To avoid forwarding loops and the transmission of unwanted replicas of multicast data packets, current multicast routing protocols designed for ad-hoc networks require routers to use packet caches listing enough information about multicast data packets that have been forwarded. In addition, existing multicast-routing solutions for ad-hoc networks either require a multicast routing protocol that operates concurrently with a unicast routing protocol, or adding substantial signaling to the baseline unicast routing protocol. We introduce a new approach for multicasting embedded in unicast routing that eliminates the need to use packet caches for multicasting along shared multicast trees by means of label switching, and incurs minimum additional signaling overhead to attain multicast routing.

RIPPLE-WiN (Routing Information Protocol with Probing for Looplessness and Efficiency in Wireless Networks) is introduced. RIPPLE-WiN replaces the sequence numbers that are used in popular routing protocols for wireless networks like OLSR, AODV and DSDV to validate updates or support loop freedom with hop-count reference distances. Such reference distances allow routers to eliminate routing-table loops with minimum signaling overhead. Simulation experiments based on the ns-3 simulator are used to illustrate that RIPPLE-WiN is much more effective that OLSR, DSDV and AODV. The simulation results show that RIPPLE-WiN attains better packet delivery rates and delays than the other routing protocols in the presence of failures and mobility while incurring less signaling overhead.

ALOHA with priority acknowledgments (ACK) is transformed into a collision-free channel access method by means of a neighborhood-understood index (NUI). Each node maintains the NUI, which allows nodes to remember all nodes that requested to share the channel and the order in which they should be allowed to transmit. The resulting protocol, ALOHA-NUI, adds signaling packets and NUI information in data packets to maintain the NUI, rather than just remembering that a data packet was sent successfully as in ALOHA. This results in ALOHA-NUI, which is compared with TDMA assuming a fixed transmission schedule, ALOHA with priority ACK’s, and CSMA with priority ACK’s analytically and by simulation. ALOHA-NUI is shown to attain the high throughput of collision-free transmission scheduling methods that usually require clock synchronization while maintaining most of the simplicity of ALOHA with priority ACK’s. ALOHA-NUI is also shown to be fair and to reach stable transmission schedules very quickly.

The Scheduling with Interference Removal Established Network-Wide (SIREN) protocol is introduced to enable the scheduling of transmissions in a way that multiple access interference (MAI) is eliminated in multi-hop networks. Unlike all prior medium access control (MAC) methods, SIREN combats MAI as a network-wide problem rather than as a problem confined within a single broadcast link. SIREN ensures that the receivers of a primary transmitter assigned a transmission turn have no MAI, and allow one or multiple concurrent secondary transmitters to transmit during the same transmission turn, as long as no MAI is created. SIREN is implemented on top of the IEEE 802.11b physical layer to show that it is a viable approach using commercial off-the-shelf hardware. SIREN is proven to ensure interference-free transmission schedules in mesh networks, and simulation experiments in ns-3 are used to illustrate the advantages of SIREN over IEEE 802.11b in terms of goodput, fairness and delays.

Key-Activation Multiple Access (KAMA) is introduced. KAMA organizes the channel into a sequence of equal time slots, uses a distributed election algorithm to determine which of the known nodes have the priority to transmit during each time slot, and uses transmission keys to eliminate the need for special signaling packets or the use of special time slots dedicated for signaling packets. Simulation results in multi-hop networks shown that KAMA is more efficient than TDMA, CSMA, and CSMA/CA.

ALOHA with Queue Sharing (ALOHA-QS) maintains most of the simplicity of ALOHA with priority acknowledgments (ACK) and attains the high throughput of transmission scheduling methods that require clock synchronization. Channel access with ALOHA-QS consists of a sequence of queue cycles, with each cycle having one or multiple collision-free transmissions by nodes that have joined the transmission queue and a single request turn to join the queue. The signaling of ALOHA-QS entails adding to packet headers the size of the shared queue, the position of the sending node in the queue, a bit indicating the end of transmissions by the transmitting node, and a bit stating whether or not a new node joined the queue successfully. The throughput of ALOHA-QS is compared with the throughput of TDMA with a fixed transmission schedule, ALOHA with priority ACK's, and CSMA with priority ACK's analytically and by simulation.

Queue-Sharing Multiple Access (QSMA) is introduced and analyzed. The new channel-access method consists of establishing and maintaining a distributed transmission queue among nodes sharing a common channel and results in a sequence of queue cycles, with each cycle having one or multiple queue turns with collision-free transmissions from nodes that have joined the transmission queue, followed by a joining period for the current cycle. Nodes can take advantage of carrier sensing to improve the efficiency with which nodes join and use the shared transmission queue. The throughput of ALOHA with priority ACK's, CSMA with priority ACK's, CSMA/CD with priority ACK's, TDMA with a fixed schedule, and QSMA with and without carrier sensing is compared analytically and by simulation in ns-3. The results show that QSMA is more efficient than TDMA with the simplicity of CSMA or ALOHA.