Performance Evaluation of Time Hopping UWB Transmission Using S-Rake Receiver (original) (raw)
Related papers
An Innovative Method for UWB Channel Estimation Using Time Hopped Modulation
2014
Channel knowledge is the important information required for good UWB communications. So many methods are available for UWB channel estimation. However, it is critical to find the multi-path clustered model of UWB transmission. In this paper, we present a new Innovative method with very simple and less complex channel estimation technique. We derived channel estimation equation for the Time Hopped Pulse Position Modulation (TH-PPM), and Time Hopped Pulse Amplitude Modulation (TH-PAM) based on the method of Maximum likelihood channel estimation. The simulations have been done for single user and multi user with varying number of Rake fingers. The simulation results show that TH-PAM with Gold Code System Model capable of determining the accurate channel parameters with very less computational complexity. These are characteristics does not exist in the available channel estimation methods. principal@srec.ac.edu KeywordUWB, Channel Estimation, Time-Hopped Pulse Position Modulation, Time-...
A New Approach for UWB Channel Estimation
2005
In this paper, a new channel estimation approach is proposed for ultra-wideband (UWB) communication systems. Performance of UWB systems employing RAKE receivers highly depends on the channel knowledge. Because UWB systems operate in dense multipath environments, channel estimation task becomes more complicated. Some channel estimation methods have been proposed for UWB systems. Here a very simple and cost effective channel estimation method is presented. We develop a data-aided estimation of channel parameters in UWB systems employing time-hopping pulse-position-modulation (TH-PPM). This method can be used in time-hopping pulse-amplitude-modulation (TH-PAM) and direct-sequence (DS) spread-spectrum systems as well. Computer simulations show that the proposed method is competitive with the maximum likelihood (ML) method, in both single-user and multi-user scenarios, with less computational complexity and the ability to extract the exact parameters of the impulse response of the channel. The latter property does not exist in the ML method in dense multipath environments
Optimal Rake Receiver Model Utilizing Time Hopping Impulse Response on Uwb System (Wpan)
2016
Impulse Radio-Time Hopping-Ultra Wideband (IR-TH-UWB) is a relatively new technology that might have a big effect on improving wireless communication. This technology uses short pulses in order to transmit large amounts of digital data over a wide spectrum of frequency bands with a very low power. This paper we derive the performance for UWB communication systems using different optimal models techniques in a RAKE Receiver. Comparisons have also been made between the techniques and conclusions have been drawn based on the requirements. We present simulation results using IEEE 802.15.3a UWB channel models. We evaluate the performances of Rake Receivers with different pulse-widths and also the effect of inter-frame interference in Ultra wideband Multipath Channels.
IEEE Transactions on Wireless Communications, 2000
The performance of Rake receivers for ultrawidebandwidth communications is discussed, taking into account the effects of multiple access interference (MAI) and channel estimation errors. Two alternative signaling formats are considered: time-hopping pulse-position modulation (TH-PPM) and TH pulseamplitude modulation (TH-PAM). The channel exhibits multipath propagation and its impulse response is either assumed known or is estimated with least squares methods.
2006
In this paper, we evaluate the performance of both uncoded and coded multiple access TH-UWB systems introduced in [1-3], in multipath Rayleigh fading channels. The receiver is a selective diversity combining receiver, known as SRake. Based on Gaussian distribution assumption for the multiple access interference at the output of SRake receiver and by using virtual branch technique as introduced in [4-5], the bit error rates for uncoded and coded schemes are derived. Our analysis shows that the effective order of diversity achieved by the coded scheme is the product of the number of branches of SRake receiver and the Hamming distance of the code applied. Furthermore, it indicates that the coded scheme significantly outperforms the uncoded scheme.
Low complexity RAKE receiver for TH-based multiuser UWB system with realistic UWB indoor channel
International Journal of Ultra Wideband Communications and Systems, 2011
We have considered multiuser communication scenario with ultra wideband (UWB) communication. UWB device is transmitting the data by time hopping (TH)-based system, TH-PPM, TH-PAM and DS-UWB. The UWB device is transmitting data over multipath rich channel model recommended by IEEE 802.15.3a working group. This channel model is based on Saleh-Valenzuela model. For better performance at receiver side, adaptive equaliser is required; this increases the complexity of receiver. Here we have considered the RAKE receiver for TH-based UWB system. This RAKE receiver structure is not a conventional RAKE, but it is pre-RAKE structure. In this case, we have evaluated performance of system by considering the RAKE receiver at the transmitter side. Here we have assumed the condition that channel sounding is available before transmission for quasi static UWB channel. Based on this knowledge RAKE fingers are selected for pre-RAKE. UWB channel is multipath rich channel so full RAKE adds more complexity in receiver and hence put limitation on effective data rate. Here we have considered low branch RAKE receiver. Performance of the system model is evaluated with realistic UWB channel model.
2005
Recently, pulse position amplitude modulation (PPAM) has been proposed for ultra-wideband (UWB) communication systems. PPAM combines pulse position modulation (PPM) and pulse amplitude modulation (PAM) to provide better performance and higher system capacity with low computational complexity. A rake receiver can make use of the rich multipath of UWB systems to improve system performance and capacity. In this paper we present the performance of a rake receiver employing maximal ratio combining (MRC) in a time hopping (TH) UWB system with PPAM modulation. Performance in a practical multipath fading channel is considered. The error probability and a union bound on performance are derived for a block fading environment Numerical results are given to illustrate the system performance.
Bit error rate analysis in IEEE 802.15.3a UWB channels
IEEE Transactions on Wireless Communications, 2010
In this paper, we present a computable bit error rate (BER) expression for the binary signals in the IEEE 802.15.3a ultra-wideband (UWB) channel. In the literature, the impacts of the RAKE receiver's finger numbers and lognormal shadowing on the BER performance have not been reported yet. We propose a characteristic function (CF) based BER formula to overcome the convergence problem of the existing moment generating function (MGF) approach when the BER calculation takes account of the shadowing effect. Simulation results demonstrate that the proposed CF-based computable BER formula can accurately estimate the complete effects of the cluster and ray arrival processes, the lognormal fading as well as shadowing, and the finger numbers at RAKE receivers. Index Terms-Bit error rate (BER), IEEE 802.15.3a channel model, RAKE receiver, shadowing, ultra-wideband (UWB). I. INTRODUCTION U LTRA-WIDEBAND (UWB) is a promising wireless communications technique for high data rate transmission. The UWB channel characteristics are very different from conventional narrowband channels. Recently, the IEEE 802.15.3a UWB channel model [1] is specified and widely adopted in the industry. However, UWB systems based on the IEEE 802.15.3a model are only evaluated by simulations or by analysis with simplified conditions. A. Problem Statement Hence, a fundamental question arises: how can a UWB system be analyzed in the complete IEEE 802.15.3a channel model? This UWB channel has two significant properties. First, because the UWB signal bandwidth is much wider than the channel coherence bandwidth, highly frequency selective fading exists. Second, UWB signals usually yield many clusters of non-Rayleigh faded rays because the extremely large bandwidth leads to high-resolution arrival time after being reflected by objects. The challenges of analyzing UWB signals in the IEEE 802.15.3a channel can be summarized into two types:
In this treatise, we quantify the effects of the UltraWideBand (UWB) on Time Hopping (TH) Impulse Radio (IR) operating in UWB propagation channels environment in terms of bandwidth utilization through diversity order selection. We select L strongest MultiPath Components (MPC) from Nr resolvable MPCs using Maximal Ratio Combining (MRC) in order to achieve maximum performance gain in single and full load scenarios. Three classical detectors have being used for analysis purposes named Correlation (Corr), Zero Forcing Detector (ZFD) and Minimum Mean Square Error (MMSE). Our results suggest that the diversity order L of 20 achieves maximum gain of 18dB and 12dB in single and full load Nu of 63 users scenarios, having spreading factor Ns of 63 over no diversity configuration. Hence, MPCs with delays greater than the TH chip time Tc are resolved by synchronization with the initial path of the received signal gives maximum performance gain.