on the analysis of the existing transmission modes and challenges of mobile ad hoc
networks, a multi-mode transmission method with self-adaptation is proposed for intraflight ad hoc networks to guarantee business transmission reliability under high
dynamic environment, and to improve the overall transmission capacity meanwhile.
2 Related Works
Since topology changes dynamically, link quality is not stable, and routing paths are
not always there in mobile ad hoc networks, the standard TCP protocol is improved by
many scholars, to avoid the dropping of network throughput caused by a slow start and
fast retransmission, which is triggered by TCP data packet loss or out-of-order.
The TCP improvement schemes are as follows.
Kim KB and Chandran K et al. introduced TCP-feedback mechanisms, improving
the performance of transmission control protocol, and dealing with the problem of
routing faults based on network state feedback in ad hoc networks [3, 4]. Compared
with the original TCP, these methods improved the throughput of ad hoc networks,
since the TCP sender can continue to carry out packet transmission in large windows
after the routing reconstruction. Prajapati HB proposed feedback mechanisms based on
cross-layer ELFN (Explicit Link Failure Notification), to decide if TCP enters the
standby mode or the normal operating condition, by sensing the information interaction
between the intermediate nodes and the sender [5]. Based on ELFN notices, Sengottaiyan N proposed EPLN-BEAD (Early Packet Loss Notification and Best-Effort
Acknowledge Delivery) mechanism, in order to distinguish whether data packets or
confirmation packets are lost, and then to reduce the TCP timeout events and improve
throughput of mobile ad hoc networks [6].
The proposed improvements to TCP for mobile ad hoc networks include ATCP
(Ad hoc TCP) and TCP-BuS (TCP Buffering capability and Sequence information) [7,
8]. The former inserts the middle layer between the transport layer and the network
layer on the sending end. And the middle tier monitors information from the network
layer, and gives feedback to TCP. Meanwhile, through monitoring the number of
received acknowledge packets to determine the merits of the channel, in order to solve
the poor performance of the transport layer owing to the routing problem or high bit
error rate conditions; The latter also uses the feedback information of the network layer
to detect the routing failure and then adopts the corresponding strategy, and in the route
reconstruction process, the related packets from the source node to the intermediate
node will be cached.
In addition, in response to the transmission spectrum switching of cognitive
wireless network, some researchers proposed TCP improved protocol TCP-CR (Cognitive Radio) based on cross-layer mechanism between TCP and MAC, to solve the
problem of TCP timeout retransmission and frequent slow start caused by frequency
spectrum switching, and to improve the channel utilization, transmission efficiency and
the end-to-end throughput [9, 10].
Schemes mentioned above mainly use the feedback information from network layer
and link layer, to distinguish reasons for packet loss, such as network congestion,
routing failure or link failures, to improve the transmission efficiency by improving the
362
S. Huang
networks, a multi-mode transmission method with self-adaptation is proposed for intraflight ad hoc networks to guarantee business transmission reliability under high
dynamic environment, and to improve the overall transmission capacity meanwhile.
2 Related Works
Since topology changes dynamically, link quality is not stable, and routing paths are
not always there in mobile ad hoc networks, the standard TCP protocol is improved by
many scholars, to avoid the dropping of network throughput caused by a slow start and
fast retransmission, which is triggered by TCP data packet loss or out-of-order.
The TCP improvement schemes are as follows.
Kim KB and Chandran K et al. introduced TCP-feedback mechanisms, improving
the performance of transmission control protocol, and dealing with the problem of
routing faults based on network state feedback in ad hoc networks [3, 4]. Compared
with the original TCP, these methods improved the throughput of ad hoc networks,
since the TCP sender can continue to carry out packet transmission in large windows
after the routing reconstruction. Prajapati HB proposed feedback mechanisms based on
cross-layer ELFN (Explicit Link Failure Notification), to decide if TCP enters the
standby mode or the normal operating condition, by sensing the information interaction
between the intermediate nodes and the sender [5]. Based on ELFN notices, Sengottaiyan N proposed EPLN-BEAD (Early Packet Loss Notification and Best-Effort
Acknowledge Delivery) mechanism, in order to distinguish whether data packets or
confirmation packets are lost, and then to reduce the TCP timeout events and improve
throughput of mobile ad hoc networks [6].
The proposed improvements to TCP for mobile ad hoc networks include ATCP
(Ad hoc TCP) and TCP-BuS (TCP Buffering capability and Sequence information) [7,
8]. The former inserts the middle layer between the transport layer and the network
layer on the sending end. And the middle tier monitors information from the network
layer, and gives feedback to TCP. Meanwhile, through monitoring the number of
received acknowledge packets to determine the merits of the channel, in order to solve
the poor performance of the transport layer owing to the routing problem or high bit
error rate conditions; The latter also uses the feedback information of the network layer
to detect the routing failure and then adopts the corresponding strategy, and in the route
reconstruction process, the related packets from the source node to the intermediate
node will be cached.
In addition, in response to the transmission spectrum switching of cognitive
wireless network, some researchers proposed TCP improved protocol TCP-CR (Cognitive Radio) based on cross-layer mechanism between TCP and MAC, to solve the
problem of TCP timeout retransmission and frequent slow start caused by frequency
spectrum switching, and to improve the channel utilization, transmission efficiency and
the end-to-end throughput [9, 10].
Schemes mentioned above mainly use the feedback information from network layer
and link layer, to distinguish reasons for packet loss, such as network congestion,
routing failure or link failures, to improve the transmission efficiency by improving the
362
S. Huang