Quansheng Guan

Prediction-Based Topology Control and Routing in Cognitive Radio Mobile Ad Hoc Networks

Cognitive radio (CR) technology will have significant impacts on upper layer performance in mobile ad hoc networks (MANETs). In this paper, we study topology control and routing in CR-MANETs. We propose a distributed Prediction-based Cognitive Topology Control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a midware-like cross-layer module residing between CR module and routing. The proposed PCTC scheme uses cognitive link availability prediction, which is aware of the interference to primary users, to predict the available duration of links in CR-MANETs. Based on the link prediction, PCTC constructs an efficient and reliable topology, which is aimed at mitigating re-routing frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme.

Topology control in mobile Ad Hoc networks with cooperative communications

Cooperative communication has received tremendous interest for wireless networks. Most existing works on cooperative communications are focused on link-level physical layer issues. Consequently, the impacts of cooperative communications on network-level upper layer issues, such as topology control, routing and network capacity, are largely ignored. In this article, we propose a Capacity-Optimized Cooperative (COCO) topology control scheme to improve the network capacity in MANETs by jointly considering both upper layer network capacity and physical layer cooperative communications. Through simulations, we show that physical layer cooperative communications have significant impacts on the network capacity, and the proposed topology control scheme can substantially improve the network capacity in MANETs with cooperative communications.

Joint Topology Control and Authentication Design in Mobile Ad Hoc Networks With Cooperative Communications

Security is the main concern and bottleneck for widely deployed wireless applications due to the fact that wireless channels are vulnerable to attacks and that wireless bandwidth is a constrained resource. In this sense, it is desirable to adaptively achieve security according to the available resource. In particular, mobile ad hoc networks (MANETs) based on cooperative communication (CC) present significant challenges to security issues, as well as issues of network performance and management. In this paper, we focus on authentication and topology control issues. Although authentication and topology control are separately studied in most existing works, they are, in fact, closely correlated in MANETs. For example, both authentication and topology control schemes have significant impacts on throughput. In this paper, we jointly consider authentication and topology control. Specifically, we analyze the effective throughput with upper layer authentication schemes and physical-layer schemes related to channel conditions and relay selections for CCs. A joint authentication and topology control (JATC) scheme is proposed to improve the throughput. JATC is formulated as a discrete stochastic optimization problem, which does not require prior perfect channel status but only channel estimate. We also mathematically prove the tracking convergence property and the convergence rate of the discrete stochastic optimization approach in this paper. Simulation results show that our scheme can substantially improve throughput in MANETs with CC.

Energy-Efficient Topology Control With Selective Diversity in Cooperative Wireless Ad Hoc Networks: A Game-Theoretic Approach

Due to the scarce bandwidth and limited power supply in mobile terminals, performance and energy consumption in wireless communications must be continually focused upon. Cooperative transmissions improve the capacity performance of wireless ad hoc networks (WANETs). However, when energy efficiency is considered, the advantage of user cooperation over non-cooperation does not always exist since it involves multiple nodes with more energy consumption in transmissions. To exploit the benefits of user cooperation in cooperative WANETs, we propose a distributed energy-efficient selective diversity (EESD) topology control to improve energy efficiency, which jointly considers network capacity and energy consumption in terms of bits per Joule. EESD forms transmission coalitions via cooperative manner (i.e, diversity) selection, by taking into account the cost of channel information exchange. We then formulate EESD as a coalition game and propose an adaptive coalition formation algorithm for EESD with proved convergence property and stable coalition structures. Simulation results show the performance improvement of EESD in energy efficiency and network lifetime compared to the existing topology control schemes.

Distributed Cooperative Topology Control for WANETs With Opportunistic Interference Cancelation

Cooperative communications has received tremendous interests in wireless systems. The communication performance of a single source-destination pair can be enhanced via the help of relays in traditional cooperative communications. Recent advances in interference cancelation (IC) can further enhance the performance of parallel cooperative transmissions between multiple source-destination pairs. Although some works have been done on cooperative communications, most existing works are focused on link-level physical-layer issues. Consequently, the potential benefits of cooperative communications on network-level upper layer issues, such as topology control, are largely ignored in existing works. In this paper, we study the impacts of cooperative communications, particularly IC-based cooperative communications, on topology control in wireless ad hoc networks (WANETs). We propose a distributed cooperative topology control scheme with opportunistic IC (COIC) to improve network capacity in WANETs by jointly considering both upper layer network capacity and physical-layer cooperative communications with IC. We show that the benefits brought by cooperative communications are opportunistic, which rely on network structures and channel conditions. These opportunistic advantages have significant impacts on network capacity, and our proposed COIC can effectively capture these opportunities to substantially improve network capacity.

Provisioning of QoS adaptability in wired-wireless integrated networks

The increasing number of mobile users and the popularity of real-time applications make wired-wireless integrated network extremely attractive. In this case, quality of service (QoS) adaptability is particularly important since some important features of the integrated network call for QoS adaptability, such as mobility, bursty applications and so on. Traditional QoS schemes include integrated service (IntServ) and differentiated service (DiffSev) as well as their variants. However, they are not able to balance well between scalability and QoS granularity. For example, IntServ faces the scalability problem, while DiffServ can only provide coarse granular QoS. In addition, they are also unable to efficiently support QoS adaptability. Therefore, a per-packet differentiated queueing service (DQS) was proposed. DQS was originally proposed to balance between scalability and QoS granularity in wired networks and then extended to wireless networks. This paper mainly discusses how to use DQS to support QoS adaptability in wired-wireless integrated networks. To this end, we propose a scheme to determine dynamic delay bounds, which is the key step to implement DQS to support QoS adaptability. Simulation studies along with some discussions are further conducted to investigate the QoS adaptability of the proposed scheme, especially in terms of its support of QoS adaptability to mobility and to bursty real-time applications.

Decoupling congestion control from TCP (semi-TCP) for multi-hop wireless networks

Although many problems for transmission control protocol (TCP) in multi-hop wireless networks have been studied with many proposals in the literature, they are not solved completely yet. Different from the existing proposals to mitigate the limitation of TCP in multi-hop wireless networks, we propose a framework of semi-TCP which decouples two functionalities of traditional TCP, i.e., congestion control and reliability control, in order to get rid of the constraint of TCP’s congestion window on performance enhancement. Specifically, we employ hop-by-hop congestion control which is more efficient than its end-to-end counterpart since the control efficiency of the later relies on the availability of end-to-end connectivity which is difficult to sustain in wireless networks. We implement hop-by-hop congestion control via intra-node and inter-node congestion control, and propose a distributed hop-by-hop congestion control algorithm based on the widely used request-to-send/clear-to-send protocol. Such a semi-TCP retains the reliability control in original TCP. Extensive simulations based on network simulator-2 show the promising performance of semi-TCP over traditional schemes.

Distributed Interference-Aware Cooperative MAC Based on Stackelberg Pricing Game

Cooperative communication can significantly enhance the efficient utilization of spectrum in wireless networks. The performance of wireless cooperative networks depends on careful medium access control (MAC) and resource allocation such as relay selection and cooperative link scheduling policy for interference management. Most of the previous centralized works rely on precise instantaneous channel state information (CSI). In this paper, considering the impact of multirelay link interference on relay selection and dynamic spectrum sharing, we propose a fully distributed relay MAC scheme for wireless cooperative networks based on a Stackelberg game framework with only one-hop local CSI, where source nodes that have their own information to send act as leader users and where the others act as follower users. In this scenario, each relay node prices its spectrum resource to the corresponding source node to maximize its revenue. In addition, the proposed scheme helps not only source nodes to find relay nodes by channel gains and obtain an optimal system performance but relay nodes to maximize their revenue by asking a suitable resource price as well. The interactions between the sources and relays iteratively lead to a Stackelberg equilibrium, in which the cooperation system achieves high throughput and low transmission delay. Simulation results are presented to show the effectiveness of the proposed approach.

Novel Pilot Design and Signal Detection for SC-FDE Systems With Frequency-Domain Pilot Multiplexing Technique

The performance of single-carrier frequency-domain equalization systems with the frequency-domain pilot multiplexing technique is affected by the level of signal distortion, which highly depends on the pilot position selection (PPS) scheme at the transmitter and the signal detection (SD) scheme at the receiver. In this letter, by exploring the relationship between distorted symbols and decision boundaries, we propose a novel PPS scheme to confine the distorted symbols within their designated decision regions, which dispenses with a priori knowledge of the channel. Based on the maximum-likelihood criterion, we also propose a novel SD scheme to avoid error propagation, which operates on a symbol-by-symbol basis. Simulation results on bit error rate show that our proposed PPS scheme achieves almost the same performance as the optimal one and our proposed SD scheme outperforms the existing one in additive white Gaussian noise channels; in addition, both proposed schemes outperform their existing counterparts in frequency-selective Rayleigh fading channels.

A deadline-aware and distance-aware packet scheduling algorithm for wireless multimedia sensor networks

We propose a wireless differentiated queuing service (WDQS) algorithm to meet the diverse delay requirements in wireless multimedia sensor networks (WMSNs). WDQS adopts novel latest departure time (LDT) scheduling criteria to differentiate forwarding emergency by considering the packets’ lifetime, the known delay it has already experienced, and the remaining delay it will experience. We also propose an effective approach to estimate the unknown delay for the remaining journey without any message overhead by exploiting the query mechanism of the sink. We further discuss analytically the packets lifetime setting to meet the end-to-end (e2e) delivery requirement. The simulation results verify our analytical discussion and show performance improvements in terms of e2e delay and packet drop rate.