text: This paper introduces a protocol that distributively constructs a collision-free schedule for multi-hop packet radio networks in the presence of hidden terminals. As a preliminary step, each wireless station computes the schedule length after gathering information about the number of flows in its neighbourhood. Then, a combination of deterministic and random backoffs are used to reach a collision-free schedule. A deterministic backoff is used after successful transmissions and a random backoff is used otherwise. It is explained that the short acknowledgement control packets can easily result in channel time fragmentation and, to avoid this, the use of link layer delayed acknowledgements is advocated and implemented. The performance results show that a collision-free protocol easily outperforms a collision-prone protocol such as Aloha. The time that is required for the network to converge to a collision-free schedule is assessed by means of simulation.
  @cite_18: This paper proposes a semi-random backoff (SRB) method that enables resource reservation in contention-based wireless LANs. The proposed SRB is fundamentally different from traditional random backoff methods because it provides an easy migration path from random backoffs to deterministic slot assignments. The central idea of the SRB is for the wireless station to set its backoff counter to a deterministic value upon a successful packet transmission. This deterministic value will allow the station to reuse the time-slot in consecutive backoff cycles. When multiple stations with successful packet transmissions reuse their respective time-slots, the collision probability is reduced, and the channel achieves the equivalence of resource reservation. In case of a failed packet transmission, a station will revert to the standard random backoff method and probe for a new available time-slot. The proposed SRB method can be readily applied to both 802.11 DCF and 802.11e EDCA networks with minimum modification to the existing DCF EDCA implementations. Theoretical analysis and simulation results validate the superior performance of the SRB for small-scale and heavily loaded wireless LANs. When combined with an adaptive mechanism and a persistent backoff process, SRB can also be effective for large-scale and lightly loaded wireless networks.
  @cite_14: Carrier sense multiple access with collision avoidance (CSHA CA) has been the access protocol of choice for IEEE 802.11-based WLANs. In addition to channel sensing before transmission, the probability of a collision in these WLANs is typically reduced by the application of a binary exponential backoff (BEB) algorithm that randomizes the selection of the time slot in which a given station transmits. In a system without adaptive modulation and coding (AHC), the reduction in spectral efficiency caused by BEB is outweighed by the reduction in the number of collisions. In contrast, in systems using the ubiquitous auto rate fallback (ARF) AHC algorithm, which is unable to distinguish a collision from an erroneous transmission, the remaining collisions induce a dramatic drop in system performance. This degradation is caused by the utilization of low-rate transmission modes even when the channel conditions would permit the use of much higher-rate modes. In an attempt to further reduce the number of collisions, a variant of CSHA CA, called enhanced collision avoidance (CSHA E2CA), has been recently proposed. In this paper, a model approach to the performance evaluation of both BEB-based CSHA CA and CSHA E2CA, used in conjunction with ARF, is presented and validated. Results reveal the synergistic properties of the E2CA and ARF combination, as demonstrated by the superior goodput performance when compared against other strategies.
  @cite_3: 
  @cite_24: Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA ECA) is a recently proposed modification to the well-known CSMA CA protocol. By using a deterministic backoff after successful transmissions, the number of collisions decreases. This article presents a model that captures the behaviour of CSMA ECA in both saturated and non-saturated scenarios. The results, which are validated by simulations, show that CSMA ECA effectively prevents collisions and, therefore, it can deliver a higher throughput than CSMA CA.
  @cite_23: CSMA with Enhanced Collision Avoidance (CSMA ECA) uses a deterministic backoff after successful transmissions to significantly reduce the number of collisions. This paper assesses by means of simulations the throughput and conditional collision probability obtained from a single-hop ad-hoc network using CSMA ECA. A comparison with the legacy CSMA CA reveals that the proposed protocol outperforms the legacy one in all considered scenarios. Specifically, it is shown that CSMA ECA presents advantages for both rigid and elastic flows.
  @cite_5: 
summary: Later works have explored the validity of the idea for different kinds of traffic @cite_23 , modelled the network performance metrics @cite_24 , and studied the possibility of traffic differentiation @cite_5 . A comprehensive simulation study, together with a model of the learning process is presented in @cite_18 . This last paper also includes performance measures in non-ideal conditions, such as the presence of legacy stations or channel errors. More results regarding the learning process and fairness with legacy stations can be found in @cite_3 . An evaluation of a collision-free protocol and its interaction with the autorate fallback mechanism (ARF) in realistic multiple-input-multiple-output (MIMO) channels is presented in @cite_14 .