Nowadays, efficient support for both time-critical and best-effort traffic in the same Local Area Net- works (LANs) is essential [1, 2] The MAC protocols for such MLANs must provide not only bounded mes- sage transmission time, as required by the hard and soft real-time tasks, but also high throughput, as de- manded by non real-time tasks that relies on best- effort services [3, 4, 5, 6]. An attractive MAC ap- proach for such networks is the timed-tokenprotocol. Consequently, the timed-tokenprotocol has been in- corporated into several high-bandwidth network stan- dards , such as, IEEE802.4 Token Bus LAN  , Fiber Distributed Data Interface (FDDI) [9, 10, 11, 12, 13 ] SAFENET , Manufacturing Automation Protocol (MAP) , High-Speed Ring Bus , in PROFIBUS , and in wireless networks [18, 19, 20]. The STOGSTT protocol is a version of the timed- tokenprotocol developed to improve the communi- cation services provided by the existing timed-token protocols . Nevertheless, the throughput of the STOGSTT protocol drops whenever some of the nodes do not have asynchronous traffic to transmit. That means, if n is the number of nodes that are heav- ily loaded with asynchronous traffic, where 1 ≤ n ≤ N , the throughput of the STOGSTT protocol drops
G UARANTEEING message deadlines is a key issue in distributed real-time applications. The timedtoken medium access control (MAC) protocol ,  is suitable for real-time applications due to its special timing property of bounded token rotation time. With this protocol , messages are distinguished into two types: synchronous and asynchronous. Synchronous messages are periodic with delivery time constraints. Asynchronous messages are nonperiodic with no delivery time constraints. During network initialization time, all nodes negotiate a common value for the Target Token Rotation Time (T T RT) which should be small enough to meet responsiveness requirements of all nodes. Each node i is assigned a fraction of the T T RT, denoted as H i , as its
The four upper layers are mainly logical and the rest are considered physical. The physical layer of wireless network therefore transmits bits and receives bits in wireless medium, while Medium Access Control (MAC) coordinates the packet transmission using the medium formed by a number of bits . However, this existing MACprotocol does not provide ‘smart’ protocol for user since it does not have the feedback element to improve the quality of network link. This may contributes to few problems due to poor link quality such as packet loss or collision during the data transmission.
We propose an optimized slot scheduling protocol that improves the energy efficiency of data transmission over industrial WSNs. In our approach, one big slot is allocated for all nodes at each tree level and shared by the nodes for data transmission to their respective parents. Since the nodes at the lower tree levels have to process much more data packets, thus have higher probability of collision. Our approach, therefore, suggests for a demand (length of a slot) based slot allocation according to tree level by a wait time generation function. The approach lowers the probability of collisions, thus minimizes the number of packet retransmission, which is definitely a major reason for energy wastage. We are also able to reduce the competition among nodes because only those nodes that belong to the same tree level are allowed to contend for wireless channel. Moreover, we optimize the energy consumption at various points in a big slot scheduling by allowing a node to enter sleep mode whenever possible. We analytically show that our approach is energy efficient and prove our claim by simulation experiments.
model. However, in our setting, we face a new challenge. Since our final protocol can be executed on polynomially many inputs, where the polynomial is not apriori known to the correlated randomness generator, we must be able to produce “different” randomness for any input on which the protocol is generated. This would require a stronger version of the OT extension technique from  that allows the extension to super-polynomial number of OTs. This is similar in spirit to constructing a PRF that can generate “super-polynomial” randomness from a short seed (even though it will only be evaluated on polynomially many inputs). In particular, we modify the technique in  to construct UC-secure unbounded number of OTs from a small number of OTs distributed as setup in the correlated randomness model. We do this as follows. In the OT extension protocol in , a sender uses a circuit that first computes a PRG that takes a small input and outputs a large random string and then uses the string to obtain a large number of OTs. The circuit is then garbled using Yao’s garbled circuit and sent to a receiver. The receiver then uses a small number of OTs to obtain a garbled input correspond to its small random seed. In our approach, the sender uses a PRF that allows us to generate super-polynomial number of such random strings. While a computationally bounded sender cannot compute or send a garbled circuit of super-polynomial size, it only needs to send a smaller subcircuit to compute the ith string in each execution. This garbled circuit is of polynomial size as in Beaver’s version, computing only the required amount of OTs at a time. This is repeated to give an (apriori) unbounded number of OTs. Composing the UC-secure unbounded number of OTs in the correlated randomness model and a UC-secure MPC in the OT-hybrid model, we get a UC-secure MPC in the correlated randomness model.
The MAC protocols for the resource competition are mainly divided into handshake protocol, channel reser- vation protocol, and the corresponding improved proto- cols. The typical handshake MAC protocols include the MACA-MN , RIPT , and S-FAMA  protocol. These protocols can obtain channels via the control packet handshake negotiation, allowing it to effectively alleviate the hiding terminal problem and reduce waste time caused by transmission delay. When data packets conflict, the backoff algorithm is used for backoff or retransmission, in order to reduce the conflictions of data packets and improve the channel reuse rate. Mul- tiple handshakes of control packets of such protocol would lead to some overhead, which not only reduces
the route table and forward the RREP message if necessary. To achieve these functionalities, two functions arc updateRoute() and arc forwardRREP() are used. RREQInit, RREQProcess and RREPProcess are three substitution transitions. If a node wants to send data packet, it first enters Routcheck state to check for an existing path. If there is no existing route in the routing table, the node enters RREQInit state and initiates route discovery process i.e Broadcasting of RREQ packet . Because protocol design is not yet an exact science, designers should take advantage of those tools which may aid them in validating the operation of their protocols. The use of design verification tools can aid in the examination of each possible usage case, and can validate the operation of a protocol in each of these situations. Because of the diﬃculty in enumerating all possible usage cases and node failure scenarios, these tools should be considered an important part of the protocol design process.
ABSTRACT: Energy efficiency has been the main factor behind the design of communication protocols for battery- powered wireless sensor networks (WSNs). The energy efficiency and the performance of the protocol stacks degrades when the low powered WSNs experience interference from high power Wireless Local Area Networks(WLANs). This thesis propose Cognitive Medium Access Control(COG-MAC) scheme for IEEE 802.15.4-compliant WSNs and enhancement of COG-MAC in terms of LZW(Lampel Ziv Welch) based power control with channel uncertainty. LZW based power control with distribution uncertainty in COG-MAC is a novel cognitive medium access control scheme for WSNs that minimizes the energy cost for multihop communications by deriving energy optimal packet lengths and one hop transmission distances based on the experienced interference from IEEE 802.11 WLANs. This technique can model the uncertain channel gain to be a random variable following a state-dependent distribution function and then propose a power control mechanism that is robust against the channel uncertainty. The advantages of this technique are the improvement of QOS parameters, energy efficiency, lifetime and reduce the packet loss rate and transmission delay.
In this paper, we have presented a multi-channel MACprotocol that utilizes multiple channels to improve through-put in wireless networks. The proposed scheme requires only one transceiver for each host, while other multi-channel MAC protocols require multiple transceivers for each host. Nodes that have packets to transmit negotiate which channels and time slots to use for data communication with their destinations. This negotiation enables MAC to exploit the advantage of both multiple channels and TDMA in an efficient way. In addition, MAC is able to support broadcast in an energy effective way. Since ECR- MAC only requires one transceiver per node, it can be implemented with hardware complexity comparable to IEEE 802.11.
OSI model has seven layers structure for computing networks. The second layer of OSI model is data link layer. The main function of data link layer is to transfer the data to neighbor network nodes. The data link layer is concerned with delivery of frames between devices on the same network. The sublayer of data link layer is MAC. The MAC layer provide mechanism that address and control channel access. This make it possible to communicate within a shared medium, e.g. a wireless sensor network. The hardware that implements the MAC is referred to as a media access controller. MAC layer is responsible for Generating and managing beacons, manages network coordinators, Channel access, Guaranteed Time Slot management, Frame validation and Acknowledged frame delivery. The MAC protocols are broadly classified as scheduled based protocols and contention based protocols.
Wireless sensor networks (WSNs) are increasingly used in environmental monitoring applications. They are designed to operate for several months by featuring low activity cycles in order to save energy. In this paper, we propose a Medium Access Control (MAC) protocol for such WSNs with very low duty-cycles of 1% and less. Nodes are activated randomly and use a history of previous successful frame exchanges to decide their next activation time. We study the choice of the history size, and we compare the performance of our protocol with other protocols from the literature. We show by simulations and real experiments that with a limited history size of only six entries, our protocol achieves better performance than other protocols from the literature, while keeping the advantages of fully asynchronous protocols.
IEEE 802.15.4 MACprotocol: The IEEE 802.15.4 Working Group for the drafting of a Personal Area Network Standard (WBAN) in September 2016 is approved by the Institute of Electrical and Electronic Engineers (IEEE). The protocol is used in three frequency bands: 868 MHz, 915 MHz and 2,4 GHz. In addition, these frequency bands are divided into 27 sub-channels i.e. 2.4 GHz frequency bands are divided into 16 sub-channels, 915 MHz in 9 sub- channels and one sub-divert in 868 MHz recurrence band. For IEEE 802.15.4 two operating modes are characterized: reference point-enabled mode and non-guide-enabled mode. Time - based correspondence and high QoS requirements are however necessary for WBAN for which IEEE misses the mark. Various protocols not based on IEEE 802.15.4 have been proposed to fulfill the QoS time - based application requirements for WBANs.
The packet loss rates of the two are shown in Figure 6. For AO ≤ 0.7, the CF-MAC and DTMAC protocols have almost the same packet loss rate, while for AO > 0.7, CF-MAC starts to perform better than DTMAC. It can be seen that proposed protocol has the lowest packet loss rate, especially for a high AO, due to its capability to deal with the merging collision problem. For instance, at AO = 0.90, the DTMAC protocol shows approximately 33.33% higher rate of packet loss than the CF-MACprotocol.
In PW-MAC , each node wakes up according to a pseudo-random schedule, rather than according to a fixed schedule. Each node stores the parameters of the pseudo- random generators of its neighbors (which are transmitted in beacons). When a sender has data to send to a given receiver, it predicts the wake-up time of the receiver (based on the parameters of the pseudo-random generator), wakes up before this estimated wake-up time, and waits. When the receiver wakes up (which happens periodically), it sends a beacon and waits for potential data. Upon receiving this beacon, the sender starts sending the data for this receiver. The drawbacks of PW-MAC come from the overhead of sending beacons before frame transmissions (in terms of energy, channel occupation and delay), from predictions errors (due to clock drift for instance), and from collisions (when several senders wakes up simultaneously for the same receiver).
We can divide the multiple handshakes between a sender and a receiver into two basic categories, i.e., sender-initiated and receiver-initiated. Both the two-way DATA/ACK and four-way RTS/CTS/DATA/ACK handshake of the IEEE 802.11 MACprotocol are sender-initiated. The sender initiates the handshake only when it has packets to send. In the four-way handshake, the exchange of RTS and CTS frames between a sender and a receiver notifies overhearing nodes to defer their access to the shared channel so as to avoid collisions. In the receiver-initiated handshake, a receiver polls its neighbors actively to see if they have packets for itself. For example, MACA-BI (multiple access collision avoidance by invitation)  adopts a three-way handshake, i.e., CTS/DATA/ACK, to control the channel access where the CTS frame serves as the polling frame. The three-way handshake has less control overhead than the four-way handshake of the IEEE 802.11 MACprotocol, which explains why MACA-BI outperforms the four-way handshake of the IEEE 802.11 when traffic characteristics are stationary or predictable. However, it does not work well in the dynamic MANET environment because the polled nodes may have no packets for the polling node and the transmission time of polling packets is therefore wasted .
The program was first run on a simple process tree, shown in Figure 3, that contained 6 unique processes and contained no forms of IPC. Table I shows the average number of seconds per request from our tests. The first data column shows the processing time for an ID type request. As described in Section III-B, an ID type request is equivalent to the traditional ident protocol request. This was run to compare how much longer a new SV type request takes over the original ident request. This shows that Linux is the most efficient at determining the UID of a socket. This operation was performed in Linux by parsing the /proc/net/tcp file and in OpenBSD by using a sysctl() system call.
The Sink is allotted with a token. During the synchronization period, all those sensor nodes that desire to send the data to the sink will send out Request packet to the sink node. The parameters of request message are node ID of the node that is requesting the token, its parent ID. If a source node requires sending a data packet to the sink node then the source node would request to its parent node and this process will go on until the request message arrives at the sink node. There exists a queue at the sink node that keeps track of the Request messages according to timestamp of the source node in an ascending order. In case if there happens a scenario when multiple nodes at once send out these Request packet to acquire token from the sink, the request messages will be staged in an FCFS (first come first serve) fashion. Post receiving the request message the sink node will allow the token to pass through the respective child nodes to the desired source node using a reply packet. The parameters of reply message are node ID of the node that requested the token, token of sink, and node ID of child node that forwarded the request.
Synchronous and asynchronous medium access control (MAC) protocols have been proposed to reduce energy consumption, e.g. such as idle energy , which operates on the basis of a duty cycle. Traffic increases with increasing number of connected devices, but node duty cycles remain unchanged. Consequently, opportunities to send data decrease and throughput decrease as listening interval durations increase. In particular, forest fire sudden and natural escalation means there is small traffic by the initial sensors that very rapidly increases as the fire develops.