WNP-MPR-Fundaments 28 Hidden, Exposed and Capture Nodes ♦ Signal strength decays with the path length ♦ Carrier sensing depends on the position of the receiver ♦ MAC protocols using carrier sensing Ł 3 type of nodes » hidden nodes – C is hidden to A D » exposed nodes – C is exposed to B A B C » capture nodes – D captures A
WNP-MPR-Fundaments 29 Hidden, Exposed and Capture Nodes • Hidden node � C is hidden to A – A transmits to B; C cannot hear A – If C hears the channel it thinks channel is idle; C starts transmitting Ł interferes with data reception at B – In the range of receiver; out of the range of the sender • Exposed node � C is exposed to B – B transmits to A; C hears B; C does not transmit; but C transmission would not interfere with A reception – In the range of the sender; out of the range of the receiver • Capture � D captures A – receiver can receive from two senders – A and D transmit simultaneously to B; but signal from D much higher than that from A D A B C
WNP-MPR-Fundaments 30 Alhoa, S-Alhoa, CSMA ♦ Alhoa � Efficiency of 18 % if station has a packet to transmit u transmits the packet u waits confirmation from receiver (ACK) u if confirmation does not arrive in round trip time, the station computes random backofftime � retransmits packet ♦ Slotted Alhoa � Efficiency of 37 % stations transmit just at the beginning of each time slot ♦ Carrier Sense Multiple Access (CSMA) � Efficiency of 54 % – station listens the carrier before it sends the packet – If medium busy � station defers its transmission ♦ ACK required for Alhoa, S-Alhoa and CSMA
WNP-MPR-Fundaments 31 CSMA/CD – Not Used in Wireless ♦ CDMA/Collision Detection � Efficiency < 80% – station monitors de medium (carrier sense) u medium free � transmits the packet u medium busy � waits until medium is free � transmits packet u if, during a round trip time, detects a collision � station aborts transmission and stresses collision � station aborts transmission and stresses collision (no ACK packet) ♦ Problems of CDMA/CD in wireless networks Carrier sensing carrier sensing difficult for hidden terminal Collision detection near-end interference makes simultaneous transmission and reception difficult
WNP-MPR-Fundaments 32 To think about? ♦ How to minimize collision in a wireless medium?
WNP-MPR-Fundaments 33 CSMA with Collision Avoidance (CSMA/CA) DIFS DATA S1 DIFS S2-bo DATA S2 S3-bo DIFS DIFS S3-bo-r S3-bo-e S3-bo-r DATA S3 DATA DIFS S2-bo - Packet arrival - Transmission of DATA - Time interval DIFS - Backoff time, station 2 - Elapsed backoff time, station 3 - Remaining backoff time, station 3 S3-bo-e S3-bo-r
WNP-MPR-Fundaments 34 CSMA with Collision Avoidance (CSMA/CA) ♦ Station with a packet to transmit monitors the channel activity until an idle period equal to a Distributed Inter-Frame Space (DIFS) has been observed ♦ If the medium is sensed busy a random backoff interval is selected. The backoff time counter is decremented as long as the selected. The backoff time counter is decremented as long as the channel is sensed idle, stopped when a transmission is detected on the channel, and reactivated when the channel is sensed idle again for more than a DIFS. The station transmits when the backoff time reaches 0 ♦ To avoid channel capture, a station must wait a random backoff time between two consecutive packet transmissions, even if the medium is sensed idle in the DIFS time
WNP-MPR-Fundaments 35 CSMA/CA – ACK Required DIFS DATA S1 SIFS SIFS ACK ACK ACK ACK AP DIFS S2-Backoff DATA S2 DATA DIFS - Packet arrival - Transmission of DATA - Time interval DIFS
WNP-MPR-Fundaments 36 CSMA/CA – ACK Required ♦ CSMA/CA does not rely on the capability of the stations to detect a collision by hearing their own transmission ♦ A positive acknowledgement is transmitted by the destination station to signal the successful packet transmission ♦ In order to allow an immediate response, the acknowledgement is transmitted ♦ In order to allow an immediate response, the acknowledgement is transmitted following the received packet, after a Short Inter-Frame Space (SIFS) ♦ If the transmitting station does not receive the acknowledge within a specified ACK timeout, or it detects the transmission of a different packet on the channel, it reschedules the packet transmission according to the previous backoff rules. ♦ Efficiency of CSMA/CA depends strongly of the number of competing stations. An efficiency of 60% is commonly found
WNP-MPR-Fundaments 37 To Think About ♦ How to enable hidden terminals to sense the carrier? D B A C Hidden node � � C is hidden to A � �
WNP-MPR-Fundaments 38 RTS-CTS Mechanism SIFS DIFS RTS DATA S1 SIFS SIFS CTS ACK AP S2-bo DIFS DATA S2 DATA DIFS - Packet arrival - Transmission of DATA - Time interval DIFS
WNP-MPR-Fundaments 39 RTS-CTS Mechanism ♦ For some scenarios where long packets are used or the probability of hidden terminals is not irrelevant, the efficiency of CSMA/CA can be further improved with a Request To Send (RTS) - Clear to Send (CTS) mechanism ♦ The basic concept is that a sender station sends a short RTS message to the receiver station. When the receiver gets a RTS from the sender, it polls the sender by sending a short CTS message. The sender then sends its packet to the receiver. After correctly receiving the packet, the receiver sends a positive acknowledgement (ACK) to the receiving the packet, the receiver sends a positive acknowledgement (ACK) to the sender ♦ This mechanism is particularly useful to transmit large packets. The listening of the RTS or the CTS messages enable the stations in range respectively of the sender or receiver that a big packet is about to be transmitted. Usually both the RTS and the CTS contain information about the number of slots required to transmit the 4 packets. Using this information the other stations refrain themselves to transmit packets, thus avoiding collisions and increasing the system efficiency. ♦ SIFS are used before the transmission of CTS, Data, and ACK ♦ In optimum conditions the RTS-CTS mechanism may add an efficiency gain of about 15%
WNP-MPR-Fundaments 40 Guaranteed Access Control ♦ Polling » AP manages stations access to the medium » Channel tested first using a control handshake
WNP-MPR-Fundaments 41 Fundamental Networking Fundamental Networking
WNP-MPR-Fundaments 42 Topics Scheduled for Today A. The Basic Framework ♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview) » Transmission » Wireless data links and medium access control » Wireless data links and medium access control » Networking » Why wireless? Mobility concepts and management » Research issues B. The Existing Practices and Concepts » …
WNP-MPR-Fundaments 43 ♦ What networking concepts shall I have present from previous courses? ♦ What are the differences between L2 and L3 networks? ♦ What is a tunnel? What is a virtual network? Why are they relevant? ♦ What is a tunnel? What is a virtual network? Why are they relevant? ♦ What are the differences between IPv4 and IPv6?
WNP-MPR-Fundaments 44 Switching: Circuits, Virtual Circuits, Datagram
WNP-MPR-Fundaments 45 Circuit Switching ♦ Technologies: ISDN: Basic Rate Access, E1 Ł time slots for 64 kbit/s channels ♦ Path defined during call establishment, based on the called number ♦ Switching » Exchange of time slots » In time and in space » Inputs required to be synchronised
WNP-MPR-Fundaments 46 Virtual Circuit Switching ♦ Technologies: ATM, MPLS ♦ Path » defined during the virtual circuit establishment » Defined as a set of nodes, ports, labels ♦ Switching » Cells, packets » Exchange of labels a b c c k n k b a 1 1 Entrada Saída comutação n m espacial 2 Porta CV Porta CV a 2 n 1 comutação b 1 n y c z y g h g M N c N g de etiqueta t t y 1 k M cabeçalho z N h controlo de c 2 m dados comutação a, b, c, ... indicador de canal virtual Tabela de translação de portas / canais virtuais
WNP-MPR-Fundaments 47 Packet Switching ♦ Technologies: Ethernet, IP ♦ Path defined by packet destination address
WNP-MPR-Fundaments 48 To Think About ♦ Suppose terminal a moves from port 2 to port 1 » What needs to be done so that terminal a can continue receiving packets?
WNP-MPR-Fundaments 49 L2 Networking – Frame Formats 7x 10101010 10101011 Protocolo=IP Ethernet Bit stuffing – 5 1s seguidos Ł emissor introduz 0 Ł Ł Ł PPP
WNP-MPR-Fundaments 50 L2 Networking - Bridge ♦ Interconnects » 2 LAN technologies » 2 segments of the same technology ♦ Bridge builds forwarding tables automatically Ł Address learning Source Address of received frame is associated to a bridge input port Ł station reachable trough that port station reachable trough that port ♦ Frame forwarding » When a frame is received, its Destination Address is analysed – If address is associated to a port � frame forwarded to that port – If not � frame transmitted through all the ports but the input port
WNP-MPR-Fundaments 51 L2 Networking - Single Tree Required • Ethernet frame – No hop-count – Could loop forever in a L2 mis- configured network – Same for broadcast packet • Layer 2 network – Tree topology – Single path between every pair of stations • Spanning Tree (ST) Protocol – Running in bridges – Helps building the spanning tree – Blocks ports
WNP-MPR-Fundaments 52 Ethernet Switch The computer attached to a port gets the illusion to have » its own LAN segment » its LAN segment bridged to all the other segments
WNP-MPR-Fundaments 53 Virtual LANs ♦ One bridge/switch simulates multiple LANs / broadcast domains ♦ One LAN may be extended to other bridges w w x x [da=broadcast; sa=x; data] [da=broadcast; sa=x; data] VLAN 100 VLAN 100 B 1 B 2 VLAN 200 VLAN 200 y z [da=broadcast; sa=x; vlanid=100 ; data]
WNP-MPR-Fundaments 54 L3 Networking – Packet Formats 0 4 8 16 24 31 0 4 8 16 19 31 Flow Label TOS Length Version Traffic Class Version HLen Ident Flags Offset Payload Lengtht Next Header Hop Limit TTL Protocol Checksum SourceAddr (4 words) SourceAddr SourceAddr DestinationAddr DestinationAddr (4 words) Pad Options (variable) (variable) Options (variable number) Data Data IPv4 IPv6
WNP-MPR-Fundaments 55 L3 Networking – Router 3ª generation router
WNP-MPR-Fundaments 56 L3 Networking – Multiple Trees … ♦ Every router » finds the shortest path to the other routers and their attached networks » Calculates its Shortest Path Tree (SPT) ♦ Routing protocol » Runs in routers » Runs in routers » Helps routers build their SPT » RIP, OSPF, BGP B’s routing view Destination Cost NextHop B A 1 A C A C 1 C D D 2 C E E 2 A F 2 A G F G 3 A
WNP-MPR-Fundaments 57 TCP ♦ Point to connection between a client and a server; port-to-port (SequenceNum) Data ♦ Reliable, flow control Sender Receiver Acknowledgment + AdvertisedWindow AdvertisedWindow ♦ Congestion control
WNP-MPR-Fundaments 58 Multimedia Traffic - Taxonomy Applications Real time (variation of the packet end-to-end delay) Elastic (packet loss) Intolerant Tolerant (application reaction to packet loss) Nonadaptive Adaptive Rate adaptive Delay adaptive (type of reaction)
WNP-MPR-Fundaments 59 RTP+RTCP/UDP ♦ Multimedia traffic ♦ Application-Level Framing ♦ Data Packets (RTP) » sequence number » timestamp (app defines “tick”) » timestamp (app defines “tick”) » transported as UDP packets ♦ Control Packets (RTCP) » sent periodically » report loss rate (fraction of packets received since last report) » report measured jitter
WNP-MPR-Fundaments 60 Traditional TCP/IP Communications Stack IETF IP address based switching APP APP TCP TCP IP IP IP IP T1 T1 | T2 T3 | T4 T4 | T5 T5 T2 | T3 host router router bridge bridge host IEEE MAC address based switching
WNP-MPR-Fundaments 61 Tunnel IP-in-IP APP TCP APP IP TCP IP IP IP IP IP T4 | T5 T1 T1 | T2 T2 | T3 T3 | T4 T5 H1 R2 bridge R1 bridge Server outer IP header inner IP header data ver. IHL TOS length IP identification flags fragment offset TTL IP-in-IP IP checksum SA= 2nd IP address of H1 DA= 2nd IP address of R2 ver. IHL TOS length IP identification flags fragment offset TTL lay. 4 prot. IP checksum SA=H1 DA= Server TCP/UDP/ ... payload
WNP-MPR-Fundaments 62 Tunnel PPP over IP (E.g PPTP) APP TCP IP IP PPP PPP APP GRE GRE TCP IP IP IP IP T1 T3 | T4 T4 | T5 T5 T1 | T2 T2 | T3 H1 R2 R1 bridge bridge Server » GRE – virtual point-to-point link – encapsulates a variety of network layer protocols – routers at remote points – over an IP network » PPP adequate for – Authentication – Transporting IP packets
WNP-MPR-Fundaments 63 PPP over Ethernet - In an ADSL router/modem the protocols of Host PC and ADSL modem are combined in a single network element
WNP-MPR-Fundaments 64 IPv6 IPv6
WNP-MPR-Fundaments 65 The Need of a New IP ♦ IPv4 – Small addressing space (32 bits) – Non-continuous usage – Some solutions used to overcome these problems private networks (NAT), classless networks (CDIR) ♦ IETF developed new IP version: IPv6 – Same principles of IPv4 – Many improvements – Header re-defined ♦ IPv6 may be relevant for mobile communications
WNP-MPR-Fundaments 66 IPv6 – Improvements » 128 bit addresses (16 octets, 8 shorts ). No classes » Better QoS support (flow label) » Native security functions (peer authentication, data encryption) » Autoconfiguration ( Plug-n-play) » Routing » Multicast
WNP-MPR-Fundaments 67 Address Representation ♦ 8 x 16 bit, hexadecimal. Separated by : 47CD : 1234 : 3200 : 0000 : 0000 : 4325 : B792 : 0428 ♦ Compressed format: FF01:0:0:0:0:0:0:43 � � FF01::43 � � ♦ Compatibility with IPv4: 0:0:0:0:0:0:13.1.68.3 or ::13.1.68.3 ♦ Loopback address: ::1 ♦ Network prefix described by / , same as IPv4 » FEDC:BA98:7600::/40 � network prefix = 40 bits � � �
WNP-MPR-Fundaments 68 Reserved Addresses Allocation Prefix Fraction of (binary) Address Space ----------------------------------- -------- ------------- Unassigned 0000 0000 1/256 Unassigned 0000 0001 1/256 Reserved for NSAP Allocation 0000 001 1/128 Unassigned 0000 01 1/64 Unassigned 0000 1 1/32 Unassigned 0001 1/16 Unassigned 0001 1/16 Global Unicast 001 1/8 Unassigned 010 1/8 Unassigned 011 1/8 Unassigned 100 1/8 Unassigned 101 1/8 Unassigned 110 1/8 Unassigned 1110 1/16 Unassigned 1111 0 1/32 Unassigned 1111 10 1/64 Unassigned 1111 110 1/128 Unassigned 1111 1110 0 1/512 Link-Local Unicast Addresses 1111 1110 10 1/1024 Site-Local Unicast Addresses 1111 1110 11 1/1024 Multicast Addresses 1111 1111 1/256
WNP-MPR-Fundaments 69 Adresses – Link-Local, Site-Local, Global Unicast, Anycast » Link-Local – Used for communication between hosts in the same LAN /link – Address built from MAC address – Routers do not foward packets having Link-Local destination addresses » Site-Local – Not used anymore – Not used anymore » Global Unicast – Global addresses – Address: network prefix + computer identifier – Structured prefixes Network aggregation; less entries in the router forwarding tables » Anycast – Group address; packet is received by any (only one) member of the group » Multicast – Group address; packet received by all the members of the group
WNP-MPR-Fundaments 70 Address Formats | n bits | m bits | 128-n-m bits | Global Unicast Address +------------------------+-----------+----------------------------+ (2000::/3) |001 global rout prefix | subnet ID | interface ID | +------------------------+-----------+----------------------------+ | 10 | | bits | 54 bits | 64 bits | Link-Local Unicast address +----------+-------------------------+----------------------------+ (fe80::/10) |1111111010| 0 | interface ID | +----------+-------------------------+----------------------------+ | 10 | | bits | 54 bits | 64 bits | Site-Local Unicast address +----------+-------------------------+----------------------------+ (fec0::/10) |1111111011| subnet ID | interface ID | +----------+-------------------------+----------------------------+ | n bits | 128-n bits | Anycast address +------------------------------------------------+----------------+ | subnet prefix | 00000000000000 | +------------------------------------------------+----------------+ | 8 | 4 | 4 | 112 bits | Multicast address +------ -+----+----+---------------------------------------------+ Scope – link, site, global, ... |11111111|flgs|scop| group ID | +--------+----+----+---------------------------------------------+ (ff::/8)
WNP-MPR-Fundaments 71 Headers IPv4 and IPv6 0 4 8 16 24 31 0 4 8 16 19 31 Flow Label TOS Length Version Traffic Class Version HLen Ident Flags Offset Payload Lengtht Next Header Hop Limit TTL Protocol Checksum SourceAddr (4 words) SourceAddr SourceAddr DestinationAddr DestinationAddr (4 words) Pad Options (variable) (variable) Options (variable number) Data Data IPv4 IPv6
WNP-MPR-Fundaments 72 IPv6 Header ♦ Flow label � identifies packet flow » QoS, resource reservation 0 4 8 16 24 31 Version Traffic Class Flow Label » Packets receive same service Payload Lengtht Next Header Hop Limit ♦ Payload length ♦ Payload length SourceAddr (4 words) » Header not included DestinationAddr (4 words) Options (variable number) ♦ Hop limit = TTL (v4) Data ♦ Next header » Identifies next header/extension ♦ Options � included as extension headers
WNP-MPR-Fundaments 73 Extension Headers IPv6 Header TCP header + data Next Header = TCP IPv6 Header Routing Header TCP header + data Next Header = Routing Next Header = TCP Fragment of IPv6 Header Routing Header Fragment Header TCP header + data Next Header = Routing Next Header = Fragment Next Header = TCP IPv6 Hop-by-hop Destination Routing Fragment Authenticate. ESP TCP
WNP-MPR-Fundaments 74 Extension Headers » Hop-by-hop additional information, inspected by every node traversed by the packet Other header are inspected only at the destination or at pre-defined nodes » Destination: » Destination: Information for the destination node Information for the destination node » Routing: List of nodes to be visited by the packet » Fragmentation: Made by the source; it shall find MPU » Authentication: Authentication (signature) of packet header » ESP: Data encryption
WNP-MPR-Fundaments 75 Routing Header - Pacote sent from S to D, through I1, I2, I3 As the packet travels from S to I1: Source Address = S Hdr Ext Len = 6 Destination Address = I1 Segments Left = 3 Address[1] = I2 Address[2] = I3 Address[3] = D As the packet travels from I1 to I2: Source Address = S Hdr Ext Len = 6 Destination Address = I2 Segments Left = 2 Destination Address = I2 Segments Left = 2 Address[1] = I1 Address[2] = I3 Address[3] = D As the packet travels from I2 to I3: Source Address = S Hdr Ext Len = 6 Destination Address = I3 Segments Left = 1 Address[1] = I1 Address[2] = I2 Address[3] = D As the packet travels from I3 to D: List of Source Address = S Hdr Ext Len = 6 Destination Address = D Segments Left = 0 visited Address[1] = I1 nodes Address[2] = I2 Address[3] = I3
WNP-MPR-Fundaments 76 Example of Lab Network quadro porta banc_3 banc_6 pc3---[HUB]---pc2----+ +----pc2---[HUB]---pc3 2000:0:0:3::/64 | | 2000:0:0:6::/64 | | banc_2 | | banc_5 banc_2 | | banc_5 pc3---[HUB]---pc2--[HUB]-+ +-[HUB]--pc2---[HUB]---pc3 2000:0:0:2::/64 | | | | 2000:0:0:5::/64 | | | | banc_1 | | | | banc_4 pc3---[HUB]---pc2----+ | | +----pc2---[HUB]---pc3 2000:0:0:1::/64 | | 2000:0:0:4::/64 | | 2000:0:0:e::/64| |2000:0:0:d::/64 | | [routerv6] 2000:0:0:1::1 2000:0:0:1::aa 2000:0:0:e::1
WNP-MPR-Fundaments 77 Configuration examples in Linux tux13:~# /sbin/ifconfig eth0 inet6 add 2000:0:0:1::1/64 tux13:~# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:C0:DF:08:D5:99 inet addr:172.16.1.13 Bcast:172.16.1.255 Mask:255.255.255.0 inet6 addr: 2000:0:0:1::1/64 Scope:Global inet6 addr: fe80::2c0:dfff:fe08:d599/10 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:81403 errors:0 dropped:0 overruns:0 frame:0 TX packets:2429 errors:0 dropped:0 overruns:0 carrier:0 TX packets:2429 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:4981344 (4.7 MiB) TX bytes:260692 (254.5 KiB) Interrupt:5 tux13:~# /sbin/route -A inet6 add 2000::/3 gw 2000:0:0:1::aa tux13:~# route -A inet6 Kernel IPv6 routing table Destination NextHop Flags Metric Ref Use Iface ::1/128 :: U 0 0 0 lo 2000:0:0:1::1/128 :: U 0 0 0 lo 2000:0:0:1::/64 :: UA 256 0 0 eth0 2000::/3 2000:0:0:1::aa UG 1 0 0 eth0 fe80::2c0:dfff:fe08:d599/128 :: U 0 0 0 lo fe80::/10 :: UA 256 0 0 eth0 ff00::/8 :: UA 256 0 0 eth0 ::/0 :: UDA 256 0 0 eth0
WNP-MPR-Fundaments 78 Identifier IEEE EUI-64 Method to create a IEEE EUI-64 identifier from an IEEE 48bit MAC identifier. This is to insert two octets, with hexadecimal values of 0xFF and 0xFE, in the middle of the 48 bit MAC (between the company_id and vendor supplied id). For example, the 48 bit IEEE MAC with global scope: |0 1|1 3|3 4| |0 5|6 1|2 7| +----------------+----------------+----------------+ |cccccc0gcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm| |cccccc0gcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm| +----------------+----------------+----------------+ 00:C0:DF:08:D5:99 where "c" are the bits of the assigned company_id, "0" is the value of the universal/local bit to indicate global scope, "g" is individual/group bit, and "m" are the bits of the manufacturer-selected extension identifier. The interface identifier would be of the form: |0 1|1 3|3 4|4 6| |0 5|6 1|2 7|8 3| +----------------+----------------+----------------+----------------+ |cccccc1gcccccccc|cccccccc11111111|11111110mmmmmmmm|mmmmmmmmmmmmmmmm| +----------------+----------------+----------------+----------------+ fe80::2c0:dfff:fe08:d599
WNP-MPR-Fundaments 79 Protocolo Neighbor Discovery (ND) ♦ IPv6 node uses ND for » Find other nodes in the same link /LAN » Find a node MAC address ND substitutes ARP » Find router(s) in its network » Mantaining information about neighbour nodes ♦ ND similar to the IPv4 functions » ARP IPv4 » ICMP Router Discovery » ICMP Redirect
WNP-MPR-Fundaments 80 ND Messages » ICMP messages (over IP); using Link Local addresses » Neighbor Solicitation Sent by a host to obtain MAC address of a neighbour / to verify its presence Neighbor Advertisement : Answer to the request Neighbor Advertisement : Answer to the request » » » Router Advertisement Information about the network prefix; periodic or under request Sent by router to IP address Link Local multicast Router Solicitation : host solicits from router a Router Advertisment message » Redirect : Used by a router to inform na host about the best route to a destination »
WNP-MPR-Fundaments 81 IPv6 Address Configuration
WNP-MPR-Fundaments 82 Packet Transmission
WNP-MPR-Fundaments 83 Mobility Management
WNP-MPR-Fundaments 84 Topics Scheduled for Today A. The Basic Framework ♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview) » Transmission » Wireless data links and medium access control » Wireless data links and medium access control » Networking » Why wireless? Mobility concepts and management » Research issues B. The Existing Practices and Concepts » …
WNP-MPR-Fundaments 85 ♦ What are the key management concepts? ♦ What functionality is associated to Mobility Management?
WNP-MPR-Fundaments 86 Handoff ♦ Transference of a call, or session, to a new cell / service-area ♦ Caused by radio link degradation ( � terminal movement) or to re-distribute traffic AP 1 1 T Terminal switch Mobility 2 2 T AP
WNP-MPR-Fundaments 87 Other Terms Used ♦ (Terminal) Mobility types » Macro-mobility: between organizations » Micro-mobility: in the same organization ♦ Handover types ♦ Handover types » Vertical handover: between different technologies » Horizontal handover: same technology, same organization
WNP-MPR-Fundaments 88 Macro Mobilility (e.g. Mobile IP) Corresponding host Home Same route Internet Organization 2 Organization 1 Mobile Mobile node node
WNP-MPR-Fundaments 89 Micro-Mobility (e.g. Mobile IP) Corresponding host Home Same route Internet Organization 2 Organization 1 Mobile node Mobile node
WNP-MPR-Fundaments 90 Mobility Management ♦ Mobility management » Enables network to be aware of terminal location » Maintains the route/connection to the terminal when it moves ♦ Mobility management Ł 2 functions – Location management – Handoff management
WNP-MPR-Fundaments 91 Location Management ♦ Location registration/update ♦ Location registration/update » Terminal informs network about its current access point; regularly » Network updates terminal location location database ♦ New Call/Session/Data delivery » When a new Call/Session/Data arrives to terminal’s home network network requested to find the terminal location, by querying location databases (or by paging the terminal)
WNP-MPR-Fundaments 92 Handoff Management ♦ Maintains terminal connection/routes when terminal moves ♦ Initiation: need for handoff identified ♦ New connection/route generation » Resources found for the handoff connection – In Network-Controlled Handoff (NCHO) � the network finds the resources – In Mobile-Controlled Handoff (MCHO) � terminal finds resources, network approves » Routing operations performed ♦ Data-flow control: delivery of data from old to new paths, maintaining QoS
WNP-MPR-Fundaments 93 To Think About How can I manage mobility at IP layer? 1.
WNP-MPR-Fundaments 94 Mobility Management • Handled at multiple layers Application – Data Link: 3GPP, IEEE networks Transport – Network: Mobile IP, HIP – Transport: Mobile TCP Network Quality of Service ce Multicast – Application: SIP Mobility Security Data link • Security and QoS Physical – Affect Mobility Management • How to avoid new authentication at every new AP? • How to guarantee that radio resources are available at the new AP?
WNP-MPR-Fundaments 95 To Think About ♦ How does Skype manage computer mobility?
WNP-MPR-Fundaments 96 Research Issues Research Issues
WNP-MPR-Fundaments 97 Topics Scheduled for Today A. The Basic Framework ♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview) » Transmission » Wireless data links and medium access control » Wireless data links and medium access control » Networking » Why wireless? Mobility concepts and management » Research issues B. The Existing Practices and Concepts » …
WNP-MPR-Fundaments 98 Classes of Research Topics • Basic connectivity Applications f Service Network Network Quality of S Multicast • Management planes Mobility Security Wireless Link – Mobility – Security – Multicast – Quality of Service
WNP-MPR-Fundaments 99 Research Topics – Basic Connectivity Applications Quality of Service Wireless link Network » Cognitive radio Multicast Mobility Security » Intelligent modulation/code Wireless Link » Multi-radio resource management » Multi-radio resource management » Optimal radio usage based on neighbours information » Software defined radio » Multi-hop mac protocols » MAC for multi-channel protocols » Combination of access techniques (increase used of SDMA)
WNP-MPR-Fundaments 100 Research Topics – Basic Connectivity Networking Applications » Auto-configuration uality of Service » Multi-homing Network » Mesh networks ulticast obility ecurity » Congestion avoidance » Congestion avoidance Wireless Link Wireless Link Sec Mu Mo Qu » Bio-inspired routing paradigms » Un-planned wireless networks » Networks growing organically » Very large networks » Adequate support of demanding applications: peer-to-peer and m � n » Networks driven by applications (sensor like networks) » Networks more aware of radio conditions (cognitive like networks)
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