Future Evolution of CSMA Protocols for the IEEE 802.11 Standard

In this paper a candidate protocol to replace the prevalent CSMA/CA medium access control in Wireless Local Area Networks is presented. The proposed protocol can achieve higher throughput than CSMA/CA, while maintaining fairness, and without additional implementation complexity. Under certain circumstances, it is able to reach and maintain collision-free operation, even when the number of contenders is variable and potentially large. It is backward compatible, allowing for new and legacy stations to coexist without degrading one another's performance, a property that can make the adoption process by future versions of the standard smooth and inexpensive.Comment: This paper has been accepted in the Second IEEE ICC Workshop 2013 on Telecommunication Standards: From Research to Standard

E-MAC: an evolutionary solution for collision avoidance in wireless ad hoc networks

Transmission collision is a main cause of throughput degradation and non-deterministic latency in wireless networks. Existing collision-avoidance mechanisms for distributed wireless networks are mostly based on the random backoff strategy, which cannot guarantee collision-free accesses. In this paper, we design a simple collision-avoidance MAC (E-MAC) for distributed wireless networks that can iteratively achieve collision-free access. In E-MAC, each transmitter will adjust its next transmission time according to which part of its packets suffering from the collision. And the iteration of this adjustment will quickly lead group of nodes converging to a collision-free network. E-MAC does not require any central coordination or global time synchronization. It is scalable to new entrants to the network and variable packet lengths. And it is also robust to system errors, such as inaccurate timing.Transmission collision is a main cause of throughput degradation and non-deterministic latency in wireless networks. Existing collision-avoidance mechanisms for distributed wireless networks are mostly based on the random backoff strategy, which cannot guarantee collision-free accesses. In this paper, we design a simple collision-avoidance MAC (E-MAC) for distributed wireless networks that can iteratively achieve collision-free access. In E-MAC, each transmitter will adjust its next transmission time according to which part of its packets suffering from the collision. And the iteration of this adjustment will quickly lead group of nodes converging to a collision-free network. E-MAC does not require any central coordination or global time synchronization. It is scalable to new entrants to the network and variable packet lengths. And it is also robust to system errors, such as inaccurate timing

Addressing Slot Drift in Decentralized Collision Free Access Schemes for WLANs

Decentralized Collision-Free Access (DCFA) schemes are an appealing family of MAC mechanisms in WLANs due to their good system throughput and decentralized nature. In this paper we consider the problem of slot drift for these schemes and provide evidence that DCFA can be vulnerable to such problems. We propose two schemes to enhance DCFA in this regard: Global View Synchronization (GVS) and Smart Collision Free (SCF). GVS aims to provide slot indexing, which helps stations correct their counters after drift. SCF accelerates the convergence process to the collision-free state for WLANs, and so reduces the impact of drift. Simulation results show that both GVS and SCF improve the system performance in the presence of slot drift

Addressing Slot Drift in Decentralized Collision Free Access Schemes for WLANs

Abstract. Decentralized Collision-Free Access (DCFA) schemes are an appealing family of MAC mechanisms in WLANs due to their good system throughput and decentralized nature. In this paper we consider the problem of slot drift for these schemes and provide evidence that DCFA can be vulnerable to such problems. We propose two schemes to enhance DCFA in this regard: Global View Synchronization (GVS) and Smart Collision Free (SCF). GVS aims to provide slot indexing, which helps stations correct their counters after drift. SCF accelerates the convergence process to the collision-free state for WLANs, and so reduces the impact of drift. Simulation results show that both GVS and SCF improve the system performance in the presence of slot drift