Dynamic Wavelength and Bandwidth Allocation Algorithms for Mitigating Frame Reordering in NG-EPON

The IEEE initialized a working group to study the 100 Gb/s next-generation passive optical networks (NG-EPON). A key technology adopted by NG-EPON is channel bonding, which enables optical network units (ONUs) to transmit data on multiple wavelength channels simultaneously to achieve higher peak rates. In the upstream, ONUs share the bandwidth of each wavelength in a time-division multiplexing manner, and dynamic wavelength and bandwidth allocation (DWBA) coordinates ONU upstream transmission. If an ONU is granted transmission of data on multiple wavelengths simultaneously, frame reordering will occur due to simultaneous parallel transmission, which needs to be minimized because buffer and extra processing time are needed to restore the original frame sequence. For a group of ONUs, DWBA can grant each ONU transmission on either a single wavelength or multiple wavelengths without affecting total bandwidth occupation. Since ONUs transmitting on single wavelength can get rid of frame reordering, different DWBA algorithms can result in different numbers of ONUs suffering frame reordering. In this paper, we investigate the impacts of DWBA algorithms on frame reordering in NG-EPON. A DWBA algorithm for mitigating frame reordering without affecting bandwidth utilization is proposed. The theoretical upper bound of a frame-reordered ONU number with the proposed algorithm is also analyzed. The performances (in terms of frame-reordered ONU number and packet delay) of DWBA algorithms are evaluated through simulations. Simulation results show that the proposed algorithm can mitigate frame reordering efficiently and reduce packet delay as well.