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IEEE 802.16 based mesh networks: the WOMEN project

IEEE 802.16 based mesh networks: the WOMEN project. D. Tarchi University of Florence tarchi@lart.det.unifi.it. Outline. Wireless Mesh Network: Definition and Characteristics Wireless Mesh Networks: application scenarios QoS scheduling solutions Heterogeneous networks solutions.

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IEEE 802.16 based mesh networks: the WOMEN project

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  1. IEEE 802.16 based mesh networks: the WOMEN project D. Tarchi University of Florence tarchi@lart.det.unifi.it COST 289 - 12th MCM - Firenze, Italy

  2. Outline • Wireless Mesh Network: Definition and Characteristics • Wireless Mesh Networks: application scenarios • QoS scheduling solutions • Heterogeneous networks solutions COST 289 - 12th MCM - Firenze, Italy

  3. WOMEN Project • Wireless 8O2.16 Multi-antenna mEsh Networks • University of Roma “La Sapienza” + University of Roma “Tor Vergata” • University of Napoli “Federico II” • University of Firenze • University of Catania • University of Trento COST 289 - 12th MCM - Firenze, Italy

  4. Research Units and WPs WP1 deals with system architecture definition and it is leaded by the University of Roma "La Sapienza". WP2 deals with physical layer aspects linked to MIMO technologies and it is leaded by the University of Napoli "Federico II". WP3 deals with the aspects of Access control and the responsible is the University Firenze WP4 deals with networking protocols and setup and it is leaded by the University of Catania. WP5 is responsible for applications, security and trials and is leaded by the University of Trento that has direct access to the WMAN testbed implemented by CREATE-NET. COST 289 - 12th MCM - Firenze, Italy

  5. Wireless Mesh Networks: Definition • A Wireless Mesh Network is a multi-hop distributed mesh topology system, with self-configuration and self-organization capabilities, where each node is potentially able to forward Informative Units toward other nearby nodes I.F. Akyildiz, X. Wang, W. Wang, “Wireless Mesh Networks: a survey” , Computer Networks No.47, pp. 445-487, 2005. COST 289 - 12th MCM - Firenze, Italy

  6. Wireless Mesh Networks: Characteristics (1/2) • Auto-configuration: all network nodes are designed to self-discover their neighbors and paths without needing of any centralized network entity • Auto-organization: nodes can autonomously resolve Out-of-Service events, due to temporary off or congested radio links, by exploiting the Mesh Topology • Scalability: the covered area can be extended by simply adding new nodes to the current Mesh Network • Mobility: the nodes can move on a limited area and keep the connectivity with (at least) a network node COST 289 - 12th MCM - Firenze, Italy

  7. Wireless Mesh Networks: Characteristics (2/2) • Mesh Clients: mobile and peripheral nodes able to communicate with other nodes only through radio interfaces. Minimal routing functions are solved by them. Moreover, they are power constrained, typically low cost and developed on already existing Wireless Cards (e.g., 802.11a/b/g Network Interface Cards (NIC) ) • Mesh Routers: nodes with minimum (or null) mobility, constituting the network backbone, with radio interfaces towards the mesh clients and mesh routers and wired interfaces towards the outside network. They are not power constrained, can process the most of network traffic and results more expensive than the mesh clients. • Additional features of the Wireless Mesh Networks: Currently there is no standard, and open questions are related to the security aspects and to proper MAC protocol developments COST 289 - 12th MCM - Firenze, Italy

  8. Wireless Mesh Networks: architectures (1/3)(Infrastructure/backbone) IEEE 802.16 • This architecture is composed by mesh routers which are employed for the wireless backbone and mesh clients are excluded by the mesh topology • Connections among the mesh routers are realized with IEEE802.16 technology • Mesh routers function also as gateway for Internet access COST 289 - 12th MCM - Firenze, Italy

  9. Wireless Mesh Networks: architectures (2/3)(Client-Mesh) IEEE 802.11 • This architecture is composed by self-configured Mesh Clients with routing functions • It represents the mesh network operating in ad-hoc mode • Currently wireless links are IEEE 802.11 based COST 289 - 12th MCM - Firenze, Italy

  10. Wireless Mesh Networks: architectures (2/3)(Hybrid-Mesh) IEEE 802.16 IEEE 802.11 • This architecture given by combing the two previous ones • Mesh Clients can access at the network through mesh routers as well as directly with other mesh clients COST 289 - 12th MCM - Firenze, Italy

  11. Broadband home networking Alternative to IEEE 802.11 and Bluetooth standards Application Scenarios (1/2) Community Networking • Low cost alternative to link difficult areas to be cabled COST 289 - 12th MCM - Firenze, Italy

  12. Application Scenarios (2/2) • Metropolitan Wireless Mesh Networks • They can be view as a low cost solution of wide band access networks COST 289 - 12th MCM - Firenze, Italy

  13. Research Activity • WP3 Space division multiple access for QoS guaranteed wide-band connection • T3.1 Link adaptation • T3.2 Hybrid ARQ Techniques • T3.3 Optimized scheduling procedures • WP5 Secure applications, development and trials • T5.1 Security protocols for multi-hop wireless networks • T5.2 Authentication and identity management COST 289 - 12th MCM - Firenze, Italy

  14. T3.3 Optimized scheduling procedures • IEEE 802.16 Scheduling in OFDM mode • Data & VoIP traffic • Heterogeneous Scenario with IEEE 802.11 hot-spots COST 289 - 12th MCM - Firenze, Italy

  15. IEEE 802.16 - MAC The MAC layer can be divided in three sublayers: • Convergence Sublayer: management of the IP and ATM interfaces • Common Part Sublayer: building of the informative packets, management of the QoS and interfaces with the PHY • Privacy Sublayer: management of the cryptography and authentication procedures Fragmentation Concatenation Packing • Building and transmissions of PDU • PHY support • Network inizialization • Scheduling services TDD or FDD (half and/or full duplex) Framing definition Timing of DL and UL framing UGS  guaranteed bandwidth without request rtPS  request of unicast bandwidth and possibility of a minimum guaranteed bandwidth. No contention nrtPS  Unicast and contention requests. Minimum guaranteed bandwidth BES  Contention requests without any guarantee on allocated resources Define the procedure for the network admission COST 289 - 12th MCM - Firenze, Italy

  16. Quality of Service The QoS management involves all that transmitting parameters that have influences on the link performance and that, after defining them, have to be maintained Main parameters: Throughput Bandwidth wastage Delay Packet-loss Techniques for QoS control and dynamic resource management (scheduling policy): Packet Fair Queueing (PFQ): at each queue is assigned a weight that determines the resource allocation. It includes the the techniques based on Round Robin as the Packet Based Round Robin (PBRR) Earliest Deadline First (EDF): at each queue a priority is assigned basing on the deadline of the first packet to be transmitted COST 289 - 12th MCM - Firenze, Italy

  17. Quality of Service – Application to WiMAX Managed traffic types: UGS, rtPS, nrtPS, BES BS Scheduler Priority: 1 = Max 4 = Min Strict semi-preemptive priority UGS rtPS nrtPS BES 1 2 3 4 PFQ Type Connection IDentifier PBRR EDF Priority Enhanced WFQ CID CID CID CID CID CID COST 289 - 12th MCM - Firenze, Italy

  18. Application environment Joint management of Best-Effort and VoIP traffic in a PMP uplink scenario with a central Base Station and a variable number of user terminals Voice over Internet Protocol (VoIP): very sensible to transmission delays and queue waiting time no request UGS Class  guaranteed bandwidth PBRR scheduling Best-Effort: low sensibility to delays and with low constraints contention requests BES Class  not guaranteed bandwidth WFQ scheduling COST 289 - 12th MCM - Firenze, Italy

  19. Framing and contention phases UL Framing and physical slot structure Contention zone VoIP Best – Effort Adaptive threshold • Procedures that characterize the system: • Contention requests • Dynamic bandwidth allocation • Packets transmissions Contention mechanism: random access on one slot that form the contention zone The slots are chosen with uniform probability 0 1 4 0 2 0 1 3 1 Empty slot Collisions Successfull requests COST 289 - 12th MCM - Firenze, Italy

  20. Bandwidth allocation and packets transmission The bandwidth allocation and packets transmission occurs in two ways for the two traffic types: The i-th terminal that can transmit is associated with the weight: Best Effort A sufficient number of byte per frame is allocated to each terminal Weighted scheduling on the winner terminals Scheduling PBRR: the guaranteed bitrate is fixed VoIP Each terminal has a bandwidth equal to the allowable bandwidth multiplied by the associated weight The Base Station transmits the allocated resources to each terminal. COST 289 - 12th MCM - Firenze, Italy

  21. TDD transmission structure Frame duration equal to 1 ms Channel Bandwidth equal to 25 MHz 5000 Physical Slot per Frame 16QAM Modulation Transmission rate equal to 80 Mb/s 4 symbols per PS Trunked Pareto statistic for Best – Effort packet length ON/OFF VoIP traffic generators with exponential interarrival time having an average value equal to 3 seconds and bitrate equal to 66 kb/s Simulation Parameters 5000 Byte per UL frame Fixed UL/DL threshold Average packet length equal to 480 Byte 10000 Byte per frame UTRAN COST 289 - 12th MCM - Firenze, Italy

  22. Queue Length The increasing of the contention zone is a good choice until a certain threshold: 25 is the best choice. COST 289 - 12th MCM - Firenze, Italy

  23. Collision percentage The performance remains quite similar for a number of slots higher than one half of the BE stations COST 289 - 12th MCM - Firenze, Italy

  24. Successful requests A small number of contention slot could imply a lower number of requests due to the increasing of collisions COST 289 - 12th MCM - Firenze, Italy

  25. Numerical results for 75 BE and 20 BE COST 289 - 12th MCM - Firenze, Italy

  26. VoIP traffic 0.181 64 COST 289 - 12th MCM - Firenze, Italy

  27. Heterogeneous network interworking • Allows the interoperability with the existing networks • Rises the WiMAX coverage in indoor environment • Based on standardized network to allow users and operator interoperability • Allow a soft-handoff in order to achieve a total coverage COST 289 - 12th MCM - Firenze, Italy

  28. Wi-Fi vs. WiMAX COST 289 - 12th MCM - Firenze, Italy

  29. Goals • Simple solution. • Interoperability without modifications to the actual standard specifications. • QoS management in the interoperability. • Simple implementation. COST 289 - 12th MCM - Firenze, Italy

  30. Application scenario PmP topology 2 transmitting WLAN Wi-Fi 2 receiving WLAN Wi-Fi WLAN rate equal to 11 Mbit/s WiMAX link in both uplink and downlink with rate equal to 5.5, 9, 11, 22 Mbit/s. COST 289 - 12th MCM - Firenze, Italy

  31. MAC direct interconnection COST 289 - 12th MCM - Firenze, Italy

  32. MAC direct interconnection • The 802.11 frame is directly incapsulated in a MAC PDU 802.16 frame 802.11 frame 802.16 COST 289 - 12th MCM - Firenze, Italy

  33. Direct interconnection • Simple • the WiMAX link is a simple tunnel for the WiFi frames • Fast • low level connection • Does not exploit definitely the IEEE 802.16 standard (skip the CS) • It implementation requires a specific mapping between IEEE 802.11 and IEEE 802.16 primitives • It is not applicable to the IEEE 802.11e. • No QoS support COST 289 - 12th MCM - Firenze, Italy

  34. Ethernet Bridge interconnection COST 289 - 12th MCM - Firenze, Italy

  35. Ethernet Bridge interconnection • The 802.11e frame is converted in a 802.3ac frame with VLAN tag and then it is sent to the WiMAX link COST 289 - 12th MCM - Firenze, Italy

  36. Ethernet Bridge interconnection • The SAP in the IEEE 802.16 MAC for the higher layers (LLC or bridge) is the CS_SAP. • The SAP in the other IEEE 802 MAC for the higher layers (LLC or bridge) is the MAC_SAP. • The other IEEE 802 standards have the same primitives for the MAC_SAP : • M_UNITDATA.indication(); • M_UNITDATA.request(); • The IEEE 802.16 standard does not define the CS_SAP primitives. At the exit from the BRIDGE ETHERNET there is a IEEE 802.3ac frame with VLAN tag for the priority support COST 289 - 12th MCM - Firenze, Italy

  37. Simulation parameters – WiMAX link • From the above parameters it is possible to derive the MAC PDU size (MAC Header + Payload) in byte:80 : 5000 = (bandwidth) : x • where • x is the number of PS assigned to the connection. • Each PS carries 4 modulation symbols.16 QAM -> 1 symbols with 4 bit => 1 PS is 2 byte COST 289 - 12th MCM - Firenze, Italy

  38. N sources with ON/OFF period Pareto distributed are aggregated. 200 ON/OFF sources for each generator. Shape factor (α) for the Pareto distribution of ON/OFF periods equal to 1.4. Average burst length for each sorce equal to 4000 byte . Frame dimension uniformly distributed between 34 e 2346 Bytes. Offered load from the WiFi hot spots between 1.1 Mbit/s to 11 Mbit/s W. Willinger, M. Taqqu, R. Sherman, and D. Wilson. “Selfsimilarity through high-variability: statistical analysis of Ethernet LAN trafficat the source level,” In Proc. ACM SIGCOMM '95, pp. 100-113, 1995. Simulation parameters – WiFi hot spot (Self-similar model) COST 289 - 12th MCM - Firenze, Italy

  39. Throughput & overhead COST 289 - 12th MCM - Firenze, Italy

  40. Packet delay COST 289 - 12th MCM - Firenze, Italy

  41. Packet Delay COST 289 - 12th MCM - Firenze, Italy

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