R. Pasand

UWB receiver based on filter bank architecture for suppression of narrowband interference noise

Ultra wideband (UWB) links are inherently subject to narrowband interference from other communication links which results in frequent disruptive outage conditions. This paper proposes a solution for suppressing the narrowband interference noise based on analog filter bank pre-processing in conjunction with maximum ratio combining (MRC) and generalized matched filter (GMF) processing. This receiver architecture requires significantly less processing than the optimum GMF processing while providing excellent suppression of the narrowband interference that rivals the comparative performance of the GMF. It is also shown that analog filter bank (AFB) forms a signal space of dimension equal to the number of bandpass filters and that the processing can effectively cancel multiple tones up to this dimensionality.

The capacity of asynchronous M-ary time hopping PPM UWB multiple access communication systems

Scholtz in (Proc. Military Comms. Conf., vol.2, p.447-450, 1993) introduced an ultra-wide bandwidth (UWB) time-hopping spread-spectrum code division multiple-access system employing a binary PPM signaling with performance analysis based on multiple-access interference represented by a Gaussian process. In this paper, the symbol error rate and the capacity of asynchronous M-ary PPM UWB are evaluated with a more precise statistical analysis of the multiuser interference which avoids the Gaussian approximation. It is shown that there is a significant error in using the Gaussian approximation as it over estimates the capacity of the M-ary PPM modulation.

Channel Estimation using Kalman Filter for Uwb Communication Systems

This paper investigates the estimation of time varying channels for ultra-wideband (UWB) impulse radio communication. The channel parameters considered are the attenuations and delays incurred by the signal echoes along the different propagation paths. Time hopping using pulse position modulation (PPM) with binary symbols is assumed. The estimation method is based on Kalman estimation using pilot pulses. Simulation results for bit error rate (BER) performance of both multi-bit rake (MBR) and single-bit Rake (SBR) receivers, using Kalman based channel estimation, are presented

Capacity of PPM ultra-wideband communications with inter pulse interference

We study the information theoretic capacity of pulse position modulation (PPM) ultra-wideband (UWB) communications for single user channels. The capacity is studied with a link impulse response with delay spread and inter pulse interference (IPI). The objective is to consider the effect of IPI on capacity and quantify the capacity with IPI. An expression for the signal-to-noise ratio is developed for UWB as a function of the decay rate of the link impulse response. The information theoretic capacity of the UWB system is studied as a function of the number of quantized PPM resolution intervals.

Ultra-wideband rake receiver based on single-bit processing

Efficient detection of the ultra-wideband(UWB) pulses used in pulse-position-modulationcommunicationlinks is a challenge due to the combinationof a significant level of multipath spreading encounteredin indoor wireless channels and the wide bandwidth of the transmitted pulses. If a conventionalrake receiver is used, then a large number of fingers are requiredto capture the pulse energy; this represents a formidable implementationchallenge due to the intensive signal processingrequired. To mitigate the problem, a rakereceiver based on uniformsampling and single-bitsampling quantizationis proposed. This approach significantly reduces the complexity and processing requirements, so that a large number of rake fingers can be efficiently implemented. The architecture and processing of the proposed receiver, denoted as the single-bit rake (SBR), are described in this paper. A comparative performance analysis of the SBR relative to a conventional rake is also given. As shown in this paper, if the transmitted ultra-wideband pulses are resolvable after passing through the multipath propagation channel, then the penalty of using single-bit quantization is limited to dB compared to a conventional rake receiver with no quantization distortion. For typical indoor wireless propagation channels it is shown that this penalty can typically be avoided by using more rake fingers. However, this incremental processing is relatively insignificant, as uniform single-bit quantization is used. The paper presents further analysis for cases in which the multipath delay spreading is so large that successive UWB pulses significantly overlap. A comparison of the SBR and conventionalrakes in terms of power consumptionand complexityis also given, demonstratingthe advantage of the SBR architecture.

Performance analysis of synchronous M-ary time-hopping PPM UWB multiple-access communication systems

The symbol error rate and the capacity of M-ary PPM UWB are evaluated with precise statistical analysis of the multi-user interference which avoids the Gaussian approximation. As shown there is a significant error in using the Gaussian approximation as it overestimates the capacity of the M-ary PPM modulation

60-channel dual tone multi-frequency signaling receiver based on Goertzel algorithm on single 100MIPS TMS320C54 DSP platform

Dual tone multi-frequency (DTMF) receiver based on modified Goertzel algorithm is developed. Performance of receiver is assessed under the ITU Q.24 standard specifications. The algorithm was tested with a variety of signals including speech, music, and DTMF tones. We found that this detector was efficient, reliable, and exceeded Bellcore standards

Optimal processing of an impulse radio signal subjected to narrow band interference

Ultra wide band (UWB) links are inherently subject to narrowband interference (NBI) from other narrowband communication links. An UWB receiver architecture that is proven effective in mitigating NBI sources is the analog filter bank (AFB) followed by a generalized matched filter (GMF) processing as introduced in J. Nielsen et al. (2004) and R. Pasand et al. (2004). In this paper, a further development of this architecture is developed, which introduces two and three level quantization (2LQ, 3LQ) for the required sampling at the output of the AFB instead of multibit linear quantization (LQ). This substantially reduces the implementation complexity of the UWB receiver as well as the computational effort required. Simulation of the AFB receiver with 2LQ, 3LQ is given in this paper, which shows the remarkable observation that the performance loss attributed to this crude quantization is negligible.

A Novel Technique for Fast Clock Phase and Frequency Offset Simulation in Digital Communication Systems

In this paper, we present the methodology of a new technique/or modeling and very fast simulation of clock offset and frequency mismatch in synchronous communication. The ease with which this technique can be expanded to extract the system parameters is a major objective of this work. This technique utilizes the Lagrange interpolator to construct the analog received signal and is alleviating the need for very high signal over sampling to simulate symbol recovery. The results from simulating different algorithms with this technique are given. A few results of simulating Mueller and Muller symbol timing recovery is also addressed within the proposed framework

Reduced complexity recovery architecture in QAM software receiver

In this paper, we present the design and implementation of a new architecture for phase and frequency synchronization in coherent QAM demodulator used in modern digital communication systems. This architecture utilizes the non data aided carrier recovery for synchronization, which is based on the DC error tracking behavior of a control loop. We exploit the hardware-software co-design in this architecture, which makes it flexible for different design parameters. The early-late gate technique as a conventional symbol timing recovery is also addressed within the proposed framework. Hardware-software implementation in field programmable gate array (FPGA) and its issues are presented for different data rates.