Adjacent Channel Interference in UMTS Networks

One of the purposes of receive filtering in a Universal Mobile Telecommunication System (UMTS) handset receiver is to attenuate out-of-channel interference to provide channel selectivity. A UMTS handset receiver using a receive filter adaptive on out-of-channel interference level can be more computationally efficient than a handset with a fixed receive filter provided that the hand-set operates in low out-of-channel interference conditions often enough. The UMTS Adjacent Channel Selectivity (ACS) test case requires the adaptive receive filter to provide a worst case ACS of 33 dB. An adaptive receive filter is more computationally efficient than a fixed receive filter when the required ACS is less than 23 dB, because the added complexity of measuring the out-of-channel interference is compensated for by the reduction in the required number of filter taps to achieve the ACS. Measurements of the out-of-channel interference show that currently the interference levels for which the maximum ACS of 33 dB is required are hardly ever reached in practice. For the currently measured interference levels an adaptive receive filter will be computationally more efficient than a fixed\ud receive filter 97% of the time. However, the current out-of-channel interference measurements might be on the optimistic side, because the loads of the UMTS networks are low. When these loads increase in the future, the out-of-channel interference levels may increase and the advantage in computational efficiency of the adaptive receive filter will be reduced

A Reconfigurable Tile-Based Architecture to Compute FFT and FIR Functions in the Context of Software-Defined Radio

Software-defined radio (SDR) is the term used for flexible radio systems that can deal with multiple standards. For an efficient implementation, such systems require appropriate reconfigurable architectures. This paper targets the efficient implementation of the most computationally intensive kernels of two significantly different standards, viz. Bluetooth and HiperLAN/2, on the same reconfigurable hardware. These kernels are FIR filtering and FFT. The designed architecture is based on a two-dimensional arrangement of 17 tiles. Each tile contains a multiplier, an adder, local memory and multiplexers allowing flexible communication with the neighboring tiles. The tile-base data path is complemented with a global controller and various memories. The design has been implemented in SystemC and simulated extensively to prove equivalence with a reference all-software design. It has also been synthesized and turns out to outperform significantly other reconfigurable designs with respect to speed and area

A Reconfigurable Tile-Based Architecture te Compute FFT en FIR Functions in de context van de Software-Defined Radio

Software-defined radio (SDR) is the term used for flexible radio systems that can deal with multiple standards. For an efficient implementation, such systems require appropriate reconfigurable architectures. This paper targets the efficient implementation of the most computationally intensive kernels of two significantly different standards, viz. Bluetooth and HiperLAN/2, on the same reconfigurable hardware. These kernels are FIR filtering and FFT. The designed architecture is based on a two-dimensional arrangement of 17 tiles. Each tile contains a multiplier, an adder, local memory and multiplexers allowing flexible communication with the neighboring tiles. The tile-base data path is complemented with a global controller and various memories. The design has been implemented in SystemC and simulated extensively to prove equivalence with a reference all-software design. It has also been synthesized and turns out to outperform significantly other reconfigurable designs with respect to speed and area

A Combined Analogue+digital Software Defined Radio Receiver Front-end for Bluetooth and HiperLAN/2

The number of wireless communication links is witnessing tremendous growth and new standards are being introduced at high pace. However, circuit development is costly and time consuming due to mask costs and design iterations. Moreover, with ever-increasing radio standard complexity, these costs are increasing. This pleads for a Software Defined Radio approach, in which one piece of flexible radio hardware is re-used for different applications and standards, downloadable and under software control. A software defined radio receiver can -at different timesreceive signals of a multitude of standards, obliviating the need to design, manufacture, stock and carry around separate receivers for all contemporary radio standards. The presented design includes both the analogue and the digital front-end. A CMOS integrated analogue downconverter containing a low-noise amplifier, downconversion mixers and filters performs all analogue processing required between RF pre-filters and the analogue-to-digital converter. The real-time baseband processing is partly implemented on an ASIC (channel selection) and partly on a standard PC (demodulation). Using a standard PC further enhances the\ud flexibility of the design. The combined set-up is capable of receiving both Bluetooth and Hiperlan/2 signals. We conclude that an analog wide-band front-end with a flexible Sample-Rate Converter (SRC) combined with appropriate software on an inherently flexible PC forms a feasible architecture for Software Defined Radio