This letter presents a hybrid conditional access system (CAS) for advanced terrestrial digital multimedia broadcasting (AT‐DMB). The proposed architecture is characterized by its use of a unified CAS channel and various communication networks for CAS message transmissions. We implement a prototype CAS based on the hybrid architecture, which improves the CAS message transmission efficiency greatly […]
Aug
Jul
Time synchronization in wireless sensor networks (WSNs) is a fundamental issue for the coordination of distributed entities and events. Non-deterministic latency, which may decrease the accuracy and precision of time synchronization can occur at any point in the network layers. Specially, random back-off by channel contention leads to a large uncertainty. In order to reduce […]
Jun
As the era of the ubiquitous computing is ushered in, consumers have been primed for a variety of automation applications. Active RFIDs can be used for a number of automation applications because it may also have other sensors to extend its applications. An active RFID instinctively focuses on a long communication range. Nevertheless, active RFIDs […]
May
ISO/IEC 18000-7 Active RFID standard, a single channel system operating at 433 MHz, faces technical difficulties in supporting some recently introduced application demands because of its low transmission rates and vulnerability to radio interference between the readers. We propose a new multi-channel active RFID system operating at the 2.4 GHz band. The special feature of […]
Mar
In the upcoming ubiquitous computing environment, almost every object that needs to be identified will be attached to an radio frequency identification (RFID) tag. Omnipresent RFID tags lead to the concern that huge volumes of RFID data could easily overwhelm related networks and systems. However, for most applications, only a small subset of ID data […]
Sep
This paper proposes an adaptive hybrid data broadcast scheme for wireless converged networks. Balanced allocation of broadcast resource between Push and Pull and adaptation to the various changes of user request are keys to the successful operation of a hybrid data broadcast system. The proposed scheme is built based on two key features, BEI (Broadcast […]
Aug
The ability to recognize many tags simultaneously is crucial for many advanced RFID-based applications. The tag anti-collision algorithm of an RFID system, which arbitrates collisions on the air interface among tags in the same reading range of a reader, makes a great influence on the speed and the reliability in multiple tag recognition. This paper […]
Aug
Handoff is one of the most important factors that may degrade the performance of TCP connections in wireless data networks. The authors present a lossless handoff scheme called LPM (Last Packet Marking). LPM signals the safe handoff cue by sending a specially marked packet to mobile hosts. Our performance study shows that LPM achieves lossless packet delivery […]
Feb
Recently, the IEEE 802.11 working group has announced a new distributed access mechanism called Enhanced DCF (EDCF) to provide service differentiation among traffic classes defined as access category. With the increasing demand for supporting Quality of Service (QoS) in IEEE 802.11 wireless LANs, the EDCF is now attracting many researchers’ attention due to its practical […]
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