Self-aligning wireless link using modulated backscatter

A self-tracking (aligning) radio communications system based on the principle of modulated backscatter detection is presented here. Using amplitude-modulated backscatter from a co-operating target, a modified IQ demodulation scheme is used to reproduce automatically and in real time both the received and conjugate of the received phase of an incoming signal. The phase conjugated demodulated IF signal can have incoming backscattered data removed and new data are inserted before being up-converted using IQ single side-band generation so that retro-directive re-transmission can be made to occur. In the absence of the backscattered modulation signal, no phase conjugation and hence no retro-directed re-transmission can occur. The system reported is therefore inherently self-authenticating a facility not readily available from previously reported retro-directive self-tracking systems. © 2010 © The Institution of Engineering and Technology.

A 60 GHz wide tuning range SiGe bipolar VCO for HDMI and wireless docking applications

A wide tuning range voltage controlled oscillator (VCO) with novel architecture is proposed in this work. The entire circuit consists of a VCO core, a summing circuit, a single-ended to differential (STD) converter and a buffer amplifier. The VCO core oscillates at half the desired frequency and the second harmonic of the VCO core is extracted by the summing circuit, which is then converted to a differential pair by the STD. The entire VCO circuit operates from 58.85 to 70.85 GHz with 20% frequency tuning range. The measured VCO gain is less than 1.6 GHz/V. The measured phase noise at 3 MHz offset is less than -78 dBc/Hz across the entire tuning range. The differential phase error of the output signals is measured by down converting the VCO output signals to low gigahertz frequency using an on-chip mixer. The measured differential phase error is less than 8°. The VCO circuit, which is constructed using 0.35 µm SiGe technology, occupies 770 × 550 µm2 die area and consumes 62 mA under 3.5 V supply.

Real-valued fixed-complexity sphere decoder for high dimensional QAM-MIMO systems

The development of high performance, low computational complexity detection algorithms is a key challenge for real-time Multiple-Input Multiple-Output (MIMO) communication system design. The Fixed-Complexity Sphere Decoder (FSD) algorithm is one of the most promising approaches, enabling quasi-ML decoding accuracy and high performance implementation due to its deterministic, highly parallel structure. However, it suffers from exponential growth in computational complexity as the number of MIMO transmit antennas increases, critically limiting its scalability to larger MIMO system topologies. In this paper, we present a solution to this problem by applying a novel cutting protocol to the decoding tree of a real-valued FSD algorithm. The new Real-valued Fixed-Complexity Sphere Decoder (RFSD) algorithm derived achieves similar quasi-ML decoding performance as FSD, but with an average 70% reduction in computational complexity, as we demonstrate from both theoretical and implementation perspectives for Quadrature Amplitude Modulation (QAM)-MIMO systems.

Turbo-MIMO for wireless communications

This article reviews an important class of MIMO wireless communications, known collectively as turbo-MIMO systems. A distinctive property of turbo-MIMO wireless communication systems is that they can attain a channel capacity close to the Shannon limit and do so in a computationally manageable manner. The article focuses attention on a subclass of turbo-MIMO systems that use space-time coding based on bit-interleaved coded modulation. Different computationally manageable decoding (detection) strategies are briefly discussed. The article also includes computer experiments that are intended to improve the understanding of specific issues involved in the design of turbo-MIMO systems.

Low Insertion Loss Substrate Integrated Waveguide Quasi–Elliptic Filters for V- Band Wireless Personal Area Network Applications

Novel V-band substrate integrated waveguide (SIW) filters have been presented. Design procedures for the filters synthesis and mechanisms providing quasi-elliptic response have been explained. The insertion loss of the filters has been measured below 2 dB with microstrip-to-SIW transitions being included.