Appendix 3.A: Using RS Code in Tactical Networks Transport Layer
This appendix presents a transport layer hybrid ARQ (automatic repeat request) technique that uses adaptive RS codes with packet erasure.19 The technique considers the existence of HAIPE encryption, where decryption erases the entire IP packet if it contains any error.20 Please refer to Section 1.4 and Figure 1.5 to see where the transport layer and the ComSec (HAIPE) encryption layers relate to each of the other layers in the tactical wireless networks protocol stack layers. This technique uses a multifaceted optimization of RS codes at the transport layer for delivery assurance, speed of service (SoS), and network throughput. The goal is for the transport layer in tactical wireless networks to fulfill the stringent requirements of QoS, imposed by the tactical network user, even under adverse conditions. These requirements define a high level of reliability (delivery assurance), a specific SoS, and optimum use of the limited bandwidth of the wireless network, where the probability of packet erasure can be very high. On one hand, focusing on network throughput alone will result in violating SoS and delivery assurance requirements. On the other hand, focusing on SoS and delivery assurance requirements can result in poor network throughput. The analysis for the optimization technique uses a homogeneous Markov chain approach to reach the desired balance between reliability, SoS, and throughput efficiency needs.