On various low-hardware-complexity LMS algorithms for adaptive I/Q correction in quadrature receivers

In this paper, the performance and convergence time comparisons of various low-complexity LMS algorithms used for the coefficient update of adaptive I/Q corrector for quadrature receivers are presented. We choose the optimum LMS algorithm suitable for low complexity, high performance and high order QAM and PSK constellations. What is more, influence of the finite bit precision on VLSI implementation of such algorithms is explored through extensive simulations and optimum wordlengths established.

Performance of an adaptive homodyne receiver in the presence of multipath, Rayleigh-fading and time-varying quadrature errors

In this paper, we carry out a detailed performance analysis of the blind source separation based I/Q corrector operating at the baseband. Performance of the digital I/Q corrector is evaluated not only under time-varying phase and gain errors but also in the presence of multipath and Rayleigh fading channels. Performance under low-SNR and different modulation formats and constellation sizes is also evaluated. What is more, BER improvement after correction is illustrated. The results indicate that the adaptive algorithm offers adequate performance for most communication applications hence, reducing the matching requirements of the analog front-end enabling higher levels of integration.

A low-complexity self-calibrating adaptive quadrature receiver

In this paper digital part of a self-calibrating quadrature-receiver is described, containing a digital calibration-engine. The blind source-separation-based calibration-engine eliminates the RF-impairments in real-time hence improving the receiver's performance without the need for test/pilot tones, trimming or use of power-hungry discrete components. Furthermore, an efficient time-multiplexed calibration-engine architecture is proposed and implemented on an FPGA utilising a reduced-range multiplier structure. The use of reduced-range multipliers results in substantial reduction of area as well as power consumption without a compromise in performance when compared with an efficiently designed general purpose multiplier. The performance of the calibration-engine does not depend on the modulation format or the constellation size of the received signal; hence it can be easily integrated into the digital signal processing paths of any receiver.

Handling the transfer of power: a note on the 1964 origins of the Douglas‐Home rules

Opposition is rarely a good preparation for government. The only post‐war government to enter office confident, well‐acquainted with the Civil Service and with a fund of administrative experience to draw on was the Attlee administration formed in 1945. The longer a party spends in opposition the more these assets disappear. Labour, by the end of the long period of Conservative rule in 1951–64, was largely unfamiliar with the burdens of office. This formed the background to the formulation of the Douglas‐Home rules, whereby informal contact is permitted between the Civil Service and the Opposition in advance of a general election. Since 1964 this arrangement has gradually become more extensive (especially after Neil Kinnock complained that the period for contact was too brief during the run‐up to the 1992 election) and more formalised. In late 1993 John Major agreed that contacts could be made from early 1996 in advance of the next election, rather than only during the last six months of a parliament, as had by then become the convention.’ The object of this short paper is, however, to explain how these rules originated.