Javier del Prado Pavon

Link adaptation strategy for IEEE 802.11 WLAN via received signal strength measurement

IEEE 802.11 wireless local area network (WLAN) physical layers (PHYs) support multiple transmission rates. The PHY rate to be used for a particular frame transmission is solely determined by the transmitting station. The transmitting rate should be chosen in an adaptive manner since the wireless channel condition varies over time due to such factors as station mobility, time-varying interference, and location-dependent errors. In this paper, we present a novel link adaptation algorithm, which aims to improve the system throughput by adapting the transmission rate to the current link condition. Our algorithm is simply based on the received signal strength measured from the received frames, and hence it does not require any changes in the current IEEE 802.11 WLAN medium access control (MAC) protocol. Based on the simulation and its comparison with a numerical analysis, it is shown that the proposed algorithm closely approximates the ideal case with the perfect knowledge about the channel and receiver conditions.

The MBOA-WiMedia specification for ultra wideband distributed networks

The WiMedia Alliance is undertaking the development of an UWB-based system specification with participation from more than 170 companies. UWB technology will provide data rates up to 480 Mb/s within a range of up to 10 m. High-rate UWB will enable fast download of content from one consumer electronic (CE) device to the next in seconds instead of minutes or longer. In addition, the low-power characteristic of UWB will make possible the ubiquitous use of this technology in portable and mobile CE devices, such as cameras, MP3 players, and CD players. The WiMedia Alliance is specifying the physical layer, the MAC sublayer, and convergence layers. The WiMedia PHY layer is based on multiband orthogonal frequency-division multiplexing. The WiMedia MAC is completely distributed, making it an excellent candidate not only for the aforementioned UWB applications, but also for the next-generation MAC protocols in the domain of cognitive radios as well as in cooperative communications