An overview of MAC issues in OFDMA-PON networks

The OFDMA-PON paradigm has recently emerged as a serious contender for next generation optical access networks. Its main characteristics are enhanced capacity, flexibility and scalability as opposed to current and upcoming TDMA-PONs as well as to the proposed WDM-PON concepts. In particular, OFDMA-PONs provide the opportunity for dynamically allocating the available optical bandwidth in multiple levels of granularity, both among different providers/services and users (groups of individual OFDM subcarriers can be arbitrarily assigned to different ONUs each time). Moreover, OFDM allows for adjustable modulation/bitrate on a subcarrier basis. It is evident that new challenges are imposed to the MAC layer and the associated Dynamic Bandwidth Assignment (DBA). This paper discusses all relevant issues and provides general guidelines for the design of an OFDMA-PON MAC layer protocol.