Quality of service for tactical data links: TDMA with dynamic scheduling

In this paper we focus on demand-assigned multiple-access (DAMA) MAC protocols utilizing time division multiple access (TDMA). In TDMA, the channel is broken down into time slots of equal duration, and nodes are allocated slots in which to transmit their data. Slots can be preassigned prior to a mission or can be allocated dynamically as the need arises. Herein, we develop and simulate two dynamic allocation algorithms: the first provides fair scheduling of data, while the second provides strict priority scheduling of data. These protocols are simulated in a Tactical Targeting Network Technologies (TTNT) single-strike scenario which is a 78-node scenario with a varied traffic profile. We compare the performance of the fair scheduling and strict priority scheduling algorithms against a preassigned TDAM protocol. In addition to the scheduling algorithms two classification methods are used in these experiments, the first based on packet size and the second based on both message type and packet size. We find that adding dynamic allocation improves overall bandwidth utilization over the preassigned TDAM protocol for either type of classification. However classification based on packet size alone is not effective in providing service differentiation. Classification based on message type and packet size used with the strict priority scheduling offers the best priority treatment for this traffic profile.