Random Access Medium Access Control Protocols Research Articles

Buffering_Slotted_ALOHA protocol for underwater acoustic sensor networks based on the slot status

The high throughput, the time saving, and the lower energy consumption are fundamental issues that draw in the consideration of the Underwater Wireless Sensor Networks (UWSNs) field specialists. Medium Access Control (MAC) protocols in UWSNs are significant methods used for increasing the network lifetime and decreasing the consumption rate of energy. ALOHA Protocol that is a class of random-access MAC protocols is considered as the precept of all the complex designs of MAC protocol such as multi-channel networks. This paper proposes a new protocol for handling the previously mentioned issues called a Buffering_Slotted_ALOHA protocol. The main idea of this protocol is based on dividing the network into small parts called closed clusters to reduce the movement of nodes from one cluster to another. Each closed cluster in the network contains some small clusters with a specific number of nodes to reduce the traffic in the network and to avoid the collision and then reduce the transmission time to the least value. In this protocol, the uw-sink node interacts with a small number of nodes and that is a one of the benefits of using a small cluster. Each node in the small cluster has two choices to send its packets, either to the uw-sink or to the uw-main sink depending on the slot status. Moreover, each node has a buffer that holds the transmitted packets until getting their acknowledgment. This buffer has a large capacity to store a lot of packets. Checking the status of the slot before the transmission is a significant point in our protocol to speed the transmission process. The simulation results of this new protocol proved a good performance related to the throughput rate, the average delay, the energy consumption, and the number of dropped nodes in comparison with the other three most common slotted protocols: Slotted ALOHA, Slotted carrier sense ALOHA protocol (Slotted-CS-ALOHA), and time-saving ALOHA protocol with slotted carrier sense (ST-Slotted-CS-ALOHA protocol). Also, the results proved that the higher the density of the network, the higher the performance of our protocol.

Power-Controlled Medium Access Control Protocol for Full-Duplex WiFi Networks

Recent advances in signal processing have demonstrated in-band full-duplex capability at WiFi ranges. In addition to simultaneous two-way exchange between two nodes, full-duplex access points can potentially support simultaneous uplink and downlink flows. However, the atomic three-node topology, which allows simultaneous uplink and downlink, leads to inter-client interference. In this paper, we propose a random-access medium access control protocol using distributed power control to manage inter-client interference in wireless networks with full-duplex-capable access points that serve half-duplex clients. Our key contributions are two-fold. First, we identify the regimes in which power control provides sum throughput gains for the three-node atomic topology, with one uplink flow and one downlink flow. Second, we develop and benchmark PoCMAC, a full 802.11-based protocol that allows distributed selection of a three-node topology. The proposed MAC protocol is shown to achieve higher capacity as compared to an equivalent half-duplex counterpart, while maintaining similar fairness characteristics in single contention domain networks. We carried out extensive simulations and software-defined radio-based experiments to evaluate the performance of the proposed MAC protocol, which is shown to achieve a significant improvement over its half-duplex counterpart in terms of throughput performance.

Topology-Transparent Scheduling in Mobile Ad Hoc Networks With Multiple Packet Reception Capability

Recent advances in the physical layer have enabled wireless devices to have multiple packet reception (MPR) capability, which is the capability of decoding more than one packet, simultaneously, when concurrent transmissions occur. In this paper, we focus on the interaction between the MPR physical layer and the medium access control (MAC) layer. Some random access MAC protocols have been proposed to improve the network performance by exploiting the powerful MPR capability. However, there are very few investigations on the schedule-based MAC protocols. We propose a novel m-MPR-l-code topology-transparent scheduling ((m, l)-TTS) algorithm for mobile ad hoc networks with MPR, where m indicates the maximum number of concurrent transmissions being decoded, and l is the number of codes assigned to each user. Our algorithm can take full advantage of the MPR capability to improve the network performance. The minimum guaranteed throughput and average throughput of our algorithm are studied analytically. The improvement of our (m, l)-TTS algorithm over the conventional topology-transparent scheduling algorithms with the collision-based reception model is linear with m. The simulation results show that our proposed algorithm performs better than slotted ALOHA as well.

Busy tone contention protocol: a new high‐throughput and energy‐efficient wireless local area network medium access control protocol using busy tone

SUMMARYDesign of an efficient wireless medium access control (MAC) protocol is a challenging task due to the time‐varying characteristics of wireless communication channel and different delay requirements in diverse applications. To support variable number of active stations and varying network load conditions, random access MAC protocols are employed. Existing wireless local area network (WLAN) protocol (IEEE 802.11) is found to be inefficient at high data rates because of the overhead associated with the contention resolution mechanism employed. The new amendments of IEEE 802.11 that support multimedia traffic (IEEE 802.11e) are at the expense of reduced data traffic network efficiency. In this paper, we propose a random access MAC protocol called busy tone contention protocol (BTCP) that uses out‐of‐band signals for contention resolution in WLANs. A few variants of this protocol are also proposed to meet the challenges in WLAN environments and application requirements. The proposed BTCP isolate multimedia traffics from background data transmissions and gives high throughput irrespective of the number of contending stations in the network. As a result, in BTCP, admission control of multimedia flows becomes simple and well defined. Studies of the protocol, both analytically and through simulations under various network conditions, have shown to give better performance in comparison with the IEEE 802.11 distributed coordination function. Copyright © 2011 John Wiley & Sons, Ltd.