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Multi-input multi-output (MIMO) is an attractive solution to high data rate underwater acoustic communications (UAC) with limited bandwidth. However, the long delay spread characteristic of UAC channels makes the equalization challenging for those MIMO schemes. Although maximum likelihood sequence estimation (MLSE) is known to be optimum and is intensively used in many terrestrial wireless applications,...
The different propagation times due to the distinct distance between the BSs and MSs result in inter-cell asynchronous interference, which severely destroy system performance. How to mitigate inter-cell asynchronous interference by making use of SLNR precoding is the key to this paper. Firstly, a framework of Cooperative Base Station Systems (Co-BS) was developed and the delay between the cells was...
In this paper, we investigate the performance of superimposed training-based channel estimation techniques considering an asynchronous code-division multiple-access (CDMA) uplink transmission over frequency-selective fading channels. In that, we analyze the performance of a channel estimation and data detection scheme based on superimposed training for space-time spreading (STS) systems. Our results...
In this paper, a tap-wise LMMSE channel estimator for MIMO W-CDMA is derived. Descrambling operations applied to delayed versions of the received signal whiten the input signal. The descrambling process thus breaks up the full channel autocorrelation matrix (including spatial and temporal correlation) into several independent, small autocorrelation matrices that include only spatial correlation. The...
Channel adaptive transmission in multi-user MIMO systems is seen as a promising concept to achieve high spectral efficiencies in future radio networks: Based on feedback on actual channel conditions, the base station allocates transmission resources to the user terminals where they can support high data rates. However, due to the delay between evaluation of the channels at the terminals and application...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
Effects of improved channel estimation are studied for a proposed IEEE 802.11n OFDM MIMO system. Three channel estimation methods are considered: maximum likelihood (ML), time-domain truncation (TDT) and model-based (MB). TDT and MB are particularly useful when the channel delay spread is short. For an MMSE receiver, MB shows a 1-2.5 dB improvement over ML on the packet error rate performance for...
Correlative minimum shift keying (MSK), a second order polynomial modulation scheme known as tamed frequency modulation (TFM), is a constant envelope type of modulation with a perfect peak to average power ratio (PAPR), besides the property of low out of band power. We apply the linearized TFM to the single carrier transmission with frequency domain equalization (SC/FDE) concept. We then obtain a...
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