The Research Of Upstream Bandwidth Allocation Algorithms In OFDMA-PON

With the numerous advantages such as high capacity access, highspectral efficiency, flexible granularity bandwidth allocation, low cost andhigh dispersion-tolerance, Orthogonal Frequency Division MultiplexingAccess Passive Optical Network (OFDMA-PON) has been the focus of theoptical communcaiton systems. In OFDMA-PON system, dynamicbandwidth allocation (DBA) and the optimization of power consumptionare two great issues. DBA can improve the performance of the system,including system throughput, channel utilization, etc. Meanwhile,minimizing power consumption of the system is always necessary inpractical application as the power consumption of fiber optic systems goeshigher and higher.In this thesis, based on the two issues of DBA and power optimizationin OFDMA-PON, we carry out several theoretical researches andexperimental studies around the upstream bandwidth allocation algorithms.The details of the researches are as follows:(1) After analyzing the classical existing three Media Access Control(MAC) protocols, we propose a new MAC protocol for OFDAM-PON.From simulation results, compared with the existing MAC protocols, thenew proposed MAC protocol has lower average packet delay and higherspectral efficiency. Moreover, when the traffic load of the networkbecomes heavy, the novel proposed MAC has high throughput and highnetwork capacity.(2) In the upstream bandwith allocation based on the data length ofeach Optical Network Unit (ONU) in OFDMA-PON, we propose aRandmozied Dynamic Bandwidth Allocation (RDBA) algorithm. By thetheoretical analysis, the proposed RDBA algorithm has low computationalcomplexity and strong throughput reliability. From the simulation results,compared with the existing algorithms, the novel proposed RDBAalgorithm has higher throughput and lower average packet delay.(3) We have proposed an efficient Weight-value Dynamic BandwidthAllocation (WBDA) algorithm for upstream access in the OFDMA PON systems to support differentiated classes of services. There is two-levelscheduling, namely Inter-ONU bandwidth scheduling and Inner-ONUbandwidth scheduling, in this novel algorithm. From the simulation results,compared with the traditional Two-layer Bandwidth Allocation (TLBA)algorithm, the proposed algorithm not only has high throughputperformance and channel utility efficiency, but guarantees the Quality ofService (QoS) and improves the fairness among differentiated services.(4) We first transforme the problem of minimizing the totaltransmission power of ONUs in OFDMA-PON by satisfying each ONUtraffic requirement to a mathematical model. Then, based on the fiberchannel characteristics, we proposed two optimized three-dimensionalDBA algorithms to solve this model for minimizing the total transmissionpower of ONUs. In the first proposed3-Dimensional Dynamic BandwidthAllocation (3D DBA-1) algorithm, considering the fiber channelcharacteristics, we modified the wireless OFDM three dimensional DBAalgorithm and applied it to upstream access in OFDMA-PON. In order tofurther minimize the transmitting power of ONUs, we proposed the second3-Dimensional Dynamic Bandwidth Allocation (3D DBA-2) algorithm byallocating the subcarrier and bit in the same procedure to solve theproposed mathematical model. From simulation results, compared with thetraditional two-dimensional DBA algorithm in OFDMA-PON, thetransmitting power of ONUs under a certain bit error rate (BER) wasreduced by～30%and～50%using the proposed3D DBA-1and3DDBA-2algorithms, respectively. The performance of the3D DBA-2algorithm is better than that of the3D DBA-1algorithm. Furthermore, bythe complexity analysis, we find that the time complexity of the twoproposed algorithms is polynomial.