Cloud computing provides various diverse services for users accessing big data through high data rate cellular networks, e.g., LTE-A, IEEE 802.11ac, etc. Although LTE-A supports very high data rate, multi-hop relaying...
详细信息
Cloud computing provides various diverse services for users accessing big data through high data rate cellular networks, e.g., LTE-A, IEEE 802.11ac, etc. Although LTE-A supports very high data rate, multi-hop relaying, and cooperative transmission, LTE-A suffers from high interference, path loss, high mobility, etc. Additionally, the accesses of cloud computing services need the transport layer protocols (e.g., TCP, UDP, and streaming) for achieving end-to-end transmissions. Clearly, the transmission QoS is significantly degraded when the big data transmissions are done through the TCP protocol over a high interference LTE-A environment. The issue of providing high data rate and high reliability transmissions in cloud computing needs to be addressed completely. Thus, this paper proposes a cross-layer-based adaptive TCP algorithm to gather the LTE-A network states (e.g., AMC, CQI, relay link state, available bandwidth, etc.), and then feeds the state information back to the TCP sender for accurately executing the network congestion control of TCP. As a result, by using the accurate TCP congestion window (cwnd) under a high interference LTE-A, the number of timeouts and packet losses are significantly decreased. Numerical results demonstrate that the proposed approach outperforms the compared approaches in goodput and fairness, especially in high interference environment. Especially, the goodput of the proposed approach is 139.42 % higher than that of NewReno when the wireless loss increases up to 4 %. Furthermore, the throughput and the response functions are mathematically analyzed. The analysis results can justify the claims of the proposed approach.
It has been known that adaptive modulation and coding (AMC) at the physical layer can be combined with a truncated automatic repeat request (ARQ) at the data link layer so as to maximize the spectral efficiency under ...
详细信息
It has been known that adaptive modulation and coding (AMC) at the physical layer can be combined with a truncated automatic repeat request (ARQ) at the data link layer so as to maximize the spectral efficiency under prescribed delay and error performance constraint. In this paper, we consider the same joint design approach when incremental redundancy-based hybrid ARQ (IR-HARQ) is associated with an AMC design at the physical layer. The extensive simulation studies for predicting the progressive combining gain with each retransmission enables to evaluate the bandwidth efficiency that can be achieved by selecting a more aggressive modulation and coding rate set (MCS) at the expense of packet error rate in earlier transmissions. It has been demonstrated that the aggressive AMC design approach in association with IR-based truncated HARQ can improve bandwidth efficiency by 5.8 and 3.3 dB, as compared to the conservative AMC design approach with truncated HARQ and aggressive AMC design approach with truncated ARQ (i.e., without taking the progressive combining gain in HARQ into account), respectively.
Robust service can be achieved in error prone Long Term Evolution-Advanced (LTE-A) by dealing with imperfect Channel Quality Information (CQI). CQI is very crucial in evolved Node B (eNodeB) to decide the correspondin...
详细信息
ISBN:
(纸本)9781509024278
Robust service can be achieved in error prone Long Term Evolution-Advanced (LTE-A) by dealing with imperfect Channel Quality Information (CQI). CQI is very crucial in evolved Node B (eNodeB) to decide the corresponding modulation and coding scheme in LTE and LTE-A. User Equipment (UE) will measure and estimate the CQI in order to maximize the throughput performance. adaptive modulation and coding (AMC) is used in order to adapt with the channel variation environments but the wireless channel itself is subject to various impairments including imperfect CQI report which may lead to degradation of the Quality of Service (QoS). The performance of two CQI reporting algorithms which are Automated CQI Reporting Algorithm and Average CQI Reporting Algorithm are being analyzed in this paper. The simulation results demonstrated that the Average CQI Reporting Algorithm produced more promising results with the increment about 15% of the system capacity and capable to support delay up to 63.6% compared to Automated CQI Reporting Algorithm with respect to the Packet Loss Ratio (PLR).
adaptive modulation and coding (AMC) is attracting research interest in wireless multicast broadcast services (MBS). AMC increases the system throughput by utilizing possible good channel states instead of using robus...
详细信息
ISBN:
(纸本)9781424425198
adaptive modulation and coding (AMC) is attracting research interest in wireless multicast broadcast services (MBS). AMC increases the system throughput by utilizing possible good channel states instead of using robust modulation and coding schemes. A model for the AMC in an MBS system with multiple MBS groups is provided, and stochastic analysis using Markov chain is also applied for modeling analysis. Simulation results show extremely high correspondence to the proposed mathematical model.
This paper evaluates the bit-error rate and spectral efficiency performance provided by the convolutional coded Quadrature Amplitude modulation (QAM) configurations whose global rates are modified mainly by changing t...
详细信息
ISBN:
(纸本)9781467381970
This paper evaluates the bit-error rate and spectral efficiency performance provided by the convolutional coded Quadrature Amplitude modulation (QAM) configurations whose global rates are modified mainly by changing the numbers of code and non-coded bits mapped on a QAM symbol. The Bit Error Rate (BER) performance provided are compared to the ones of the convolutional coded modulations which map only code bits and have the same configuration rates, aiming to show that coded configurations mapping non-coded bits as well, ensure a target BER value at smaller values of the Signal/Noise Ratio (SNR) than the ones mapping only code bits The paper also presents an approximate method to compute the BER of the configurations mapping both code and non-coded bits, which is validated by computer simulations and is shown to provide good accuracy in the range of BER values of practical interest.
In this paper we propose a novel connection admission control scheme named Rate Transition Area assisted Guaranteed Handover Scheme (GHS-RTA), which utilizes the geographical information, rate transition areas and ove...
详细信息
ISBN:
(纸本)9781424435746
In this paper we propose a novel connection admission control scheme named Rate Transition Area assisted Guaranteed Handover Scheme (GHS-RTA), which utilizes the geographical information, rate transition areas and overlap areas to intelligently decide when to block a new call. This scheme helps avoid possible inter-cell and intra-cell handover failures for HAP communications systems with adaptive modulation and coding in the physical layer. Simulation results show that the GHS-RTA can improve the average new call blocking probability greatly (by a minimum of 21.5% for the system model with the parameter values chosen) while maintaining zero inter-cell and intra-cell handover call dropping probabilities compared with Extended Time-based Channel Reservation Algorithm, and that the larger the rate transition area and the overlap area, the better the average new call blocking performance.
We propose an adaptive loading algorithm to flexibly tailor each OFDM subcarrier in three dimensions including modulation formats, power and FEC codes. With look-up table operation introduced, the iterations are notab...
详细信息
ISBN:
(纸本)9784885523052
We propose an adaptive loading algorithm to flexibly tailor each OFDM subcarrier in three dimensions including modulation formats, power and FEC codes. With look-up table operation introduced, the iterations are notably reduced without performance sacrifice.
Emerging 4G standards, such as WiMAX, LTE, and TD-SCDMA, have adopted the proven technique of adaptive modulation and coding (AMC) to dynamically react to channel fluctuations while maintaining bit-error rate targets ...
详细信息
ISBN:
(纸本)9781424456383
Emerging 4G standards, such as WiMAX, LTE, and TD-SCDMA, have adopted the proven technique of adaptive modulation and coding (AMC) to dynamically react to channel fluctuations while maintaining bit-error rate targets of the transmission. To mitigate the vicious effects due to stale channel state indication (CSI) problem, this paper introduces a novel framework by incorporating AMC with layered transmission through Superposition coding (SPC). A Markov chain model is adopted under this framework, to effectively assist the system in selecting the optimal modulation and coding scheme for each layer in every multi-resolution unicast transmission. Extensive simulation is conducted to verify the proposed framework and compare it with a number of counterparts. The results demonstrate that the proposed framework can achieve a much better spectrum efficiency due to improved robustness by addressing the stale CSI problem at each multi-resolution modulated transmission.
A new transmission scheme is presented for a two-hop relay network including two AF relays, considering physical layer security where relays are not able to detect signal with an acceptable bit error rate (BER) but th...
详细信息
A new transmission scheme is presented for a two-hop relay network including two AF relays, considering physical layer security where relays are not able to detect signal with an acceptable bit error rate (BER) but the combined received signal is detected with an acceptable BER at the final receiver. It is assumed that there is no direct path between the transmitter and the receiver (relay network without diversity). adaptive modulation and coding is utilised at the transmitter and transmission powers of the transmitter and of the relays are continuously adapted provisioning individual average power constraint for each node. Numerical evaluations show that an acceptable performance degradation is seen by the proposed secure relaying scheme compared to the optimum relay selection scheme without security constraint.
The demand for high-speed services and multimedia applications anywhere and anytime has led to the rise of wireless communications. In particular, WiMAX technology is nowadays considered one of the most prominent solu...
详细信息
The demand for high-speed services and multimedia applications anywhere and anytime has led to the rise of wireless communications. In particular, WiMAX technology is nowadays considered one of the most prominent solutions capable to provide a Broadband Wireless Access (BWA) in metropolitan areas with a simpler installation and lower cost than traditional wired alternatives. This paper deals with the proposal of efficient adaptive modulation and coding techniques to be used in WiMAX based wireless networks, that allow to improve network performance in the case of Non Line-of-Sight communications, which are typical in urban environments. Through these techniques it is possible to switch the modulation order and coding rate in order to better match the channel conditions, and, hence, obtaining better performance both in terms of error probability and data throughput.
暂无评论