一种基于博弈论的无线mesh网络信道分配算法

无线mesh网络中的信道分配会极大地影响网络的性能。为了解决无线mesh网络中的信道分配问题,提出了一种基于博弈论的信道分配(GBCA)算法。该算法将网络中每一个节点模型化为一个博弈者,每个博弈者的策略为信道的分配方案,并将整个网络的吞吐量作为效用函数的目标,效用函数的物理意义则是在给定流量需求矩阵下传输的成功率。博弈者通过相互博弈来优化收益函数,以最大化网络吞吐量。并针对GBCA算法的不足,提出了一种改进算法———GBCA-TP算法。通过NS2.34仿真分析得出,GBCA算法和GBCA-TP算法在收敛性、分组丢失率和吞吐量上都要优于当前的算法。     

利用部分重叠信道的多无人机自主协同优化抗干扰

针对多无人机通信网络抗干扰中的功率和信道联合优化问题,考虑多无人机通信网络中的部分重叠信道切换、外部恶意干扰与网络内部互扰问题,通过构建Stackelberg博弈抗干扰模型,设计无人机用户和干扰机的效用函数,并提出了基于次梯度迭代的算法求解博弈的均衡解,获得无人机用户在干扰条件下的部分重叠信道选择和功率选择联合优化结果。仿真结果表明,所提算法能使多无人机用户获得良好的信道选择和传输功率策略,优化多无人机通信网络抗干扰性能。     

UWB系统MIMO传输的功率分配算法

针对目前多输入多输出(MIMO)系统功率分配中只考虑在奇异值分解(SVD)前提下运用注水原理进行功率分配的缺点,采用满足一定性能的(QoS)服务质量,在奇异值分解和注水原理的基础上,根据是否满足服务质量来关闭某些子信道以节约发射功率和减少信道间的干扰,根据发射速率和发射功率的关系,将发射速率归一化到离散传输速率并在此基础上计算发射该速率所用的功率,将剩余功率按注水原理分配给各个子信道以提高信道性能。     

MIMO-OFDM系统中基于效用函数的跨层资源分配算法

针对多业务MIMO-OFDM系统的下行链路提出了一种基于效用函数的跨层资源分配算法.建立了以效用函数最大化为目的的跨层优化目标,分别设计了语音、流媒体和"尽力而为"三种业务的边界效用函数.算法首先在所有用户中分配子载波,然后进行单用户和空间子信道的功率、比特分配,并对比特数目进行取整处理.仿真结果表明算法满足了多种业务的QoS要求,对时延敏感的业务能提供更小的时延,同时对"尽力而为"业务提供了更高的吞吐量.     

基于最大化网络吞吐量的WMN信道分配算法

为了解决无线Mesh网络中的信道分配问题,提出了一种基于博弈论的信道分配算法.该算法将网络中每一个节点模型化为一个博弈者,每个博弈者的策略为信道的分配方案,并将整个网络的吞吐量作为效用函数的目标,效用函数的物理意义则是在给定流量需求矩阵下传输的成功率.博弈者通过相互博弈来优化收益函数以最大化网络吞吐量.通过NS2.34仿真分析得出,GBCA算法在收敛性、丢包率和吞吐量上都要优于当前的算法.     

基于网络分割的无线传感器网络多信道MAC协议

无线传感器网络中,可用正交信道数目较少和噪声干扰问题制约着多信道MAC协议性能的提升,结合数据采集应用的特点,提出一种基于网络分割的多信道MAC协议。在最小化网络总干扰值的基础上,网络分割引入碰撞因子进一步优化子树结构、降低树内干扰。并利用基于图着色理论的分配策略为每棵子树分配一条高质量信道。仿真实验结果表明,该协议显著提高了网络吞吐量,并且大幅降低了传输延迟和分组丢失率。     

认知无线多跳网中保证信干噪比的频谱分配算法

为解决无线多跳网络在固定频谱分配方式下所固有的信道冲突等问题,利用认知无线电的动态频谱分配技术,提出了一种适用于次用户组成的无线多跳网络的、underlay方式下的全分布式频谱分配算法。该算法将频谱分配问题建模成静态非合作博弈,证明了纳什均衡点的存在,并给出了一种求解纳什均衡点的迭代算法。大量仿真实验证明,该算法能实现信道与功率的联合分配,在满足主用户干扰功率限制的同时,保证次用户接收信干噪比要求。     

基于网络编码的双向多中继系统中断概率分析

网络编码在双向多中继系统中已经得到了广泛地研究,并有效地提高了双向多中继系统的吞吐量。首先本文导出了在译码转发方式时,独立正交信道和多接入信道下基于网络编码的双向多中继系统平均中断概率表达式。Monte Carlo仿真和理论分析非常吻合,验证了理论分析的正确性。之后分析了系统平均中断性能在不同信噪比和不同中继节点个数等多种情形下与功率分配因子的关系,揭示了功率分配因子与系统总功率和中继节点数量之间的内在关系。仿真结果表明,双向多中继系统采用网络编码进行传输时,在独立正交信道下和多接入信道下的功率分配因子取值在区间 内能够获得最优的系统中断概率性能,并且多接入信道下的系统中断性能要好于独立正交信道。      

信息优先级保护的动态频谱分配算法

为提高海上无人艇编队无线网络频谱利用率,同时满足不同优先级信息的传输需求,提出了一种信息优先级保护的动态频谱分配算法。算法采用完全信息动态博弈模型,引入异步分布式定价（Asynchronous Distributed Pricing,ADP）算法设计效用函数。鉴于传统ADP算法在有较多通信余量时干扰价格定价过高,改进干扰价格定义。为体现优先级对分配的影响,在效用函数中加入信息权重。对效用函数成本部分进一步更改,可在实现高优先级信息优先传输的同时,依据通信速率需求合理分配信道通信容量。经过仿真验证,所提算法在吞吐量和可靠性方面优于基于节点优先级的分配算法。     

OFDMA毫微微小区双层网络中基于分组的资源分配

毫微微小区(Femtocell)网络能够增强室内覆盖,提高系统容量,但是在频谱共享的正交频分多址(OFDMA)毫微微小区网络中,毫微微小区之间的同层干扰以及毫微微小区与宏小区(Macrocell)之间的跨层干扰严重限制了系统的性能。针对这两种干扰,该文提出一种基于分组的资源分配算法。该算法包括两部分:一部分是宏基站先利用改进的匈牙利算法为宏小区用户分配信道,再用注水算法分配功率,保证宏小区用户的正常传输;另一部分是在避免干扰宏小区用户的基础上,先采用模拟退火算法对毫微微小区进行分组,再进行信道和功率分配,满足毫微微小区用户的数据速率需求,最大化频谱效率。仿真结果表明,该算法有效地抑制了这两种干扰,既能保证用户的数据速率需求,又能有效提升网络频谱效率。     

Packet-Based Power Allocation for Forward Link Data Traffic

We consider the allocation of power across forward-link packets in a wireless data network. The packets arrive according to a random (Poisson) process, and have fixed length so that the data rate for a given packet is determined by the assigned power and the channel gain to the designated user. Each user's service preferences are specified by a utility function that depends on the received data rate. The objective is to determine a power assignment policy that maximizes the time-averaged utility rate, subject to a constraint on the probability that the total power exceeds a limit (corresponding to an outage). For a large, heavily loaded network, we introduce a Gaussian approximation for the total transmitted power, which is used to decompose the power constraint into three more tractable constraints. We present a solution to the modified optimization problem that is a combination of admission control and pricing. The optimal trade-off between these approaches is characterized. Numerical examples illustrate the achievable utility rate and power allocation as a function of the packet arrival rate.     

Channel allocation for priority packets in the GPRS network

As the general packet radio service (GPRS) network begins to provide such as "push-to-talk" (PTT) service, delay-sensitive packets should be given higher priority in transmission. In this paper, we study two channel allocation schemes that implement priority queues for priority packets in the GPRS network: bitmap channel allocation (BCA) and uplink state flag channel allocation (USFCA). Our study shows that the transmission delay of priority packets in the GPRS network can be better guaranteed using USFCA.     

Optimal resource allocation for wireless video over CDMA networks

We present a multiple-channel video transmission scheme in wireless CDMA networks over multipath fading channels. We map an embedded video bitstream, which is encoded into multiple independently decodable layers by 3D-ESCOT video coding technique, to multiple CDMA channels. One video source layer is transmitted over one CDMA channel. Each video source layer is protected by a product channel code structure. A product channel code is obtained by the combination of a row code based on rate compatible punctured convolutional code (RCPC) with cyclic redundancy check (CRC) error detection and a source-channel column code, i.e., systematic rate-compatible Reed-Solomon (RS) style erasure code. For a given budget on the available bandwidth and total transmit power, the transmitter determines the optimal power allocations and the optimal transmission rates among multiple CDMA channels, as well as the optimal product channel code rate allocation, i.e., the optimal unequal Reed-Solomon code source/parity rate allocations and the optimal RCPC rate protection for each channel. In formulating such an optimization problem, we make use of results on the large-system CDMA performance for various multiuser receivers in multipath fading channels. The channel is modeled as the concatenation of wireless BER channel and a wireline packet erasure channel with a fixed packet loss probability. By solving the optimization problem, we obtain the optimal power level allocation and the optimal transmission rate allocation over multiple CDMA channels. For each CDMA channel, we also employ a fast joint source-channel coding algorithm to obtain the optimal product channel code structure. Simulation results show that the proposed framework allows the video quality to degrade gracefully as the fading worsens or the bandwidth decreases, and it offers improved video quality at the receiver.     

Utility-Based Wireless Resource Allocation for Variable Rate Transmission

For most wireless services with variable rate transmission, both average rate and rate oscillation are important performance metrics. The traditional performance criterion, utility of average transmission rate, boosts the average rate but also results in high rate oscillations. We introduce a utility function of instantaneous transmission rates. It is capable of facilitating the resource allocation with flexible combinations of average rate and rate oscillation. Based on the new utility, we consider the time and power allocation in a time-shared wireless network. Two adaptation policies are developed, namely, time sharing (TS) and joint time sharing and power control (JTPC). An extension to quantized time sharing with limited channel feedback (QTSL) for practical systems is also discussed. Simulation results show that by controlling the concavity of the utility function, a tradeoff between the average rate and rate oscillation can be easily made.     

Power control and channel allocation for real‐time applications in cellular networks

The next‐generation packet‐based wireless cellular network will provide real‐time services for delay‐sensitive applications. To make the next‐generation cellular network successful, it is critical that the network utilizes the resource efficiently while satisfying quality of service (QoS) requirements of real‐time users. In this paper, we consider the problem of power control and dynamic channel allocation for the downlink of a multi‐channel, multi‐user wireless cellular network. We assume that the transmitter (the base‐station) has the perfect knowledge of the channel gain. At each transmission slot, a scheduler allots the transmission power and channel access for all the users based on the instantaneous channel gains and QoS requirements of users. We propose three schemes for power control and dynamic channel allocation, which utilize multi‐user diversity and frequency diversity. Our results show that compared to the benchmark scheme, which does not utilize multi‐user diversity and power control, our proposed schemes substantially reduce the resource usage while explicitly guaranteeing the users' QoS requirements. Copyright © 2007 John Wiley & Sons, Ltd.     

Capture Effect of Randomly Addressed Polling Protocol

The capture effect, discussed in this paper, is generally considered to enhance the system's performance in a wireless network. This paper also considers the Randomly Addressed Polling (RAP) protocol in the presence of a fading mobile radio environment. Herein, a deterministic channel, which rules according to inverse power propagation law, is established to obtain the probability that one collided packet can capture the channel from distance distribution. Through the probability, we analyze the performance of the RAP protocol by using an embedded Markov chain. According to our results, the performance of the RAP protocol does not obviously change in terms of power control, implying that it can be more aptly applied in power control skill than other protocols.     

Downlink user selection and resource allocation for semi-elastic flows in an OFDM cell

We are concerned with user selection and resource allocation in wireless networks for semi-elastic applications such as video conferencing. While many packet scheduling algorithms have been proposed for elastic applications, and many user selection algorithms have been proposed for inelastic applications, little is known about optimal user selection and resource allocation for semi-elastic applications in wireless networks. We consider user selection and allocation of downlink transmission power and subcarriers in an orthogonal frequency division multiplexing cellular system. We pose a utility maximization problem, but find that direct solution is computationally intractable. We first propose a method that makes joint decisions about user selection and resource allocation by transforming the utility function into a concave function so that convex optimization techniques can be used, resulting in a complexity polynomial in the number of users with a bounded duality gap. This method can be implemented if the network communicates a shadow price for power to power allocation modules, which in turn communicate shadow prices for rate to individual users. We then propose a method that makes separate decisions about user selection and resource allocation, resulting in a complexity linear in the number of users.     

Joint Algorithm of Channel Allocation and Power Control in Multi-channel Wireless Sensor Network

In the wireless sensor network, the interference incurred by another transmitter’s transmission may disturb other receivers’ correct receptions of packets, thus, the add of a new transmission must consider its effect on other transmissions. Additionally, in order to reduce the interference and increase QoS, multi-channel technology is introduced into wireless communication, but the energy cost by the channel switch increases with the interval of channels increasing. Based on the above analysis, we consider an energy efficient joint algorithm of channel allocation and power control (JCAPC) for wireless sensor network. In JCAPC, each link firstly establishes its available channel set on which the transmitter of the link can guarantee its transmission successfully and don’t disturb other receivers’ transmissions, and then each link chooses a channel from the available channel set according to the energy cost on anti-interference and channel switch. After that, we formulate power control on each channel as a non-cooperative game with utility function including Signal-to-Interference-and-Noise Ratio (SINR) price. In order to reduce the energy cost of the information exchange during the traditional game, we introduce the thought of game virtual playing, in which each link can decide its own transmission power by imitating the game among links with its once collected information. Consequently, JCAPC can not only increase the transmission efficiency but also reduce the nodes’ energy waste. Moreover, the existence of Nash Equilibrium (NE) is proven based on super-modular game theory, and it’s able to obtain the unique NE by relating this algorithm to myopic best response updates. The introduction of game virtual playing saves the energy cost of network further more by reducing the number of information exchange. Simulation results show that our algorithm can select a channel with good QoS using less energy consumption and provide adequate SINR with less transmit power, which achieves the goal of efficiently reducing energy waste.     

Throughput-oriented MAC for mobile ad hoc networks: A game-theoretic approach

The conservative nature of the 802.11 channel access scheme has instigated extensive research whose goal is to improve the spatial reuse and/or energy consumption of a mobile ad hoc network. Transmission power control (TPC) was shown to be effective in achieving this goal. Despite their demonstrated performance gains, previously proposed power-controlled channel access protocols often incur extra hardware cost (e.g., require multiple transceivers). Furthermore, they do not fully exploit the potential of power control due to the heuristic nature of power allocation. In this paper, we propose a distributed, single-channel MAC protocol (GMAC) that is inspired by game theory. In GMAC, each transmitter computes a utility function that maximizes the link’s achievable throughput. The utility function includes a pricing factor that accounts for energy consumption. GMAC allows multiple potential transmitters to contend through an admission phase that enables them to determine the transmission powers that achieve the Nash equilibrium (NE). Simulation results indicate that GMAC significantly improves the network throughput over the 802.11 scheme and over another single-channel power-controlled MAC protocol (POWMAC). These gains are achieved at no extra energy cost. Our results also indicate that GMAC performs best under high node densities and large data packet sizes.     

Feedback-assisted MAC protocol for real time traffic in high rate wireless personal area networks

During the past decade, there has been much standardization effort for indoor or shot-range networks, as communication devices and applications for such networks populate. As a prominent example of these activities, the IEEE 802.15.3 Task Group (TG) published a standard for high-rate wireless personal area network (HR-WPAN). To support strictly timed multimedia services, the TG adopts a time-slotted channel access protocol controlled by a central device (DEV). Although the channel time allocation algorithm plays a key role in deciding the network performance, it remains unspecified in the standard. Therefore, in this paper, we propose a novel feedback-assisted channel time allocation method for HR-WPAN. After initial channel times are allocated based on packet inter-arrival time statistics, the allocation is dynamically adjusted by utilizing feedback information from each DEV. The feedback information includes the buffer status, the packet transmission delay, and the physical transmission rate. By utilizing this feedback information, the central DEV can allocate sufficient channel time for transmissions of pending packets from a DEV. Moreover, the allocated channel times can be synchronized to the packet arrival times so that the overall transmission delay is reduced. To cope with time-varying wireless channels, a dynamic rate selection algorithm assisted by physical layer information is proposed in this paper. Performance evaluation is carried out through extensive simulations, from which significant performance enhancements are observed.