In most wireless ad-hoc multi-hop networks, a node competes
for access to the same wireless communication channel, often resulting in
collisions (interference) and ineffective carrier sensing. These issues have been
targeted through the medium access control (MAC) interconnection layer by a variety
of channel access schemes, towards improving how the nodes share the wireless
channel and achieve a high quality of service. For example, there are contention-based
MAC schemes, like Carrier-Sense Multiple Access (CSMA) and Additive Links
On-Line Hawaii Area (ALOHA), and contention-free MAC schemes, like time
division multiplexing access (TDMA). However, the former is a poor performer in
hidden- and exposed-terminal environments, and the latter, where the node
system is time-synchronized and the time frame is divided and multiple
time-slots are allocated to the nodes, has limited data rates (bandwidth) and undesirable
Over the years, there have been many other MAC schemes that address interference and conflict, as well as improving criteria like throughput, fairness, latency, energy, and overhead. These modern protocols implement more sophisticated distributed transmission queues consisting of a sequence of transmission turns that grows and shrinks on demand. However, challenges remain in these more recent MAC protocols, such as long delays for allowing nodes to join the network, and/or the use of transmission frames with complex structures to allocate time slot portions to signaling packets for elections.
To overcome these challenges, researchers at UC Santa Cruz (UCSC) have developed a new networking protocol called Key-Activation Multiple Access (KAMA). KAMA is designed to match the high throughput of topology-dependent scheduling schemes based on elections with the transmission frame simplicity of topology-independent scheduling schemes, like TDMA. The novel protocol processes new node arrivals without the need for special signaling packets (i.e., does not require bandwidth) and without dedicating time slots for such packets or the use of mini-slots. UCSC research results showed in concept that KAMA is the state-of-the-art in distributed transmission scheduling scheme by achieving near-optimal channel utilization in steady state.
ad-hoc multi-hop networks
collision avoidance, data packet, Multiple Access Interference, networking, network protocols, networks, wireless networks, multi-hop wireless networks, CSMA, TDMA, medium access control