Increased dynamic range multi-rate waveform for mobile satellite communications: Adaptive Coding Spreading and Modulation (ACSM)

Spectrum efficiency (SE) and QoS guarantee are two critical issues in wireless communication systems. The truncated ARQ and the adaptive modulation and coding (AMC) are often used to improve the SE and transmission reliability in wireless communications. In this paper, we study the SE and QoS performance of a system with a cross-layer combining of the truncated ARQ with the AMC. First, we analyze the performance of current combinations of the ARQ and the AMC. The analysis results indicate that the current combination is too “ineffectiveness” or “conservative.” Then, based on the analysis, we design a new rule for the AMC, which is used to adaptively choose transmission mode. Through analyzing the AMC and the combination algorithm using the proposed rule, both the SE and the packet dropped probability of the system are improved. Furthermore, the analysis result also point outs the suitable scenario of each algorithm. Simulation results verify the analysis result and demonstrate that the proposed algorithm can achieve higher SE while the QoS requirement is guaranteed. At last, to further improve the SE of the system, we propose an algorithm jointing power control and the combination of the ARQ with the AMC under the QoS constraint.

Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configuration is studied. With channel station information feedback from the mobile receiver to the base station transmitter, adaptive modulation and coding can be applied to adapt to the mobile wireless channels condition to increase spectral efficiencies without increasing bit error rate in noisy channels. In High-Speed Downlink Packet Access (HSDPA) in Universal Mobile Telecommunications System (UMTS), AMC can be used to choose modulation types and forward error correction (FEC) coding rate.

Rain attenuation can cause a serious problem that an availability of space communication link on Ka band becomes low. To reduce the effect of rain attenuation on the error performance of space communications in Ka band, an adaptive coding and modulation (ACM) scheme is required. In this paper, to achieve a reliable telemetry data transmission, we propose an adaptive coding and modulation level using turbo code recommended by the consultative committee for space data systems (CCSDS) and various modulation methods (QPSK, 8PSK, 4+12 APSK, and 4+12+16 APSK) adopted in the digital video broadcasting-satellite2 (DVB-S2).

Very small aperture terminal (VSAT) satellite networks have matured beyond simple terrestrial line replacements to unique application niches and geographic 'communities of interest'. These communities of interest are now evolving from multiple organizations sharing a central hub earth station to multiple organizations sharing individual remote VSATs. The remote VSAT serves as a focal point for a community of interest, and when shared can provide economic and strategic benefits. The author examines the need for the shared remote VSAT, describes the technical requirements, and assesses the shared VSAT economics. >

One of the most important features of the IMT-Advanced system is to utilize adaptive modulation and coding (AMC) in order to counteract time and/or frequency varying channel conditions. Due to increasing importance of integrated satellite and terrestrial networks, a satellite system specification needs to be designed by considering compatibility with terrestrial systems. In this paper, we propose an efficient utilization of AMC scheme for mobile satellite systems compatible with the LTE-Advanced. Due to a long round-trip delay (RTD) of a satellite system, the adaptation strategy of a satellite system should be quite different from that for the terrestrial system. In our scheme, a variable margin is allocated along with AMC in a comparatively slow fading condition such as open environment, while a long time interleaver is utilized along with AMC in a comparatively fast fading condition such as sub-urban area.

This paper is concerned with a wireless access system with adaptive modulation and coding (AMC) at the physical layer (PHY), Type-Ill hybrid automatic repeat request (HARQ) at the data link layer (LL) and transport control protocol (TCP) at the transport layer. In order to evaluate the quality-of-service (QoS) of TCP, we analyze the queueing behavior induced by both AMC and Type-Ill HARQ with an embedded Markov chain and study the interaction between AMC, Type-Ill HARQ and TCP via a fixed-point procedure. To maximize the TCP throughput for QoS-guaranteed traffic, we propose a cross-layer design which optimizes the target packet error rate (PER) for AMC at the PHY as well as the maximum number of retransmission for Type-III HARQ at the LL.

In this paper, we combine adaptive modulation and coding (AMC) with multiple input multiple output (MIMO) VBLAST multiplexing to improve the throughput performance of AMC in next generation mobile communication systems. In addition, we propose a system that adopts selection transmit diversity (STD) in the combined AMC-MIMO VBLAST system. The received signal-to-noise ratio (SNR) is improved by adopting STD techniques and an improved SNR increases a probability of selecting modulation and coding scheme (MCS) level that supports higher data rate. From the simulation results, the investigated MIMO-STD VBLAST system provides a throughput gain of 1Mbps compared with simply combined AMC-MIMO VBLAST system when the required SNR is 15dB. Also, the higher throughput is achieved by AMC-TD schemes and AMC-STTD scheme provides about 250kbps increase in throughput. And AMC-STD with 2 transmit antennas achieves about 420 kbps throughput improvement over the conventional AMC at 9dB SNR.

This paper presents performance analysis and cross-layer design approaches for hybrid ARQ (HARQ) protocol in wireless networks which employ adaptive modulation and coding (AMC) at the physical layer and are subject to time-correlated fading channels. Utilizing a Markov channel model which accounts for the temporal correlation in successive parity transmissions by the adaptive rate HARQ protocol, we derive the system throughput and the packet loss probability based on a rate compatible punctured convolutional (RCPC) code family. As an application, we then present a cross-layer AMC design which takes into account the performance gain of the HARQ protocol at the link layer. The results illustrate that including AMC in the HARQ protocol leads to a substantial throughput gain, but the channel correlation strongly diminishes the performance of the HARQ protocol in terms of throughput and packet loss rate.

In this paper, we propose a throughput optimization scheme for relay protocols based on Adaptive Modulation and Coding (AMC). The performance of relay protocols with the AMC scheme and show that relay protocols with the AMC scheme are capable of providing better average throughput at a lower Signal to Noise Ratio (SNR) level as compared to the conventional scheme with no AMC. We perform 3GPP Long Term Evolution-Advanced (LTE-A) parameters based simulations to prove the performance comparison of adaptive Modulation and Coding Scheme (MCS) relay protocols with non-adaptive MCS relay protocols. The simulation results of the proposed system with adaptive MCS prove that among the Amplify-and-Forward (AF), Decode-and-Forward (DF) and De-Modulate-and-Forward (DMF), the DMF protocol performs best, at a lower SNR value and higher average throughput.

The challenge of the adaptive modulation and coding (AMC) scheme is to make a decision when to switch between different modulation and coding scheme. This is difficult because the performance of the AMC system is very sensitive to channel quality estimation errors and other channel impairments. In this paper, block error rate (BLER) performance of the wideband code division multiple access (WCDMA) system using AMC techniques are studied with nonideal channel and signal-to-interference-and-noise ratio (SINR) estimation and with the presence of multiuser interference. Also, the throughput of the adaptive system is simulated.

GOFDM (generalized OFDM) has been proposed as a tradeoff solution between cyclic prefix single carrier (CP-SC) and OFDM system that can alleviate the peak to average power ratio (PAPR) problem of OFDM. In this paper, a novel estimation method for the estimation of the received SNR of GOFDM signal that is required in the adaptive modulation and coding (AMC) is presented. The simulation results of the estimated SNR show excellent correlation with the analytical results. Furthermore, the received SNRs of the GOFDM exhibit repetition of as set values that can be clustered for modulation and coding scheme (MCS) allocation in group-based AMC. The paper also presents various performances of the proposed GOFDM with AMC and compares them with the corresponding performance of OFDM and CP-SC under same operating conditions.

A New Adaptive Modulation and Coding Method for Communication-Based Train Control Systems using WLAN

Research on Threshold Adjustment Algorithm in Adaptive Modulation and Coding

One of the major factors which degrades the Free Space Optics (FSO) link performance is the atmospheric turbulence. Turbulence manifests in increased Bit Error Rate (BER) leading to degradation in the link performance. Adaptive Coding and Modulation (ACM) technique is used to mitigate this effect. This technique is an adaptive transmission scheme wherein transmission parameters such as modulation scheme, code rate, etc., are adjusted based on Channel State Information (CSI). In this paper, we have considered lognormal channel model in low turbulence conditions. Three adaptive transmission schemes viz., variable data rate, variable modulation schemes and variable coding rate are considered. The entire work has been carried out in MATLAB. We see improvement in FSO link performance in terms of average transmitted data rate when variable data rate adaptation scheme is used. Improvement in spectral efficiency is observed when the other two adaptation schemes are used. Design of adaptive transmitter for all the three schemes is presented and data rate of RF feedback channel is determined.

Based on adaptive theory, an adaptive modulation and coding (AMC) multiple input multiple output (MIMO) system with adaptive Turbo receiver is designed to increase the overall capacity and decrease the processing delay. The scheme sets several factors including channel coding rate, modulation mode and iteration times of Turbo receiver as adjustable elements. To guarantee the superiority of the proposed adaptive Turbo receiver in terms of decreasing processing delay and power consuming, an MMSE based no-ordered parallel soft interference cancellation (NOPSIC) MIMO detector which takes error propagation into account is explored for the non-first iteration. Simulation results reveal that the proposed scheme could significantly raise the system capacity, meanwhile bring down overall times of iteration processing by nearly one third.