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Adaptive Modulation and cooperative Diversity are considered as two of the most commonly deployed techniques for wireless communication, which aims to compensate the performance degradation and enhance the capacity as much as possible. In this survey, several studies and research works that were introduced in the literature will be investigated, aided by the followed methodology and main concepts...
In this paper, we propose the user grouping and adaptive modulation algorithms for downlink Multi-Carrier Code Division Multiple Access (MC-CDMA) systems. Under a frequency-selective fading channel, we adaptively assign users into groups by their channel state information (CSI) such that spectrum efficiency is improved and BER is reduced. After grouping, we assign bit loading and allocate transmission...
Adaptive M-ary quadrature amplitude modulation (M-QAM) with subset diversity is a way to cope with the quality of service variations in small and large-scale fading channels. We consider a pilot-assisted slow adaptive modulation (SAM) technique that adapts the constellation size and the pilots energy to slow variations of the channel due to shadowing. The SAM technique is less complex and requires...
In recent years, Orthogonal Frequency Division Multiplexing (OFDM) technology has been widely used in many wireless communication systems, including LTE and WiMAX. Bandwidth is always precious over wireless channel, so it is important to have an effective bandwidth arrangement. On a multi-user system, each user needs to share entire bandwidth with others. In order to enhance the transmission rate,...
In narrowband multiple-input multiple-output (MIMO) communication systems with perfectly known channel state information (CSI), the singular value decomposition (SVD) is commonly used to decompose the MIMO channel into independent single-input single-output subchannels. In theory, optimal interference-free data multiplexing may then be carried out using the subchannel power levels provided by the...
We develop a link adaptation scheme based on non-binary LDPC codes for two scenarios: a frequency-selective quasi-static channel and a time-selective flat fading channel with very limited channel state information at the transmitter. For both cases, we present a unified characterization of the coding performance including puncturing and repetition coding which is based on the accumulated mutual information...
In this paper, we investigate a communication strategy combining of transmit antenna selection with adaptive modulation and coding for space-time block coded system. The antenna selection is based on the criterion of maximizing the average spectral efficiency (ASE) of the whole system for a given bit error rate (BER) constraint. In order to enhance system performance, low density parity check codes...
We consider the design and performance analysis of adaptive modulation and coding (AMC) applied to regenerative dual-hop transmission systems, where a source node communicates with a corresponding destination node only indirectly via an intermediate relay station operating in the well-known decode-and-forward mode. Specifically, we consider the general case where the AMC over both hops is performed...
The adaptive modulation and coding can provide robust and spectrally efficient transmission over generalized ??-?? (or generalized gamma) wireless fading channels. The key idea of our proposal is to transmit the low-density parity-check (LDPC) encoded sequence over the generalized fading channel, feedback the channel state information of by an RF feedback channel, and adapt the powers and rates of...
The resource allocation problem to maximize the bit rate of a linear precoded orthogonal frequency division multiplexing (LP-OFDM) system is considered taking into account the effects of imperfect channel state information. A discrete bit loading algorithm is proposed, which sustains the target bit error rate even under high mean square error (MSE) of estimation. The proposed scheme enhances the robustness...
The traditional adaptive modulation and coding (AMC) scheme has been designed separately from higher protocol layers. In this paper, we consider the joint effects of finite-length buffer at the data link layer and the channel state information (CSI) at the physical layer for the adaptive transmission over the multiple input multiple output (MIMO) fading channel. A novel cross-layer adaptive transmission...
Adaptive modulation and coding (AMC) is a powerful technique to enhance the link performance by adjusting the transmission power, channel coding rates and modulation levels according to channel state information. In order to efficiently utilize the AMC scheme, an accurate signal-to-noise ratio (SNR) value is normally required for determining the AMC level. In this paper, we propose a simple method...
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...
In this paper we provide an adaptive cross layer design in single input multiple output systems which combines adaptive modulation at the physical layer with truncated automatic repeat request at the data link layer to maximize the spectral efficiency. The maximization is performed in the presence of imperfect channel state information at the receiver under prescribed quality of service such as delay...
Adaptive modulation and coding (AMC) scheme suffers performance degradation with the signaling feedback delay, as channel state information (CSI) is outdated with time variant channel. In this paper, we propose a robust AMC scheme to mitigate the effect of signaling feedback delay, especially in vehicular environments. Channel information estimated in current time interval is utilized to obtain the...
IMT-advanced systems of the future will be based on OFDMA and frequency divicion duplex will be widely used. Multihop techniques, e.g. the use of fixed relays, are also considered a key technology. The OFDMA resources have the dimensions time, frequency and space. In all these dimensions a radio channel is variable due to fading. On the other hand a complete utilization of the channel capacity close...
This paper presents a joint adaptive modulation and coding (AMC) scheme, which exploits the coherence bandwidth of the wireless channel to divide the transmitted frame into independent sub-channels that correspond to the channel coherence bandwidth. This strategy is implemented for orthogonal frequency division multiplexing (OFDM) systems with channel state information (CSI) feedback. Low density...
MIMO-OFDM wireless systems require adaptive modulation and coding based on channel state information (CSI) to maximize throughput in changing wireless channels. Traditional adaptive modulation and coding attempts to predict the best rate available by estimating the packet error rate for each modulation and coding scheme (MCS) by using CSI, which has shown to be challenging. This paper considers supervised...
Adaptive modulation of subcarriers for orthogonal frequency division multiplexing (OFDM) has been shown to improve system performance significantly. As a prerequisite, accurate channel state information (CSI) must be available at the transmitter. For time varying, noisy channels, however, this is difficult to achieve in practical systems. In this paper, we consider optimal subcarrier assignment under...
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