In this paper, a cross-layer approach introducing new design parameters is developed for multi-rate wireless links. The novel design jointly exploits the finite-length queuing at the data link layer and the adaptation...
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ISBN:
(纸本)9780769530482;0769530486
In this paper, a cross-layer approach introducing new design parameters is developed for multi-rate wireless links. The novel design jointly exploits the finite-length queuing at the data link layer and the adaptation capability of the adaptive modulation and coding (AMC) scheme at the physical layer to optimize system performance for a wireless link. The analytical framework is based on discrete time Markov chain. The performance metrics such as packet drop probability, channel packet error rate and packet loss rate are derived. Using these metrics, a constrained optimization problem is solved numerically to maximize the overall system throughput.
This paper proposes a multipath interference canceller (MPIC) associated with orthogonal code-multiplexing with orthogonal variable spreading factor (OVSF) channelization codes that achieves high throughput performanc...
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This paper proposes a multipath interference canceller (MPIC) associated with orthogonal code-multiplexing with orthogonal variable spreading factor (OVSF) channelization codes that achieves high throughput performance with adaptive data modulation in multipath fading channels in the W-CDMA forward link, and evaluates its throughput performance by computer simulation. The simulation results elucidate that sufficient multipath interference suppression is achieved by a four-stage MPIC with 6-12 orthogonal code-multiplexing using one iterative channel estimation with pilot and decision feedback data symbols hard-decided after RAKE combining. We show that the maximum peak throughput using MPIC is approximately 2.1 fold that without MPIC in a 2-path Rayleigh fading channel and that the peak throughput of 8.0 Mbps is achieved using 64QAM data modulation within a 5-MHz bandwidth. Furthermore, the required average E/sub b//N/sub 0/ for satisfying the same throughput with MPIC is decreased by more than 2.0 dB.
Bit interleaved coded multiple beamforming (BICMB) was previously designed to achieve full spatial multiplexing of min(N, M) and full spatial diversity of NM for N transmit and M receive antennas over flat fading chan...
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Bit interleaved coded multiple beamforming (BICMB) was previously designed to achieve full spatial multiplexing of min(N, M) and full spatial diversity of NM for N transmit and M receive antennas over flat fading channels. Furthermore, BICMB when combined with orthogonal frequency division multiplexing (OFDM) achieves full spatial multiplexing and full diversity order of NML over L-tap frequency-selective channels. BICMB requires full channel state information (CSI) both at the transmitter and receiver, however it uses uniform power and rate over the parallel channels established by multiple beamforming. In this paper, our main goal is to investigate the performance of the previously analyzed BICMB system via adaptive modulation and coding (AMC) to further utilize CSI and to improve system throughput performance. Hence, we name the new systems as adaptive BICMB (ABICMB) over flat fading, and ABICMB-OFDM over frequency-selective channels. Simulation results show that adaptive system achieves 4-13 dB performance gain compared to non-adaptive case depending on the antenna configuration and environment. Systems analyzed require perfect CSI both at the transmitter and receiver, which may be difficult to obtain in a practical scenario. However, high performance gains achieved makes it worthwhile to study the performance of the proposed systems, leaving room for significant gain with limited feedback
In this paper we present simple closed-form expressions for the probability of error for M-ary phase-shift key (M-PSK) signaling over a channel with additive white Gaussian noise and nonselective Rayleigh fading. Thes...
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In this paper we present simple closed-form expressions for the probability of error for M-ary phase-shift key (M-PSK) signaling over a channel with additive white Gaussian noise and nonselective Rayleigh fading. These expressions can be used to analyze the performance of standard uniform M-PSK constellations and nonuniform M-PSK constellations. Nonuniform M-PSK has previously been shown to be useful for multimedia communication, multicast transmission, and adaptive signaling. We analyze several systems that employ nonuniform M-PSK for multicast transmission over Rayleigh fading channels, and we determine the performance of nonuniform, M-PSK with convolutional coding.
In this paper, we consider optimum rate quantization of Adaptive modulation and coding (AMC) systems by jointly designing the MCS levels and intervals. Optimum quantization leads to coupled non-algebraic equations, an...
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In this paper, we consider optimum rate quantization of Adaptive modulation and coding (AMC) systems by jointly designing the MCS levels and intervals. Optimum quantization leads to coupled non-algebraic equations, and is generally not amenable for analysis. Here, we propose two approximate AMC rate quantization methods, which are based on an observation of the optimal condition and the numerical results in the literature. The numerical results show that both proposed methods are near-optimum in expected throughput.
Broadcasting live digital TV to a small battery-powered handheld device is very challenging. One of the evolving technologies to provide such services is DVB-H (Digital Video Broadcasting over Handheld). Wireless chan...
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Broadcasting live digital TV to a small battery-powered handheld device is very challenging. One of the evolving technologies to provide such services is DVB-H (Digital Video Broadcasting over Handheld). Wireless channels constitute a fast varying environment that is hostile to reliable communications. Adaptive modulation and coding (AMC) is one of the most promising mechanisms to cope with the dynamic fading of wireless channels. However, the broadcast nature of DVB-H systems restricts the use of AMC as the transmitter must adapt to the user experiencing the worst channel. This would constitute a penalty to other users experiencing good channels. In this paper, a novel framework for AMC is proposed for broadcast DVB-H systems. The transmitted frames are arranged such that higher modulation symbols are transmitted followed by lower modulation symbols. Each group of symbols having the same modulation technique are arranged such that higher code rates (i.e. weaker codes) are transmitted first and then incremental symbols (constituting stronger codes) are transmitted afterwards. The proposed framework is then deployed as a power saving mechanism since power consumption has always been a crucial challenge for handheld devices. The proposed adaptive receiver adjusts its modulation and coding configuration to receive and detect the minimal amount of bits that guarantee a target Bit Error Rate (BER) performance. This is shown to result in significant potential for saving of reception and processing powers (up to 71.875%). Numerical analysis for the power saving potential and BER performance of the proposed scheme is performed for flat Rayleigh fading channel. Simulation results for the operation of DVB-H under the proposed scheme in a Typical Urban 6-paths (TU6) channel are presented. Finally, the effect of adaptation rate (i.e. how often the modulation and coding are allowed to change) on power saving potential is investigated.
The challenge for broadband fixed wireless access (BFWA) systems, which represent an attractive solution for broadband access in the last mile and for wireless backhauling applications in the "middle mile", ...
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The challenge for broadband fixed wireless access (BFWA) systems, which represent an attractive solution for broadband access in the last mile and for wireless backhauling applications in the "middle mile", lies in providing high data rates and quality of service (QoS). Such requirements mainly derive from the need to provide new bandwidth consuming multimedia services and applications, efficient handling of IP traffic, effective use of the limited radio spectrum and a greater backhaul capacity to support the increased number of users per cell site. IEEE 802.16 family of standards and its associated consortium WiMAX are gaining more and more interest in the telecommunication areas as broadband fixed wireless access solution with possible extension in nomadic and mobile area. Its main leverages are an efficient handling of IP traffic, the support of channel adaptivity and advanced QoS management. This paper aims at defining a new packet-based scheduling strategy for an IEEE 802.16 system supporting variable length MAC protocol data units (PDUs) and adaptive coding and modulation while fulfilling QoS requirements. A performance analysis of the proposed scheduler is presented and discussed in terms of packet transfer delay, MAC overhead and average throughput
In this paper, we propose two adaptive schemes where either the modulation mode or the space-time block code (STBC) pattern is changed for a space-time coded system with transmit antenna selection. Simulation results ...
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In this paper, we propose two adaptive schemes where either the modulation mode or the space-time block code (STBC) pattern is changed for a space-time coded system with transmit antenna selection. Simulation results show that the improvements in terms of capacity, data throughput and BER can be obtained over the nonadaptive schemes
This paper examines the potential benefits of employing downlink feedforward transmit diversity (FF-TxD) in wireless systems which utilise adaptive modulation and coding. Instead of employing FF-TxD in such a system, ...
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This paper examines the potential benefits of employing downlink feedforward transmit diversity (FF-TxD) in wireless systems which utilise adaptive modulation and coding. Instead of employing FF-TxD in such a system, the results presented suggest that multiple node B transmit antennas could better be utilised to implement a spatial processing technique which exploits parallelism in the MIMO channel, such as one of the space-time coding schemes.
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