3,134 research outputs found
Cooperative and fair MAC protocols for cognitive radio ad-hoc networks
A secondary user (SU) in multichannel cognitive
radio ad hoc network (CRAHN) has a limited transmission
range, which may raise a hidden multichannel sensing
problem. In addition, CRAHNs can be deployed ubiquitously,
and SUs from any CRAHNs could co-exist utilizing
the spectrum. This situation leads to the fairness issue of
spectrum resource sharing between the SUs. Both cooperative
and fairness issues are important to CRAHN performance.
In this paper, a cooperative and a non-cooperative
multichannel (MC)-MAC protocol is proposed. In order to
address the fairness issue, a fair multichannel (FMC)-MAC
protocol for CRAHN is proposed, which orientates to the
fairness in resource sharing. In this FMC-MAC, the SU
keeps the current backoff (CB) counter when a PU appears
to claim the intended channel. These proposed MAC protocols
are simulated using NS2 and compared with other
protocols. In addition, a mathematical model using Markov
chain is constructed for FMC-MAC and the performance
measures are derived. From results, the MC-MAC protocol
has enhanced the network utilization and the cooperative
scheme has significantly enhanced the packet delivery ratio
and decreased the end-to-end delay of SUs in high traffic.
The cooperative protocol enhances packet delivery ratio up
to 15 % and decreases end-to-end delay down to 32 %,
compared to the non-cooperative one. The FMC-MAC
protocol with other two existing protocols. From the
comparison results, a higher fairness has been shown by
FMC-MAC CB while still maintaining a high throughput
An analysis on decentralized adaptive MAC protocols for Cognitive Radio networks
The scarcity of bandwidth in the radio spectrum has become more vital since the demand for more and more wireless applications has increased. Most of the spectrum bands have been allocated although many studies have shown that these bands are significantly underutilized most of the time. The problem of unavailability of spectrum and inefficiency in its utilization has been smartly addressed by the Cognitive Radio (CR) Technology which is an opportunistic network that senses the environment, observes the network changes, and then using knowledge gained from the prior interaction with the network, makes intelligent decisions by dynamically adapting their transmission characteristics. In this paper some of the decentralized adaptive MAC protocols for CR networks have been critically analyzed and a novel adaptive MAC protocol for CR networks, DNG-MAC which is decentralized and non-global in nature, has been proposed. The results show the DNG-MAC out performs other CR MAC protocols in terms of time and energy efficiency
- …