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41
Analysis of energy efficiency in fading channel under QoS constrains
- IEEE Global Communications Conference (GLOBECOM
, 2008
"... Abstract — 1 Energy efficiency in fading channels in the pres-ence of QoS constraints is studied. Effective capacity, which provides the maximum constant arrival rate that a given process can support while satisfying statistical delay constraints, is considered. Spectral efficiency–bit energy tradeo ..."
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Cited by 18 (11 self)
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Abstract — 1 Energy efficiency in fading channels in the pres-ence of QoS constraints is studied. Effective capacity, which provides the maximum constant arrival rate that a given process can support while satisfying statistical delay constraints, is considered. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation, rather than the Shannon capacity, and energy requirements under QoS constraints are identified. The analysis is conducted for the case in which perfect channel side information (CSI) is available at the receiver and also for the case in which perfect CSI is available at both the receiver and transmitter. In particular, it is shown in the low-power regime that the minimum bit energy required in the presence of QoS constraints is the same as that attained when there are no such limitations. However, this performance is achieved as
The impact of QoS constraints on the energy efficiency of fixed-rate wireless transmissions,” submitted to the
- IEEE International Conference on Communications (ICC
, 2009
"... Transmission over wireless fading channels under quality of service (QoS) constraints is studied when only the receiver has channel side information. Being unaware of the channel conditions, transmitter is assumed to send the information at a fixed rate. Under these assumptions, a two-state (ON-OFF) ..."
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Cited by 9 (7 self)
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Transmission over wireless fading channels under quality of service (QoS) constraints is studied when only the receiver has channel side information. Being unaware of the channel conditions, transmitter is assumed to send the information at a fixed rate. Under these assumptions, a two-state (ON-OFF) transmission model is adopted, where information is transmitted reliably at a fixed rate in the ON state while no reliable transmission occurs in the OFF state. QoS limitations are imposed as constraints on buffer violation probabilities, and effective capacity formulation is used to identify the maximum throughput that a wireless channel can sustain while satisfying statistical QoS constraints. Energy efficiency is investigated by obtaining the bit energy required at zero spectral efficiency and the wideband slope in both wideband and low-power regimes assuming that the receiver has perfect channel side information (CSI). In the wideband regime, it is shown that the bit energy required at zero spectral efficiency is the minimum bit energy. A similar result is shown for a certain class of fading distributions in the low-power regime. In both wideband and lowpower regimes, the increased energy requirements due to the presence of QoS constraints are quantified. Comparisons with variable-rate/fixed-power and variable-rate/variable-power cases are given. Energy efficiency is further analyzed in the presence of channel uncertainties. The scenario in which a priori unknown fading coefficients are estimated at the receiver via minimum mean-square-error (MMSE) estimation with the aid of training symbols, is considered. The optimal fraction of power allocated to training is identified under QoS constraints. It is proven that the minimum bit energy in the low-power regime is attained at a certain nonzero power level below which bit energy increases without bound with vanishing power. Hence, it is shown that it is extremely energy inefficient to operate at very low power levels when the channel is only imperfectly known.
Cognitive Radio Resource Management for QoS Guarantees in Autonomous Femtocell Networks
"... Abstract—Deploying femtocell networks embedded in the Macrocell coverage greatly benefits communication quality in variety manners. However, the lack of schemes to effectively mitigate detractive interference, fully utilize radio resources and provide quality-of-service (QoS) guarantee (in terms of ..."
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Cited by 9 (2 self)
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Abstract—Deploying femtocell networks embedded in the Macrocell coverage greatly benefits communication quality in variety manners. However, the lack of schemes to effectively mitigate detractive interference, fully utilize radio resources and provide quality-of-service (QoS) guarantee (in terms of delay) creates challenges to practically facilitate the concept of femtocell. To tackle these challenges to achieve a successful dense femtocell deployment, this paper proposes a cognitve radio resource management (CRRM) scheme which is inspired by the spirit of cognitive radio technology. Instead of the need of a centralized manner, the femtocell with the proposed CRRM can autonomously sense the radio resource usage of the Macrocell so as to mitigate interference. By analytical deriving the effective capacity of the CRRM that specifies the QoS guarantee capability of the system, the optimum sensing period and radio resource allocation are proposed for the CRRM to achieve a fully radio resource utilization while statistically guaranteeing the QoS of the femtocell. Numerical results demonstrate that the proposed CRRM outperforms the randomized scheme (without CRRM) in terms of the radio resource utilization efficiency. Simulation results also support the effectiveness on the delay guarantee performance. Index Terms—Femtocell network, cognitive radio resource management (CRRM), autonomous interference mitigation, sta-tistical QoS guarantee, effective capacity, OFDMA. I.
Performance Analysis of Cognitive Radio Systems under QoS Constraints and Channel Uncertainty
- Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE
, 2010
"... Abstract—In this paper, performance of cognitive transmission over time-selective flat fading channels is studied under quality of service (QoS) constraints and channel uncertainty. Cognitive secondary users (SUs) are assumed to initially perform channel sensing to detect the activities of the prima ..."
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Abstract—In this paper, performance of cognitive transmission over time-selective flat fading channels is studied under quality of service (QoS) constraints and channel uncertainty. Cognitive secondary users (SUs) are assumed to initially perform channel sensing to detect the activities of the primary users, and then attempt to estimate the channel fading coefficients through training. Energy detection is employed for channel sensing, and different minimum mean-square-error (MMSE) estimation methods are considered for channel estimation. In both channel sensing and estimation, erroneous decisions can be made, and hence, channel uncertainty is not completely eliminated. In this setting, performance is studied and interactions between channel sensing and estimation are investigated. Following the channel sensing and estimation tasks, SUs engage in data transmission. Transmitter, being unaware of the channel fading coefficients, is assumed to send the data at fixed power and rate levels that depend on the channel sensing results. Under these assumptions, a state-transition model is constructed by considering the reliability of the transmissions, channel sensing decisions and their correctness, and the evolution of primary user activity which is modeled as a two-state Markov process. In the data transmission phase, an average power constraint on the secondary users is considered to limit the interference to the primary users, and statistical limitations on the buffer lengths are imposed to take into account the QoS constraints of the secondary traffic. The maximum throughput under these statistical QoS constraints is identified by finding the effective capacity of the cognitive radio channel. Numerical results are provided for the power and rate policies. Index Terms—Cognitive radio, quality of service constraints, channel sensing, channel estimation, effective capacity, fixed-rate transmissions, state-transition model. I.
MIMO wireless communications under statistical queuing constraints
- IEEE Trans. Inform. Theory
, 2011
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Performance Analysis of Spectrum Handoff for Cognitive Radio Ad Hoc Networks without Common Control Channel under Homogeneous Primary Traffic
- IEEE INFOCOM
, 2011
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Energy Efficiency of Fixed-Rate Wireless Transmissions under Queueing Constraints and Channel Uncertainty
, 901
"... Energy efficiency of fixed-rate transmissions is studied in the presence of queueing constraints and channel uncertainty. It is assumed that neither the transmitter nor the receiver has channel side information prior to transmission. The channel coefficients are estimated at the receiver via minimum ..."
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Cited by 4 (2 self)
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Energy efficiency of fixed-rate transmissions is studied in the presence of queueing constraints and channel uncertainty. It is assumed that neither the transmitter nor the receiver has channel side information prior to transmission. The channel coefficients are estimated at the receiver via minimum mean-square-error (MMSE) estimation with the aid of training symbols. It is further assumed that the system operates under statistical queueing constraints in the form of limitations on buffer violation probabilities. The optimal fraction of of power allocated to training is identified. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation. In particular, it is shown that the bit energy increases without bound in the lowpower regime as the average power vanishes. On the other hand, it is proven that the bit energy diminishes to its minimum value in the wideband regime as the available bandwidth increases. For this case, expressions for the minimum bit energy and wideband slope are derived. Overall, energy costs of channel uncertainty and queueing constraints are identified. Abstract — 1 I.
Power-Delay Tradeoff over Wireless Networks
"... Abstract—When transmitting stochastic traffic flows over wire-less networks, there exists an inherent tradeoff between average transmit power and corresponding queuing-delay bound. In this paper, we investigate such a tradeoff and show how average power increases as delay-bound requirement for wirel ..."
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Cited by 4 (0 self)
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Abstract—When transmitting stochastic traffic flows over wire-less networks, there exists an inherent tradeoff between average transmit power and corresponding queuing-delay bound. In this paper, we investigate such a tradeoff and show how average power increases as delay-bound requirement for wireless network traffics becomes stringent. Specifically, we propose the resource allocation schemes to minimize the power consumption subject to a delay quality-of-service (QoS) constraint, where the delay constraint is in terms of queue-length decay rate when an arrival traffic is transmitted through the wireless networks. We focus on orthogonal-frequency-division-multiplexing (OFDM) communications under three different network infrastructures, namely, point-to-point link, multihop amplify-and-forward (AF) network, and multiuser cellular network. We derive the optimal resource allocation policies for each scenario, and compare their performances with other existing resource-allocation policies. The obtained simulation and numerical results show that using our proposed optimal resource-allocation policies, significant power saving can be achieved. Furthermore, our OFDM-based communications systems can significantly reduce the power consumption, especially under stringent delay constraint. Index Terms—Power control, statistical delay-bounded quality-of-service (QoS) guarantees, effective capacity, wireless networks, resource allocation and management, scheduling, OFDM-based communications systems, convex optimization, information the-ory. I.
Proactive Spectrum Handoff in Cognitive Radio Ad Hoc Networks based
- on Common Hopping Coordination,” in Proc. IEEE INFOCOMM
, 2010
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Radio resource management for QoS guarantees in cyber-physical systems
- IEEE Transactions on Parallel and Distributed Systems
, 2012
"... Abstract—The recent deployment of Cyber-Physical Systems (CPS) has emerged as a promising approach to provide extensive interaction between computational and physical worlds. For a large-scale distributed CPS comprising of numerous machines, sharing radio resource efficiently with the existing wirel ..."
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Abstract—The recent deployment of Cyber-Physical Systems (CPS) has emerged as a promising approach to provide extensive interaction between computational and physical worlds. For a large-scale distributed CPS comprising of numerous machines, sharing radio resource efficiently with the existing wireless networks while maintaining sufficient quality of service (QoS) for machine-to-machine (M2M) communications becomes an essential and challenging requirement. By clustering CPS machines as a swarm with the cluster head managing radio resources inside the swarm, spectrum sharing among numerous machines can be achieved in a distributed and scalable fashion. Specifically, we apply the recent innovation, cognitive radio, and a special mode in cognitive radio, interweave coexistence, to leverage machines to collect radio resource usage information for autonomous and interference-free radio resource management in the CPS. To reduce the communication overheads of channel sensing feedbacking from machines, we apply compressive sensing to construct a spectrum map indicating the radio resource availability on any given locations within the CPS coverage. Such spectrum map resource management (SMRM) only utilizes a small portion of machines to perform channel sensing but enables distributed cluster-based spectrum sharing in an efficient way. Through the concept of effective capacity, the SMRM controls available resources to guarantee the QoS for communications of CPS. By evaluating the performance of the proposed SMRM in the most promising realization of CPS based on LTE-Advanced machine-type communications coexisting with LTE-Advanced Macrocells to utilize identical spectrum, the simulation results show effective QoS guarantees of CPS by SMRM in the realistic environments. Index Terms—Cyber-physical systems (CPS), cognitive radio (CR), spectrum map, compressive sensing, machine-to-machine (M2M) communication, quality of service (QoS), effective capacity, radio resource management. Ç 1