31 |
THE EFFECTS OF CARRIER FREQUENCY AND ANTENNA DIAMETER ON FREQUENCY SELECTIVE MULTIPATH FADINGPaje, Vladimir I. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper uses ARTM channel sounding data collected at Edwards Air Force Base to investigate the
dependency between the characteristics of frequency selective multipath fading and carrier frequency
and ground based received antenna diameter. Channel model parameters are obtained from data sets
measured at different frequencies and various ground based antenna diameters. The analysis shows that
the multipath characteristics do not statistically change between the L-band and S-band carrier
frequencies, but do change with antenna diameter. Furthermore, Flight 18 data shows that antenna
diversity may be a useful technique to reduce data loss from multipath fading.
|
32 |
On models for multi-user gaussian channels with fadingEl Haddad, Rony 03 September 2009 (has links)
An analytically tractable model for Gaussian multiuser channels with fading is studied, and the capacity region of this model is found to be a good approximation of the capacity region of the original Gaussian network. This
work extends the existing body of work on deterministic models for Gaussian multiuser channels to include the physical phenomenon of fading. In particular, it generalizes these results to a unicast, multiple node network setting with fading. / text
|
33 |
Low complexity adaptive equalisation for wireless applicationsPerry, Russell January 1997 (has links)
No description available.
|
34 |
Information, theoretic and practical considerations of cellular DS-CDMA systemsGuan, Yong Liang January 1997 (has links)
No description available.
|
35 |
Performance analysis and control of wireless communication networks with multi-user receivers /Catrein, Daniel. January 2007 (has links)
Zugl.: Aachen, Techn. Hochsch., Diss., 2007.
|
36 |
Error Rate Performance of Multi-Hop Communication Systems Over Nakagami-m Fading ChannelSajjad, Hassan, Jamil, Muhammad January 2012 (has links)
This work examines error rate performance of Multi-Hop communication systems, employing Single Input Single Output (SISO) transmissions over Nakagami-m fading channel. Mobile multi-hop relaying (MMR) system has been adopted in several Broadband Wireless Access Networks (BWAN) as a cost-effective means of extending the coverage and improving the capacity of these wireless networks. In a MMR system, communication between the source node and destination node is achieved through an intermediate node (i.e., Relay Station). It is widely accepted that multi-hop relaying communication can provide higher capacity and can reduce the interference in BWANs. Such claims though have not been quantified. Quantification of such claims is an essential step to justify a better opportunity for wide deployment of relay stations.In this thesis, Bit Error Rate (BER) of multi-hop communication systems has been analysed. Different kinds of fading channels have been used to estimate the error rate performance for wireless transmission. Binary Phase Shift Keying (BPSK) has been employed as the modulation technique and Additive White Gaussian Noise (AWGN) has been used as the channel noise. The same Signal to Noise Ratio (SNR) was used to estimate the channel performance. Three channels were compared by simulating their BER, namely, Rayleigh, Rician and Nakagami. Matlab has been used for simulation.
|
37 |
A Study on Blind Phase EstimationWang, Po-hsuan 16 August 2011 (has links)
In this thesis, the blind phase estimator algorithms are studied, including Histogram Algorithm (HA), Modified Histogram Algorithm (MHA), Maximum Likelihood (ML), 4th power-law and modified 4th power-law to compare their performance under quadrature amplitude modulation and additive white gaussian noise(AWGN) channel. Owing to the development of wireless communication, I used the fading channel of wireless communication and studied the performance of all algorithms again.
After differential encoding and quadrature amplitude modulation, signals enter additive white gaussian noise(AWGN), constant phase offset and fading channel. At receiver, I use the above estimator to find the phase offset. If there is not line of sight under fading channel, all estimators performance are not good from simulation results, if there is a strong line of sight, all estimators performance are good and approximate to the AWGN channel.
|
38 |
Design and performance evaluation of RAKE finger management schemes in the soft handover regionChoi, Seyeong 15 May 2009 (has links)
We propose and analyze new finger assignment/management techniques that
are applicable for RAKE receivers when they operate in the soft handover region.
Two main criteria are considered: minimum use of additional network resources and
minimum call drops. For the schemes minimizing the use of network resources, basic
principles are to use the network resources only if necessary while minimum call drop
schemes rely on balancing or distributing the signal strength/paths among as many
base stations as possible. The analyses of these schemes require us to consider joint
microscopic/macroscopic diversity techniques which have seldom been considered before
and as such, we tackle the statistics of several correlated generalized selection
combining output signal-to-noise ratios in order to obtain closed-form expressions for
the statistics of interest. To provide a general comprehensive framework for the assessment
of the proposed schemes, we investigate not only the complexity in terms of
the average number of required path estimations/comparisons, the average number
of combined paths, and the soft handover overhead but also the error performance of
the proposed schemes over independent and identically distributed fading channels.
We also examine via computer simulations the effect of path unbalance/correlation as
well as outdated/imperfect channel estimations. We show through numerical exam ples that the proposed schemes which are designed for the minimum use of network
resources can save a certain amount of complexity load and soft handover overhead
with a very slight performance loss compared to the conventional generalized selection
combining-based diversity systems. For the minimum call drop schemes, by
accurately quantifying the average error rate, we show that in comparison to the
conventional schemes, the proposed distributed schemes offer the better error performance
when there is a considerable chance of loosing the signals from one of the
active base stations.
|
39 |
Performance of Complementary Code Based CDMA in Time Variant ChannelsSu, Po-Jung 04 September 2006 (has links)
First, we proved that the - Columnwise Complementary codes is better than - Columnwise Complementary code in time selective channel by explaining the probability of happening MAI elimination in frequency domain and proposing a method to use - Columnwise Complementary codes in one cell.
Furthermore, we proposed the method to increase the capability of resisting of frequency selective fading channel without decreasing the capability of resisting of time selective fading channel.
Finally, we showed some simulation results about receiver velocity and MAI elimination in frequency domain.
|
40 |
The Improvement of Blind Adaptive Detection for MC-CDMA System in Rayleigh Fading ChannelLai, Ruei-Chin 23 June 2000 (has links)
In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is transmitted in the frequency-selective channel, and the signal is severely distorted by the multiple propagation paths. Each bandwidth of the signals for Multi-Carrier CDMA system is smaller. If the bandwidth is smaller than the coherence bandwidth of the channel, the channel is said to be frequency-nonselective. Besides, the data rate of Multi-carrier-CDMA is higher than the data rate of CDMA.
If the traditional combing detector is used for Multi-Carrier CDMA system, the channel coefficients have to be estimated first. The error of the estimated channel coefficients will result in the performance of detector degrade. The blind adaptive algorithm doesn
|
Page generated in 0.0557 seconds