Multilevel Space Time Trellis Codes Research Articles

Error Analysis of Grouped Multilevel Space-Time Trellis Coding with the Combined Application of Massive MIMO and Cognitive Radio

In today’s scenario, demand for error-correcting codes with minimal error constraints for wireless communications. Multilevel coding scheme with trellis codes as component codes provides flexible data transmission rates, coding gain, diversity gain with improved spectral efficiency and low decoding complexity. This paper investigates the potential improvements by using the Multilevel coding scheme with massive Multiple-Input Multiple-Output in Cognitive Radio Networks with trellis codes as component codes. This paper discussed space-time coding with beamforming and antenna grouping according to the channel state information. Multilevel Space-time coding is based on multi-level Quadrature Amplitude Modulation signaling and beamforming to mitigate the effect of primary users for the enactment of secondary users in Cognitive Radio. The primary users provide channels dynamically to the secondary user for an unknown duration. Our transmission use Quadrature Amplitude Modulation based signals, with an adaptive grouping of antenna which weight according to the optimization, which inherently depends upon the resource allocation of the secondary user. The results show that the proposed coded system achieves Bit error rate/Symbol error rate/Frame error rate and Signal to noise ratio varies according to sources sensing time.

Performance Analysis of Grouped Multilevel Space-Time Trellis Coding Technique Using Cognitive Radio in Different Deployment Models

In this era, the number of users in a network is increasing tremendously at a faster rate; as a consequence, quality of service (QoS) is drastically deteriorating. To compensate such kinds of problems, we attempted to enhance the QoS of the network, which leads to an improvement in throughput, link quality, spectral efficiency, and many more. To meet the requirements mentioned above, many researchers intervene to advance and propose different techniques with an appropriate design methodology. In this work, we try to emphasize symbol error rate (SER) and frame error rate (FER) by implementing some of the existing space-time coding techniques like Space-Time Trellis Coding (STTC), multilevel space-time trellis coding (MLSTTC), and grouped multilevel space-time trellis coding (GMLSTTC). Though all these techniques are proved to be efficient enough, we explicitly included a powerful method of cooperative diversity-based spectrum sensing in cognitive radio scenario. From this analysis, we landed on to the conclusion that this technique is far better to deal with all these parameters, which can improve the QoS of the network. This paper has also analyzed the effect of the proposed model of GMLSTTC with cognitive radio on various deployment setups such as urban, suburban, and rural macrodeployment setup of the ITU-R M.2135 standard.

A Novel Cooperative Diversity Technique Based on Multilevel Pseudo Space–Time Trellis Coding

Several multilevel space---time trellis coding (MLSTTC) techniques have been investigated in the past few years to attain the benefits of spectral efficiency, coding gain and diversity gain. Howeve...

Cooperative multilevel dynamic space–time trellis coding scheme for improved system performance

This study proposes a system that employs multilevel coding scheme with dynamic space–time trellis codes (DSTTCs) as component codes in order to cooperatively transmit the information of mobile nodes to a common destination node. Perfect channel state information is available at both transmitter and receiver. Every mobile node has a DSTTC encoder at each information level, which receives feedback information from destination node and adapts to the current channel conditions by modifying its code set of generator sequences. The feedback information is in the form of an index of predefined channel profile with power gain in close proximity to the power gain of current channel profile at destination node. The proposed cooperative multilevel dynamic space–time trellis coding (CMLDSTTC) system has the potential of improving spectral efficiency, system throughput, diversity gain, coding gain with low decoding complexity. The CMLDSTTC system outperforms cooperative multilevel space–time trellis coding (CMLSTTC) system with predefined space–time trellis codes and non-cooperative multilevel dynamic space–time trellis coding system by ∼5 and ∼2.5 dB, respectively, at frame error rate of 10−2 using two transmit and two receive antennas. The performance of CMLDSTTC system improves further with an increase in the bits of feedback information.

Multilevel space–time trellis coded cooperation with channel state information at transmitter

SummaryIn this paper, the authors propose a system where a number of cooperating mobile nodes transmit information to a common destination node. Each cooperating node has a set of decoders to detect the information of other nodes and a set of encoders to further encode the decoded information as well as its own information using multilevel space–time trellis coding (MLSTTC) scheme. The coded information is mapped using multi‐resolution modulation partitioning to M‐ary quadrature amplitude modulation constellation. The mapped symbols are weighted based on the available channel state information at transmitting nodes. The weighting of transmitting symbols provides beamforming resulting in receive signal‐to‐noise ratio gain. The weighted symbols are sent to destination node through two transmit antennas. If the information of other nodes has been correctly decoded at the cooperating node, then the destination node receives the information of each node as many times as there are number of transmitting nodes, thus achieving full diversity order. A multistage Viterbi decoder is used at the destination node to extract information of each mobile node. The results indicate that the performance of proposed cooperative MLSTTC system is superior to non‐cooperative MLSTTC system. Copyright © 2016 John Wiley & Sons, Ltd.

Low complex decoding algorithm for multilevel space time trellis codes over MIMO channel

It has been proved in literatures that the multilevel space time trellis codes MLSTTC provides higher order diversity with low complex component codes compared to single STTC. The throughput increases with manageable complexity compared to single space time trellis codes STTC. But the computational complexity increases with the number of levels in the MLSTTC system. And also the metric calculation is a complex equation which needs more multiply and accumulate operation compared to single STTC. In this paper, reduced complexity decoding algorithm for multilevel space time trellis code is proposed to reduce the decoding delay and computational power required at the receiver. The simulation results show that the proposed algorithm gives a BER performance nearer to that of the system with full complexity. Further, the impact of correlation between the antennas in the system is also analysed. The simulation results show that with correlated antennas we could maximise the performance.

Performance Analysis of Adaptively Grouped Multilevel Space-Time Trellis Coded Systems using Different Component Codes

Adaptively grouped multilevel space-time trellis codes (AGMLSTTCs) utilize multilevel coding (MLC), space time trellis codes (STTCs) and adaptive transmit antenna grouping for simultaneously providing coding gain, diversity improvement and increased spectral efficiency. AGMLSTTCs use Chen, Yuan, and Vucetic (CYV) STTCs as component codes in MLC. In this paper, we present performance comparison of AGMLSTTCs generated using different component STTCs. We use Tarokh, Seshadri, and Calderbank (TSC), Baro, Bauch and Hansmann (BBH) and CYV codes as component STTCs. The simulation results show that AGMLSTTCs with CYV as component STTCs outperforms in comparison with the AGMLSTTCs with TSC and BBH as component STTCs.

Weighted adaptively grouped multilevel space time trellis codes

In existing grouped multilevel space-time trellis codes (GMLSTTCs), the groups of transmit antennas are predefined, and the transmit power is equally distributed across all transmit antennas. When the channel parameters are perfectly known at the transmitter, adaptive antenna grouping and beamforming scheme can achieve the better performance by optimum grouping of transmit antennas and properly weighting transmitted signals based on the available channel information. In this paper, we present a new code designed by combining GMLSTTCs, adaptive antenna grouping and beamforming using the channel state information at transmitter (CSIT), henceforth referred to as weighted adaptively grouped multilevel space time trellis codes (WAGMLSTTCs). The CSIT is used to adaptively group the transmitting antennas and provide a beamforming scheme by allocating the different powers to the transmit antennas. Simulation results show that WAGMLSTTCs provide improvement in error performance of 2.6 dB over GMLSTTCs.

Adaptively Grouped Multilevel Space–Time Trellis Codes Combined with Beamforming and Component Code Selection

The performance of adaptively grouped multilevel space---time trellis codes (AGMLSTTCs) is limited due to predefined component space---time trellis codes (STTCs) used in multilevel coding and lack of beamforming. In this paper, we present improvement in performance of AGMLSTTCs by combining beamforming and dynamic selection of component STTCs with AGMLSTTCs to design new codes henceforth referred to as weighted adaptively grouped multilevel dynamic space---time trellis codes. The channel state information at transmitter (CSI) is used to select a code set having different sets of generator sequences. The selected code set is used for generating dynamic STTCs (DSTTCs). The DSTTCs are used as component codes in multilevel coding. We use a single full-diversity DSTTC at some initial levels and multiple DSTTCs at some later levels. The single full diversity DSTTC at each initial level spans all transmit antennas and the DSTTC at each later level spans a group of transmit antennas. The CSI is further used to provide a beam forming scheme by properly weighting transmitted signals. Weights are selected that based on CSI at transmitter. The simulation results show that AGMLSTTCs combined with beamforming and DSTTCs provide significant improved error performance over grouped multilevel space---time trellis codes and AGMLSTTCs.

A novel grouped multilevel dynamic space–time trellis coding scheme

SummaryGrouped multilevel space–time trellis codes (GMLSTTCs) utilize multilevel coding, antenna grouping and STTCs for simultaneously providing coding gain, diversity improvement and increased spectral efficiency. The performance of GMLSTTCs is limited because of using predefined STTCs as component codes in multilevel coding. GMLSTTCs assume perfect channel state information (CSI) at the receiver only and do not consider the CSI at the transmitter. It has been shown that when perfect or partial CSI is available at the transmitter, the performance and capacity of a space–time coded system can be further improved. In this paper, we present new codes, designed by combining GMLSTTCs and the CSI information at the transmitter, henceforth referred to as grouped multilevel dynamic space–time trellis codes (GMLDSTTCs). A code set having different sets of generator sequences is selected that matches best with the current channel profile. The selected code set is used for generating DSTTCs. DSTTCs are used as component codes in GMLSTTCs instead of predefined STTCs to generate GMLDSTTCs. Analysis and simulation results show that GMLDSTTCs outperform GMLSTTCs. Copyright © 2014 John Wiley & Sons, Ltd.

Adaptive Generator Sequence Selection in Multilevel Space–Time Trellis Codes

It has been shown that multilevel space–time trellis codes (MLSTTCs) designed by combining multilevel coding (MLC) with space–time trellis codes (STTCs) can provide improvement in diversity gain and coding gain of the STTCs. MLSTTCs assume perfect channel state information (CSI) at receiver and no knowledge of CSI at transmitter. Weighted multilevel space–time trellis codes (WMLSTTCs), designed by combining MLSTTCs and perfect CSI at transmitter are capable of providing improvement in coding gain of MLSTTCs. In this paper, we present improvement in performance of MLSTTCs by using channel feedback information from the receiver for adaptive selection of generator sequences. The selected generator sequences are used for encoding the component STTCs. The receiver compares current channel profile at receiver with a set of predetermined channel profiles, and sends an index of a predefined channel profile closest to the current channel profile to the transmitter. The transmitter selects a code set that matches best with the current channel profile at receiver using the index. The selected code set having different sets of generator sequences is used by STTC encoders to generate dynamic space–time trellis codes (DSTTCs). The DSTTCs act as component codes in multilevel coding for generating new codes henceforth referred to as multilevel dynamic space–time trellis codes (MLDSTTCs). Analysis and simulation results show that MLDSTTCs provide improvement in performance over MLSTTCs.

Adaptively Grouped Multilevel Space-Time Trellis Codes

Grouped multilevel space-time trellis codes (GMLSTTCs) utilize multilevel coding (MLC), antenna grouping and space time trellis codes (STTCs) for simultaneously providing coding gain, diversity improvement and increased spectral efficiency. The performance of GMLSTTCs is limited due to predefining of the antenna groups. It has been shown that when perfect or partial channel state information is available at the transmitter, the performance and capacity of space-time coded system can be further improved. In this paper, we present a new code designed by combining MLC, STTCs, antenna grouping and channel state information at transmitter, henceforth referred to as adaptively grouped multilevel space time trellis codes (AGMLSTTCs). AGMLSTTCs use a single full-diversity STTC at initial some levels and multiple STTCs at some later levels. The single full diversity STTC at each initial level spans all transmit antennas and the STTC at each later level spans a group of transmit antennas. The channel state information at the transmitter is used to adaptively group the transmit antennas for the later levels. Instantaneous channel power gain is calculated between each transmit antenna and all the receive antennas. A subset of transmit antennas having maximum channel power gain is selected to form a group. The simulation results show that AGMLSTTCs enable to transmit more than one data symbol per time slot with improved error performance over GMLSTTCs with predefined transmit antenna grouping.

A novel weighted multilevel space–time trellis coding scheme

It has been shown that when perfect or partial channel state information (CSI) is available at the transmitter, the performance and capacity of a space–time coded system can be further improved. Multilevel space–time trellis codes (MLSTTC’s) are capable of simultaneously providing bandwidth efficiency, diversity improvement and coding gain with significantly reduced decoding complexity, especially for larger constellations and higher throughputs. In this paper, we present a design of combined multilevel space–time trellis codes and beam forming based on feedback from receiver, henceforth referred to as weighted multilevel space–time trellis codes (WMLSTTCs). The channel profile is used to provide a beam forming scheme that achieves the better performance by properly weighting transmitted signals. Weights are selected that matches best with a channel profile feedback from the receiver indicative of long-term characteristics of the wireless channel. WMLSTTCs provide improvement in performance of MLSTTCs.