In this paper, we propose an optimal TCP throughput framework to optimize the TCP throughput in CR networks, which jointly considers the channel sensing decision and access policy as well as low layer design parameter...
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In this paper, we propose an optimal TCP throughput framework to optimize the TCP throughput in CR networks, which jointly considers the channel sensing decision and access policy as well as low layer design parameters. The TCP throughput optimization is achieved by a two step process. First, we select a channel to maximize the spectrum utilization by reducing the probability of collision with primary users. Secondly, for an available and accessed channel, a cross-layer approach is proposed to improve TCP throughput which adaptively adjusts the modulation and coding scheme/frame size based on the observed channel gain. Simulation results show that the TCP throughput can be improved substantially compared with the existing approach that maximizes physical layer throughput.
In this work, we will consider coding for a bit-shift channel with applications to inductively coupled channels. Inductive coupling is a technique wherein one device (the reader) induces an electrical current in anoth...
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In this work, we will consider coding for a bit-shift channel with applications to inductively coupled channels. Inductive coupling is a technique wherein one device (the reader) induces an electrical current in another device (the tag), thereby providing not only power for the tag, but also a communications channel. Most errors in the reader-to-tag channel are due to incorrect timing. In this work, we propose to model the timing errors in the reader-to-tag communications channel by a simple bit-shift channel. We will present optimal single bit-shift error-correcting codes for this simple bit-shift channel that also have large average power. This is important, since the tag gets its entire power from the received signal, and the information should be modulated in a way that maximizes the power transferred to the tag.
In this paper, we derive space-time code design criteria for continuous phase frequency-shift keying (CPFSK) over multipath fast fading channels, aiming at maximizing the overall space-time diversity. We also propose ...
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In this paper, we derive space-time code design criteria for continuous phase frequency-shift keying (CPFSK) over multipath fast fading channels, aiming at maximizing the overall space-time diversity. We also propose a space-time coding scheme to meet the dominated design criterion, the rank criterion. Our encoding scheme consists of a ring convolutional encoder and a spatial encoder with an extender in it. Both the theoretical and simulation results show that with the effective code length ECL of the convolutional encoder, L T transmit antennas, L R receive antennas, and L + 1 paths in the fading channel, a maximal overall diversity ECL ldr L T ldr L R ldr (L + 1) is achievable.
We present an adaptive soft-input soft-output (SISO) turbo equalization receiver for doubly-selective multiple-input-multiple-output (MIMO) channels. The proposed receiver exploits the complex exponential basis expans...
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We present an adaptive soft-input soft-output (SISO) turbo equalization receiver for doubly-selective multiple-input-multiple-output (MIMO) channels. The proposed receiver exploits the complex exponential basis expansion model (CE-BEM) for the overall channel variations, and an autoregressive (AR) model for the BEM coefficients. We extend an existing single-user turbo equalization approach based on symbol-wise AR modeling of channels to multiuser/MIMO channels based on BEMs. Simulation examples demonstrate that our CE-BEM-based approach has superior performance over a symbol-wise AR model-based turbo equalizer.
In this paper, we describe a recently proposed bit-loading algorithm and a novel power-loading algorithm for block fading channels with channel state information (CSI) at the transmitter. We consider channels that off...
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ISBN:
(纸本)9781424425143
In this paper, we describe a recently proposed bit-loading algorithm and a novel power-loading algorithm for block fading channels with channel state information (CSI) at the transmitter. We consider channels that offer a relatively small order of diversity, the so-called limited diversity fading channels. Limited diversity channels such as those encountered in indoor orthogonal frequency division multiplexing systems are characterized by the fact that achievable diversity orders are small and are limited by the channel and not by complexity of the code used. We first discuss a recently proposed analysis technique for the performance of bit-interleaved coded modulation on block fading channels. We then describe a bit-loading technique for maximizing the throughput at a fixed bit error probability. We also propose a new and simple power loading solution to minimize the bit error probability at a fixed rate. Lastly, we show comparative simulation results that corroborate the arguments presented in this paper.
Orthogonal frequency division multiplexing (OFDM) has several properties which make it an attractive modulation scheme for high speed wireless transmission links. In this paper, a novel power sharing technique is prop...
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Orthogonal frequency division multiplexing (OFDM) has several properties which make it an attractive modulation scheme for high speed wireless transmission links. In this paper, a novel power sharing technique is proposed for different users to improve the system performance. The proposed technique is based on use of variable amplitude of subcarriers (VAS). Power can be increased to the users who are crossing the reference boundary (RB) and moving farther towards foot print (FP) of a cell. In this way the users having weak SNR can sustain their call even in multipath fading environment. Assuming knowledge of the instantaneous channel gain estimation for all users, we propose an OFDM dynamic adaptive subcarriers scheme to maintain optimum SNR level of the subchannels which are in deep fade. Simulation results show that the performance of the proposed algorithm is much better than that of other algorithms.
In this paper, cross-layer combining of an adaptive modulation-coding (AMC) scheme at the physical layer and the use of automatic repeat request (ARQ) retransmissions at the medium access control (MAC) layer is integr...
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In this paper, cross-layer combining of an adaptive modulation-coding (AMC) scheme at the physical layer and the use of automatic repeat request (ARQ) retransmissions at the medium access control (MAC) layer is integrated into the design of scheduling for multi-user wireless networks. A class of scheduling algorithms capable of jointly collecting retransmission diversity and multi-user diversity are developed for delay sensitive real-time network traffic. Numerical computer simulations are provided to examine the merits of our novel schemes for multiple real-time transmissions over Nakagami block fading channels. Analytical and simulation results show that the proposed scheduling schemes can asymptotically guarantee the prescribed fairness and average delay requirements for real-time traffic, even when the underlying fading channel distribution is unknown a priori.
Based on the design concept of virtual instrument and the design method of function modulation, using PC machine and data acquisition card as hardware system, proposed a design of sewage multi-parameter online monitor...
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Based on the design concept of virtual instrument and the design method of function modulation, using PC machine and data acquisition card as hardware system, proposed a design of sewage multi-parameter online monitoring system which based on application program platform of Lab VIEW. The system has friendly human-machine interface, the function is comprehensive and it is easy to operate. It has achieved the sewage multiparameter collecting, recording, controlling and management automatic, and enhanced the automaticity of the sewage collecting and examination. The test indicated that the system worked well, achieved the anticipated target.
A new power allocation method for irregularly modulated signaling in single carrier point-to-point multiple input multiple output (MIMO) systems with an iterative frequency-domain (FD) soft cancellation (SC) minimum m...
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ISBN:
(纸本)9781424458257
A new power allocation method for irregularly modulated signaling in single carrier point-to-point multiple input multiple output (MIMO) systems with an iterative frequency-domain (FD) soft cancellation (SC) minimum mean squared error (MMSE) equalization is proposed. The proposed method explicitly takes into account the convergence properties of the iterative equalizer while transmission power is minimized. The proposed scheme is based on the combination of irregular modulation, different signal constellations within one code word, and convergence constraint precoding (CCP), technique that decouples the spatial interference between streams using singular value decomposition (SVD), and minimizes the transmission power while achieving the target mutual information for each stream after iterations at the receiver side. Numerical results show that the proposed scheme improves the transmission rate adaptivity of the original CCP while ensuring the convergence with reduced transmission power.
This paper presents a link adaptation scheme for the MIMO-OFDM system to achieve high spectral efficiency in a required BER performance. The modulation order and MIMO transmission mode are selected via a look-up table...
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This paper presents a link adaptation scheme for the MIMO-OFDM system to achieve high spectral efficiency in a required BER performance. The modulation order and MIMO transmission mode are selected via a look-up table according to the SNR and Rician channel K-factor instead of the channel relative condition number. The BER and spectral efficiency performance of the MIMO-OFDM system is evaluated by simulation. Result shows that the spectral efficiency can be achieved up to 9 bps/Hz under Rician channel K-factor of 3.3 dB when SNR is 30 dB. The spectral efficiency is higher under low K-factor Rician channel than in high K-factor one. The throughput of the proposed adaptive MIMO-OFDM system considers both K-factor of the Rician channel and SNR can be achieved up to 80 Mbps higher than the method without considering the Rician channel K-factor.
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