机器类通信中集中式与分布式Q学习的资源分配算法研究

针对海量机器类通信（massive machine type communication,mMTC）场景,以最大化系统吞吐量为目标,且在保证部分机器类通信设备（machine type communication device,MTCD）的服务质量（quality of service,QoS）要求前提下,提出两种基于Q学习的资源分配算法：集中式Q学习算法（team-Q）和分布式Q学习算法（dis-Q）。首先基于余弦相似度（cosine similarity,CS）聚类算法,考虑到MTCD地理位置和多级别QoS要求,构造代表MTCD和数据聚合器（data aggregator,DA）的多维向量,根据向量间CS值完成分组。然后分别利用team-Q学习算法和dis-Q学习算法为MTCD分配资源块（resource block,RB）和功率。吞吐量性能上,team-Q 和 dis-Q 算法相较于动态资源分配算法、贪婪算法分别平均提高了 16%、23%;复杂度性能上,dis-Q算法仅为team-Q算法的25%及以下,收敛速度则提高了近40%。     

一种基于IEEE802.15.3 MAC协议的动态资源分配算法

介绍了IEEE802.15.3 MAC协议及其QoS机制,分析了超帧中的CAP,针对实时VBR业务流,提出了一种动态资源分配算法,在性能上与平均资源分配算法进行了比较和分析,通过仿真验证了此动态资源分配算法能有效降低实时VBR码流的丢帧率,提高系统传输的QoS.     

Optimal resource allocation for heterogeneous traffic in multipath networks

Multipath networks allow each source to send packets from it to its destination over multiple paths, which increases the available bandwidth and throughput for source‐destination pairs. Recently, a variety of flow control schemes have been presented for multipath networks to achieve optimal resource allocation. Unfortunately, much of the investigation focused on elastic traffic with controllable packet injection rates. Networks have witnessed an increase in real‐time traffic (voice and video), which are inelastic. We consider resource allocation for heterogeneous traffic in multipath networks and formulate an optimization problem, which is intrinsically difficult nonconvex. In order to address the aforementioned issue and obtain the optimum, we approximate an equivalent problem of the original optimization problem to a strictly convex problem and present a primal‐dual resource allocation algorithm for the approximation problem, which converges to an optimal solution satisfying the Karush‐Kuhn‐Tucker conditions of the original problem. We evaluate its convergence performance through theoretical analysis and illustrate it with numerical examples. Copyright © 2014 John Wiley & Sons, Ltd.     

An uplink resource allocation scheme for OFDMA‐based cognitive radio networks

Cognitive radio makes it possible for an unlicensed user to access a spectrum unoccupied by licensed users. In cognitive radio networks, extra constraints on interference temperature need to be introduced into radio resource allocation. In this paper, the uplink radio resource allocation is investigated for OFDMA‐based cognitive radio networks. In consideration of the characteristics of cognitive radio and OFDMA, an improved water‐filling power allocation scheme is proposed under the interference temperature constraints for optimal performance. Based on the improved water‐filling power allocation, a simple subcarrier allocation algorithm for uplink is proposed. The subcarrier allocation rules are obtained by theoretical deduction. In the uplink subcarrier allocation algorithm, the subcarriers are allocated to the users with the best channel quality initially and then adjusted to improve the system performance. A cursory water‐filling level estimation method is used to decrease the complexity of the algorithm. Asymptotic performance analysis gives a lower bound of the stability of the water‐filling level estimation. The complexity and performance of the proposed radio resource allocation scheme are investigated by theoretical analysis and numerical results. Copyright © 2008 John Wiley & Sons, Ltd.     

5G异构网络中基于优先级的深度强化学习联合资源分配

为了研究基于深度强化学习(Deep Reinforcement Learning, DRL)的5G异构网络模型的性能,同时在最小化系统能耗并满足不同类型终端用户的服务质量要求的基础上制定合理的资源分配方案,提出了一种基于DRL的近端策略优化算法,并结合一种基于优先级的分配策略,引入了海量机器类型通信、增强移动宽带和超可靠低延迟通信业务。所提算法相较于Greedy和DQN算法,网络延迟分别降低73.19%和47.05%,能耗分别降低9.55%和6.93%,而且可以保证能源消耗和用户延迟之间的良好权衡。     

End-to-end utility-based resource allocation for multi-RAT nodes in heterogeneous cognitive wireless networks

This paper studies the problem of effective resource allocation for multi-radio access technologies (Multi-RAT) nodes in heterogeneous cognitive wireless networks (HCWNs). End-to-end utility, which is defined as the delay of end-to-end communication, is taken into account in this paper. In the scenario of HCWNs, it is assumed that the cognitive radio nodes have the ability of Multi-RAT and can communicate with each other through different paths simultaneously by splitting the arrival packets. In this paper, the problem is formulated as the optimization of split ratio and power allocation of the source cognitive radio node to minimize the delay of end-to-end communication, and a low complexity step-by-step iterative algorithm is proposed. Numerical results show good performance of the proposed algorithm over two other conventional algorithms.     

Cross-Layer Multi-Packet Reception Based Medium Access Control and Resource Allocation for Space-Time Coded MIMO/OFDM

In this paper, a cross-layer design framework for multi-input multi-output (MIMO)/orthogonal frequency division multiplexing (OFDM) based wireless local area networks (WLANs) is proposed. In contrast to conventional systems where the medium access control (MAC) and physical (PHY) layers are separately optimized, our proposed methodology jointly designs a multi-packet reception (MPR) based protocol with adaptive resource allocation. Specifically, a realistic collision model is employed by taking into consideration the PHY layer parameters such as channel information, space-time coded beamforming and multiuser detection, as well as sub-carrier, bit, and power allocation. The allocation problem is formulated, so as to maximize the system throughput, subject to the constraints from both the MAC and PHY layers. These constraints depend on the results of access contention, data packets? length, users? spatial correlation and the quality of channel feedback information. An iterative algorithm is then provided to obtain the optimal solution. Simulation results will show that our proposed approach achieves significant improvement in system performance such as average throughput and packet delay, compared with conventional schemes where cross-layer design and optimization is not used.     

QoS‐Guaranteed Slot Allocation Algorithm for Efficient Medium Access in HR‐WPAN

It is very important to provide a parameterized quality of service (QoS) using traffic specification (TSPEC), such as mean data rate, maximum burst size, and peak data rate, when packets from the application layer need to be transmitted with guaranteed services in a high‐rate wireless personal area network (HR‐WPAN). As medium resources are limited, the optimal medium time required for each device needs to be estimated to share the resources efficiently among devices. This paper proposes a variable‐service interval‐based resource allocation algorithm to efficiently make a reservation of medium resources based on a parameterized QoS. In other words, the proposed algorithm calculates the number of medium access slots (MASs) based on TSPEC, local resources, and local conditions and determines suitable locations for the MASs within a superframe to accommodate more devices. The simulation results show that the proposed algorithm can accommodate more devices and has greater than 10% resource allocation efficiency in an HR‐WPAN compared to existing schemes.     

Random access scheme for different MTC scenario requirement

For the different random access requirements of the mixed scenarios of ultra-reliable low latency (URLLC) and massive machine type communications (mMTC) in MTC,a random access scheme based on devices grouping was proposed.The proposed scheme divided the MTC devices into several groups based on the timing advance (TA) information:for the URLLC scenario,preamble resources were reserved for core devices in each group,and the URLLC devices accessed the network via the contention-free mechanism,to satisfy the ultra-reliable low latency access requirement; for the mMTC scenario,the base station utilized the different TA information in different group to identify devices selecting the same preamble,and performed successive interference cancellation (SIC) algorithm to detect the data information,to satisfy the massive access requirement.Simulation results demonstrate that the proposed scheme can significantly increase the number of the successful devices.     

Hierarchical Dynamic Bandwidth Allocation Algorithm for Multimedia Services over Ethernet PONs

In this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm for multimedia services over Ethernet PONs (passive optical networks). The proposed algorithm is composed of a low‐level scheduler in the optical network unit (ONU) and a high‐level scheduler in the optical line terminal (OLT). The hierarchical DBA algorithm can provide expansibility and efficient resource allocation in an Ethernet PON system in which the packet scheduler is separated from the queues. In the proposed DBA algorithm, the OLT allocates bandwidth to the ONUs in proportion to the weight associated with their class and queue length, while the ONU preferentially allocates its bandwidth to queues with a static priority order. The proposed algorithm provides an efficient resource utilization by reducing the unused remaining bandwidth caused by the variable length of the packets. We also define the service classes and present control message formats conforming to the multi‐point control protocol (MPCP) over an Ethernet PON. In order to evaluate the performance, we designed an Ethernet PON system on the basis of IEEE 802.3ah “Ethernet in the first mile” (EFM) using OPNET and carried out simulations. The results are analyzed in terms of the channel utilization, queuing delay, and ratio of the unused remaining bandwidth.     

Output and delay process analysis for slotted CDMA wirelesscommunication networks with integrated voice/data transmission

This paper presents the output and delay process analysis of integrated voice/data slotted code division multiple access (CDMA) network systems with random access protocol for packet radio communications. The system model consists of a finite number of users, and each user can be a source of both voice traffic and data traffic. The allocation of codes to voice calls is given priority over that to data packets, while an admission control, which restricts the maximum number of codes available to voice sources, is considered for voice traffic so as not to monopolize the resource. Such codes allocated exclusively to voice calls are called voice codes. In addition, the system monitoring can distinguish between silent and talkspurt periods of voice sources, so that users with data packets can use the voice codes for transmission if the voice sources are silent. A discrete-time Markov process is used to model the system operation, and an exact analysis is presented to derive the moment generating functions of the probability distributions for packet departures of both voice and data traffic and for the data packet delay. For some cases with different numbers of voice codes, numerical results display the correlation coefficient of the voice and data packet departures and the coefficient of variation of the data packet delay as well as average performance measures, such as the throughput, the average delay of data packets, and the average blocking probability of voice calls     

Dynamic Resource Allocation in Non-orthogonal Multiple Access Using Weighted Maximin Fairness Strategy for a UAV Network

Non-orthogonal multiple access (NOMA) with power domain multiplexing and successive interference cancellation (SIC) is one of the promising technologies for future wireless communication. The performance of NOMA is highly dependent on resource allocation such as power allocation and channel assignment. In this paper, we investigate the power allocation (PA) scheme, to optimize the weighted maximin fairness (MMF) for 2-user and 3-user clusters. We utilize the particle swarm optimization (PSO) based algorithm for power allocation due to its promising behavior. Application area of NOMA is becoming broader, then, we considered a cellular network, assisted by an unmanned aerial vehicle (UAV) as the base station (BS) which is integrated with the NOMA system. The PA for weighted MMF problem in NOMA is non-convex, it is difficult to find out the optimal solution directly. Simulation results show the performance of PSO-based algorithm in different adaptive weights and its convergence characteristics. We have also shown that the rate and fairness tradeoff using weighted maximin fairness. Numerical results compare the performance of NOMA and orthogonal multiple access (OMA) and prove the significance of the proposed algorithm.

     

Wide-band TD-CDMA MAC with minimum-power allocation and rate- and BER-scheduling for wireless multimedia networks

A wide-band time-division-code-division multiple-access (TD-CDMA) medium access control (MAC) protocol is introduced in this paper. A new minimum-power allocation algorithm is developed to minimize the interference experienced by a code channel such that heterogeneous bit-error rate (BER) requirements of multimedia traffic are satisfied. Further, from analysis of the maximum capacity of a time slot, it is concluded that both rate and BER scheduling are necessary to reach a maximum capacity. Based on the new minimum-power allocation algorithm as well as on rate and BER scheduling concepts, a new scheduling scheme is proposed to serve packets with heterogeneous BER and quality of service (QoS) requirements in different time slots. To further enhance the performance of the MAC protocol, an effective connection admission control (CAC) algorithm is developed based on the new minimum-power allocation algorithm. Simulation results show that the new wide-band TD-CDMA MAC protocol satisfies the QoS requirements of multimedia traffic and achieves high overall system throughput.     

OFDMA系统基于QoS保证和最大最小公平性准则下的动态资源分配

正交频分多址(OFDMA)技术以其更高的频谱效率和抗多径衰落特性成为高速无线通信网络的候选标准。兼顾效率和公平性是OFDMA系统资源分配亟待解决的问题。本文研究了OFDMA系统中的无线资源分配问题,既要保证QoS用户的最小速率要求,同时“尽力而为”用户之间必须满足最小速率最大化公平性(max-min fairness)准则;该资源分配问题可以表述为一个系统总功率约束下的子载波分配和功率控制的混合离散型优化模型,这是难解的NP-hard问题,穷举搜索的代价是极其巨大的。针对该非凸模型,本文设计一个拉格朗日松弛的优化算法,该算法中采用修正的椭球算法求解对偶问题。算法具有多项式时间复杂度,且与子载波数目呈线性增长关系。仿真结果表明,该算法能近似最优地满足用户QoS及最大最小公平性要求。      

An OFDM-TDMA/SA MAC Protocol with QoS Constraints for Broadband Wireless LANs

Orthogonal frequency division multiplexing (OFDM) is an important technique to support high speed transmission of broadband traffic in wireless networks, especially broadband wireless local area networks (LANs). Based on OFDM, a new multiple access scheme, called OFDM-TDMA with subcarrier allocation (OFDM-TDMA/SA), is proposed in this paper. It provides more flexibility in resource allocation than other multiple access schemes such as OFDM-TDMA, OFDM-frequency division multiple access (OFDM-FDMA), and orthogonal frequency division multiple access (OFDMA). With OFDM-TDMA/SA, a medium access control (MAC) is designed for broadband wireless LANs. It optimizes bit allocation in subcarriers so that maximum bits are transmitted in each OFDM symbol under a frequency selective fading environment. The OFDM-TDMA/SA MAC protocol also supports three classes of traffic such as guaranteed, controlled-load, and best effort services. Based on the optimum subcarrier bit-allocation algorithm and considering heterogeneous QoS constraints of multimedia traffic, a hierarchical scheduling scheme is proposed to determine the subcarriers and time slots in which a mobile terminal can transmit packets. In such a way, the OFDM-TDMA/SA MAC protocol significantly increases system throughput in a frequency selective fading environment and guarantees QoS of multimedia traffic. Computer simulation is carried out to evaluate the performance of the OFDM-TDMA/SA MAC protocol. Results show that the new MAC protocol outperforms other MAC protocols for OFDM-based wireless LANs. This work was supported by the State of Georgia Yamacraw Project (E21-105).     

Wireless Adaptive Framed Pseudo-Bayesian Aloha (AFPBA) Algorithm with Priorities

In this paper, we propose a new priority algorithm to control the access to the wireless ATM MAC uplink frame, for multimedia traffic like wireless ATM, similar to the Pseudo-Bayesian algorithm presented in [1]. The adaptive framed Pseudo-Bayesian Aloha (AFPBA) algorithm ensures minimum access delay for high priority traffic classes with small delay degradation to low priority traffic classes. Control packets are transmitted in each slot according to transmission probabilities based on the history of the channel and in contention with other packets of the same priority class. The number of contention slots assigned for each priority class, on a given frame, changes adaptively according to its priority index and the estimated arrival rate on each frame using an adaptive slot assignment mechanism. Finally, the throughput analysis of the algorithm is presented and the delay performance is evaluated by simulation on a wireless channel in the presence of shadowing, Rayleigh fading and capture. Results show that the wireless channel offers significant delay improvements to all priority packets, especially in the presence of fast fading.     

Combined Connection Admission Control and Packet Transmission Scheduling for Mobile Internet Services

Mobile Internet access is expected to be the most popular communication service in the near future. In this paper, we investigate radio resource management for mobile Internet multimedia systems that use the orthogonal frequency division multiple access and adopt the adaptive modulation and coding technique. It is assumed that real-time (RT) service such as streaming video and best-effort (BE) services such as file transfer protocol and hypertext transfer protocol coexist in the systems. We suggest two levels of radio resource management schemes: the connection admission control (CAC) scheme at the first level and the packet transmission scheduler at the second level. The proposed scheduler does not assign higher priority to RT packets over BE packets unconditionally. Instead, only the RT packets that are close to the deadline are given higher priority. Therefore, the performance of BE services is improved at the cost of RT services. To control the performance degradation in RT services within an acceptable level, the CAC algorithm functions as a congestion controller. The combined effects of the proposed CAC and packet scheduling by using the cross-layer simulation that covers from the physical layer to the Internet application layer are evaluated. The numerical results show that the proposed schemes greatly improve the performance of BE services while maintaining the quality of video service at an acceptable level.     

Dynamic reservation TDMA protocol for wireless ATM networks

A dynamic reservation time division multiple access (DR-TDMA) control protocol that extends the capabilities of asynchronous transfer mode (ATM) networks over the wireless channel is proposed in this paper. DR-TDMA combines the advantages of distributed access and centralized control for transporting constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR) traffic efficiently over a wireless channel. The contention slots access for reservation requests is governed by the framed pseudo-Bayesian priority (FPBP) Aloha protocol that provides different access priorities to the control packets in order to improve the quality-of-service (QoS) offered to time sensitive connections. DR-TDMA also features a novel integrated resource allocation algorithm that efficiently schedules terminals' reserved access to the wireless ATM channel by considering their requested bandwidth and QoS. Integration of CBR, voice, VBR, data, and control traffic over the wireless ATM channel using the proposed DR-TDMA protocol is considered in this paper. Simulation results are presented to show that the protocol respects the required QoS of each traffic category while providing a highly efficient utilization of approximately 96% for the wireless ATM channel     

Resource allocation algorithm in LTE uplink SC-FDMA system for time-varying channel with imperfect channel state information

In long term evolution (LTE) uplink single carrier frequency division multiple access (SC-FDMA) system, the restriction that multiple resource blocks (RBs) allocated to a user should be adjacent, makes the resource allocation problem hard to solve. Moreover, with the practical constraint that perfect channel state information (CSI) cannot be obtained in time-varying channel, the resource allocation problem will become more difficult. In this paper, an efficient resource allocation algorithm is proposed in LTE uplink SC-FDMA system with imperfect CSI assumption. Firstly, the resource allocation problem is formulated as a mixed integer programming problem. Then an efficient algorithm based on discrete stochastic optimization is proposed to solve the problem. Finally, simulation results show that the proposed algorithm has desirable system performance.     

Joint Optimal Access Point Selection and Channel Assignment in Wireless Networks

In wireless cellular networks or in other networks with single-hop communication, the fundamental access control problem pertains to access point (AP) selection and channel allocation for each user. For users in the coverage area of one AP, this involves only channel allocation. However, users that belong in the intersection of coverage areas of more than one AP can select the appropriate AP to establish connection and implicitly affect the channel assignment procedure. We address the joint problem of AP selection and channel assignment with the objective to satisfy a given user load vector with the minimum number of channels. Our major finding is that the joint problem reduces to plain channel allocation in a cellular network that emerges from the original one after executing an iterative and provably convergent clique load balancing algorithm. For linear cellular networks, our approach leads to minimum number of required channels to serve a given load vector. For 2D cellular networks, the same approach leads to a heuristic algorithm with a suboptimal solution due to the fact that clique loads cannot be balanced. Numerical results demonstrate the performance benefits of our approach in terms of blocking probability in a dynamic scenario with time-varying number of connection requests. The presented approach constitutes the basis for addressing more composite resource allocation problems in different context.