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SOFSEM 07 A Software Architecture for Shared Resource Management in Mobile Ad hoc Networks by Orhan Dagdeviren, Kayhan E

SOFSEM 07 A Software Architecture for Shared Resource Management in Mobile Ad hoc Networks by Orhan Dagdeviren, Kayhan Erciyes. Izmir Institute of Technology presented by Orhan Dagdeviren January 2007, Harrachov. Outline. Introduction Layer 1: Merging Clustering Algorithm(in brief)

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SOFSEM 07 A Software Architecture for Shared Resource Management in Mobile Ad hoc Networks by Orhan Dagdeviren, Kayhan E

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  1. SOFSEM 07A Software Architecture for Shared Resource Management in Mobile Ad hoc Networksby Orhan Dagdeviren, Kayhan Erciyes Izmir Institute of Technology presented by Orhan Dagdeviren January 2007, Harrachov

  2. Outline • Introduction • Layer 1: Merging Clustering Algorithm(in brief) • Layer 2: Backbone Formation Algorithm(in brief) • Layer 3: Mobile Ricart-Agrawala Algorithm • Conclusions

  3. Introduction Wireless communication is growing fast in last few years. Future information technology will be mainly based on wireless technology.[STOJMENOVIC02a] GSM World’s Research shows the cellular phone usage exceeds 2 billion.

  4. Introduction Traditional Cellular and Mobile Networks Base Stations, access points • Traditional cellular and mobile networks are limited by their need for infrastructure. This final limitation is eliminated in MANETs. Wi-Fi ad hoc mode

  5. Introduction Applications of Mobile Ad hoc Networks -Battlefields -Rescue Operations -Personal Area Network -Mobile Sensor Network

  6. Introduction • Cluster • Virtual Group which provides 1. Energy control by clusterheads. 2. Routing by clusterheads and gateways. 3. Construction of a backbone architecture( Dominating set based algorithms ) Backbone: Path which connects clusterheads

  7. Introduction Distributed Mutual Exclusion The mutual exclusion problem involves a group of process, each of which requires access to a resource or a piece of code called the critical section. It is an one of fundamental computer science problem and a relatively new research area for the mobile ad hoc environment.

  8. Introduction The steps of this study • Partition the MANET into balanced, non-overlapped clusters by MCA [Dagdeviren06]. • Provide a ring backbone for a clustered MANET by BFA [Dagdeviren06-2]. • Implement the Mobile Ricart-Agrawala algorithm [ERCIYES04,ERCIYES05].

  9. Layer 1: Merging Clustering Algorithm [Dagdeviren05, Dagdeviren06] 1. General Idea 2. Description of the Algorithm 3. An Example Operation

  10. General Idea of the Algorithm • Algorithm merges clusters to higher level clusters like Gallagher’s distributed MST algorithm. However ; • First idea is to focus on clustering operation by discarding spanning tree. This reduces message complexity from O(nlogn) to O(n) (also time complexity is O(n). • Second idea is to use upper(2K) and lower(K) bound heuristics for clustering.

  11. Description of the Algorithm • Each node has distinct node_id. • Each node knows its cluster_leader_id, cluster_level. • Leader node of a cluster is the node with maximum node_id.

  12. Description of the Algorithm • Algorithm consists of sending receving messages over adjoining links, waiting for incoming messages and processing messages. • We assume no packet loss, if any loss occurs tout occurs in sender and sends the packet again. (Discussed Later)

  13. An Example Operation K=7

  14. Layer 2: Backbone Formation Algorithm 1. General Idea 2. Description of the Algorithm 3. An Example Operation

  15. General Idea of the Algorithm • MCA • Balanced clusters. • No backbone construction. • DS-based algorithms • Backbone is constructed. • Clusters may be overlapping and balancing is not mentioned

  16. General Idea of the Algorithm The backbone formation algorithm constructs a backbone of clusterheads on a clustered MANET.

  17. General Idea of the Algorithm • Contributions • Since our backbone is directed ring architecture, better services can be given to middleware (traversing of message) • Two essential needs of clustering, balanced clustering and backbone formation • Partial Fault-tolerant

  18. Description of the Algorithm Each clusterhead floods Leader_Info message to network which consists of their id and if needed their position.( O(cn) message and time complexity where c is the total number of clusterheads ) In this phase, cluster member nodes are acting as router to transmit Leader_Info messages.

  19. Description of the Algorithm • The main idea is maintaining of same minimum spanning tree between clusterheads to construct a directed ring architecture. • Minimum Spanning Tree can be obtained in two ways.

  20. Minimum Spanning Tree Construction 1. Hop–based minimum spanning tree construction Minimum number of hops between clusterheads are considered. For highly mobile scenarios, an agreement between clusterheads must be maintained.

  21. Hop-based mst construction 2 hops clusterhead id=13 clusterhead id=13 member id=5 member id=5 member id=6 member id=6 clusterhead id=20 clusterhead id=20 3 hops Hop information can rapidly change for high mobile scenarios. Agreement between clusterheads must be maintained.

  22. Minimum Spanning Tree Construction 2. Position–based minimum spanning tree construction: Positions of clusterheads are used. Velocity and the direction information can be appended with a timestamp to the Leader_Info message. Position-tracker like a GPS Receiver must be maintained.

  23. Directed Ring Construction After constructing mst, clusterheads are classified into two groups: LEAF: Clusterheads with degree 1 in mst. BACKBONE: Other clusterheads than LEAFs. LEAFs are filled with white. BACKBONEs are filled with black.

  24. An Example Ring construction 1. BACKBONE leaders are connected to each other. Starting BACKBONE is selected with minimum connectivity to other BACKBONE leaders. If there are more than one, select the one with minimum id. Connect each other from starting to end, last BACKBONE leader is connected to its LEAF with minimum node_id. 27 13 52 Starting BACKBONE 34 45 25 67 29 76 18 61 55

  25. Ring construction 2. LEAF leaders of same parent are connected to each other from smallest node_id to greater. 27 13 52 34 45 25 67 29 76 18 61 55

  26. Ring construction 3. LEAF leaders of different parents are connected to each other from LEAF leader with maximum node_id to other LEAF leaders with minimum node_id of previous BACKBONE clusterheads. 4.Last leaf is connected to starting BACKBONE leader. Advantages : + Connection of BACKBONE leaders + LEAF leaders of same parent are connected. + LEAF leaders of different parents connected on BACKBONE leaders. 27 13 52 34 45 25 67 29 76 18 61 55

  27. Fault Tolerance of Algorithm • Clusterheads can maintain the list of member nodes during clustering operation. • Clusterheads can maintain the list of all nodes in MANET during backbone formation. • If a clusterhead detects the crash of its next clusterhead: • 1. It can update its next clusterhead to next-next clusterhead. • 2. It can multicast a Leader_Dead message to cluster members of crashed clusterhead to initate clustering.

  28. Example Cluster 1 A leader election must be maintained Leader_Dead New_Leader leader 1 leader 1, crashed new leader is selected leader 4, detected leader 4 leader 4,updated leader 2 Cluster 2 Cluster 4 leader 3 Cluster 3

  29. Distributed Mutual Exclusion Performance Metrics • Metrics • Number of Messages per Request(M): Total messages for CS. • Response Time(R): Interval between requesting and finishing CS. • Synchronization Delay(S): Time to enter a node to CS after another finishes. • System can be lightly or heavily loaded. In lightly loaded system, when a process makes a request, no other process is in CS. Other situation of system is heavily loaded.

  30. Classification of distributed mutual exclusion algorithms • Token-based mutual exclusion algorithms [SUZUKI85] [RAYMOND89]. • Permission based mutual exclusion algorithms [LAMPORT78][RICART81][MAEKAWA85].

  31. Permission based algorithms: Ricart-Agrawala Algorithm executing CS wants to enter CS N-1 request N-1 replay Total Messages: N-1 + N-1 = 2N-2

  32. Ricart-Agrawala Algorithm executing CS or have a request with lower timestamp wants to enter CS 3 N-1 request 5 request is deferred and enqueued

  33. Ricart-Agrawala Algorithm • MUTEX is charecterized by the permission. • Fairness, liveness and safety is ensured. • Crash of a single node is a big problem, they propose a timeout solution for this problem. • System must provide clock synchronization.

  34. Mutual Exclusion Algorithms on MANETs • Permission based mutual exclusion algorithms: • Look-ahead technique: Singhal [SINGHAL97 ], Wu et. al’s [WU05 ] • which is based on construction of a competing set of CS requesting processses. • Token-based mutual exclusion algorithms: • Walter [WALTER01b ], Baldoni [BALDONI02 ]

  35. Layer 3: Mobile Ricart-Agrawala Algorithm 1. General Idea 2. Description of the Algorithm 3. An Example Operation 4. Analysis 5. Results

  36. General Idea of the Algorithm The main idea is to make coordinators interface to other nodes to the ring for Ricart-Agrawala Algorithm. Requests are processed according to their timestamps.

  37. Mobile Ricart-Agrawala Algorithm Cluster 1 3 leader 1 leader 3 leader 2 Cluster 3 Cluster 2 13 leader 4 Cluster 4

  38. Finite State Machine for leaders of Mobile_RA

  39. 6 15 9 19 18 4 3 13 0 14 17 5 11 10 16 7 1 2 12 8

  40. An Example Operation Node 6 makes a CS request at 3.75s. Node 4 makes a CS request at 3.85s. Node 16 makes a CS request at 3.90s. CS execution time is 350ms.

  41. Enters the mutex Clock:3,78s Clock:3,80s Clock:3,81s Clock:3,82s Clock:3,76s Clock:3,83s Node_Req 6 6 15 9 19 Coord_Req 6 Coord_Rep 6 IDLE WAIT_RP 18 IDLE 4 3 Coord_Req 6 13 0 Coord_Req 6 IDLE 14 IDLE Coord_Req 6 17 5 11 10 16 7 1 2 12 8

  42. Executing CS Clock:3,93s Clock:3,90s Clock:3,87s Clock:3,85s 6 15 9 19 Req 4 Coord_Req 4 Node_Req 4 18 4 3 Req 16 13 Coord_Req 16 0 14 17 Node_Req 16 5 11 10 16 7 1 2 12 8

  43. Finished CS Execution Clock:4,18s Clock:4,26s Node_Rel 6 15 9 19 Req 4 Coord_Rep 18 4 3 Coord_Req 4 Req 16 13 0 Enters Mutex 14 17 5 11 10 16 7 1 2 12 8

  44. Finished CS Execution Clock:5,03s Clock:4,61s 6 15 9 19 Node_Rel 18 4 3 Coord_Req 16 Req 16 13 0 14 17 Node_Rel 5 11 Coord_Rep 10 16 7 Enters the mutex 1 2 12 8

  45. Analysis Theorem:Total number of messages per CS: k+3d k  number of elements on the ring d  upperbound diameter a cluster

  46. Analysis Proof: d * Node_Req + k * Coord_Req + d * Coord_Rep + d * Node_Rel = k+3d Cluster 1 Cluster 3 d k Cluster 4 Cluster 2

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