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In the cooperative spatial multiplexing MIMO-OFDM systems in multipath fading environments, the streams from different transmit antennas are not aligned in the time domain, and have different frequency offsets. The preambles and synchronization algorithms in the centralized MIMO-OFDM systems can no longer apply. A new preamble structure is proposed for this system, and the corresponding timing and...
An improved space-time-frequency (STF) code using digital phase sweeping (DPS) is proposed for multi-input multi-output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. It achieves full diversity attainable over frequency-selective channels and works for arbitrary power delay profile. The maximum transmission rate of the proposed code is one symbol per channel use independently of the...
A new space-time block code (STBC) achieving full rate and full diversity for general QAM and four transmit antennas is proposed. This code also possesses a quasi-orthogonal (QO) property like the conventional minimum decoding complexity QO-STBC (MDC-QO-STBC), leading to joint ML detection of only two real symbols. The proposed code is shown to exhibit the identical error performance with the existing...
In this paper, we propose a numerical formulation of decoupling matrix with rate one quasi-orthogonal space-time block code (QOSTBC) for eight transmit antennas. Tirkkonen et al. provided zero-forcing decoupling matrix for eliminating inter-symbol interference (ISI) in QOSTBC with 4 transmit antennas. We expand zero-forcing decoupling matrix with 8 transmit antennas, and also MMSE decoupling matrix...
In this paper, the new detection scheme proposed by Tarokh and Alamouti is investigated and expanded to two schemes of two transmit two receive antennas and four transmit one receive antennas. Previously, Tarokh and Alamouti, based on the simple transmit diversity scheme proposed by Alamouti, have provided two new detection methods to decode signals at the receiver without channel information. We...
Space time coding in the case where the channel state information is unknown has received only limited attention, although a signaling scheme called unitary space-time modulation (USTM) has already been proposed. An important reason for the impracticability of USTM is its too large calculation amount when meeting with a large size constellation. We propose a size-reduced method for constellation of...
MIMO-OFDM systems are expected to realize higher data rates and larger capacity. With more transmit and receive antennas the capacity of MIMO-OFDM systems increases. However, when the number of demodulators is limited, it is essential to select antenna points which achieve selection diversity. On the other hand, through Fractional Sampling (FS), it is possible to separate multipath components and...
In MIMO (multiple input multiple output) system, a wireless channel can be divided into several individual subchannels in order to expand the processing capacity comparing to SISO (single input single output) system. The correlation between these subchannels is critical to the system performance, and can be reduced by various diversity schemes. The space diversity has better performance for NLOS(non-line-of-sight)...
In this paper, enhanced OSIC (ordered successive interference cancellation) algorithm combined with ML (maximum likelihood) is considered for double TxAA (transmit antenna array) MIMO (multi-input multi-output) system. Error propagation is known to be inherent drawback of OSIC algorithm and deteriorate system performance significantly. Its performance is seriously affected, in particular, by the last...
Efficient resource management has been a very appealing issue in the operation of wireless communication system. With the goal of minimizing the total transmit power, we mainly discussed the constant-bit-rate (CBR) case for multiuser MIMO-OFDM system, and developed a novel dynamic subcarrier allocation criteria based on Alamouti scheme with a tradeoff between the complexity of implementation and BER...
We propose an efficient space-time coded cooperative relay communications scheme that employs linear precoding and transmission-pattern selection. If effectively exploited, distributed spatial diversity and the cooperative nature of multihop communications could significantly increase the coverage area of a wireless network that consists of a number of power-limited relay nodes. We build upon an existing...
To achieve full transmission rate, quasi-orthogonal space-time block coding is under research. But its performance still needs to be improved due to complex channel condition. Here we derive its expression for average signal to noise rate and provide a scheme with Quasi-Orthogonal STBC via Antenna Selection, which can improve its performance without extra RF chain.
This paper presents a novel space-time fast frequency hopping (FFH) multiple input multiple output (MIMO) wireless communication system over rayleigh fading channel. With the M-ary frequency shifting keying (MFSK) modulation and noncoherent demodulation, the structure of a new system is discussed based on the combination of FFH technique and MIMO system. The concept of generalized wide-interval FH...
In this paper, a serial concatenated scheme combining USTM with LDPC codes over GF(2m) is presented. A modulation technique of USTM, Unitary space-time modulation, can efficiently work on decoding when the channel state information is unknown at the receiver in multi-input multi output system over flat raleigh fading channel. The BER performance of USTM system in MIMO channel will largely be improved...
We study the impact of channel spatial correlation on the ergodic capacity of multiple-input multiple-output (MIMO) systems with channel estimation errors in block-fading channels. We consider transmit antenna correlation and use an accurate capacity lower bound to carry out the theoretical analysis for MIMO systems with and without covariance feedback. We show that for non-feedback systems, the capacity...
This paper investigates the spatial multiuser scheduling strategies that apply different pairing criteria to select a pair of users carrying out transmission simultaneously in virtual MIMO (VMIMO) systems. Five kinds of criteria are described and compared, which are categorized as channel correlation minimization, bit error rate (BER) minimization and capacity maximization depending on their diverse...
Single carrier (SC) FDMA was agreed to be chosen for 3GPP-long term evolution (LTE) uplink. A recent discussed feature for boosting up bit rates in LTE uplink is to apply SDMA (space division multiple access) to enable users to communicate with the serving base station using the same frequency resource. This paper analyzes the achievable sum rate in SC-FDMA system uplink, where SDMA with frequency...
The multiple-input-multiple-output (MIMO) technology has been extensively used to improve wireless physical channel capacity at the expense of increased implementation complexities especially at mobile terminals since either an antenna array or inter-terminal cooperation is required for implementation. Differently, this short paper discusses an alternative MIMO application, called logical MIMO (L-MIMO),...
Cooperative diversity is an emerging technique that enables single-antenna terminals to share their resources (bandwidth and power) and achieve transmit diversity in a distributed fashion. In this work, an adaptive decode-and-forward(DF) cooperative diversity system based on quadrature signaling is proposed. Then a tight closed-form approximate bit error rate(BER) expression is derived in terms of...
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