A receiver-centric multi-channel MAC protocol for wireless networks

A novel multi-channel MAC protocol with directional antenna for enhancing spatial reuse and bandwidth utilization in WLANs

In multi-channel WLANs, the MAC protocol allocates a channel to each transmission pair while avoiding interference. In the channel allocation phase, if the MAC protocol allocates one channel iteratively to multiple narrowly spaced transmission pairs, both channel utilization and network throughput can be improved. However, such an approach leads to traffic overload; thus, if a transmission takes place over a transmission channel, the number of terminals that can receive the transmission decreases. B-MAC, a multi-channel MAC protocol designed for broadcast, starts a new broadcast transmission after waiting for a certain period of time; however, this waiting time increases the transmission overhead and degrades channel utilization. In this paper, we propose CA-BMAC, a new multi-channel MAC protocol that reduces the waiting time associated with B-MAC, and thus, the transmission overhead. Performance evaluations of the proposed protocol clarify its advantages over B-MAC.

In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.

Recently, many MAC protocols have been proposed for effective communication in the single transceiver multi-channel environment. In these MAC protocols, however, the multi-channel hidden terminal problem degrades the throughput of the communication systems. In order to mitigate the effects of the multi-channel hidden terminals, two MAC protocols have been proposed: cooperative asynchronous multi-channel MAC (CAM-MAC), where neighbouring terminals inform a sender of its bad channel selection and virtual topology MAC (VT-MAC), where redundant channel usage information is reduced by considering the network topology. However, these MAC protocols mainly focus on avoiding bad channel selections by the sender, and not on increasing good channel selections (concurrent transmissions). Therefore, in this paper, to further improve throughput performance by concurrent transmissions, we propose new multi-channel MAC protocols in which neighbour terminals of a sender recommend a better transmission channel prior to the data transmission. The performance evaluations verify that the proposed MAC protocol effectively improves the throughput performance when compared to existing MAC protocols, especially when the channel negotiation process induces the larger overhead at the short data transmission.

A vehicular ad hoc network (VANET) is designed to enable efficient and authentic node/infrastructure communication. The primary role of VANETs is to distribute time-sensitive safety messages (sm) regularly, which causes packet congestion and broadcast failure due to the network’s limited spectrum. For efficient and reliable delivery, the proposed paper uses a spatial hybrid division multiple access (SDMA) and time division multiple access (TDMA) over the control channel interval and hence termed a spatially distributed multichannel MAC (SDM-MAC) protocol. The frequency reuse approach is used to transfer data while efficiently utilising bandwidth, and throughput is considerably enhanced with carrier sense multiple access with collision avoidance (CSMA/CA) and with the help of TDMA. Moreover, an adaptive algorithm is proposed for an intelligent channel frame structure using this protocol to manage the highly dynamic scenario. The Markov chain defines the protocol, and the network simulator (NS2) analyses several performance metrics. Comparing the response with two existing MAC protocols, the proposed protocol reduces average latency compared to current MAC methods and improves the packet delivery ratio and throughput by an average of 26% and 28%, respectively.

Recent research has demonstrated the feasibility of full-duplex (FD) communication over the same frequency channel. This capability, facilitated by new self-interference suppression techniques, has great potential to increase the network capacity. However, exploiting FD in the context of a multi-user, multi-channel network is still being debated. This paper focuses on the channel access issue and presents a novel multi-channel MAC (MMAC) protocol for wireless ad hoc networks with FD and orthogonal frequency-division multiple access (OFDMA) capabilities. Through these capabilities, a node can simultaneously carry out multiple transmissions and/or receptions over the same or different channels. In our MMAC protocol, a pair of nodes negotiate data channels, transmission rates, transmission powers, and transmission modes (e.g., FD or half-duplex) in a distributed manner so that their spectral usages are minimized while their rate demands are still met. Extensive ns3 simulations show that our MMAC protocol increases the end-to-end network goodput by up to 150% and decreases the end-to-end delay by up to 300% compared with an OFDMA-based protocol without FD.

Transmission power plays a crucial role in the design and performance of wireless networks. The issue is therefore complex since an increase in transmission power implies that a high quality signal is received at the receiver and hence an increase in channel capacity. Conversely, due to the shared nature of the wireless medium an increase in transmission power also implies high interference in the surrounding region and hence a quadratic reduction in the capacity of wireless networks. Recent literatures indicate that employing multiple channels can mitigate the negative effects of wireless interference and thus greatly improve the overall network capacity. Therefore, it is worth investigating the effect of exploiting power on the capacity of multi-channel multi-radio (MC-MR) wireless networks. Specifically, in this paper we address the following questions: (a) Can we maximize the capacity of MC-MR wireless networks by exploiting power? (b) Under what criteria can we increase the transmission power of the nodes in a MC-MR network? %In this paper, we address these issues and investigate the impact of employing high transmission power and multiple channels in a static wireless network when node placements are chosen arbitrarily. When $n$ nodes each with $m$ half-duplex interfaces are optimally deployed in a torus of unit area, traffic patterns are optimally assigned, each transmission's range is optimally chosen and in the presence of $c$ channels, we show that in contrast to the setting where nodes transmit at minimum power level $P_0$ the transport capacity, measured in bit-meters per second, of MC-MR network exploiting power is increased by $\Theta(\frac{c}{c_{min}})$ in region $c_{min} mn/2$ when nodes tune to transmit power level of $P_0(\frac{c}{c_{min}})^(\frac{\alpha}{2})$ and $P_0n^{\frac{\alpha}{2}}$ respectively. Where $c_{min}$ is the minimum number of channels required to achieve conflict-free transmissions in a network. Our analysis also sheds light into several insights that designers may want to consider to improve the performance of energy-efficient bandwidth-constrained wireless networks.

We address the problem of improving the throughput and security of multi-channel MAC (MMAC) protocols. We design a protocol called FD-MMAC that exploits recent advances in full duplex (FD) communications to coordinate channel access in a distributed manner. Compared with prior MMAC designs, our protocol eliminates the use of dedicated in-band or out-of-band control channels for resolving contention, discovering the resident channel of destinations, and performing load balancing. The elimination of the control channel improves spectral efficiency and mitigates denial-of-service attacks that specifically target the exchange of control information. Moreover, FD-MMAC enables the operation of multi-channel exposed terminals. To achieve these goals, we integrate an advanced suite of PHY-layer techniques, including self interference suppression, error vector magnitude and received power measurements, and signal correlation. We validate the proposed PHY-layer techniques on the NI USRP testbed. Furthermore, we theoretically analyze the throughput performance of FD-MMAC and verify our analysis via packet level simulations. Our results show that FD-MMAC achieves significantly higher throughput compared with prior art. Finally, we analyze the resilience of FD-MMAC to reactive jamming attacks.

A number of multichannel MAC protocols have been developed earlier with the objective of maximizing energy efficiency and guaranteeing QoS requirements in wireless sensor networks. However, the trade-off between energy efficiency and QoS requirements remains an open issue. In this paper, we propose a multichannel MAC protocol so that nodes dynamically switch their interface between the channels to achieve this goal. The proposed protocol works in two phases, the advertisement (ADV) phase and data phase, which run concurrently. During the ADV phase, the nodes having data try to contend the advertisement channel to transmit the ADV packet. The nodes after receiving the acknowledgement from the receiver switch to the available free channel for the transmission of data packet. We analyze the performance of our proposed protocol through simulation. The simulation results reveal the proposed protocol performs better than the existing MAC protocols in terms of data delivery ratio, end-to-end delay and energy efficiency.

A hybrid wireless network is an extension to an infrastructure network, where a mobile host may connect to an access point using multi-hop wireless routes, via other mobile hosts. The access points are configured to operate on one of multiple available channels. Mobile hosts and wireless routers can select its operating channel dynamically through channel switching. In this environment, we propose a routing protocol that finds routes to balance load among channels while maintaining connectivity. The protocol works with nodes equipped with a single network interface, which distinguishes our work with other multi-channel routing protocols that require multiple interfaces per node. The protocol discovers multiple routes to multiple access points, possibly operating on different channels. Based on traffic load information, each node selects the "best" route to an access point, and synchronizes its channel with the access point. With this behavior, the channel load is balanced, removing hot spots and improving channel utilization. The protocol assures every node has at least one route to an access point, where all intermediate nodes are operating on the same channel. Our simulation results show that the proposed protocol successfully adapts to changing traffic conditions and improves performance over a single-channel protocol and a multi-channel protocol with no load balancing.

Network load in mobile networks is continuously growing, putting pressure on mobile operators to deliver target network performance and user experience. This paper focuses on network capacity improvement through increased spectral efficiency, which can be achieved with overhead reduction by optimizing the demodulation reference signal (DM-RS) configuration, which is one of the channels/reference signals with the largest contribution to overhead. In a high-speed scenario, the Doppler effect noticeably influences the temporal nature of the channel such that a channel interpolation process is required within a slot. However, increasing the number of symbols used for DM-RS has a negative impact on capacity. The Doppler effect was analyzed for various 5G NR configurations of operating frequency and subcarrier spacing (SCS), and various use cases were considered using user equipment (UE) speed as the main parameter. For suitable use cases, the DM-RS configuration was optimized in networks with live traffic. The impact of the configuration change on 5G/NR spectral efficiency, user experience and link adaptation performance was assessed through a deep-dive analysis of active measurements, available performance Management (PM) counters and key performance indicators. An optimized DM-RS configuration is proposed, and it is demonstrated to achieve gains of 5–15%, depending on the metric used, use case analyzed, network load, traffic mix and other relevant network characteristics such as topology and clutter type.

Adhoc Wireless network's performance is always measured by the number of packets successfully transmitted corresponding to power consumption of the nodes. This indirectly quantifies the battery's life. In multihop wireless networks, every node acts as intermediate node to forward packets to other nodes. The overall network connectivity depends on the battery life. As soon as one node dies the topology of the network changes. The standard protocol IEEE 802.11 DCF MAC protocol is designed to allow transfer of packets between two neighboring nodes through the wireless media. But it consumes lot of energy, and is also unable to avoid the hidden node problem completely, thereby leading to numerous packet collisions. Researchers have proposed many MAC protocols to resolve this problem, but these schemes degrade network throughput as well as bring unfairness to the network in order to reduce power consumption. Our protocol uses the concept of Bounded Wait State to reduce power consumption and at the same time improve the fairness in the network. Through simulations we have shown that our proposed protocol shows better performance.

In this paper, an interference and throughput aware multi-channel MAC protocol (ITMMAC) is designed for actor-actor coordination in wireless sensor-actor networks (WSAN). Each actor consists of multiple transceivers, hence it can simultaneously transmit or sense on multiple non-interference channels. ITMMAC protocol divides the beacon interval into ad-hoc traffic indication message (ATIM) window and data transmission phase. In the ATIM window, sender negotiates the minimum interference and maximum throughput channel among the available channels with the destination. Each actor processes the channel negotiation phase in the dedicated control channel. The proposed ITMMAC protocol is simulated using NS2. The obtained simulation results are analyzed using network parameters such as average throughput and average packet delay in the network. The simulation results indicate that the proposed ITMMAC protocol performs well as compared to the existing MAC protocols.

Using multi-channel MAC protocols in mobile ad hoc networks (MANETs) is a promising way to improve the through-put performance. Channel assignment, which directly determines the efficiency of the frequency utilization, is the critical part of multi-channel schemes. Current 802.11-like schemes of multi-channel MAC do not efficiently use the multiple channels due to the overhead caused by channel assignment. Moreover, the control channel saturation problem limits the number of channels of these previous schemes. In this paper, we propose a new scheme called SAM-MAC (Self-Adjustable Multi-channel MAC), which features with one common channel and two half-duplex transceivers for each node. A method called self-adjustment is used to reassign the channels and balance the traffic on different channels. Due to less contention in common channel and smaller channel assignment overhead, this scheme increases the throughput compared with previous approaches. Control channels are free from saturation problem and can furthermore be used for data transmission.

Mobile Ad-hoc Networks (MANETs) are special kind of wireless networks with no centralized control. They are ideal candidate for several real world applications where network need to be established on the fly e.g. disaster hit areas, hospitals, military surveillance etc. Researchers have been actively working in this area for a decade or so to make this concept a reality. MANETs differ from conventional fixed networks and therefore pose several challenges to the researchers working in the area. Among many others, access to shared medium is the major problem in MANETs. In such networks MAC layer protocol plays an important role in efficient utilization of shared media in distributed fashion. At the MAC layer we have three contradicting requirements, Maximize channel utilization, Minimize Control overhead and Fairness. Multi-Channel MAC protocols are considered is the most suitable solution to achieve the desired objectives but channel assignment and reservation in a distributed fashion is still a big challenge. In this paper, we have proposed a Multi- Channel scheme to address the problem of channel assignment the proposed scheme is Nodeid based. The proposed Scheme has been compared with conventional single channel scheme using ns-2 simulation and results shows that the proposed technique gives better performance. Keywords- BEB algorithm, Clear to send, Control channels, Dedicated Channels, MAC, Overhead, and request to send.