Access Methods for Mobile Ad Hoc Networks (MANET)

1. Access Methods for Mobile Ad Hoc Networks (MANET) Nishitha Ayyalapu KUID: 2335165

2. Outline • Introduction • 2. Effect of Mobility on Protocol Stack • 3.Challenges in Mobile Environment • 4. Goals of MAC in MANET • 5. Issues in Designing MAC for MANET • 6. Performance Metrics • General Broad Classification of MAC • DCF of IEEE 802.11 • Performance Limitations of DCF with MANET • Enhancement of Channel Utilization • Enhancements in RTS/CTS Mechanism • Enhancements in Backoff Algorithm • Multi Channel MAC Schemes • Transmission power control MAC Schemes • Others. • Conclusions • References

3. Introduction • Classification of Wireless Networks • Single Hop vs. Multi-Hop Wireless Networks • What is a MANET ? • Need for MANETS ?

4. Classification of Wireless Networks • Infrastructured Networks • These are the networks with fixed gateways. • The bridges for these networks are known as base stations. • Handoffs occur. • Eg: wireless local area networks (WLANs), Cellular Systems • Infrastructure-less Networks • No fixed routers; all nodes are capable of movement and can be connected dynamically in an arbitrary manner. • Nodes of these networks function as routers which discover and maintain routes to other nodes in the network. • Example applications of ad-hoc networks are emergency search-and-rescue operations, meetings or conventions in which persons wish to quickly share information, and data acquisition operations in inhospitable terrains.

5. Single-Hop Vs. Multi-Hop • Single-Hop Wireless Connectivity: • Space divided into cells • A base station is responsible to communicate with hosts in its cell • Mobile hosts can change cells while communicating • Hand-off occurs when a mobile host starts communicating via a new base station • Multi-Hop Wireless Connectivity: • May need to traverse multiple links to reach destination. • Mobility causes route changes From: Tutorial at CIT’2000. Bhubaneshwar, Dec 20-23. Sridhar Iyer. IIT Bombay www.it.iitb.ac.in/~sri/talks/manet.ppt

6. What is a MANET ? • A MANET can be defined as a collection of wireless mobile nodes (e.g., portable computers or PDAs) that form a dynamically changing network, without using any existing network infrastructure or centralized administration. • Can be Single-hop or Multi-hop. • But, Mostly Multi-hop. Hence, a mobile ad hoc network is sometimes also called a Multihop wireless network.

7. Need for MANET ? • Do not need backbone infrastructure support • Are easy to deploy • Useful when infrastructure is absent, destroyed or impractical Many Applications • Personal area networking • cell phone, laptop, ear phone, wrist watch • Military environments • soldiers, tanks, planes • Civilian environments • taxi cab network • meeting rooms • sports stadiums • boats, small aircraft • Emergency operations • search-and-rescue • policing and fire fighting

8. Effect of Mobility on Protocol Stack • Application - new applications and adaptations • Transport - congestion and flow control • Network - addressing and routing • Link - media access and handoff • Physical - transmission errors and interference

9. Challenges in Mobile Environment Limitations of the Wireless Network • packet loss due to transmission errors • frequent disconnections/partitions • limited communication bandwidth • Broadcast nature of the communications Limitations Imposed by Mobility • dynamically changing topologies/routes • lack of mobility awareness by system/applications Limitations of the Mobile Computer • short battery lifetime • limited capacities

10. Goals of MAC in MANET • High channel efficiency • Low power • Scalability • Fairness • Support for prioritization • Distributed operation • QoS support • Low control overhead

11. Issues in Designing MAC Protocol for MANET • Hidden Node Problem: • A hidden node is a node which is out of range of a transmitter node (node A in Figure ), but in the range of a receiver node (node B in Figure ). • A hidden node does not hear the data sent from a transmitter to a receiver (node C is hidden from node A). When node C transmits to node D, the transmission collides with that from node A to node B. • The hidden nodes lead to higher collision probability. Generally, the probability of successful frame transmission decreases as the distance between source and destination increases and/or the traffic load increases. From: “Medium access control protocols for wireless mobile ad hoc networks: issues and approaches”, Teerawat Issariyakul, Ekram Hossain, and Dong In Kim, Wirel. Commun. Mob. Comput. 2003; 3:935–958 (DOI: 10.1002/wcm.118) http://citeseer.ist.psu.edu/cache/papers/cs2/137/http:zSzzSzwww.win.trlabs.cazSz~teerawatzSzpublicationszSzWCMC_Dec03MAC_survey.pdf/issariyakul03medium.pdf

12. Issues in Designing MAC Protocol for MANET • Exposed Node Problem: • An exposed node (node C is exposed to B in Figure ) is a node which is out of range of a receiver (node A), but in the range of the corresponding transmitter (node B). • Node C defers transmission (to node D) upon detecting data from node B, even though a transmission from node C does not interfere with the reception at node A. • The link utilization may be significantly impaired due to the exposed node problem. This would impact the higher layer protocol (e.g. TCP) performance considerably. From: “Medium access control protocols for wireless mobile ad hoc networks: issues and approaches”, Teerawat Issariyakul, Ekram Hossain, and Dong In Kim, Wirel. Commun. Mob. Comput. 2003; 3:935–958 (DOI: 10.1002/wcm.118) http://citeseer.ist.psu.edu/cache/papers/cs2/137/http:zSzzSzwww.win.trlabs.cazSz~teerawatzSzpublicationszSzWCMC_Dec03MAC_survey.pdf/issariyakul03medium.pdf

13. Issues in Designing MAC Protocol for MANET • Radio Link Vulnerability: • Wireless channel capacity is limited due to high bit-error rate. • Causes: noise, interference, free space loss, shadowing and multipath fading. • The radio link vulnerability may tremendously impact the utilization of the radio channel (s) and the service fairness among different mobile nodes (and flows). • Control Measures: Forward error correction (FEC) Automatic repeat request (ARQ) have been developed. • Unfortunately, they result in inefficient bandwidth utilization. Again, increase in transmission power to combat with the above undesirable radio propagation properties can broaden interference region, thereby resulting in the reduction of spatial reuse. • Capture Effect: • Capture is an ability of a mobile node to perfectly receive a signal (presumably one with the dominating signal level) in the presence of more than one simultaneous transmissions. • Improves the utilization of the channel, but it may cause unfairness among mobile nodes.

14. Performance Metrics • Throughput and Delay: • Throughput is generally measured as the percentage of successfully transmitted radio link level frames per unit time. Transmission delay is defined as the interval between the frame arrival time at the MAC layer of a transmitter and the time at which the transmitter realizes that the transmitted frame has been successfully received by the receiver. • Fairness: • Generally, fairness measures how fair the channel allocation is among the flows in the different mobile nodes. The node mobility and the unreliability of radio channels are the two main factors that impact fairness. • Energy Efficiency: • Generally, energy efficiency is measured as the fraction of the useful energy consumption (for successful frame transmission) to the total energy spent. • Multimedia Support: • It is the ability of an MAC protocol to accommodate traffic with different service requirements such as throughput, delay and frame loss rate. • Vulnerable Period: • Time interval during which for a node to transmit a packet successfully without collisions, other interfering nodes should not attempt to transmit during the node’s transmission time

15. General Broad Classification of MAC • Fixed-Assignment Channel Access: • In this, nodes are statically allocated a certain time slot (frequency band or spread spectrum code), as is the case for most of voice-oriented wireless networks. • TDMA • FDMA • CDMA • Random Access Methods: • Here the sender dynamically competes for a time slot with other nodes. This is a more flexible and efficient method of managing the channel in a fully distributed way, but suffers from collisions and interference. • Pure Aloha • Slotted Aloha • Carrier-Sensing Mechanisms(-for MANET-Why?)

16. Basic DCF (Distributed Coordination Function) of IEEE 802.11 MAC • 802.11 MAC: • The 802.11 MAC is designed to provide mandatory asynchronous data service along with an optional time-bounded service that is only usable in an infrastructured wireless networks with access points. • The asynchronous data service is usable by both ad hoc networks and infrastructured wireless networks Distributed coordination function (DCF): • The mandatory basic asynchronous service is provided by a method known as carrier sense multiple access with collision avoidance (CSMA/CA) and an optional channel reservation scheme based on a four-way handshake between the sender and receiver nodes. • These two methods provides the mechanism for achieving distributed coordination amongst uncoordinated wireless terminals that do not use a fixed access point (i.e, infrastructure–less networks), and are known as the Distributed coordination function (DCF). • Therefore DCF provides two access Mechanisms: • 1. Two-Way Handshake i.e., DATA/ACK. • 2. Four-Way Handshake i.e., RTS/CTS/DATA/ACK

17. DCF of IEEE 802.11 MAC • Key Elements: • ACK • - For Collision Detection • 2. RTS/CTS and NAV • - For Solving Hidden Terminal Problem • IFS • - For Prioritized Access to the Channel • Backoff Algorithm with Contention Window • - To Provide Fair Access with Congestion Control

18. DCF • ACK for Collision Detection: • ACKnowledgement (ACK) packets enable a mobile node to determine whether its transmission was successful or not. • The sender is made aware of the collision after it times out waiting for the corresponding ACK for the packet transmitted. • If no ACK packet is received or an ACK is received in error, the sender will contend again for the medium to retransmit the data packet until the maximum allowed number of retransmissions has been tried. • If all fails, the sender drops the packet consequently leaving it to a higher level reliability protocol. • 2. RTS/CTS and NAV for Solving Hidden Terminal Problem: • Four-way handshake based on Request-To-Send (RTS) and Clear-To-Send (CTS) packets is used to avoid collisions from the nodes hidden in the vulnerable region. • By exchanging the two short control packets between a sender and a receiver, all neighboring nodes recognize the transmission and back off during the transmission time advertised along with the RTS and CTS packets. • Network Allocation Vector (NAV) • Increased Control Overhead. • RTSThreshold

19. DCF • IFS for Prioritized Access to the Channel: • Inter-Frame Spacing (IFS) is the time interval during which each node has to wait before transmitting any packet and is used to provide a prioritized access to the channel. • DCF IFS (DIFS) is larger than SIFS and is used when initiating a data transfer. When RTS/CTS is used, the RTS packet can be transmitted after waiting for DIFS duration of time. • Short IFS (SIFS) is the shortest and is used after receiving a DATA packet to give the highest priority to an ACK packet. All other frames (CTS, DATA, and ACK) use SIFS before attempting to transmit. From: “Medium Access Control Mechanisms in Mobile Ad Hoc Networks “, Chansu Yu, Ben Lee, Sridhar Kalubandi, Myungchul Kim, http://web.engr.oregonstate.edu/~benl/Publications/Book_Chapters/MCH_MAC_AdHoc05.pdf

20. DCF • 4. Backoff Algorithm with CW to Provide Fair Access with Congestion Control • IFS is followed by an additional waiting time defined by the backoff algorithm. After waiting for the IFS duration, each competing node waits for a backoff time, which is randomly chosen in the interval (0, CW), defined as contention window. • The main purpose of the backoff algorithm is to reduce the probability of collisions when contention is severe. • DCF employs Binary Exponential Backoff Algorithm. The flow chart of algorithm is as below:

21. DCF Flow Chart of BEB Algorithm in DCF: From: “Medium Access Control Mechanisms in Mobile Ad Hoc Networks “, Chansu Yu, Ben Lee, Sridhar Kalubandi, Myungchul Kim, http://web.engr.oregonstate.edu/~benl/Publications/Book_Chapters/MCH_MAC_AdHoc05.pdf

22. Performance Limitations of DCF with MANET • Though RTS/CTS option of DCF reduces hidden terminal problem, it exacerbates exposed node problems • Though it simple to implement, it can be overly conservative, leading to low spatial re-use, low energy efficiency and as well as high co-channel interference. • Additional Control Overhead • Collisions of Control Packets • Radio Interference • Capture Effect • Low Spatial re-use • BEB suffers from both fairness and efficiency • According to Simulation Results: • The theoretical throughput is bounded by around 80% when the typical DCF parameters are used (with propagation delay of 1 ms and packet size of 50msec~5msec). In reality, DCF operates very far from the theoretical limits due to collisions and control overhead associated with RTS/CTS and the backoff algorithm. • In a multihop MANET, the situation becomes worse. It was shown that end-to-end throughput is at most 1/4 of the channel bandwidth even without any other interfering nodes. This is mainly due to collisions among intermediate forwarding nodes of the same data stream • In addition, the control overhead of DCF aggravates the situation and the maximum throughput is reduced to about 1/7 of the channel bandwidth

23. Enhancement of Channel Utilization 1. Enhancing RTS/CTS Mechanism 2. Enhancing Exponential Backoff Algorithm a.) Conservative CW Restoration to Reduce Collisions - MILD • b.) Dynamic Tuning of CW to Minimize the Collision Probability 3. Multi Channel MAC Schemes a.)Schemes with a Common Control Channel - BTMA - DBTMA b.) Schemes without a Common Control Channel - ICSMA - JMAC • Transmission power control MAC Schemes - PCMA - BPCMP 5. Others. Enhancing Temporal Channel Utilization Enhancing Spatial Channel Utilization

24. Enhancement of Channel Utilization • Enhancements in RTS/CTS Mechanism: • Optimal Setting of RTSThreshold to Tradeoff between Control and Collision Overhead • Better idea would be to adjust the parameter depending on the traffic and the collision probability. • Simulation Results: (by Khurana and Weinmiller) optimal RTSThreshold = 200-500 bytes. • 2. Enhancements in Backoff Algorithm: a.) Conservative CW Restoration to Reduce Collisions: • Goal is to address the fairness and collision problem in the DCF backoff algorithm: From: “Medium Access Control Mechanisms in Mobile Ad Hoc Networks “, Chansu Yu, Ben Lee, Sridhar Kalubandi, Myungchul Kim, http://web.engr.oregonstate.edu/~benl/Publications/Book_Chapters/MCH_MAC_AdHoc05.pdf

25. Enhancement of Channel Utilization • Solutions: “MILD” back off algorithm. • MILD (Multiplicative Increase Linear Decrease): • Bharghavan et al. proposed a Multiplicative Increase and Linear Decrease (MILD) algorithm where the contention window size increases multiplicatively on collisions but decreases linearly on successful transmission. • In MILD, the backoff interval is increased by a multiplicative factor (1.5) upon a collision and decreased by 1 step upon a successful transmission, where step is defined as the transmission time of a RTS frame. • The “linear decrease” sometimes is too conservative, and it suffers performance degradation when the traffic load is light or the number of active nodes changes sharply because of the additional delay incurred to return the CW to CWmin. • Used in MACAW protocol.

26. Enhancement of Channel Utilization • b.) Dynamic Tuning of CW to Minimize the Collision Probability: • Cali et al. observed that the collision probability increases as the number of active nodes increases. • There is need for dynamic control of this collision probability, but the static backoff algorithm of DCF does not address. • Adaptive contention schemes has been proposed, where optimal setting of CW, and thus the optimal backoff time for the next transmission can be achieved by estimating the number of active nodes in its vicinity at run time. • Each node can estimate the number of empty slots in a virtual transmission time by observing the channel status, the number of active nodes can be computed and exploited to select the appropriate CW without paying the collision costs. Summary: From: [2]

27. Enhancement of Channel Utilization • Multi Channel MAC Schemes • In IEEE 802.11 protocols ,schemes use only one channel for all kinds of packets, such as RTS/ CTS/ DATA/ ACK. To avoid the collisions, the bidirectional exchanges of these packets significantly limit the spatial reuse due to the coupling of hidden and exposed terminal problems. • The other approach to reduce collisions between different kinds of packets is to exploit the advantage of multiple channels, and transmit different kinds of packets over different separate channels • a.)Schemes with a Common Control Channel: • These schemes use a separate channel for transmitting control packets, such as RTS and CTS, and one or more channels for transmitting data and acknowledgements, i.e., DATA and ACK. • - BTMA (Busy Tone Multiple Access) • - DBTMA (Dual Busy Tone Multiple Access) • b.) Schemes without a Common Control Channel: • Unlike those schemes that use a common control channel, this kind of schemes does not rely on it. Instead, they are flexible in arranging different channels for RTS/ CTS/ DATA/ ACK to reduce collisions. • - ICSMA (Interleaved CSMA) • - JMAC (Jamming based MAC)

28. Enhancing Channel Utilization BTMA (Busy Tone Multiple Access): • BTMA scheme splits the single common channel into two sub-channels: a data channel and a control channel. • Base station broadcasts an out of band busy tone signal to keep the hidden terminals from accessing the channel when it senses a transmission. • Does not address exposed nodes problem and also it requires additional channels and transceivers. • The busy tone channel must be close to the DATA channel and hence can have similar channel gain to that of the DATA channel, and there must also be enough spectral separation between these channels to avoid inter-channel interference.

29. Enhancing Channel Utilization • DBTMA (Dual Busy Tone Multiple Access): • Splits one common channel into two sub-channels: One Data channel: For Data Packets. One Control Channel : Two Control Packets (RTS and CTS); Two busy tones (BTt and BTr). • Transmit Busy Tone “BTt”: Set by the transmitter node to indicate that it is transmitting on the data channel. All nodes that sense BTt do not attempt to receive. And all exposed nodes are prevented from becoming new receivers. • Receive Busy Tone “BTr”: Set by the Receiver node to indicate that it is receiving on the data channel. All the nodes that sense BTr do defer their transmissions. i.e, All Hidden nodes are prevented from becoming new transmitters. • Exposed Terminals can sense “BTt” but not “BTr” so that they can safely reuse the space by transmitting their packets. • Drawback: No ACKs are sent to acknowledge a transmitted DATA packet, makes it worst suited for unreliable wireless links. From: [2]

30. Enhancing Channel Utilization • ICSMA (Interleaved CSMA): • It divides the entire bandwidth into two channels of equal bandwidth and employ one half-duplex transceiver for each channel and it is flexible in arranging different channels for RTS/ CTS/ DATA/ ACK to reduce collisions. • The transmitter sends RTS and DATA on one channel, and the receiver responds by sending CTS and ACK on the other channel. • Supports simultaneous transmissions between two nodes: when one node is sending RTS or DATA, or receiving CTS or ACK from the other node, the latter one is also sending the same kind of packets at a different channel to the former one. JMAC (Jamming based MAC): • In JMAC, the medium is divided into two channels: S channel and R channel. • S Channel: RTS, DATA and jamming signal are transmitted. • R Channel: CTS and ACK are transmitted. • Transmitter also sends a jamming signal on S channel, while it waiting or receiving CTS/ACK on R Channel. • Receiver, while it is waiting or receiving RTS/DATA on S channel it jams the R channel to prevent neighboring nodes from transmitting RTS frames on the S channel. • Effectively resolves Hidden Terminal problem. • It will stop if the RTS/CTS exchange fails, it resolves the erroneous reservation problem in the IEEE 802.11 protocol. • Drawbacks: Jamming signal is of sufficient energy and can cause the medium to become busy.

31. Enhancing Channel Utilization • 4. Transmission Power Control MAC Schemes: • Mobile nodes are usually powered by batteries that provide only a limited amount of energy, how to reduce the energy consumption is of great importance for providing QoS (quality of service) assurance for MANET. • IEEE 802.11 MAC protocol though avoids the collisions caused by hidden terminal problem in MANETs, and is widely used, there is no consideration of power control in the protocol at all. Hence, consumes significant battery power since transmitters send all kinds of packets at the same transmitting power level all the time. • Benefits from energy conserving schemes: - Minimal Transmit power - Improvement in Spatial reuse - Reduction in Co-channel interference. • One way to reduce energy consumption in MAC protocol design is using transmission power control MAC schemes. • The main idea of these power control schemes is to use a maximum possible power level for transmitting RTS/CTS and the lowest acceptable power for sending DATA/ACK. - BPCMP (Basic Power Control MAC Protocol) - PCMA (Power Control Multiple Access)

32. Enhancing Channel Utilization • BPCMP (Basic Power Control MAC Protocol) • BPCMP is a power controlled MAC protocol that can be incorporated into the IEEE 802.11 protocol and which allows a node to specify its current transmit power level according to different packet types. • Unlike IEEE 802.11 which sends all packets at the same power level, BPCMP sends RTS/CTS packets using the maximum possible power level “pmax”,but sends DATA/ACK packets at the lowest acceptable power level “pdesired”. • The transmit power levels will affect the radio range, battery life time, and capacity of the network. • Timing diagram and Ranges of different power levels in BPCMP is as below: From: “Autonomous Power Control MAC Protocol for Mobile Ad Hoc Networks”,Hsiao-Hwa Chen, Zhengying Fan, and Jie Li, EURASIP Journal on Wireless Communications and Networking Volume 2006, Article ID 36040, Pages 1–10 DOI 10.1155/WCN/2006/36040 http://www.hindawi.com/GetArticle.aspx?doi=10.1155/WCN/2006/36040

33. Enhancing Channel Utilization • In BPCMP, the desired power level for transmitting DATA/ACK is determined after RTS/CTS handshake. The procedures for a complete transmission cycle are described as follows: • 1. The transmitter sends RTS packets using the maximum possible power level pmax. • 2. The receiver receives the RTS at signal power prec, and calculates the minimum desired • transmit power level pdata for transmitting data packets as follows: • where Rxthresh is the lowest acceptable received signal strength. Then, the receiver marks • the minimum desired transmit power level in the control message field of CTS and sends • CTS back to the transmitter. • 3. Once having received CTS, the transmitter begins to transmit data packet using the power • level pdata. • 4. The receiver sends back an ACK as soon as it receives DATA. The transmitting power level • for sending ACK is determined in a similar way as done for DATA.

34. Enhancing Channel Utilization • Problems with BPCMP: • Using the fixed transmitting power level, pmax, for RTS/CTS is not energy efficient since the distance between the transmitter and the receiver may change from time to time. • The transmission at maximum possible power level causes to interfere other existing radio applications. • Different transmitting power levels result in asymmetric topologies, and thus may consume more energy. • BPCMP was proposed under the assumption that signal attenuation between transmitters and receivers is kept the same in both transmission directions. It may make the communications unreliable if the assumption is not held.

35. Enhancing Channel Utilization • PCMA (Power Control Multiple Access) • The Power Controlled Multiple Access (PCMA) Protocol proposes flexible “variable bounded power” collision suppression model that allows variable transmit power levels on a per-packet basis. • Source-destination pair uses Request power to send (RPTS) and Acceptable power to send (APTS) handshake to compute the optimal transmission power based on their received signal strength, which will be used when transmitting data packets. • PCMA also uses the busy tone channel to advertise the noise level the receiver can tolerate. During data transmission periods, each active receiver will periodically send a busy tone to advertise the maximum additional noise power it can tolerate. • A potential transmitter first senses the busy tone to detect the upper bound of its transmission power for all control and data packets. • PCMA protocol with busy tone is as shown below: From: [2]

36. Enhancing Channel Utilization • Merits of PCMA: • PCMA works effectively in energy conservation since it allows more concurrent data transmission compared with IEEE 802.11 standard by adapting the transmission ranges to be the minimum value required for successful reception on the receiver side. • Results show that PCMA can improve the throughput performance by more than a factor of 2 compared to the IEEE 802.11 for highly dense networks. • The throughput gain over 802.11 will continue to increase as the connectivity range is reduced. • The power controlled transmission in PCMA helps increase channel efficiency at the same time preserving the collision avoidance property of multiple access protocols.

37. Enhancing Channel Utilization • Other Possible Channel Utilization Enhancement Schemes: • Antenna Based Mechanisms • Rate Adaptive MAC schemes • Fairness Enhanced MAC Schemes • Power off Mechanisms (another energy conserving MAC protocol design). Summary of Enhancing spatial channel Utilization: (From [2])

38. Conclusions • Mobile ad hoc networks are composed of nodes that are self-organizing and communicate over wireless channels usually in a multi-hop fashion. They exhibit dynamic topology, share limited bandwidth, with most nodes having limited processing abilities, and energy constraints. • We have discussed about the effect of mobility on protocol stack, challenges in mobile environment and issues in designing MAC protocol for MANET. • We have considered some of the Enhancement techniques in the design of medium access control protocols with DCF of IEEE 802.11 as a reference model. • Each of these schemes tries to maximize network capacity, reduce congestion at the MAC layer, and ensure fairness by balancing the control overhead to avoid collisions. • Key techniques used to enhance temporal utilization is to optimize the DCF parameters such as RTSThreshold and those associated with the backoff algorithm, which is used to avoid collisions in DCF. • Key techniques used to enhance Spatial channel utilization are Multi Channel MAC, transmission power control. • Among these, Transmission power control methods not only help in reducing interference but also in energy conservation.

39. References • [1]Tutorial at CIT’2000. Bhubaneshwar, Dec 20-23. Sridhar Iyer. IIT Bombay • www.it.iitb.ac.in/~sri/talks/manet.ppt • [2] “Medium Access Control Mechanisms in Mobile Ad Hoc Networks “, Chansu Yu, Ben Lee, Sridhar Kalubandi, Myungchul Kim, • http://web.engr.oregonstate.edu/~benl/Publications/Book_Chapters/MCH_MAC_AdHoc05.pdf • [3]Medium access control protocols for wireless mobile ad hoc networks: issues and approaches”, Teerawat Issariyakul, Ekram Hossain, and Dong In Kim, Wirel. Commun. Mob. Comput. 2003; 3:935–958 (DOI: 10.1002/wcm.118) http://citeseer.ist.psu.edu/cache/papers/cs2/137/http:zSzzSzwww.win.trlabs.cazSz~teerawatzSzpublicationszSzWCMC_Dec03MAC_survey.pdf/issariyakul03medium.pdf • [4] “Autonomous Power Control MAC Protocol for Mobile Ad Hoc Networks”,Hsiao-Hwa Chen, Zhengying Fan, and Jie Li, EURASIP Journal on Wireless Communications and Networking Volume 2006, Article ID 36040, Pages 1–10 DOI 10.1155/WCN/2006/36040. http://www.hindawi.com/GetArticle.aspx?doi=10.1155/WCN/2006/36040 • [5] “A Survey, Classification and Comparative Analysis of Medium Access Control Protocols for Ad Hoc Networks”, Raja Jurdak, Cristina Videira Lopes, and Pierre Baldi, IEEE Communications Surveys, FIRST QUARTER 2004, VOLUME 6, NO. 1 • http://www.comsoc.org/livepubs/surveys/public/2004/jan/pdf/jurdak.pdf • [6]“Mobile Ad Hoc Networks”, Asis Nasipuri,http://citeseer.ist.psu.edu/cache/papers/cs/31158/http:zSzzSzwww.ece.uncc.eduzSz~anasipurzSzpubszSzadhoc.pdf/mobile-ad-hoc-networks.pdf • [7]” Medium Access Control in Mobile Ad Hoc Networks: Challenges and Solutions”,Hongqiang Zhai, Jianfeng Wang, Xiang Chen, and Yuguang Fang • http://www.ecel.ufl.edu/~jwang/publications_files/macsurvey.pdf

40. References • [8] E. M. Royer, S.-J.Lee, and C. E. Perkins, "The Effects of MAC Protocols on Ad Hoc Network Communication," Proc. WCNC 2000. • http://www.hpl.hp.com/personal/Sung-Ju_Lee/abstracts/papers/wcnc2000c.pdf • [9] Energy-efficient MAC layer protocols in ad hoc Networks Fang Liu, Kai Xing, Xiuzhen Cheng, Shmuel Rotenstreich • Resource Management in Wireless Networking 2004 Kluwer Academic Publishers • http://www.seas.gwu.edu/~cheng/Publication/PowerMACSurvey.pdf • [10] “Mobile Ad-Hoc Networks” Silvia Giordano • http://portal.acm.org/citation.cfm?coll=GUIDE&dl=GUIDE&id=512336 • [11] “An Overview of Wireless Ad hoc Networks: Challenges and Future” Yi Wang • http://www.net-glyph.org/~wangyi/papers/Mobile%20Ad%20hoc_Survey.pdf • [12] “Research Issues for Data Communication in Mobile Ad-Hoc Network Database Systems”Leslie D. Fife, Le Gruenwald • http://www.cs.ou.edu/~database/documents/fg03.pdf

41. Chronological MAC Protocol Classification for MANET From : [5]

42. Comparisions