Reservation Medium Access Control Protocol Research Articles

A Priority-Based Reservation MAC Protocol in Multi-Channel Cognitive Radio Networks

Cognitive radio network can improve under-utilized licensed wireless channels called the primary channels where secondary users (SUs) can opportunistically share the primarychannels allocated to primary users (PUs) but which are not used by the PUs. This paper proposes a priority-based reservation medium access control protocol in cognitive radio network where a common control channel is exclusively used for SUs to transmit control packets in order to determine the priority for accessing the primary channels. The position of a control packet that did not collide with others becomes a priority. With the proposed protocol, any new SUs can join the network whenever it wants without knowing any past information. The analytic results show that the number of SUs affects the performance due the collision possibility of random access. However, if the SU can transmit its control packet successfully without collision, then it can transmit its data packet based on its priority without worrying about additional collision.

An OFDMA-based joint reservation and cooperation MAC protocol for the next generation WLAN

The rapidly increasing use of mobile devices and the explosive growth of wireless traffic demands continuously drive the development of wireless networks. IEEE 802.11ax, as the emerging standard for the next generation wireless local area network (WLAN), aims to improve the network throughput in the densely deployed wireless networks. In the dense networks, the increased collisions for the large number of nodes and the inevitable transmission failures for aggregate interference and channel fading severely degrade the network throughput, posing an intractable challenge that urgently requires resolution. Channel reservation scheme that reduces the access collisions, and cooperative relay scheme that enhances the transmission reliability have consequently drawn considerable attention in recent years. Joint channel reservation and cooperation has been proved as a promising way to improve the network throughput in our recent study, but how to design a high-performance medium access control (MAC) protocol combined with reservation and cooperation for the next generation WLAN still remains an open issue. In this paper, we propose an orthogonal frequency-division multiple access (OFDMA) based joint reservation and cooperation MAC (OJRC-MAC) protocol for the next generation WLAN. The OJRC-MAC adopts the channel reservation scheme to reduce the access collisions, and enables the cooperative relay scheme to enhance the transmission reliability simultaneously. A resource unit based Markov model is introduced to analyze the network throughput, and the impacting factors on the throughput can be clarified by the derived closed-from expression. Simulation results validate the analytical results, and show that OJRC-MAC outperforms the basic uplink OFDMA-based random access (UORA), only reservation-enabled MAC (RES-MAC), and only cooperation-enabled MAC (COOP-MAC).

A novel contention-based MAC protocol with channel reservation for wireless LANs

In this paper, we present a novel contention-based medium access control (MAC) protocol, namely, the Channel Reservation MAC (CR-MAC) protocol. The CR-MAC protocol takes advantage of the overhearing feature of the shared wireless channel to exchange channel reservation information with little extra overhead. Each node can reserve the channel for the next packet waiting in the transmission queue during the current transmission. We theoretically prove that the CR-MAC protocol achieves much higher throughput than the IEEE 802.11 RTS/CTS mode under saturated traffic. The protocol also reduces packet collision, thereby saving the energy for retransmission. We evaluate the protocol by simulations under both saturated traffic and unsaturated traffic. Our simulation results not only validate the theoretical analysis on saturated throughput, but also reveal other good features of the protocol. For example, under saturated traffic, both the saturated throughput and fairness measures of the CR-MAC are very close to the theoretical upper bounds. Moreover, under unsaturated traffic, the protocol also achieves higher throughput and better fairness than IEEE 802.11 RTS/CTS.

Centralized transmission probability control scheme for non-real-time traffic in wireless ATM networks

This article proposes a contention-based reservation medium access control protocol for transporting bursty traffic efficiently in wireless ATM networks. The proposed protocol is characterized by a contention-based transmission of the reservation request and a contention-free transmission of the bursty traffic. The design objective of the proposed protocol is to reduce the contention delay while maximizing the channel utilization. In order to reduce the collision of reservation request packets, the base station calculates and broadcasts the transmission permission probability of reservation request packets. The calculation of the transmission permission probability is based on the estimated load of reservation requests and the number of random access minislots. The wireless terminal, which has a bursty traffic, selects a random access minislot and transmits its reservation request packet with the received transmission permission probability. Based on the successfully received reservation packets, the scheduler allocates the uplink data slots to the wireless terminal. Simulation results are presented to show that the proposed protocol provides high channel utilization, and furthermore, maintains a constant delay performance in a heavy traffic environment.

The arrayed-waveguide grating-based single-hop WDM network: an architecture for efficient multicasting

Research on multicasting in single-hop wavelength-division-multiplexing (WDM) networks has so far focused on networks based on the passive star coupler (PSC), a broadcast device. It has been shown that multicasting performance is improved by partitioning multicast transmissions into multiple multicast copies. However, the channel bottleneck of the PSC, which does not allow for spatial wavelength reuse, restricts the multicast performance. We investigate multicasting in a single-hop WDM network that is based on an arrayed-waveguide grating (AWG), a wavelength routing device that allows for spatial wavelength reuse. In our network, optical multicasting is enabled by wavelength-insensitive splitters that are attached to the AWG output ports. Multicasts are partitioned among the splitters and each multicast copy is routed to a different splitter by sending it on a different wavelength. We demonstrate that the spatial wavelength reuse in our network significantly improves the throughput-delay performance for multicast traffic. By means of analysis and simulations, we also demonstrate that, for a typical mix of unicast and multicast traffic, the throughput-delay performance is dramatically increased by transmitting multicast packets concurrently with control information in the reservation medium access control protocol of our AWG-based network.