Performance Analysis of Unified Failure Model for Emerging WiMAX Networks

In this paper, we present a failure model for WiMAX network developed by considering the collision due to contention, unavailability of bandwidth and channel error assuming them as independent events. Using this model, the performance of bandwidth request based on contention resolution with exponential increase and exponential decrease (EIED) backoff is investigated and observed low contention efficiency with high access delay. Hence, we modify the EIED mechanism by computing the backoff factor with average contention window and estimating the response time from the transmission failure. Simulations validate the developed model with modified EIED backoff and shows better performance than conventional scheme.

Heuristic polling sequence to enhance sleep count of EPON

Next-generation passive optical networks(PONs)demand power conservation to create a green environment.A reduction in power consumption of the traditional Ethernet passive optical network(EPON)can be achieved by increasing the sleep count in optical network units(ONUs).In this paper,this is accomplished by introducing a first-in-last-out(FILO)polling sequence in the place of a fixed polling sequence to increase the number of ONUs entering sleep mode(sleep count).In a fixed polling sequence,the optical line terminal(OLT)allocates idle time to the ONUs based on the overall load of the ONUs.This leads to a situation that whenever the idle time does not meet the wakeup time threshold of sleep mode,the ONUs are put into doze/active mode,which consumes more power.In the FILO polling sequence,the first polled ONU in the current cycle is made to be polled last in the following cycle.Polling continues in this way,and by this rearrangement,the idle time of delayed poll ONUs increases;hence,it helps to reduce the power consumption.Additionally,a modified load adaptive sequence arrangement(MLASA)method is suggested,where the ONUs are categorized into doze ONUs and sleep ONUs.A numerical simulation of the FILO polling sequence with a vertical cavity surface emitting laser(VCSEL)ONU shows a maximum reduction in power consumption of 15.5 W and a 20%improvement in energy savings compared with the traditional fixed polling sequence.The MLASA method results in better power consumption with minimum delay than that of the proposed FILO and existing LASA methods.

Bridging electrical power and entropy of ONU in EPON

This letter deliberates bridging of overall electricity power requirements of the optical network unit(ONU) with the entropy noted through the ONU state transition models considered in ethernet passive optical network(EPON). The entropy depends on the steady state and transition probabilities of data. On the other hand, the power requirements(consumption) of ONUs depend on the steady sate probability of ONUs. The potential relation derived between the entropy and electrical power reveals that they related exponentially but for their logarithmic reliance. Also, the relation is validated through the numerical simulation. The deduced relation has its importance to understand the nuances of one entity given the other.