Time division multiple access(TDMA) protocol has been applied to various wired and wireless communication network including passive optical network(PON). The purpose of this TDMA protocol is to avoid the packet collisions in shared medium and then provides reliable communications. It also provides a predictable transfer delay.
In TDMA systems, the bandwidth allocation method affects significantly the system performances, such as channel utilization, latency, jitter, and packet loss.
In order to analysis the queuing delay in TDMA system, we used the centralized point to multi-point(P2MP) topology. The upstream data(or packets) from the node to the access point(AP) is authorized by the AP. There are two bandwidth allocation methods in TDMA system. One is the static bandwidth allocation(SBA) method for guaranteed bandwidth service and the other is the dynamic bandwidth allocation(DBA) method for on-demand and dynamic traffic services.
In order to reduce the bandwidth allocation complexity, we assume that bandwidth allocation methods have a cycle period in our analysis. And also, for the purpose of simplifying analysis, we assume that the allocated time period for a node is equal to the required bandwidth of the node. From these assumptions, we derived simplified formulas to estimate the required queue size and the queuing delay is proportional to the cycle time and the arrival data rate according to the SBA and the DBA method.
To confirm the reliability of our analysis model, we measured the average transfer delay from one optical network unit(ONU) to optical line Terminal(OLT) in PON system. From our experimental results, the measured average transfer delay is almost equal to the theoretical queuing delay.
In this paper, we proposed a model of the queue operation in cyclic bandwidth allocation TDMA system and derived formulas to estimate the required queue size and the queuing delay from the model. In the queue modelling, we used cyclic bandwidth allocation algorithm which allocate the bandwidth periodically for multiple access control.
From our simplified numerical analysis, we can estimate intuitively the required queue size and the queuing delay in the cyclic bandwidth allocation TDMA system. It is expected very useful in the design and implementation of centralized network system, such as PON.