Multiuser Scheduling Scheme Research Articles

Securing Multiuser Communications via an Energy Harvesting Node: Jammer or Relay?

In this paper, we study the secure communication problem of a wireless multiuser network consisting of a base station (BS), multiple users, and an energy harvesting (EH) node in the face of an eavesdropper. We focus on the question that which role the EH node plays, as a friendly jammer or as a cooperative decode-and-forward (DF) relay. Accordingly, we propose two EH node aided multiuser scheduling schemes to help the secure communications between BS and multiple users, i.e., the EH jammer aided transmission (EHJT) scheme where the EH node acts as a friendly jammer and the EH relay aided transmission (EHRT) scheme where the EH node acts as a cooperative DF relay. For comparison purposes, the direct transmission (DT) scheme is also presented. We analyze the security-reliability trade-off (SRT) performance of the proposed EHJT and EHRT schemes as well as the DT scheme in terms of deriving their exact and asymptotic expressions of outage and intercept probabilities. Additionally, we propose an iterative algorithm based on the golden search to determine the optimal time allocation factor (OTAF) for the sake of minimizing the sum of outage and intercept probabilities for the proposed EHJT and EHRT schemes. Numerical results show that the EH node can improve the SRT performance of the multiuser network more significantly as a friendly jammer than as a cooperative DF relay. It is also shown that the best SRT performance of the EHJT and EHRT schemes can be achieved by adjusting the signal-to-noise ratio (SNR) and time allocation factor.

Secrecy Outage Analysis of Relay Aided Multiuser Scheduling for Wireless Networks in the Face of Co-Channel Interference

In this paper, we analyze the secrecy outage probability of a relay aided multiuser network which consists of a cluster head (CH), a decode-and-forward (DF) relay, and multiple users in the presence of an eavesdropper and co-channel interference (CCI). Firstly, we propose two relay aided multiuser scheduling (RMS) schemes to improve the secrecy outage performance of the network by considering the availability of channel state information (CSI) of CCI links, including the partial CSI based RMS (PCSI-RMS) scheme and the full CSI based RMS (FCSI-RMS) scheme. For comparison purposes, the relay aided round-robin scheduling (RRRS) scheme is also employed as a baseline. Then, we derive closed-form expressions for the proposed PCSI-RMS and FCSI-RMS schemes as well as the RRRS scheme in terms of their exact and asymptotic secrecy outage probabilities over Rayleigh fading channels in the face of CCI. Finally, numerical results show that the secrecy outage performance of the proposed PCSI-RMS and FCSI-RMS schemes is better than that of the RRRS scheme, where FCSI-RMS achieves the best secrecy outage performance. With an increase of the number of users, the secrecy outage performance of the PCSI-RMS and FCSI-RMS schemes is significantly improved, while that of the RRRS scheme keeps unchanged, which demonstrates the benefits of adopting the proposed PCSI-RMS and FCSI-RMS schemes against eavesdropping in CCI environments. Moreover, there is an optimal power allocation factor between the CH and the relay, which makes the network have the best secrecy outage performance.

Physical Layer Security for Cognitive Multiuser Networks With Hardware Impairments and Channel Estimation Errors

In this paper, we investigate the physical layer security for a cognitive multiuser network which is composed of multiple cognitive sources, a cognitive destination and an eavesdropper under the joint impact of hardware impairments (HIs) and channel estimation errors (CEEs). We consider a practical scenario where mutual interference exists between the primary users and cognitive users. To achieve high physical layer security with low implementation complexity, we propose three pure user scheduling schemes, namely, selection combining (SC) scheme, threshold-based switched diversity (tSD) scheme and switch-and-examine combining with post-selection (SECps) scheme. To further improve physical layer security, we present an extension of our SC framework to a jammer aided multiuser network and propose a jammer aided SC (JSC) scheme. We derive the closed-form intercept probability (IP), outage probability (OP) and effective secrecy throughput (EST) expressions for SC, tSD, SECps and JSC schemes over Nakagami- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m$ </tex-math></inline-formula> channels to analyze the system performance. Numerical results show that among the three pure multiuser scheduling schemes, the SC scheme achieves the best secrecy performance with the highest complexity, the SECps scheme obtains the worst secrecy performance with the lowest complexity. In addition, the secrecy performance of JSC scheme is better than that of SC scheme in the high SNR region.

Impact of Hardware Impairment and Co-Channel Interference on Security-Reliability Trade-Off for Wireless Sensor Networks

In this paper, we investigate the security and reliability trade-off (SRT) for a wireless sensor network (WSN) which consists of one cluster head (CH), multiple users, and one eavesdropper (E), where the eavesdropper attempts to tap the confidential transmission between multiple users and CH. We first present two multiuser scheduling schemes, namely the selection combining (SC) scheme and the switch-and-examine combining with post-selection (SECps) scheme to enhance physical-layer security (PLS) of the WSN system. For comparison purposes, the round-robin scheduling (RRS) scheme is also considered as a baseline. Then, we analyze the SRT of the RRS, SECps, and SC schemes by deriving their closed-form outage and intercept probability expressions under the joint impact of hardware impairment (HI) and co-channel interference (CCI). And, secrecy diversity analysis of the three schemes is also carried out. Numerical results show that the SC and SECps scheme outperform the RRS scheme in terms of the SRT performance, where the SC scheme can achieve the best SRT performance at the cost of an increased channel estimation complexity. Moreover, a trade-off between the security and reliability can be achieved for each of the RRS, SECps, and SC schemes by adjusting the overall data rate and signal-to-noise ratio (SNR).

Security-Reliability Tradeoff for Friendly Jammer Aided Multiuser Scheduling in Energy Harvesting Communications

In this paper, we investigate the physical-layer security in an energy-harvesting (EH) multiuser network with the help of a friendly jammer (J), where multiple eavesdroppers are considered to tap the information transmission from users (Us) to base station (BS). In this system, a power beacon (PB) transmits radio frequency (RF) signals to Us for charging. In order to enhance the security of wireless transmission, we propose non-energy-aware multiuser scheduling (NEAMUS) scheme and energy-aware multiuser scheduling (EAMUS) scheme. For the purpose of comparison, we introduce conventional round robin multiuser scheduling (CRRMUS) scheme. The closed-form outage probability (OP) and intercept probability (IP) expressions of NEAMUS, EAMUS, and CRRMUS schemes are derived over Rayleigh fading channels. Additionally, we analyze the security-reliability tradeoff (SRT) of NEAMUS, EAMUS, and CRRMUS schemes in terms of OP and IP. Numerical results show that the proposed EAMUS scheme is superior to the CRRMUS scheme and NEAMUS scheme in terms of SRT, demonstrating the advantage of the proposed EAMUS scheme in improving the physical-layer security and reliability. Moreover, SRT performance of NEAMUS and EAMUS schemes can also be improved by increasing the number of users.

Secure Multiuser Scheduling for Hybrid Relay-Assisted Wireless Powered Cooperative Communication Networks With Full-Duplex Destination-Based Jamming

In this paper, we investigate secure communication in a hybrid relay (HR)-assisted wireless powered cooperative communication network (WPCCN), where an eavesdropper tries to intercept the data transmitted by a source user and the HR simultaneously. The HR has the ability to wireless powered the energy-constrained multiple users in the downlink and to relay the received confidential information in the uplink. In particular, the full-duplex destination-based jamming (FD-DBJ) strategy is exploited to improve the secrecy performance. Moreover, in order to conduct effective secure communications, we design two multiuser scheduling schemes, i.e., random user selection (RUS), and best user selection (BUS) based on the main channel quality. In order to evaluate the secrecy performance, we analytically derive the energy outage probability (EOP), the secrecy outage probability (SOP), and the hybrid outage probability (HOP), respectively. As such, we formulate the secrecy throughput (ST) maximization problem to optimize the predetermined transmission rate. Our analysis and numerical results reveal that: 1) The BUS scheme has better security performance. 2) Both of the energy conversion efficiency and the number of users have a positive effect on secrecy performance. 3) The FD-DBJ scheme is an effective method to achieve secure communications. 4) The time-switching factor and predetermined transmission rate have a crucial influence on the secrecy performance, which should be considered carefully in system design.

Secrecy Performance Analysis of Wireless Powered Sensor Networks Under Saturation Nonlinear Energy Harvesting and Activation Threshold.

In this paper, we investigate the impact of saturation nonlinear energy harvesting (EH) and activation threshold on the multiuser wireless powered sensor networks (WPSNs) from the physical layer security (PLS) perspective. In particular, for improving the secrecy performance, the generalized multiuser scheduling (GMS) scheme is exploited, in which the Kth strongest sensor is chosen based on the legitimate link. For evaluating the impact of various key parameters on the security of system, we obtain the exact closed-form expressions for secrecy outage probability (SOP) under linear EH (LEH), saturation nonlinear EH (SNEH) and saturation nonlinear EH with activation threshold (SNAT), respectively, and solve the maximization problem of secure energy efficiency (SEE). Simulation results demonstrate that: (1) the number of source sensors, the EH efficiency and the transmit power of power beacon (PB) all have positive impact on SOP, and the smaller generalized selection coefficient is advantageous for secrecy performance; (2) LEH is an ideal situation for SNEH when the saturation threshold is large enough and SNEH is a special situation for SNAT when the activation threshold is low enough; (3) the time-switching factor and the activation threshold both have an important impact on the secrecy performance, which are worth considering carefully.

Secure Green-Oriented Multiuser Scheduling for Wireless-Powered Internet of Things

In this paper, we consider the secure green-oriented multiuser scheduling for the wireless-powered Internet of Things (IoT) scenario, in which multiple source sensors communicate with a controller assisted by an intermediate sensor with the existence of a passive tapping device. Due to the limited energy, all sensors must acquire energy from external power beacons (PBs). Specifically, for the security improvement, we introduce two multiuser scheduling schemes possessing the optimal PB chosen by the relay, i.e., the best source sensor is scheduled in a random way (BSR), while the best source sensor is decided by the best PB (BSBP). Furthermore, for every scheme, we derive the analytical expressions for the secrecy outage probability (SOP) and investigate the secure energy efficiency (SEE) optimization problem with constricted transmission power in PBs. Simulation results reveal that the BSBP scheme provides better secrecy performance, and elevating the PBs quantity or reducing both the ratio of distance from PBs to source users and the total communication distance to some extent is helpful for improving SEE. In addition, the time-switching factor shows an important effect upon secrecy performance of the considered system.

Performance Analysis of Integrated Satellite-Terrestrial Multiantenna Relay Networks With Multiuser Scheduling

In this article, we investigate the performance of a multiuser integrated satellite-terrestrial relay network (ISTRN) with the threshold-based decode-and-forward protocol, where the satellite-relay link undergoes shadowed-Rician (SR) fading, while the relay-user links experience Nakagami-m fading. We first formulate a constrained optimization problem with an objective to maximize the system capacity in order to determine the beamforming weight vectors at the relay and thereby develop two multiuser scheduling schemes, namely, best user scheduling and user fairness scheduling. Then, we present a closed-form expression for the probability density function (PDF) of the square sum of independent and identically distributed SR random variables, which is more accurate and concise than the existing solutions. Based on the new PDF results, we derive closed-form expressions for the outage probability (OP) and ergodic capacity of the considered network using the two scheduling schemes. Furthermore, the asymptotic OP expressions at high signal-to-noise ratio are also deduced to reveal the asymptotic behavior of the considered ISTRN. Finally, simulation results are provided to validate our theoretical analysis and show the impact of various parameters on the system performance.

Security and reliability trade‐off analysis of joint user and jammer selection in the face of co‐channel interference

In this study, the authors investigate the security and reliability trade-off (SRT) performance of a multiuser wireless network, where an eavesdropper attempts to overhear the confidential transmissions between a base station and multiple users under the impact of co-channel interference. To enhance the SRT performance of the network, the authors propose two joint user and jammer selection schemes, namely the joint optimal user and random jammer selection (JOU-RJS) scheme and the joint optimal user and optimal jammer selection (JOU-OJS) scheme. For SRT performance comparison purposes, the traditional multiuser scheduling (TMUS) scheme is also considered. The authors derive closed-form outage and intercept probability expressions for the JOU-RJS and JOUOJS schemes. Simulation results show that the SRTs of both JOU-RJS and JOU-OJS schemes are better than that of the TMUS scheme, where JOU-OJS achieves the best SRT performance. Additionally, this study also shows that an expected outage or intercept probability of the TMUS, JOU-RJS, and JOU-OJS schemes can be achieved by giving an appropriate overall rate. Finally, the sum of the outage and intercept probability can be minimised through an optimal power allocation between the selected user and friendly jammer for the proposed JOU-RJS and JOU-OJS.

The Security of Cognitive Multiuser Networks Over Space-and-Time Correlated Channels

In this paper, we investigate the secrecy performance of cognitive multi-input multi-output multiuser (MIMO-MU) wiretap networks over space-and-time correlated fading channels. Specifically, we propose a joint transmit antenna selection (TAS) and multiuser scheduling scheme to improve the security of the considered system. To thoroughly analyze the impact of the joint TAS and multiuser scheduling scheme and the channel correlation on the physical layer security, the new exact and asymptotic closed-form expressions for the secrecy outage probability of cognitive MIMO-MU wiretap networks are derived in two distinct scenarios, i.e., space-and-time correlated fading channels and independent-and-perfect fading channels. From the theoretical and simulation results, several important remarks are concluded as follows. 1) The channel space correlation does not affect the achievable secrecy diversity order in a high main-to-eavesdropper ratio (MER) regime. While it produces different impacts on the secrecy performance with different values of the MER in a low MER regime. 2) The channel time correlation on the main channel can reduce the achievable secrecy diversity order from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N_{\rm A}N_{\rm B}$</tex-math></inline-formula> to 1. 3) The joint TAS and multiuser scheduling scheme can achieve better performance than the traditional random scheduling scheme over space-and-time correlated fading channels.

MIMO Relay Networks: Scheduling and Outage Probability

We study a dual-hop multiple-input multiple-output (MIMO) relay network where the traffic source uses a relay node, selected among several possible ones, to serve multiple users. Considering that the nodes deployment can be described by Poisson point processes in a sector area, we derive the distribution of the signal-to-interference-plus-noise ratio over the two communication hops. Then, assuming that the user to be served is selected according to opportunistic, proportional fair, or selective multiuser diversity scheduling, we investigate the system outage probability, and derive a closed-form tight lower bound for it. Our analysis provides useful guidelines on the system design of MIMO relay networks. Unlike existing works, our analysis accounts for the joint impact of various multiuser scheduling schemes and nodes placement.

Optimal Multi-User Scheduling for the Unbalanced Full-Duplex Buffer-Aided Relay Systems

Multi-User scheduling is challenging due to the channel unbalance problem, which leads to system performance degradation. In this paper, two optimal multi-user scheduling schemes maximizing the system throughput are proposed for the fixed and adaptive power transmission scenarios of the full-duplex (FD) multi-user buffer-aided relay system, respectively. Independent and non-identically distributed (i.ni.d.) model is used to characterize the unbalanced channels of different links. In particular, the optimal weight factor of each pair is designed based on the statistical channel state information in both scenarios. With the weight factors, the proposed schemes are able to balance the throughput gaps between different links. In addition, we propose an optimal power allocation scheme with closed-form expressions under average power constraint for the adaptive power transmission scenario. By combining the optimal weight factor and the power allocation scheme, novel optimal selection function is obtained to facilitate the selection process. Considering the specific i.ni.d. Rayleigh fading, the system throughput is further derived in both cases. Theoretical analysis is verified by the numerical simulations and the results demonstrate the superiority of the proposed schemes.

Fog-Assisted Multiuser SWIPT Networks: Local Computing or Offloading

This paper investigates a fog computing-assisted multi-user simultaneous wireless information and power transfer (SWIPT) network, where multiple sensors with power splitting (PS) receiver architectures receive information and harvest energy from a hybrid access point (HAP), and then process the received data by using local computing mode or fog offloading mode. For such a system, an optimization problem is formulated to minimize the sensors' required energy while guaranteeing their required information transmissions and processing rates by jointly optimizing the multi-user scheduling, the time assignment, the sensors' transmit powers and the PS ratios. Since the problem is a mixed integer programming (MIP) problem and cannot be solved with existing solution methods, we solve it by applying problem decomposition, variable substitutions and theoretical analysis. For a scheduled sensor, the closed-form and semi-closedform solutions to achieve its minimal required energy are derived, and then an efficient multi-user scheduling scheme is presented, which can achieve the suboptimal user scheduling with low computational complexity. Numerical results demonstrate our obtained theoretical results, which show that for each sensor, when it is located close to the HAP or the fog server (FS), the fog offloading mode is the better choice; otherwise, the local computing mode should be selected. The system performances in a frame-by-frame manner are also simulated, which show that using the energy stored in the batteries and that harvested from the signals transmitted by previous scheduled sensors can further decrease the total required energy of the sensors.

Secrecy Outage Probability Analysis of Friendly Jammer Selection Aided Multiuser Scheduling for Wireless Networks

In this paper, we study a multiuser uplink network consisting of one base station (BS), multiple users and one eavesdropper (E), where the users are intended to transmit their confidential messages to BS, while the eavesdropper attempts to tap their transmissions. To improve the transmission secrecy, we propose two friendly jammer selection-aided multiuser scheduling schemes, namely, the random jammer selection-aided multiuser scheduling (RJS-MUS) without knowing the eavesdropper's channel state information (CSI) and the optimal jammer selection-aided multiuser scheduling (OJS-MUS), where the CSIs of eavesdropper are available. For comparison purposes, the conventional non-jammer selection-aided multiuser scheduling (NJS-MUS) scheme is considered as a benchmark. We derive exact and asymptotic closed-form secrecy outage probability expressions for the conventional NJS-MUS as well as proposed RJS-MUS and OJS-MUS schemes. The numerical results show that the proposed RJS-MUS and OJS-MUS schemes with equal power allocation between the selected friendly jammer and scheduled user perform worse than the conventional NJS-MUS approach in terms of the secrecy outage probability in the low signal-to-noise ratio (SNR) region. As the SNR increases, the secrecy outage performance of RJS-MUS and OJS-MUS schemes substantially improves, which is, in turn, better than that of conventional NJS-MUS approach. Moreover, the secrecy advantage of RJS-MUS and OJS-MUS over NJS-MUS becomes more significant with an increasing SNR. Also, it is shown that for both the RJS-MUS and OJS-MUS schemes, a better secrecy performance can be achieved through an optimal power allocation (OPA) between the scheduled user and friendly jammer. In addition, the proposed RJS-MUS and OJS-MUS schemes with OPA strictly outperform the conventional NJS-MUS approach in terms of the secrecy outage probability.

Secrecy Versus Computation Overhead for Wireless Networks in the Face of Co-Channel Interference

In this paper, we analyze the secrecy outage probability and computation overhead of a multi-user multi-eavesdropper wireless system which is composed of one cluster head (CH) transmitting to multiple users, while multiple eavesdroppers attempt to tap the transmission from CH to multiple users in the presence of co-channel interference (CCI). To achieve high security and low computation overhead, we present two multi-user scheduling schemes, namely, the switch-and-examine combining with post-selection user scheduling (SECpsUS) scheme and the selection combining-based user scheduling (SCbUS) scheme. For the purpose of comparison, the conventional round-robin scheduling (RRS) is also considered as a benchmark scheme. Furthermore, we derive closed-form secrecy outage probability expressions and analyze computation overheads for the conventional RRS, SCbUS, and SECpsUS schemes. Numerical results and Monte Carlo simulations are provided to verify the correctness of our theoretical secrecy outage analysis and to demonstrate the effect of CCI on the system performance. It is shown that the SECpsUS and SCbUS schemes outperform the conventional RRS scheme in terms of their secrecy outage probabilities, where SCbUS achieves the best secrecy outage performance but at cost of the highest computation overhead, while the conventional RRS scheme has no computation overhead with the worst secrecy performance. Moreover, a flexible tradeoff between the secrecy outage performance and computation overhead can be achieved by the proposed SECpsUS scheme by adjusting a so-called switching threshold. In addition, as the number of users increases, the secrecy outage performance of the SECpsUS and SCbUS is improved significantly, whereas no secrecy benefit is achieved by the conventional RRS scheme.

MLOPS: A SIC-Based Minimum Frame Length With Optimized Power Scheduling for UANs

Due to the large propagation delay and scarce spectrum resource of the underwater wireless acoustic channels, it is essential to design efficient and reliable multiuser scheduling scheme for underwater network communication systems. The successive interference cancellation (SIC) technology that supports multiple parallel transmissions can improve spectrum efficiency, which is vital for the underwater acoustic networks (UANs). The SIC technology has been widely studied in the underwater network communication systems. However, there is no appropriate technology solving the link scheduling problem in the SIC-based UANs. In this paper, we propose a link-scheduling model for SIC-based UANs and formulate the problem of minimizing the transmission delay and overall network power consumption by combining transmitters scheduling and power allocating. We also present a polynomial-time algorithm named UMLOPS with the complexity of O(n) for unified traffic load, and for weighted traffic load, we present a universal algorithm named WMLOPS with the complexity of O(n 3 ), where n denotes the number of source nodes. The extensive simulation results reveal that both scheduling frame length and aggregate power consumption of MLOPS significantly outperform those of the existing time-division multiple access protocols in underwater sensor equipped aquatic swarm architecture networks.

Closed-Form Secrecy Outage Analysis of Cellular Downlink Systems in the Presence of Co-Channel Interference

This paper analyzes the secrecy outage probability of a cellular downlink system which consists of multiple users, one base station (BS), and one eavesdropper in the presence of co-channel interferers, where the BS transmits its signals to users which are distributed according to a Poisson point process with a fixed density, while the eavesdropper attempts to tap the transmission from the BS to the users. To enhance the transmission security against eavesdropping, we propose two multiuser scheduling schemes, namely, the partial channel state information (CSI) aided user scheduling (PCSI-US) scheme where only the CSIs of users are available without knowing the co-channel interferers’ CSIs and the full CSI aided user scheduling (FCSI-US) scheme which requires the CSIs of both users and interferers. For comparison purposes, the conventional round-robin scheduling scheme is also considered as a baseline. We derive closed-form expressions of the secrecy outage probability for the proposed PCSI-US and FCSI-US as well as conventional round-robin scheduling schemes in co-channel interference (CCI) environments. Numerical results show that the proposed FCSI-US and PCSI-US schemes outperform the conventional round-robin scheduling in terms of their secrecy outage probabilities, where FCSI-US achieves the best secrecy outage performance in CCI environments. It is also demonstrated that increasing the mean number of users has a marginal effect on the secrecy performance of conventional round-robin scheduling, which can significantly decrease the secrecy outage probabilities of PCSI-US and FCSI-US schemes. This further validates the secrecy effectiveness of the proposed user scheduling methods in terms of combating the CCI.

Energy-Aware Multiuser Scheduling for Physical-Layer Security in Energy-Harvesting Underlay Cognitive Radio Systems

In this paper, we consider an energy-harvesting underlay cognitive radio (CR) system, which is comprised of multiple cognitive users (CUs), a common cognitive base station (CBS), and multiple passive eavesdroppers (Es). When CUs transmit to CBS, Es may overhear the confidential transmissions from CUs. In the aforementioned system, all CUs are considered to be equipped with energy harvesters to collect energy from their surrounding environments. Meanwhile, the transmit power of CUs shall be limited by a tolerable interference temperature to guarantee the quality-of-service of a primary user. In order to improve the physical-layer security of energy-harvesting CR systems, we propose an Energy-AwaRe mulTiuser scHeduling (EARTH) scheme, which takes into account both the interference temperature constraint and residual energy level harvested from the ambient surroundings. We consider the use of security-reliability tradeoff (SRT) as a metric to evaluate the performance of proposed EARTH scheme. To be specific, we derive closed-form expressions of outage probability (OP) and intercept probability (IP) for the proposed scheme over Rayleigh fading channels. For the purpose of comparison, the SRT analysis of round-robin scheduling (RRS) and conventional multiuser scheduling (CMUS) methods is also carried out. Numerical results show that the SRT of proposed EARTH scheme is better than that of RRS and CMUS methods, demonstrating the advantage of our proposed scheme against eavesdropping attacks. Additionally, it is illustrated that the sum of IP and OP can be minimized for RRS and CMUS as well as EARTH schemes through a time allocation between the energy harvesting and information transmission phases.

Energy and Bursty Packet Loss Tradeoff Over Fading Channels: A System-Level Model

Energy efficiency and quality of service (QoS) guarantees are the key design goals for the 5G wireless communication systems. In this context, we discuss a multiuser scheduling scheme over fading channels for loss tolerant applications. The loss tolerance of the application is characterized in terms of different parameters that contribute to quality of experience (QoE) for the application. The mobile users are scheduled opportunistically such that a minimum QoS is guaranteed. We propose an opportunistic scheduling scheme and address the cross-layer design framework when channel state information (CSI) is not perfectly available at the transmitter and the receiver. We characterize the system energy as a function of different QoS and channel state estimation error parameters. The optimization problem is formulated using Markov chain framework and solved using stochastic optimization techniques. The results demonstrate that the parameters characterizing the packet loss are tightly coupled and relaxation of one parameter does not benefit the system much if the other constraints are tight. We evaluate the energy-performance tradeoff numerically and show the effect of channel uncertainty on the packet scheduler design.