. Furthermore, the proposed scheme supports mobile network. Simulation results show that the proposed scheme reduces the average signalling messages significantly.

We propose a of control architecture for mobile multimedia streaming in which RTP monitoring agents report QoS information to media servers. The RTP monitoring agents lie midway between wired networks and radio links, monitor RTP packets sent from media servers to mobile terminals, and report quality information to media servers so that the servers can realize network-adaptive QoS control. By analyzing the information sent from the agents, the servers can distinguish quality degradation caused by network congestion from that caused by radio link errors, and can improve service quality by controlling the transmission rate and robustness against packet loss. Simulation results show our implemented QoS control schemes that use the feedbacks from the agent and control transmission rate and robustness provide better video quality than a simple rate control mechanism.