Multiple-symbol differential detection for MPSK space-time block codes: decision metric and performance analysis

In distributed space-time coding cooperative systems, differential detection gains much attention because it needs no channel state information at the receivers. But conventional differential detection performs about 3dB loss than coherent detection. In this paper, we propose a multiple-symbol differential detection algorithm for relay networks based on maximum-likelihood principle. The simulation results show that the multiple-symbol differential detection can narrow the performance gap between the conventional differential detection and coherent detection for Alamouti and square real orthogonal coding systems with corresponding numbers of relays, especially in high signal-tonoise ratio regime. And with the increase of observation window size, the Doppler effect on performance is decreased and the error floor encountered in conventional differential detection can be eliminated provided that the value of observation window size is sufficiently high.

In this paper, multiple-symbol differential detection (MSDD) is applied to the differential single-carrier frequency-division multiple access (SC-FDMA) system. Both time domain and frequency domain MSDD are investigated to compensate for the performance loss of conventional differential detection comparing with coherent detection. The decision metric of time and frequency domain MSDD for SC-FDMA are derived respectively. Simulation results demonstrate the effectiveness of MSDD in some situations.

We present a new differential space-time block coding (DSTBC) scheme. The new scheme can be represented by a trellis and decoded using the Viterbi algorithm. It provides a differential coding gain of 1 dB due to the redundancy introduced in the differential coding and it is only 2 dB away from the coherent space-time block codes (STBC). Furthermore, we extend this design of DSTBC to three and four transmit antennas.

The error performance of multiple-symbol differential detection of uncoded QPSK signals transmitted over correlated Rayleigh fading channels is studied. The optimal detector is presented, along with an exact expression for the corresponding pairwise error event probability. It is shown that multiple-symbol differential detection is a very effective strategy for eliminating the irreducible error floor associated with a conventional differential detector. In all of the cases investigated, a detector with an observation interval as small as two symbols is sufficient for this purpose. It is also found that the error performance of a multiple-symbol differential detector is not sensitive to the mismatch between the decoding metric and the channel fading statistics. >

The conventional multiple-symbol differential detection (MSDD) of differential phase-shift keying (DPSK) signals is studied in the presence of frequency offset. It is shown that in the case of nonzero frequency offset, the performance of the conventional MSDD receiver degrades by increasing the number of observed samples. A double DPSK (DDPSK) modulation scheme is then introduced and it is shown that in the presence of nonzero frequency offset, an MSDD receiver with DDPSK modulation outperforms a conventional MSDD receiver with DPSK modulation, when both receivers use a large number of received samples. Examples lead to a conjecture that the performance of an optimum MSDD receiver with DDPSK modulation and an infinite number of received samples, approaches that of a conventional DPSK demodulator with two received samples.

It is well known that the performance of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique, and has been incorporated into the IEEE 802.11n standard, i.e. one of the Wi-Fi systems. The MIMO technique has also been adopted by the 3GPP Long Term Evolution (LTE) and the 3GPP2 Ultra Mobile Broadband (UMB) standards. The space-time coding is a promising way to realize the gain in the wireless communications system using MIMO. The space time block code, and the orthogonal space time block code in particular have been proposed in research and implemented in practical wireless communication systems due to their low computational complexity in maximum likelihood decoding implementation. However, the code rates of the orthogonal space time block codes are usually lower than $3/4$ when the number of transmit antennas is greater than two, which limit their throughput. To increase the code rate and the throughput of the orthogonal space time block code for more than two transmit antennas, a family of new space-time block codes (STBC) for 3 and 4 transmit antennas in a MIMO wireless communication system have been proposed in this Ph.D. research. These new codes are orthogonal and achieve full diversity, full rate using Triple QPSK'' modulation, which is proposed in this research. We investigated the performance of these STBCs when the channel state information (CSI) is perfectly known at the receiver. The CSI is not known to the transmitter in all of the studies in this dissertation. An analytical bound of the probability of bit error is developed and the Monte Carlo simulation is used when investigating these new STBC codes. In practical wireless communication system, the CSI is generally not available at the receiver and it is usually estimated by the receiver through the pilot signals or training signals known to the receiver. No matter what channel estimation method is used, the estimate of CSI will not match the CSI exactly and is noisy. The performance of these new STBCs using theTriple QPSK'' modulation when the estimate of the CSI is employed to detect the symbol is investigated in this dissertation. An upper bound of the bit error probability is developed when the noisy CSI is used to detect the symbols. The performance of the new STBCs using the Triple QPSK'' modulation is also evaluated using Monte Carlo simulation. When the CSI is not available to either the receiver or the transmitter, the differential encoding and decoding algorithm is applied to these new STBCs, which use theTriple QPSK'' modulation. The results showed that these orthogonal STBCs achieve full diversity full rate using ""Triple-QPSK"" modulation with differential detection. This provides a means of achieving space diversity and multiplexing gain without the CSI. A new differential encoding and decoding algorithm is proposed and analyzed for STBCs with 3 transmit antennas, whose transmission matrix is not square matrix, as part of this Ph.D. research. The STBCs using this algorithm achieve full diversity the MIMO system can possibly provide.

This paper compares the performance of both differential space-time block codes (DSTBC) and differential unitary space-time block codes (DUSTBC) for multiple transmitters with one receiver over spatially correlated narrowband slow Rayleigh fading channels. It is shown that the relative performance of all candidate codes is improved when the number of transmit antennas is kept low. Improved performance is also observed when differential STBC are used compared to coherent STBC.

The performance of multiple symbol differential detection applied to differentially encoded QPSK signals, is examined by simulation in the mobile radio channel with slow Rayleigh and Rician fading, and cochannel interference (CCI). Performance gains observed in the slow Rician fading channel when compared to conventional differential detection, are maintained in the CCI environment. Using a signal quality measure from the multiple symbol differential detection algorithm for selection diversity, performance gains are observed over conventional differential detection in Rayleigh fading as well. >

In this paper, we propose a novel multiple symbol differential detection (MSDD) based on symbol error position estimation (SEPE) and compensation for use in terrestrial digital multimedia broadcasting (T-DMB) system. By estimating the symbol error position and compensating for the symbol error using MSDD outputs, it can improve the receive performance of T-DMB system. Also by providing soft-outputs to Viterbi decoder, an additional coding gain can be obtained. Simulation results in the typical urban (TU) channel show that the proposed algorithm is superior to the conventional differential detection (DD) and hard decision based MSDD T-DMB receivers.

Differential distributed space-time coding (DDSTC) technique has been considered for relay networks to provide both diversity gain and high throughput in the absence of channel state information. Conventional differential detection (CDD) or two-symbol non-coherent detection over slow-fading channels has been examined and shown to suffer 3–4 dB loss when compared to coherent detections. Moreover, it has also been shown that the performance of CDD severely degrades in fast-fading channels and an irreducible error floor exists at high signal-to-noise ratio region. To overcome the error floor experienced with fast-fading, a nearly optimal “multiple-symbol” differential detection (MSDD) is developed in this paper. The MSDD algorithm jointly processes a larger window of received signals for detection and significantly improves the performance of D-DSTC in fast-fading channels. The error performance of the MSDD algorithm is illustrated with simulation results under different fading scenarios.

We propose a technique that enhances the bandwidth efficiency of the two transmit antenna differential space-time block code (DSTBC) by use of space-time block code (STBC) expansion and trellis coding. STBC expansion is realized by expanding the conventional Alamouti STBC using unitary matrix transformation. This is followed by trellis code-aided mapping of additional bits to space-time codes of the expanded set. Trellis code-aided mapping of additional bits enhances the bandwidth efficiency of the proposed DSTBC scheme. The proposed scheme sends more information bits in each transmitted space-time code than the conventional differential detection-aided DSTBC (CDD-DSTBC) scheme, and yet retains the same error performance. For each additional bit sent with the transmitted space-time codeword, the proposed scheme using 16QAM achieves a 12.5% increase in bandwidth efficiency, while the scheme using 64QAM realises an 8.3% increase. Simulation results demonstrate that the error performance of the proposed scheme tightly matches that of CDD-DSTBC with improvement in bandwidth efficiency. The bandwidth efficiency is enhanced at the expense of a moderate increase of the computational complexity at the receiver.

The object of this research is the methods and algorithms of space-time block coding, which are also used in multi-antenna radio communication systems (Multiple Input Multiple Output – MIMO). The implementation of MIMO systems for coherent reception or precoding of data implies knowledge of information about the state of the communication channel and, accordingly, compensation for its impact. For channel estimation, together with information signals, pilot signals are transmitted, previously known at the receiving side. The frequency of sending these signals depends on factors that change the state of the communication channel, for example, one of which is the high speed of movement of mobile stations. But since the pilot signals do not carry user information, the resource of the system is consumed, which impedes the efficient use of the radio frequency spectrum.In the course of the study, a method was considered that admits the absence of the need for knowledge of the state of the communication channel – relative phase modulation, which was taken as a basis and distributed for use in MIMO systems. This method provides for incoherent reception, but, despite this, its use is fully justified, based on the results of the study. Effective tree coding and an algorithm for compensating the noise components of the received signal were also developed and integrated into the system. This, accordingly, allows to optimize the computational power of the system implementation and to approximate the proposed method of differential space-time block coding (DSTBC) to the methods of coherent reception.Using the MATLAB software package, the proposed DSTBC method is simulated for various options for the number of transmitting and receiving antennas and types of modulation. A comparison is made and the advantages of the DSTBC method are determined. The described method can find application in modern radio communication systems with rapidly changing communication channel parameters due to the high speed of movement of mobile stations.

Multiple symbol differential detection of /spl pi//4 QPSK in land mobile satellite communication channels (modeled as correlated Rician fading) is studied. BER performance of this scheme in land mobile satellite communication channels are evaluated using union bounds of pairwise bit error probabilities for situations of ideal channel information and no channel information. It has been found that in light or medium fading Rician channels, about a 1 dB gain in E/sub b//N/sub o/ at a BER=10/sup -4/ can be achieved by using four-symbol differential detection instead of conventional two-symbol differential detection. It is also proved that multiple-symbol differential detection is not suitable for severe fading Rician channels or Rayleigh channels. The influence of the fading rate on the BER performance is also evaluated. Part of the results are compared with those from previous literature.

MIMO technology has the advantage of providing multiplexing gain and diversity gain this is beneficial in wireless communication to improve the data rate and the coverage. In communication when there is the presence of more than one transmitter and receiver the use of non-coherent techniques have been increasing because they do not require the channel state information. In this paper, we analyze the performance of differential and coherent cooperative Multiple-Input-Multiple-Output (MIMO) method using Space-Time Block Codes (STBC). Aiming to minimize the energy consumption per bit, we have applied Multiple-symbol differential detection (MSDD) based on STBC in Wireless Sensor Network (WSN). The simulation results show that utilizing differential multiple symbols provides appreciable energy saving compared to the conventional two-symbol processing.

We consider multiple?symbol differential detection (MSDD) for multiple?input multiple?output Rayleigh?fading channels. MSDD, which jointly processes blocks of received symbols to detect N -1 data symbols, allows for power?efficient transmission without requiring channel state information at the receiver. In previous work, we showed that computationally efficient sphere decoding algorithms can be used to accomplish MSDD. In this paper, we analyze the computational complexity of this sphere?decoding based MSDD. In particular, we prove by means of a lower bound that the complexity of the Fincke?Pohst multiple?symbol differential sphere decoder (FP?MSDSD), while being very low over wide ranges of N and signal?to?noise ratios, is exponential in N in principle. We further derive expressions for the exact complexity of FP?MSDSD, which allow for quick assessment of ranges of useful window sizes N.