Mobility Chapter 5. Rating. First steps Text book. No apps Mission critical. Not really Must have. Overview. Motivation for Mobile IP.

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1 Raing Mobiliy Chaper 5 Area mauriy Firs seps Tex book Pracical imporance No apps Mission criical Theoreical imporance No really Mus have Ad Hoc and Sensor Neworks Roger Waenhofer 5/1 Ad Hoc and Sensor Neworks Roger Waenhofer 5/2 Overview Moivaion for Mobile IP Mobile IP Moivaion Daa ransfer Encapsulaion Locaion Services & Rouing Classificaion of locaion services Home based GLS MLS Example: Locaion service of GSM Mobiliy Models Rouing based on IP desinaion address, nework prefix (e.g ) deermines physical subne change of physical subne implies change of IP address o have a opological correc address (sandard IP) or needs special enries in he rouing ables Changing he IP-address? adjus he hos IP address depending on he curren locaion almos impossible o find a mobile sysem, DNS updaes are oo slow TCP connecions break securiy problems Change/Add rouing able enries for mobile hoss? worldwide! does no scale wih he number of mobile hoss and frequen changes in heir locaion Ad Hoc and Sensor Neworks Roger Waenhofer 5/3 Ad Hoc and Sensor Neworks Roger Waenhofer 5/4

2 Requiremens on Mobile IP (RFC 2002) Daa ransfer from mobile sysem Compaibiliy suppor of he same layer 2 proocols as IP no changes o curren end-sysems and rouers required mobile end-sysems can communicae wih fixed sysems Transparency mobile end-sysems keep heir IP address coninuaion of communicaion afer inerrupion of link possible poin of connecion o he fixed nework can be changed Efficiency and scalabiliy only lile addiional messages o he mobile sysem required (connecion ypically via a low bandwidh radio link) world-wide suppor of a large number of mobile sysems Securiy auhenicaion of all regisraion messages home nework (physical home nework of MN) CN HA FA foreign nework MN Mobile Node (mobile end-sysem) User (end-sysem) Ad Hoc and Sensor Neworks Roger Waenhofer 5/5 Ad Hoc and Sensor Neworks Roger Waenhofer 5/6 Daa ransfer o mobile sysem Daa ransfer back o CN HA 2 FA foreign nework 3 HA FA foreign nework home nework MN home nework MN 1 CN User (end-sysem) 1. Sender sends o he IP of MN, HA inerceps packe (proxy ARP) 2. HA unnels packe o FA by encapsulaion 3. FA forwards packe o he MN CN User (end-sysem) MN sends o he IP address of he receiver (CN) as usual, FA works as defaul rouer. Ad Hoc and Sensor Neworks Roger Waenhofer 5/7 Ad Hoc and Sensor Neworks Roger Waenhofer 5/8

3 Terminology Mobile Node (MN) sysem (node) ha can change he poin of connecion o he nework wihou changing is IP address Home Agen (HA) sysem in he home nework of he MN, ypically a rouer regisers he locaion of he MN, unnels IP daagrams o he COA Foreign Agen (FA) sysem in he curren foreign nework of he MN, ypically a rouer ypically he defaul rouer for he MN Care-of Address (COA) address of he curren unnel end-poin for he MN (a FA or MN) acual locaion of he MN from an IP poin of view can be chosen, e.g., via DHCP Corresponden Node (CN) Overview HA home nework CN User(end-sysem) COA FA HA unnels packes o he COA of he FA foreign nework MN Ad Hoc and Sensor Neworks Roger Waenhofer 5/9 Ad Hoc and Sensor Neworks Roger Waenhofer 5/10 Agen adverisemen Agen Adverisemen HA and FA periodically send adverisemen messages ino heir physical subnes MN lisens o hese messages and deecs if i is in he home or a foreign nework (sandard case for home nework) MN reads a COA from he FA adverisemen messages Regisraion (always limied lifeime!) MN signals COA o he HA via he FA, HA acknowledges via FA o MN hese acions have o be secured by auhenicaion Adverisemen HA adverises he IP address of he MN (as for fixed sysems), i.e. sandard rouing informaion rouers adjus heir enries, hese are sable for a longer ime (HA responsible for a MN over a longer period of ime) packes o he MN are sen o he HA independen of changes in COA/FA ype code checksum #addresses addr. size lifeime rouer address 1 preference level 1 rouer address 2 preference level 2... ype lengh sequence number regisraion lifeime R B H F MG V reserved COA 1 COA 2... Ad Hoc and Sensor Neworks Roger Waenhofer 5/11 Ad Hoc and Sensor Neworks Roger Waenhofer 5/12

4 IP-in-IP Encapsulaion Minimal Encapsulaion Mandaory in RFC 2003 unnel beween HA and COA HA CN COA MN opional avoids repeiion of idenical fields such as TTL, IHL, version, TOS only applicable for unfragmened packes, no space lef for fragmen idenificaion ver. IHL TOS lengh IP idenificaion flags fragmen offse TTL IP-in-IP IP checksum IP address of HA Care-of address COA ver. IHL TOS lengh IP idenificaion flags fragmen offse TTL lay. 4 pro. IP checksum IP address of CN IP address of MN TCP/UDP/... payload ver. IHL TOS lengh IP idenificaion flags fragmen offse TTL min. encap. IP checksum IP address of HA care-of address COA lay. 4 prooc. S reserved IP checksum IP address of MN IP address of CN (only if S=1) TCP/UDP/... payload Ad Hoc and Sensor Neworks Roger Waenhofer 5/13 Ad Hoc and Sensor Neworks Roger Waenhofer 5/14 Daa ransfer from he mobile sysem Reverse unneling (RFC 2344) HA FA foreign newor HA 2 FA foreign newor 1 home nework MN home nework MN 3 CN User(end-sysem) Problems: - Firewall a CN - TTL - Mulicas CN User(end-sysem) 1. MN sends o FA 2. FA unnels packes o HA by encapsulaion 3. HA forwards he packe o he receiver (sandard case) Ad Hoc and Sensor Neworks Roger Waenhofer 5/15 Ad Hoc and Sensor Neworks Roger Waenhofer 5/16

5 Mobile IP wih reverse unneling Opimizaion of packe forwarding a packe from he MN encapsulaed by he FA is now opologically correc furhermore mulicas and TTL problems solved (TTL in he home nework correc, bu MN is oo far away from he receiver) Reverse unneling does no solve problems wih firewalls, he reverse unnel can be abused o circumven securiy mechanisms (unnel hijacking) opimizaion of daa pahs, i.e. packes will be forwarded hrough he unnel via he HA o a sender (double riangular rouing) Reverse unneling is backwards compaible he exensions can be implemened easily and cooperae wih curren implemenaions wihou hese exensions Triangular Rouing sender sends all packes via HA o MN higher laency and nework load sender learns he curren locaion of MN direc unneling o his locaion HA informs a sender abou he locaion of MN big securiy problems Change of FA packes on-he-fly during he change can be los new FA informs old FA o avoid packe loss, old FA now forwards remaining packes o new FA his informaion also enables he old FA o release resources for he MN Ad Hoc and Sensor Neworks Roger Waenhofer 5/17 Ad Hoc and Sensor Neworks Roger Waenhofer 5/18 Change of foreign agen Locaion services CN HA FA old FA new MN reques updae updae ACK daa ACK daa regisraion warning daa updae ACK daa daa regisraion daa daa MN changes locaion Service ha maps node names o (geographic) coordinaes Should be disribued (no require for specialized hardware) Should be efficien Lookup of he posiion (or COA) of a mobile node Mobile IP: Ask home agen Home agen is deermined hrough IP (unique ID) of MN Possibly long deours even hough sender and receiver are close OK for Inerne applicaions, where laency is (normally) low Oher applicaion: Rouing in a MANET MANET: mobile ad hoc nework No dedicaed rouing hardware Limied memory on each node: canno sore huge rouing ables Nodes are mosly baery powered and have limied energy Nodes roue messages, e.g. using georouing Ad Hoc and Sensor Neworks Roger Waenhofer 5/19 Ad Hoc and Sensor Neworks Roger Waenhofer 5/20

6 Home based georouing in a MANET Home based locaion service how good is i? How can he sender learn he curren posiion of anoher node? Flooding he enire nework is undesirable (raffic and energy overhead) Home based approach Similar o Mobile IP, each node has a home node, where i sores and regularly updaes is curren posiion The home is deermined by he unique ID of he node. One possibiliy is o hash he ID o a posiion p and use he node closes o p as home. Thus, given he ID of a node, every node can deermine he posiion of he corresponding home. Home based rouing 1. Roue packe o h, he home of he desinaion 2. Read he curren posiion of 3. Roue o s h p Visiing he home of a node migh be waseful if he sender and receiver happen o be close, bu he home far away The rouing srech is defined as srech := lengh of roue lengh of opimal roue We wan rouing algorihms wih low srech. Simulaneous message rouing and node movemen migh cause problems Can we do beer? s h p h p s Classificaion of locaion services Locaion services: Lookup & Publish Proacive Mobile node divulges is posiion o all nodes whenever i moves E.g. hrough flooding Any node A can invoke o basic operaions: Lookup(A, B): A asks for he posiion of B Reacive Sender searches mobile hos only when i wans o send a message E.g. hrough flooding Hybrid Boh, proacive and reacive. Some nodes sore informaion abou where a node is locaed Arbirarily complicaed sorage srucures Suppor for simulaneous rouing and node mobiliy Publish(A, x, y): A announces is move from posiion x o y Open quesions How ofen does a node publish is curren posiion? Where is he posiion informaion sored? How does he lookup operaion find he desired informaion? Ad Hoc and Sensor Neworks Roger Waenhofer 5/23 Ad Hoc and Sensor Neworks Roger Waenhofer 5/24

7 The Grid Locaion Service (GLS), Li e. al (2000) The Grid Canno ge reasonable srech wih one single home. Therefore, use several homes (locaion servers) where he node publishes is posiion. Level-1 (2 M,2 M ) The locaion servers are seleced based on a grid srucure: The area in which he nodes are locaed is divided ino squares All nodes agree on he lower lef corner (0,0) and upper righ corner (2 M, 2 M ), which forms he square called level-m Recursively, each level-n square is spli ino 4 level-(n-1) squares The recursion sops for level-1 Level-M (0,0) Level-(M-1) Ad Hoc and Sensor Neworks Roger Waenhofer 5/25 Ad Hoc and Sensor Neworks Roger Waenhofer 5/26 Addressing of nodes Selecing locaion servers Unique IDs are generaed for each node (e.g. by using a hashfuncion) ID space (all possible hash values) is circular Every node can find a leas greaer node w.r.. he ID space (he closes node) Each node A recruis locaion servers using he underlying grid: In each of he 3 level-1 squares ha, along wih A, make up a level-2 square, A chooses he node closes o is own ID as locaion server. The same selecion process is repeaed on higher level squares. Example: Le he ID space range from 1 o 99 and consider he IDs {3, 43, 80, 92}. Then, he leas greaer node wih respec o he given ID space is 3 43; 43 80; 80 92; Example for node 92, which selecs he nodes {23, 17, 11} on he level-1 and {2, 3, 31} on level Ad Hoc and Sensor Neworks Roger Waenhofer 5/27 Ad Hoc and Sensor Neworks Roger Waenhofer 5/28

8 Complee example Querying locaion of oher nodes , 72, 76, 81, 1, 5, 6, 10, 12, 82, 84, 14, 37, 62, 70, 90, 1, 5, 16, 37, 16, 17, 19, 21, 62, 63, 90, 23, 26, 28, 31, 32, 35 1, 62, 70, 90 1, 5, 16, 37, 39, 41, 43, 45, 50, 51, 55, 61, , 35, 37, 45, 50, 51, 82 19, 35, 39, 45, 39, 41, 43 51, 82 1, 2, 16, 37, 35, 39, 45, 50 19, 35, 39, 45, 62, 70, 90, 50, 51, 55, 61, 62, 63, 70, 72, 76, 81 62,, 19, 20, 21, 23, 26, 28, 31, 32, 51, 82 14, 17, 19, 20, 2, 17, 20, 63 2, 17, 23, 26, 21, 23, 31, 32, 43, 55, 61, 62 14, 23, 26, 31, 32, 43, 55, 61, 63, 81, 82, 84 1, 2, 5, 6, 10, 12, 14, 16, 17, 82, 84,, 90,, 19 28, 31, 32, 35, 10, 20, 21, 28, 37, 39 41, 43, 45, 50, 51, 55, 61, 62, 63, 70 2, 12, 26,, 1, 17, 23, 63, 2, 12, 14, 16, 6, 10, 20, 21, 81,, 23, 63 23, 26, 41, 72, 76, 84 6, 72, 76, , 81, 31, 32, 81,, 12, 43, 45, 50, 12, 43, 55 1, 2, 5, 21, 76, 6, 10, 20, 76 6, 10, 12, 14, 90, 51, 61 84,, 90,, 16, 17, 19, 84 31, 32, 43, 55, 61, 63, 70, 72, 76, 2, 12, 14, 17, 23, 26, 28, 32, 81, 12, 14, 17, 23, 26, 31, 32, 35, 37, 39, 41, 55, 61 2, 5, 6, 10, 6, 21, 28, 41, 20, 21, 28, 41, 43, 55, 61, 72 72, 76, 81, 82 63, 81,, Lookup(A, B): Find a locaion server of node B 1. Node A sends he reques (wih georouing) o he node wih ID closes o B for which A has locaion informaion 2. Each node on he way forwards he reques in he same way 3. Evenually, he query reaches a locaion server of B, which forwards i o B. Example: Send packe from 81 o 23 14, 17, 19, 20, 21, 23, 26 14, 23, 26, 31, 32, 43, 55, 61, 63, 81, 82, , 12, 26,, 14 31, 81, 31, 32, 81,, 90, 31, 32, 43, 55, 61, 63, 70, 72, 76, 2, 12, 14, 17, 23, 26, 28, 32, 81, 31 2, 17, 20, 63 2, 17, 23, 26, 31, 32, 43, 55, 61, 62 1, 17, 23, 63, 81,, , 43, 45, 50, 51, , 14, 17, 23, 26, 31, 32, 35, 37, 39, 41, 55, , 12, 14, 16, 23, 63 12, 43, , 5, 6, 10, 43, 55, 61, 63, 81,, 12 Ad Hoc and Sensor Neworks Roger Waenhofer 5/29 Lookup Example Analysis of GLS Lookup for 17 from 76, 39 and , 72, 76, 81, 82, 84, , 5, 6, 10, 12, 14, 37, 62, 70, 90, 1, 5, 16, 37, 16, 17, 19, 62, 63, 90, 21, 23, 26, 28, 31, 32, 35 1, 62, 70, 90 1, 5, 16, 37, 39, 41, 43, 45, 50, 51, 55, 61, , 35, 37, 45, 50, 51, 82 19, 35, 39, 45, 39, 41, 43 51, 82 1, 2, 16, 37, 35, 39, 45, 50 19, 35, 39, 45, 62, 70, 90, 50, 51, 55, 61, 62, 63, 70, 72, 76, 81 62,, 19, 20, 21, 23, 26, 28, 31, 32, 51, 82 1, 2, 5, 6, 10, 12, 14, 16, 82 17, 84,, 90,, Theorem 1: A query needs no more han k locaion query seps o reach a locaion server of he desinaion when he sender and receiver are colocaed in a level-k square. Theorem 2: The query never leaves he level-k square in which he sender and desinaion are colocaed. 14, 17, 19, 20, 2, 17, 20, 63 2, 17, 23, 26, 21, 23, 31, 32, 43, 55, 61, , 23, 26, 31, 32, 43, 55, 61, 63, 81, 82, , 31, 32, 35, 10, 20, 21, 28, 37, 39 41, 43, 45, 50, 51, 55, 61, 62, 63, 70 2, 12, 26,, 1, 17, 23, 63, 2, 12, 14, 16, 6, 10, 20, 21, 81,, 23, 63 23, 26, 41, 72, 76, 84 31, 81, 31, 32, 81,, 12, 43, 45, 50, 12, 43, 55 1, 2, 5, 21, 76, 6, 10, 20, 76 90, 51, 61 84,, 90,, 31, 32, 43, 55, 61, 63, 70, 72, 76, 2, 12, 14, 17, 23, 26, 28, 32, 81, 12, 14, 17, 23, 26, 31, 32, 35, 37, 39, 41, 55, 61 2, 5, 6, 10, 43, 55, 61, 63, 81,, 6, 72, 76, , 21, 28, 41, 20, 21, 28, 41, 72, 76, 81, , 10, 12, 14, 16, 17, 19, Ad Hoc and Sensor Neworks Roger Waenhofer 5/32

9 GLS has no wors case guaranees GLS and mobiliy The lookup cos beween wo nodes migh be arbirarily high even hough he nodes are very close The publish cos migh be arbirarily high even hough a node only moved a very shor disance In sparse neworks, rouing o he locaion server may have wors case cos, while rouing direcly can be more efficien Node crosses boundary line: wha happens o he Mus redisribue all informaion in he old level Gaher new informaion in he new level Publish cos is arbirarily high compared o he moved disance 14, 17, 19, 20, 21, 23, 26 14, 23, 26, 31, 2, 12, 26,, 32, 43, 55, 61, 63, 81, 82, 84 31, 81, 31, 32, 81,, 90, 14 2, 17, 20, 6 2 1, 17, 23, 6 81,, 12, 43, 45 50, 51, 61 1, 5, 16, 37, 62, 63, 90, 1, 62, 70, , 17, 19, 20, 21, 23, 14, 23, 26, 31, 32, 43, 55, 61, 63, 81, 82, , 72, 76, 81, 82, 84, 90 1, 5, 16, 37, 39, 41, 43, 45, 50, 51, 55, 61, , 5, 6, 10, 12, 14, 37, 62, 70, 90, 16 1, 2, 16, 37, 62, 70, 90, , 17, 19, 21, 23, 26, 28, 31, 32, , 35, 39, 45, 51, , 39, 45, 50 62,, 19, 20, 21, 23, 26, 28, 31, 32, 51, 82 2, 12, 26,, 31, 81, 31, 32, 81,, 90, 31, 32, 43, 55, 61, 63, 70, 72, 76, 2, 12, 14, 17, 23, 26, 28, 32, 81, 2, 17, 20, 63 2, 17, 23, 26, 31, 32, 43, 55, 61, 62 1, 17, 23, 63, 81,, 12, 43, 45, 50, 51, 61 12, 14, 17, 23, 26, 31, 32, 35, 37, 39, 41, 55, 61 2, 12, 14, 16, 23, 63 28, 31, 32, 35, 37, 39 12, 43, 55 1, 2, 5, 21, 76, 84,, 90,, A B 2, 5, 6, 10, 43, 55, 61, 63, 81,, 6, 10, 20, 21, 23, 26, 41, 72, 76, 84 6, 10, 20, 76 6, 21, 28, 41, , 35, 37, 45, 50, 51, 82 39, 41, , 2, 5, 6, 10, 12, 14, 16, 17, 82, 84,, 90,, 10, 20, 21, 28, 41, 43, 45, 50, 51, 55, 61, 62, 63, 70 6, 72, 76, 84 20, 21, 28, 41, 72, 76, 81, , 35, 39, 45, 50, 51, 55, 61, 62, 63, 70, 72, 76, 81 6, 10, 12, 14, 16, 17, 19, A lookup happening in parallel wih node movemen migh fail. Thus, GLS does no guaranee delivery for real concurren sysems, where nodes migh move independenly a any ime , 32, 43, 55, 61, 63, 70, 72, 76, 81 2, 12, 14, 17, 23, 26, 28, 32, 81, , 14, 17 26, 31, 32 37, 39, Ad Hoc and Sensor Neworks Roger Waenhofer 5/33 Ad Hoc and Sensor Neworks Roger Waenhofer 5/34 Improving GLS Locaion poiners (aka locaion servers) Goals for MLS Publish cos only depends on moved disance Lookup cos only depends on he disance beween he sender and receiver Nodes migh move arbirarily a any ime, even while oher nodes issue lookup requess Difference o GLS: Only one locaion poiner (LP) per level (L) (GLS: 3 locaion servers) The locaion poiner only knows in which sub-level he node is locaed (GLS: he locaion server knows he exac posiion) L M LP M L 0 L 1 Deermine he maximum allowed node speed under which MLS LP 1 sill guaranees delivery LP M 1 L 2 LP 2 L M 1 Ad Hoc and Sensor Neworks Roger Waenhofer 5/35

10 Locaion poiner & Noaion Rouing in MLS Noaion: LP k L k Locaion poiner for node on level-k Level-k ha conains node Rouing from a node s o a node consiss of wo phases: 1. Find a locaion poiner LP k The locaion poiners are placed depending on heir ID, as in he home-based lookup sysem. The posiion of LP k is obained by hashing he ID of node o a posiion in. The locaion poiner is sored on he neares nodes. L k 2. Once a firs locaion poiner is found on level-k, we know in which of he 4 sub-squares is locaed and hus in which L k 1 has published anoher locaion poiner LP k 1. Recursively, he message is roued owards locaion poiners on lower levels unil i reaches he lowes level, from where i can be roued direcly o. Ad Hoc and Sensor Neworks Roger Waenhofer 5/37 Ad Hoc and Sensor Neworks Roger Waenhofer 5/38 Rouing in MLS (2) Suppor for mobiliy in MLS When a node s wans o find a locaion poiner of a node, i firs searches in is immediae neighborhood and hen exends he search area wih exponenial growing coverage. Firs, ry o find a locaion poiner LP 0 in L s 0 or one of is 8 neighboring levels. Repea his search on he nex higher level unil a LP k is found The lookup pah draws a spiral-like shape wih exponenially increasing radius unil i finds a locaion poiner of. Once a locaion poiner is found, he lookup reques knows in which sub-square i can find he nex locaion poiner of. A locaion poiner only needs o be updaed when he node leaves he corresponding sub-square. LP 2 is OK as long as remains in he shaded area. Mos of he ime, only he closes few locaion poiners need o be updaed due o mobiliy. No enough: If a node moves across a level boundary, many poiners need o be updaed. E.g. a node oscillaes beween he wo poins a and b. LP 1 LP i+2 LP i+1 LP i LP 2 LP i+1 LP i ab Ad Hoc and Sensor Neworks Roger Waenhofer 5/39

11 Lazy publishing Lazy publishing wih forwarding poiners LP k is sill somewha close o he level L k where poins. LP k No problem, add a forwarding poiner ha indicaes in which neighboring level he locaion poiner can be found. LP i+2 LP i+2 LP i+1 LP i+1 LP i FP i LP i Breaks he lookup: LP i+1 poins o a level ha does no conain LP i Ad Hoc and Sensor Neworks Roger Waenhofer 5/41 Ad Hoc and Sensor Neworks Roger Waenhofer 5/42 Concurrency in MLS Concurrency in MLS (2) Allowing for concurren lookup requess and node mobiliy is somewha ricky, especially he deleion of poiners. Noe ha a lookup reques needs some ime o ravel beween locaion poiners. The same holds for requess o creae or delee locaion (or forwarding) poiners. No problem eiher: Insead of removing a locaion poiner or forwarding poiner, replace i wih a emporary poiner ha remains here for a shor ime unil we are sure ha no lookup reques migh arrive anymore on his oudaed pah. Similar o he forwarding poiner, a emporary poiner redirecs a lookup o he neighbor level where he node is locaed. Example: A lookup reques follows LP i+1, and node moves as indicaed updaes is LP iand LP i+1 and removes he FP i and he old LP i The lookup reques fails if i arrives afer he has been removed FP i LP i+1 FP i LP i LP i LP i+1 TP i LP i TP i Ad Hoc and Sensor Neworks Roger Waenhofer 5/43 Ad Hoc and Sensor Neworks Roger Waenhofer 5/44

12 Properies of MLS MLS Conclusions Consan lookup srech The lengh of he chosen roue is only a consan longer han he opimal roue Publish cos is O(d log d) where moved disance is d Even if nodes move considerably, he induced message overhead due o publish requess is moderae. Works in a concurren seup Lookup requess and node movemen migh inerleave arbirarily Nodes migh no move faser han 1/15 of he underlying rouing speed We can deermine he maximum node speed ha MLS suppors. Only if nodes move faser, here migh arise siuaions where a lookup reques fails. Use of emporary forwarding poiners MLS is he firs locaion service ha deermines he maximum speed a which nodes migh move Wihou he speed limiaion, no delivery guaranees can be made! Drawbacks MLS uilizes an underlying rouing algorihm ha can deliver messages wih consan srech given he posiion of he desinaion MLS requires a relaively dense node populaion Ad Hoc and Sensor Neworks Roger Waenhofer 5/45 Ad Hoc and Sensor Neworks Roger Waenhofer 5/46 Locaion service of GSM: elemens and inerfaces Archiecure of he GSM sysem U m radio cell MS MS BSS radio cell GSM is a PLMN (Public Land Mobile Nework) several providers seup mobile neworks following he GSM sandard wihin each counry RSS NSS A bis A BSC VLR BTS MSC HLR O BSC VLR MS BTS MSC GMSC IWF signaling ISDN, PSTN PDN componens MS (mobile saion) BS (base saion) MSC (mobile swiching cener) LR (locaion regiser) subsysems RSS (radio subsysem): covers all radio aspecs NSS (nework and swiching subsysem): call forwarding, handover, swiching OSS (operaion subsysem): managemen of he nework OSS EIR AUC OMC Ad Hoc and Sensor Neworks Roger Waenhofer 5/47 Ad Hoc and Sensor Neworks Roger Waenhofer 5/48

13 GSM: Mobile Terminaed Call GSM: Mobile Originaed Call 1: calling a GSM subscriber 2: forwarding call o GMSC 3: signal call seup o HLR 4, 5: reques MSRN from VLR 6: forward responsible MSC o GMSC 7: forward call o curren MSC 8, 9: ge curren saus of MS 10, 11: paging of MS 12, 13: MS answers 14, 15: securiy checks 16, 17: se up connecion calling saion 4 HLR VLR PSTN GMSC 1 2 MSC BSS BSS BSS MS 1, 2: connecion reques 3, 4: securiy check 5-8: check resources (free circui) 9-10: se up call PSTN 6 5 GMSC MS 10 VLR 3 4 MSC 2 9 BSS Ad Hoc and Sensor Neworks Roger Waenhofer 5/49 Ad Hoc and Sensor Neworks Roger Waenhofer 5/50 GSM signaling from/o MS in MTC and MOC Mobiliy Models MS MTC BTS paging reques channel reques immediae assignmen paging response auhenicaion reques auhenicaion response ciphering command ciphering complee seup call confirmed assignmen command assignmen complee alering connec connec acknowledge daa/speech exchange MS MOC BTS channel reques immediae assignmen service reques auhenicaion reques auhenicaion response ciphering command ciphering complee seup call confirmed assignmen command assignmen complee alering connec connec acknowledge daa/speech exchange When sudying mobiliy, one migh resolve o models. We have: Wors-case model wih maximum speed resricions (as seen) Census-based models in which areas, and how do hey move beween hese areas This is also popular in research abou viruses and diseases Random models Brownian moion Random waypoin Random rip Ad Hoc and Sensor Neworks Roger Waenhofer 5/51 Ad Hoc and Sensor Neworks Roger Waenhofer 5/52

14 The Random Waypoin Model [following slides by JY Le Boudec, EPFL] The Random Trip model In is simples form: Mobile picks nex waypoin M n uniformly in area Mobile picks nex speed V n uniformly in [v min ; v max ] Boh independen of pas and presen Mobile moves owards M n a consan speed V n Random Waypoin is a special case of Random Trip: Mobile picks a pah in a se of pahs and a speed A end of pah, mobile picks a new pah and speed Mobiles may decide o wai and sleep a desinaions before going on he nex leg E.g. shores Euclidean pah in non-convex area, or shores pah on sree map M n-1 M n Ad Hoc and Sensor Neworks Roger Waenhofer 5/54 Simulaion problems If you simulae mobiliy, you need o ake care abou sysem Samples of locaion a imes 0s and 2000s Average node speed The problem is ha he seady- Ad Hoc and Sensor Neworks Roger Waenhofer 5/55 55 Ad Hoc and Sensor Neworks Roger Waenhofer 5/56

15 Simulaion soluion The problem is ha your simulaions my show resuls The correc soluion is o simulaneously draw posiion and velociy from he seady-sae disribuion (see work by Le Boudec for deails.) If you wan o simulae for ime T, you really need o simulae ime 2T, and hrow he firs half of your simulaion away. Anoher (also wrong) soluion is o sar each node a a posiion p which is uniformly random beween uniformly random poins s and, and wih velociy according o he disribuion 1/v. However, also his Ad Hoc and Sensor Neworks Roger Waenhofer 5/57 Open problem Even sysems like MLS sill make way oo many simplifying assumpions. So here is he obvious quesion abou a locaion service which is pracical. Essenially a good locaion service sysem needs o 1. work in dynamic environmens 2. give accepable memory and communicaion loads 3. provide srech guaranees be secure Ad Hoc and Sensor Neworks Roger Waenhofer 5/59