Adaptive Coding and Modulation

Satellite broadcasting has been considered lately as a promising media for IP streaming due to their wide coverage and high reliable bandwidth. Long propagation delay in GEO satellite system will affect the adaptive algorithms in DVBS-2/RCS systems. Long feedback delay will cause improper physical layer selection of modulation and coding (ModCod). This paper aims to provide an algorithm for physical layer selector in DVB-S2/RCS satellite systems. This algorithm will makeless ModCod switching of the adaptive coding and modulation (ACM) using reduced number of ModCod combinations. We conclude that the number of ModCods in ACM algorithm can be relatively adjusted to maximize DVB-S2 system stability.

Satellite broadcasting has been considered lately as a promising media for IP streaming due to their wide coverage and high reliable bandwidth. Long propagation delay in GEO satellite system will affect the adaptive algorithms in DVBS-2/RCS systems. Long feedback delay will cause improper physical layer selection of modulation and coding (ModCod). This paper aims to provide an algorithm for physical layer selector in DVB-S2/RCS satellite systems. This algorithm will makeless ModCod switching of the adaptive coding and modulation (ACM) using reduced number of ModCod combinations. We conclude that the number of ModCods in ACM algorithm can be relatively adjusted to maximize DVB-S2 system stability.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

Abstract—Within the EU FP6 Integrated Project WINNER, adaptive transmission in a TDMA/OFDMA system is investigated as a key technology for boosting the spectral efficiency of a new radio interface for 4G systems. Adaptive allocation and linkadaptation of ...

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

Mobile WiMAX technology is proposed for ATS and AOC communications in airport areas. This technology provides a large amount of flexibility, incorporating optional use of advanced communication techniques and signal processing. Of particular importance is the use of multiple antenna techniques. In this paper the performance of Mobile WiMAX technology is assessed by means of simulations for communications over channel models suited for airport communications. The simulations include space time coding (STC) and spatial multiplexing (SM). The results illustrate the gain obtained using multiple antenna techniques in the case of non line-of-sight between transmitter and receiver, which may be exploited for increased cell size or increased throughput per cell. In addition, the effect of Weibull fading is illustrated for b-factors lower than 2. This leads to worse than Rayleigh fading, and should be taken into account when setting thresholds in the adaptive coding and modulation scheme.

Broadband multi-beam satellite networks play a substantial role in worldwide telecommunication and providing direct satellite services to users. Geostationary satellite has always been serving as the backbone of the commercial satellite communication networks. In broadband satellite communication, the high frequency bands are generally used. At these frequencies, there are various impairment factors that degrade the quality of signals. Among these factors, rain attenuation is the dominant factor at frequencies of 10 GHz and above. Using different models for rain attenuation prediction and power allocation algorithm, it has been shown that the number of served users is increased. In this paper, a new dynamic power allocation algorithm is proposed, which provides better results in terms of time elapsed and number of users served. The advantage of algorithm is the simplicity with which it allows the simulation. This is important for complex models of adaptive networks where finite response time is of great importance.

This paper presents a practical method of potential replacement of several different Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) codes with one, with the intention of saving as much memory as required to implement the LDPC encoder and decoder in a memory-constrained System on a Chip (SoC). The presented method requires only a very small modification of the existing encoder and decoder, making it suitable for utilization in a Software Defined Radio (SDR) platform. Besides the analysis of the effects of necessary variable-node value fixation during the Belief Propagation (BP) decoding algorithm, practical standard-defined code parameters are scrutinized in order to evaluate the feasibility of the proposed LDPC setup simplification. Finally, the error performance of the modified system structure is evaluated and compared with the original system structure by means of simulation.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

Abstract Wireless mobile channels suer from time-varying channel conditions, and are commonly modelled as multipath fading channels. Systems using adaptive coding and modulation (ACM) have been introduced to increase spectral eciency,on such channels. An ACM system can be designed by segmenting a (slow) fading channel into time slots, and using an additive white Gaussian noise (AWGN) channel as an approximation within each given time slot. Then, coding schemes for AWGN channels of varying qualities can be temporarily

An enhanced adaptive scheme based on threshold method with a reduced complexity that combine adaptive modulation and coding with diversity combining is presented for throughput maximization in broadband code division multiple access (CDMA) satellite networks. The proposed algorithm is a modify, enhanced, and more robust version of the existing algorithms for adaptive transmission rate and modulation in CDMA networks. The rate compatible punctured turbo-coded (RCPT), which has been found to give improved throughput performance in a direct sequence (DS) CDMA is exploited. A semianalytical process and simulations were carried out. It is found that there are significant improvement in the average throughput and the bit-error performance. The proposed algorithm using adaptive coding and modulation (instead of variable spreading gain) outperforms other systems such as Selective Power Control with Active Link Protection (SPC-ALP) algorithm proposed for adaptive transmission rate and power control in CDMA networks.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

Recent research on Frequency Reuse (FR) schemes for OFDM/OFDMA based cellular networks (OCN) suggest that a single fixed FR cannot be optimal to cope with spatiotemporal dynamics of traffic and cellular environments in a spectral and energy efficient way. To address this issue this paper introduces a novel Self Organizing framework for adaptive Frequency Reuse and Deployment (SO-FRD) for future OCN including both cellular (e.g. LTE) and relay enhanced cellular networks (e.g. LTE Advance). In this paper, an optimization problem is first formulated to find optimal frequency reuse factor, no of sectors per site and number of relays per site. The objective is designed as an adaptive utility function which incorporates three major system objectives 1) spectral efficiency 2) fairness, and 3) energy efficiency. An appropriate metric for each of the three constituent objectives of utility function is then derived. Solution is provided by evaluating these metrics through a combination of analysis and extensive system level simulations for all feasible FRD's. Proposed SO-FRD framework uses this flexible utility function to switch to particular FRD strategy, which is suitable for system's currant state according to predefined or self learned performance criterion. The proposed metrics capture the effect of all major optimization parameters like frequency reuse factor, number of sectors and relay per site, and adaptive coding and modulation. Based on the results obtained, interesting insights into the tradeoff among these factors is also provided.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

Recent research on Frequency Reuse (FR) schemes for OFDM/OFDMA based cellular networks (OCN) suggest that a single fixed FR cannot be optimal to cope with spatiotemporal dynamics of traffic and cellular environments in a spectral and energy efficient way. To address this issue this paper introduces a novel Self Organizing framework for adaptive Frequency Reuse and Deployment (SO-FRD) for future OCN including both cellular (e.g. LTE) and relay enhanced cellular networks (e.g. LTE Advance). In this paper, an optimization problem is first formulated to find optimal frequency reuse factor, no of sectors per site and number of relays per site. The objective is designed as an adaptive utility function which incorporates three major system objectives 1) spectral efficiency 2) fairness, and 3) energy efficiency. An appropriate metric for each of the three constituent objectives of utility function is then derived. Solution is provided by evaluating these metrics through a combination of analysis and extensive system level simulations for all feasible FRD's. Proposed SO-FRD framework uses this flexible utility function to switch to particular FRD strategy, which is suitable for system's currant state according to predefined or self learned performance criterion. The proposed metrics capture the effect of all major optimization parameters like frequency reuse factor, number of sectors and relay per site, and adaptive coding and modulation. Based on the results obtained, interesting insights into the tradeoff among these factors is also provided.

This paper investigates the performance and capacity of a WiMAX 802.16e cellular system deployed via High Altitude Platform (HAP WiMAX) through extensive simulations. HAP WiMAX link performance is evaluated for a wide range of channel conditions in terms of elevation angle and signal to noise ratio (SNR) through a comprehensive link level simulator based on 802.16e. The obtained results are then used to investigate HAP WiMAX cellular system performance in terms of user capacity, cell throughput and Grade of Service (GoS) by modelling a multi cellular scenario. The performance is evaluated for frequency reuse of 1 and 3 with and without Adaptive Coding and Modulations (ACM) for two different user data rates. Simulation results show that, cell throughputs as high as 3.6 Mbps per cell can be achieved for 5MHz channel bandwidth while attaining an acceptable GoS with a minimum frequency reuse of 3 in a HAP WiMAX 802.16e system.

In this paper we are concerned with broadband wireless access via high altitude platform system, providing the Internet access and broadband multimedia services to passengers equipped with WLAN terminals connecting through a collective terminal mounted on the train. The main challenge in such scenario is the development of efficient and reliable radio interface for the broadband communication link in the mobile wireless access segment. We are focusing on performance analysis of the adaptive coding and modulation scheme in the communication link between a high altitude platform and a collective terminal on-board moving train. In order to increase the reliability of the communication system in a fading environment we also exploit space and platform diversity. The proposed approach significantly increases the throughput of the wireless access system, while bit error rate remains below the target value regardless of the considered propagation environment.

This paper presents a practical method of potential replacement of several different Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) codes with one, with the intention of saving as much memory as required to implement the LDPC encoder and decoder in a memory-constrained System on a Chip (SoC). The presented method requires only a very small modification of the existing encoder and decoder, making it suitable for utilization in a Software Defined Radio (SDR) platform. Besides the analysis of the effects of necessary variable-node value fixation during the Belief Propagation (BP) decoding algorithm, practical standard-defined code parameters are scrutinized in order to evaluate the feasibility of the proposed LDPC setup simplification. Finally, the error performance of the modified system structure is evaluated and compared with the original system structure by means of simulation.