Cooperative Medium Access Research Articles

Cross-layer cooperative multichannel medium access for internet of things

Wireless networking in the Internet of Things is a challenging problem because a huge amount of devices in a relatively small region need to be interconnected. Particularly, the carrier sensing multiple access with collision avoidance (CSMA/CA) operation of IoT devices is not viable solution, since dense network leads to high channel contentions. Moreover, given an intensive network traffic load, long queues or even queue overflows are expected, which further deteriorates network performance. To address these issue, multichannel medium access is proposed and it attracts great attention recently. In this paper, we firstly establish models based on combinatorics theory to analyze the performance of dynamic multichannel medium access. Then, a Cross-layer Cooperative Multichannel Medium Access (CCMMA) is proposed to effectively avoid channel contentions by enabling neighboring devices to communicate on orthogonal channels. The CCMMA also introduces a routing-enhanced mechanism that enables relaying nodes to wake up intelligently if there is incoming traffic, that successfully mitigates delay and queue overflow problems caused by low-power operation of IoT devices. The performance of CCMMA is evaluated through extensive simulations. The results show that it provides significant improvement in terms of quality of service over existing solutions.

Distributed Reciprocal-Selection-Based ‘Win-Win’ Cooperative Medium Access and its Stability Analysis

In this paper, a distributed “Win-Win” reciprocal-selection-based medium access scheme (DWWRS-MAS) is designed for a cooperative spectrum leasing system hosting multiple licensed transmission pairs and multiple unlicensed transmission pairs. Based on the proposed DWWRS-MAS, the primary transmitter (PT) intends to lease its spectral resources to an appropriate secondary transmitter (ST) in exchange for cooperative transmission assistance for the sake of minimizing its transmit power and simultaneously satisfying its transmit rate requirement. The ST has an incentive to collaborate with the best PT for the sake of minimizing the ST’s transmit power under the constraint of its Quality of Service (QoS) requirement, while simultaneously winning a transmission opportunity for its own traffic. Moreover, based on the matching theory and queueing theory, we analyze the algorithmic stability and the queueing stability of the cooperative spectrum leasing system exploiting our DWWRS-MAS, respectively. Simulation results demonstrate that our DWWRS-MAS is capable of providing both considerable energy savings and substantial rate improvements for the cooperative spectrum leasing system hosting multiple licensed transmission pairs and multiple unlicensed transmission pairs.

Throughput and delay analysis of a reliable cooperative MAC protocol in ad hoc networks

In this paper, we present the performance evaluation of the reliable cooperative media access control (RCO-MAC) protocol, which has been proposed in [1] by us in order to enhance system throughput in bad wireless channel environments. The performance of this protocol is evaluated with computer simulation as well as mathematical analysis in thispaper. The system throughput, two types of average delays, average channel access delay, and average system delay, which includes the queuing delay in the buffer, are used as performance metrics. In addition, two different traffic models are used for performance evaluation: The saturated traffic model for computing system throughput and average channel access delay, and the exponential data generation model for calculating average system delay. The numerical results show that the RCO-MAC protocol proposed by us provides over 20% more system throughput than the relay distributed coordination function (rDCF) scheme. The numerical results show that the RCO-MAC protocol provides a slightly higher average channel access delay over a greater number of source nodes than the rDCF. This is because a greater number of source nodes provide more opportunities for cooperative request to send (CRTS) frame collisions and because the value of the related retransmission timer is greater in the RCO-MAC protocol than in the rDCF protocol. The numerical results also confirm that the RCO-MAC protocol provides better average system delay over the whole gamut of the number of source nodes than the rDCF protocol.

Flow-Specific Medium Access for Networked Satellite System

Prior work in modeling the satellite-based detection and tracking components of the ballistic missile defense system as a large-scale, wireless sensor network relies on a medium access scheme that can accommodate the large propagation delays encountered in these networked satellite systems. While existing satellite-based systems typically employ a form of time division multiple access, recent efforts have begun to explore contention-based approaches. In this work, we quantify the effect of the large propagation delays on both contention-based and contention-free solutions and propose a flow-specific medium access solution that provides improved delay performance by dynamically adapting the networked satellite medium access scheme to changes in both individual flow and link characteristics. A comparison with CSMA and TDMA is provided through simulation results using a version of the traffic-adaptive cooperative wireless sensor medium access control protocol that has been modified to accommodate large propagation delays.