Sheu Sheu Tan

Performance of DS-UWB multiple-access systems with diversity reception in dense multipath environments

Ultrawideband (UWB) technology is characterized by transmitting extremely short duration radio impulses. To improve its multiple-access capability, the UWB technology can be combined with traditional spread-spectrum techniques. This paper demonstrates the influence of spatial and temporal diversities on the performance of direct-sequence (DS) UWB multiple-access systems in dense multipath environments. Numerical results show that the bit error rate performance of the DS-UWB system can be improved significantly by increasing the number of antenna array elements and/or by adding more multipaths coherently at the receiver. Furthermore, this paper studies the impact of array geometry on system performance and shows that a rectangular array can capture more energy and thus can offer better performance than a uniform linear array

Performance of UWB multiple-access impulse radio systems with antenna array in dense multipath environments

In this letter, the influence of temporal and spatial diversities on the performance of ultra-wideband time-hopping pulse-position modulated multiple-access impulse radio (IR) systems is analyzed. We investigate how an antenna array can be used at the receiver to improve the bit-error rate (BER) performance and can cope with the effects of multiple-access interference of IR system in dense multipath environments. Analytical and simulation results show that the BER performance of the IR systems can be improved when the number of array elements is increased. The performance can be further improved by coherently adding more multipaths at the receiver

Performance of UWB multiple access impulse radio systems in multipath environment with antenna array

Impulse radio (IR) is based on the ultra-wideband (UWB) time-hopping spread spectrum technique in which subnanosecond pulses are modulated to convey information by precisely shifting the relative time position of the pulses. The influence of temporal and spatial diversities on the performance of ultra-wideband impulse radio systems is analyzed. We investigate how antenna diversity (uniform linear array and rectangular array) can be used to improve the bit error rate performance and to mitigate multiple user interference (MUI) of an IR system in multipath fading channels. Numerical results show that the bit error rate performance and multiple access capability of the IR system can be improved when the number of array elements and selected multipaths are increased.

Multiple access performance of UWB M-ary impulse radio systems with diversity reception

Impulse radio (IR) is based on ultra-wideband (UWB) time-hopping spread spectrum technology. The influence of temporal and spatial diversities on the multiple access performance of M-ary pulse position modulation (PPM) IR systems in multipath environments is analyzed. We investigate the used of an antenna array at the receiver to improve the multiple access performance of the system in terms of the number of active users supported by the system for a given bit error rate and bit transmission rate. Numerical results show that the bit error rate performance and multiple access capacity of the M-ary IR system can be improved by increasing the number of antenna array elements and selected multipaths at the receiver.

Multiple access capacity of UWB m-ary impulse radio systems with antenna array

In this paper, the multiple access capacity of an Mary pulse position modulation (PPM) impulse radio (IR) system with antenna array is analyzed in dense multipath environments. An antenna array with Rake receivers is used to capture the signal energy from multipaths. Multiple access performance of the system is evaluated in terms of number of supported users for a given bit error rate and bit transmission rate with different number of antenna elements and selected paths. Numerical results show that the multiple access capacity of an M-ary IR system can be improved significantly by increasing the number of antenna elements and/or by adding more paths coherently at the receiver.

Ultra-wideband impulse radio systems with temporal and spatial diversities

Impulse radio (IR) is based on an ultra-wideband time-hopping spread spectrum technique in which sub-nanosecond pulses are modulated to convey information by shifting the relative time position of the pulses. The paper analyzes the influence of temporal and spatial diversities on the performance of ultra-wideband impulse radio systems. We investigate how antenna diversity (uniform linear array and rectangular array) can be used to improve the bit error rate (BER) performance of the IR systems in dense multipath environments. Analytical and simulation results show that the BER performance of the IR system can be improved when the number of array elements is increased. The performance can be further improved by coherently adding more multipaths at the receiver.

Multiple access performance of direct sequence ultra wideband communications with diversity reception

Ultra-wideband (UWB) technology is characterized by transmitting extremely short duration of radio impulses. To improve its multiple access capability, UWB technology can be combined with traditional spread-spectrum techniques. In this paper, we present the multiple access performance of direct-sequence (DS) UWB system with diversity reception. Numerical results show that the multiple access performance of a DS-UWB system can be improved significantly by increasing the number of antenna array elements and/or by adding more paths at the receiver

A pilot symbol assisted channel estimation scheme for UWB IR systems with diversity reception

Impulse radio (IR) is an ultra-wideband (UWB) time-hopping spread spectrum technique in which sub-nanosecond pulses are modulated to convey information by shifting the position of the pulses in the time axis. We investigate channel estimation for an IR UWB system with an antenna array receiver in multipath environments with multiuser interference. The estimation method is pilot symbol assisted and it is based on the maximum likelihood criterion.