This paper proposes and analyzes a distributed MAC protocol that achieves zero collision with no control message exchange nor synchronization. ZC (ZeroCollision) is neither reservation-based nor dynamic TDMA; the protocol supports variable-length packets and does not lose efficiency when some of the stations do not transmit. At the same time, ZC is not a CSMA; in its steady state, it is completely collision-free. The stations transmit repeatedly in a round-robin order once the convergence state is reached. If some stations skip their turn, their transmissions are replaced by idle @math -second mini-slots that enable the other stations to keep track of their order. Because of its short medium access delay and its efficiency, the protocol supports both real-time and elastic applications. The protocol allows for nodes leaving and joining the network; it can allocate more throughput to specific nodes (such as an access point). The protocol is robust against carrier sensing errors or clock drift. While collision avoidance is guaranteed in a single collision domain, it is not the case in a multiple collision one. However, experiments show ZC supports a comparable amount of goodput to CSMA in a multiple collision domain environment. The paper presents an analysis and extensive simulations of the protocol, confirming that ZC outperforms both CSMA and TDMA at high and low load.
Some protocols as in @cite_22 and @cite_13 are classified as dynamic TDMA. Time is divided into a sequence of frames and each frame consists of at least two constant-length phases - one control phase which is used for competition for slot allocation via random access, auction @cite_6 @cite_0 @cite_29 , or distributed election @cite_10 and the remaining phase(s) which is (are) devoted to data @cite_13 . Stations are synchronized at start of each phase, except for some cases as in @cite_19 and @cite_5 . TRAMA @cite_10 , MMAC @cite_19 and their derivatives belong to this class in the context of wireless sensor networks.
@cite_22 @cite_10 @cite_29 @cite_6 @cite_0 @cite_19 @cite_5 @cite_13
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The Wideband (packet satellite) network is an experimental 3 Mbit s communications system developed under sponsorship of the Defense Advanced Research Projects Agency and the Defense Communications Agency. This system is being used to evaluate the use of packet transmission for efficient voice communication, voice conferencing, and integration of voice and data over a satellite channel. Each station in the Wideband network consists of an earth terminal (dedicated 5 m antenna plus associated IF RF equipment), a burst-modem and codec unit, and a station controller. Station controllers provide interfaces to host computers (including packet speech sources) and manage the allocation of the satellite channel on a TDMA demand-assigned basis. TDMA demand-assignment is implemented using a reservation-based packet-oriented protocol capableof handling traffic at multiple priority levels. The channel protocol provides a reservation-per-message mode of service (datagrams) to support transmission from bursty traffic sources and a reservation-per-call mode of service (streams) to support traffic with more regular arrival statisticS (e.g., vioce). A distributed scheduler running in every station controller eliminates the need for a central control station and minimizes network transit delay for datagram transmission as well as stream creation, modification, and deletion. In this paper we describe the protocols and mechanisms upon which the Wideband packet satellite network is based. The traffic-adaptive medium access protocol (TRAMA) is introduced for energy-efficient collision-free channel access in wireless sensor networks. TRAMA reduces energy consumption by ensuring that unicast, multicast, and broadcast transmissions have no collisions, and by allowing nodes to switch to a low-power, idle state whenever they are not transmitting or receiving. TRAMA assumes that time is slotted and uses a distributed election scheme based on information about the traffic at each node to determine which node can transmit at a particular time slot. TRAMA avoids the assignment of time slots to nodes with no traffic to send, and also allows nodes to determine when they can become idle and not listen to the channel using traffic information. TRAMA is shown to be fair and correct, in that no idle node is an intended receiver and no receiver suffers collisions. The performance of TRAMA is evaluated through extensive simulations using both synthetic- as well as sensor-network scenarios. The results indicate that TRAMA outperforms contention-based protocols (e.g., CSMA, 802.11 and S-MAC) as well as scheduling-based protocols (e.g., NAMA) with significant energy savings. In this paper, we present a new collision-free MAC protocol-carrier sense media access with ID countdown (CSMA IC) for ad hoc wireless networks that can achieve 100 collision-free performance by solving the "hidden terminal" problem and the concurrent sending problem. Compared to CSMA IC of IEEE 802.11, it also improves the network's performance in decreasing the network's throughput significantly. Furthermore, it can enable different packets with different priority to access the media and thus gain QoS. Although collision free TDMA schemes have been proposed and used for more than two decades, an important ingredient of these schemes, the initialization of stations (that is, assigning ID numbers 1,2,...,n) was not investigated until recently. Binary and n-ary partitioning algorithms were recently proposed for the case of stations with collision detection capability. The main contribution of this paper is a new randomized hybrid initialization protocol which combines the two partitioning algorithms into a more efficient one. The new scheme optimizes the binary partition protocol for small values of n (e.g. n=2, 3, 4). The hybrid scheme then applies n-ary partition protocol on the whole set, followed by binary partition on the stations that caused collision. We proved analytically that the expected number of time slots in the hybrid algorithm with known number of users is <2.20? n. Performance of these algorithms was also evaluated experimentally by comparing it with existing algorithms, and an improvement from e? n to approximately 2.15? n was obtained. Mobility in wireless sensor networks poses unique challenges to the medium access control (MAC) protocol design. Previous MAC protocols for sensor networks assume static sensor nodes and focus on energy-efficiency. In this paper, we present a mobility-adaptive, collision-free medium access control protocol (MMAC) for mobile sensor networks. MMAC caters for both weak mobility (e.g., topology changes, node joins, and node failures) and strong mobility (e.g., concurrent node joins and failures, and physical mobility of nodes). MMAC is a scheduling-based protocol and thus it guarantees collision avoidance. MMAC allows nodes the transmission rights at particular time-slots based on the traffic information and mobility pattern of the nodes. Simulation results indicate that the performance of MMAC is equivalent to that of TRAMA in static sensor network environments. In sensor networks with mobile nodes or high network dynamics, MMAC outperforms existing MAC protocols, like TRAM A and S-MAC, in terms of energy-efficiency, delay, and packet delivery. A centralized, integrated voice data radio network for fading multipath indoor radio channels is proposed and analyzed. The packets of voice and data are integrated through a movable boundary method. The uplink channel access uses a framed-polling protocol whereas the downlink uses a time-division multiple-access (TDMA) scheme. This system dynamically switches between two transmission rates and uses multiple antennas to maximize the throughput in the fading multipath indoor environment. Throughput and delay characteristics of the system are analyzed using four different techniques. The results are compared with those of Monte Carlo computer simulations. A simple relationship between the number of voice terminals and the throughput of the data traffic are derived for an upper bound of 10-ms delay for the data packets. >