WiFlex: Multi-Channel Cooperative Protocols for Heterogeneous Wireless Devices

Abstract

Abstract-1 In ISM bands, many wireless protocols proliferate such as 802.11, Bluetooth, and ZigBee. However, these incompatible protocols create complex coexistence and connectivity problems. If the same trend continues, similar interference and performance problems will continue to exist in future unlicensed bands. As new unlicensed bands open up, one can take a different approach to spectrum sharing. Instead of proposing a new MAC protocol for each type of application, we propose a family of parameterized MAC protocols called WiFlex that can tailor to different application needs ranging from wireless sensors to media center. Yet, these protocols within this family are compatible with each other to allow communication and spectrum-sharing coordination among different types of devices. We envision this family to be based on an OFDM-like multichannel physical layer.The contribution of this paper includes the discovery of an asynchronous split phase (ASP) protocol with dynamic priority support. This protocol enables powerful devices to achieve a high throughput and protects low power devices with urgent but only occasional transmissions. It is distributed and data collision-free. Moreover, it can support low delays for real time applications.The performance of the protocols are evaluated using an extension of NS-2. The results demonstrate the coexistence of devices with disparate radio characteristics and the support of applications with different requirements with good performance.

Performance Modeling of Communication Networks with Markov Chains

“…• Note first that the entries of the columns of the matrices converge to the same value as the power of P increases.The difference of two values in the first column decreases from 0.35(0.6 − 0.25) in P to 0(0.3846 − 0.3846) in P (16) . After convergence, any row of the converged matrix, is a row vector equal to the steady state distribution.…”

“…If we calculate powers of matrix P, P (2) = 0.4600 0.5400 0.3375 0.6625 P (4) = 0.3938 0.6061 0.3788 0.6212 P (8) = 0.3848 0.6152 0.3845 0.6155 P (16) = 0.3846 0.6154 0.3846 0.6154 .…”

“…16 shows the state transition diagram of the multichannel example with three channels. The model is not a birth-and-death model since there is a possible transition from state 2 to state 0.…”

Energy-Efficient Strategies for Cooperative Multichannel MAC Protocols

“…Although this can be largely offset by the cooperation gain, it is still desired to reduce the overhead. One effective way is to use packet train to amortize the overhead, which was also used by MMAC [10], SSCH [14], and WiFlex [54]. We have adopted this technique in [55] for cognitive radio networks.…”

A Scalable Spectrum-Sharing Mechanism for Local Area Network Deployment

“…Unfortunately, as CSMA/CA is currently implemented [13], it is not scalable neither to high data rate nor to a large number of users [19]. In [20] the Authors proposed a cooperative multichannel MAC protocol solution which supports wireless devices of vastly different capabilities and applications with different requirements. A three phase asynchronous split MAC algorithm has been used to achieve spectral efficiency and fairness goals.…”