Max-Min Fairness for TCP Flow in MANET

High speed satellite networks are emerging fast in the communication domain. Bandwidth Delay Products (BDP) plays an important role in the design of a congestion control algorithm for the effective usage of network resources. Bandwidth delay products (BDPs) are referred as the maximum amount of unacknowledged data that allowed in flight at any moment in the network. TCP is originally designed for a general wired network. In case of BDP, packet losses rarely occur. TCP can no longer guarantee good bandwidth utilization.

Solutions proposed to provide reliable packet delivery in MANETs are non TCP variants and TCP variants. Non TCP variants focus on the modification of congestion control algorithms in the transport protocol. It requires complicated mathematical computation and incur excessive network overhead. Although relatively accurate congestion information obtained, it cannot retain the end-to-end semantics of a transport protocol.

 The work presented in this paper extends the Datagram Transport Protocol over Ad Hoc Networks (DTPA) for efficient adaptable MANETs in the changing network scenario. The extension is carried out by achieving fairness in the TCP flow of the MANET with adaptive Max-Min Fairness algorithm. The extended work incorporates a fixed size window based flow control algorithm and a cumulative bit vector based SACK (selective ACK) strategy. Simulation carried out guarantees reliable transmission and recovering packet losses. It improves the network performance in terms of throughput, round trip time, number of retransmissions, and IP queue size demonstrated by simulation conducted using NS2.