DS-CDMA microcellular networks with adaptive antennas

This paper considers the performance of a DS-CDMA system which employs adaptive antenna technology at the basestation site of a microcell. Results for a typical microcellular environment produced with the help of a ray tracing tool highlight the behaviour of the adaptive antenna and with the help of a Monte-Carlo type DS-CDMA capacity analysis, the potential performance enhancement of the system is evaluated. Finally, scenarios with inter-cell interference and moving users are discussed, and the fixed beam steering and the reduced sidelobe techniques are considered against the adaptive antenna technique

A hybrid Cartesian loop and envelope modulated PA linear transmitter architecture

A high efficiency and linearity PA solution is presented based on hybrid linearisation schemes that employ complementary techniques to overcome the weakness (or constraints) of either method on its own. In particular, the high linearity of Cartesian loop is combined with the high efficiency of envelope elimination and restoration (EER). The results of a prototype hybrid linearised PA built using digital generation of the phase and amplitude signals for the EER amplifier, and utilizing a digital Cartesian feedback loop are presented. Limitations of the amplitude modulator on system performance are demonstrated using PWM and delta-modulated switching amplifier

Delayed adaptive antenna subset selection in measured wireless MIMO channels

Adaptive antenna subset selection can improve the expected theoretical capacity of a multiple-input, multiple-output (MIMO) wireless channel, whilst maintaining the tractable complexity of the lower order MIMO system. This paper seeks to explore the effects of delayed selection using measured indoor channel data at 5.2GHz, reflecting more accurately the situation facing a real-time system. Several selection schemes are considered and results show that delayed selection, while not as effective as instantaneous selection, can still improve the expected capacity by a significant margi

Downlink calibration requirements for the TSUNAMI (II) adaptive antenna testbed

The TSUNAMI (II) project is an investigation into the use of adaptive antenna technology. The field trial system has been developed for the purposes of investigating the feasibility of implementing such a system using a GSM-1800 base station system. The field trial system uses a digital baseband beamforming technique (DBF) which, like all DBF systems, relies on the accurate transfer of weighted signals to and from the antenna array elements. As such, an accurate and reliable calibration system is required to combat effects arch as temperature and humidity on the individual antenna array paths. In this paper, results are presented of studies made on the field trial system, with regard to the operational temperature variations over an extended period of time. Investigations are presented of the TSUNAMI (II) downlink calibration technique and the implications for future adaptive antenna array calibration systems

Dynamic spatial-temporal propagation measurement and super-resolution channel characterisation at 5.2 GHz in a corridor environment

This paper presents the analysed results from a dynamic spatial-temporal measurement campaign conducted at 5.2 GHz in a corridor environment within a modern building. The single-input-multiple-output (SIMO) measurement was performed by moving the transmitting antenna with a specialised trolley along a predefined route, while the receiving linear array was fixed at one location. Subsequent post-processing was conducted using the 2-D Unitary ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) super-resolution algorithm to extract the direction-of-arrival (DoA) and time-delay-of-arrival (TDoA) of the multipath components. The corridor was then characterised in terms of delay spread, azimuth spread, K-factor and coherence bandwidth. It was found that the corridor favours a wave-guiding effect whereas locations adjacent to the corridor enjoy the leakage of energy from the waves propagating along the corridor. The dynamic power delay spectra are shown. Finally, the correlations between the delay spread, azimuth spread and coherence bandwidth are assesse