Delay analysis of Ethernet passive optical networks with gated service

Abstract

We analyze the mean packet delay in an Ethernet passive optical network (EPON) with gated service. For an EPON with a single ONU, we derive (i) a closed form delay expression for reporting at the end of an upstream transmission, and (ii) a Markov chain based approach requiring the numerical solution of a system of equations for reporting at the beginning of an upstream transmission. Reporting at the beginning, which has not been previously examined in detail, achieves significantly smaller delays than reporting at the end of an upstream transmission for a small number of ONUs. Both of these analyses are fundamentally different from existing polling system analyses in that they consider the dependent switchover times of the EPON. We extend the analysis for reporting at the beginning of an upstream transmission to approximate the mean packet delay in an EPON with multiple ONUs and verify the accuracy of the analysis with simulations. Overall, our numerical results indicate that for utilizations up to around 75%, the mean packet delay is close to its minimum of four times the one-way propagation delay.

Shortest propagation delay (SPD) first scheduling for EPONs with heterogeneous propagation delays

“…This scenario resembles the case of a single ONU treated in [61]. Inserting τ HL := (1) and (39) in [61], namely…”

FiWi Access Networks Based on Next-Generation PON and Gigabit-Class WLAN Technologies: A Capacity and Delay Analysis

“…For Poisson frame traffic, the downstream queueing delay is thus modeled by an M/G/1 queue characterized by the Pollaczek-Khintchine formula [46] (8) giving the total downstream frame delay (9) Weighing the downstream delays in the sectors by the relative downstream traffic intensities in the sectors, gives the average downstream delay of the wavelengthrouting multistage WDM PON (10) For the upstream delay, we model each wavelength channel , as a single upstream wavelength channel of a conventional EPON. Accordingly, from (39) in [47], we obtain for the mean upstream delay of sector (11) and the average upstream delay of the wavelength-routing multistage WDM PON equals (12) To improve the accuracy of our delay analysis, we take into account that traffic coming from an ONU in sector and destined to ONU in sector is queued at the intermediate OLT before being sent downstream to ONU , i.e., the OLT acts like an insertion buffer between ONUs and . Consequently, to compensate for the queueing delay at the OLT we subtract the correction term proposed in [48] (13) whereby for the setting that for all channels (14) denotes the rate of upstream traffic in sector destined for sector , from the above calculated mean downstream delay.…”

Offline and Online Multi-Thread Polling in Long-Reach PONs: A Critical Evaluation

“…Elementary grant sizing mechanisms are gated grant sizing, which allocates the full ONU request and can lead to fairness issues, and limited grant sizing, which allocates the ONU request up to a prescribed limit, thus preserving fairness [28]- [30]. Grant sizing has a significant influence on PON performance and can be aided by traffic prediction [31]- [37].…”