Supporting the WWW in Wireless Communications Through Mobile Agents

Mobile computing is considered of major importance to the computing industry for the forthcoming years due to the progress in wireless mobile communications. We present a proxy-based architecture that manages to accelerate Web browsing in wireless Customer Premises Networks (CPN). We discuss how such an architecture is implemented using the IBM Aglets framework for mobile agents. The suggested architecture relies heavily on proxy caches – maintained in base stations – which are relocated to follow a roaming user in other control areas (clusters of cells). The cache management scheme involves relocation of full caches to the most-likely-to-be visited control areas, but also fractions of the cache to less-likely-to-be-visited neighbours. A movement prediction algorithm, based on a learning automaton, is used to determine the future location of the terminal. The discussed architecture components have been implemented as Aglets to allow for the efficient introduction of the service in a CPN infrastructure.     

Detailed characterisation of an indoor MIMO channel in the double directional spatial domain

The spatial domain characteristics of an indoor multiple-input multiple-output (MIMO) communication system are examined in detail. Using a high-resolution algorithm, the authors were able to effectively estimate multipath parameters on the joint azimuth of arrival/azimuth of departure (AoA/AoD) domain. The analysis showed dense clustering phenomena at the vast majority of considered locations and a strong correlation between the azimuth spreads of the two angular domains with the presence of line-of-sight (Los) specular components or when the distance between the transmitter (Tx) and the receiver (Rx) is low. The authors also noticed higher azimuth dispersions, compared with those reported in the literature, which can be attributed to low antenna heights and local scattering interactions in the vicinity of both the transmit and receive arrays. Finally, the impact of the spatial global parameters on the ergodic MIMO capacity was tested revealing a direct relation between them.     

Two-parameter nyquist pulses with better performance

We present three novel Nyquist (intersymbol interference free) pulses that outperform two sophisticated pulses reported in literature by Bealieu et al. and Assalini and Tonello. The pulses are based on the concept of inner and outer functions, which was recently explored by the authors. Apart from requiring only two design parameters, the proposed pulses offer an enhanced error performance for various values of roll-off factor and timing jitter along with a smaller maximum distortion.