Background of Ad hoc Wireless Networks Student Presentations Wireless Communication Technology and Research Ad hoc Routing and Mobile IP and Mobility Wireless Sensor and Mesh Networks Mobile and Ad hoc Networks QoS in Ad Hoc

Overview  Introduction  Ad-hoc Network definition  Overview: Ad-hoc networks  Network architecture  Applications of ad-hoc networks  Ad-hoc networks characteristics and requirements  Overview: QoS  What is QoS ?  The need of QoS in MANETs  Why QoS is hard in MANETs  Current Solutions for Support in MANETs  Flexible QoS Model for MANETs  INSIGNIA-MANETs QoS Signaling  SWAN for MANETs  Conclusions  Q&A

3 Ad Hoc Network definition  An ad-hoc network is a wireless LAN, in which some devices are part of the network only for the duration of a communication session or while in some close proximity to the rest of the network.  A "mobile ad hoc network" (MANET) is an autonomous system of mobile routers (and associated hosts) connected by wireless links forming an arbitrary graph. Routers are free to move randomly and organize themselves arbitrarily; network topology may change rapidly and unpredictably. May operate in a stand-alone fashion, or may be connected to the Internet.  An ad hoc network can be regarded as a “spontaneous network”: a network that automatically “emerges” when nodes gather together

4 MANET – Mobile Ad hoc NETworks A CB D - Mobility- Self configuring and healing- Rapid Deployment - High capacity- Independent of public infrastructure- Relaying - Internet compatible standards-based wireless systems

5 Network Architecture  Flat network infrastructure  Multi-layered network infrastructure Cluster Head Cluster Head Cluster Head

6 Applications of Ad Hoc Networks  Personal communications  Cell phones, laptops  Cooperative environments  Taxi cab network  Meeting rooms  Emergency operations  Policing and fire fighting  Military environments  Battlefield  Network of sensors or floats over water

7 Ad Hoc Networks Characteristics and Requirements  Autonomous and spontaneous nature of nodes  Distributed Algorithms to support security, reliability and consistency of exchanged and stored information  Time-varying network topology (no pre-existing infrastructure or central administration)  Scalable routing and mobility management techniques to face network dynamics  Fluctuating link capacity and network resources  Enhanced functionalities to improve link layer performance, QoS network support and end-to-end efficiency  Low-power devices  Energy conserving techniques at all layers

8 What is QoS ?  Hard to agree on a common definition of QoS  A QoS enabled network shall ensure:  That its applications and/or their users have their QoS parameters fulfilled, while at the same time ensuring an efficient resource usage  That the most important traffic still has its QoS parameters fulfilled during network overload  What are the most important QoS parameters:  Throughput, availability, delay, jitter and packet loss

9 The need for QoS in MANETs  Applications have special service requirements  VoIP: delay, jitter, minimum bandwidth  Needs intelligent buffer handling and queueing  High mobility of users and network nodes  Routing traffic is important  No retransmission of lost broadcast messages  Routing contol messages must be prioritized  For use in emergency and military operations  User traffic prioritization is needed  user, role, situation etc  Wireless bandwidth and battery capacity are scarce resources  Need efficient resource usage  E.g. only route high priority traffic through terminals that are low on power  Need QoS aware routing

10 Video frame without QoS Support Video frame with QoS Support Why QoS is Hard in Mobile Ad Hoc Networks?

11 Why QoS is Hard in Mobile Ad Hoc Networks?  Dynamic network topology  Flow stops receiving QoS provisions due to path disconnections  New paths Must be established, causing data loss and delays  Imprecise state information  Link state changes continuously  Flow states change over time  No central control for coordination  Error-prone shared medium  Hidden terminal problem  Limited resources availability  Bandwidth, battery life, storage, processing capabilities  Insecure medium

12 Current Solutions for QoS support in Mobile Ad Hoc Networks  Because of the unique characteristics of the ad-hoc environment three models provide some good insight into the issues of QoS in MANETs  These models provide a comprehensive solutions, namely  FQMM  INSIGNIA  SWAN  FQMM  INSIGNIA  SWAN Can be integrated with multiple routing protocols Flexibility!  

13 Flexible QoS Model for MANETs (FQMM)  First QoS Model proposed in 2000 for MANETs by Xiao et al  Proposes a “hybrid” provisioning that combines the per-flow granularity on IntServ and per-class granularity of DiffServ  Adopts DiffServ, but improves the per-class granularity to per-flow granularity for certain class of traffic  Built over IntServ and DiffServ models, it can operate with extranet traffic  Classification is made at the source node  QoS provisioning is made on every node along the path  FQMM Model provisions the traffic into two portions  the highest priority is assigned per-flow granularity.  the rest is assigned per-class granularity.  Three types of nodes defined  Ingress (transmit)  Interior (forward)  Egress (receive)

Comparison Service Service Scope Complexity Scalability Connectivity No isolation No guarantees End-to-end No set-up Highly scalable (nodes maintain only routing state) Best-Effort Per aggregation isolation Per aggregation guarantee Domain Long term setup Scalable (edge routers maintains per aggregate state; core routers per class state) Diffserv Per flow isolation Per flow guarantee End-to-end Per flow setup Not scalable (each router maintains per flow state) Intserv

15 INSIGNIA – MANETs QoS Signaling  First signalling protocol designed solely for MANETs by Ahn et al  In-band signaling  Base and enhanced QoS levels  Per-flow management  Resources management adapted as technology  Intelligent packet scheduling  Flow reservation, restoration and adaptation  QoS reports periodically sent to source node  Source node takes action to adapt flows to observed network condition  Routing  Any routing protocol can be used  Route maintenance procedure will affect  In-band signaling  Establish, adapt, tear down reservations  Control information embedded in data packets

16 INSIGNIA – OPTION Field  Supports in-band signaling by adding a new option field in the IP header to carry the signaling control  Reservation Mode (REQ/RES): indicates whether there is already a reservation for this packet.  If “no”, the packet is forwarded to INSIGNIA Module which in coordination with a AC may either: grant resources  Service Type = RT (real-time). deny resources  Service Type = BE (best-effort).  If “yes”, the packet will be forwarded with the allowed resources.  Bandwidth Request (MAX/MIN): indicates the requested amount of bandwidth.

17 INSIGNIA – Bottleneck Node During the flow reservation process a node may be a bottleneck: The service will degrade from RT/MAX -> RT/MIN. If M2 is heavy-loaded it may also degrade the service level to BE/MIN where there is actually no QoS.

18 SWAN - Stateless Wireless Ad Hoc Networks  An alternative to INSIGNIA with improved scalabilities properties  Is a stateless network scheme designed specifically for MANETs with no need to process complex signaling, or to keep per-flow information, to achieve scalability and robustness  Promotes rate control system that can be used at each node to treat traffic either as real-time or best-effort  Excessive real-time traffic is automatically demoted to best-effort  While provides a model that deals with traffic on a per-class, it uses merely two level of service, best-effort and real-time traffic  Both level of service can be mapped to DSCPs with known PHB (based on bandwidth requirement) to facilitate extranet QoS  May decide to demote part of the real-time traffic to best-effort service due to lack of resources  The transmission rate for the best-effort traffic is locally estimated and adjusted to accommodate the bandwidth required by Real Time traffic  Supports source-based admission control and distributed congestion control for real-time traffic  Uses Explicit Congestion Notification (ECN)

19 Ad hoc QoS interconnectivity with fixed network  Ad-Hoc network needs to cling to a host network in order to gain access to the internet  Co-operation between ad hoc network and the host network can facilitate end-to-end QoS support  Framework proposed by Morgan and Kunz defines a solution for interaction between ad hoc and host networks  This framework is not affected by the specific QoS model implemented on either side  Ad-Hoc network may decide to implement INSIGNIA, SWAN, or FQMM, while host network may decide to implement DiffServ or IntServ  Ad-hoc networks rely on the host network resources and services in order to access to the outside world  The host network provides support for the ad-hoc by providing access to specific domain services and agreements

20 Conclusion  In this lecture, we have discussed different existing QoS model for wireless ad-hoc networks  INSIGNIA, SWAN and FQMM, each model provide the basics for a more comprehensive model  Mobile nodes can connect to the Internet gateways of different types, providing different QoS  Classified different approach with respect to different mobility scenarios  In order to achieve an end-to-end QoS approach, QoS information in both fixed and ad-hoc networks should be involved  This demands an interaction between these sections

21 References  [1] Towards End-to-End QoS in Ad-Hoc Networks Connected to Fixed Networks, David Remondo Catalonia Univ. of Technology (UPC)  [2] An architectural framework for MANET QoS interaction with access domains, Yasser Morgan and Thomas Kunz, Carleton University  [3]A proposal for an ad-hoc network QoS gateway, Yasser Morgan and Thomas Kunz, Carleton University  [4] A Glance at Quality of Services in Mobile Ad-Hoc Networks, Zeinalipour-Yazti Demetrios  [5] Quality of Service in Ad-Hoc Networks, Eric Chi, Antoins Dimakis el  [6] QoS in Mobile Ad Hoc Networks, Prasant Mohapatra, Jian Li and Chao Gui, University of California  [7] QoS-aware Routing Based on Bandwidth Estimation for Mobile Ad Hoc networks, Lei Chen and Wendi Heinzelman, University of  [8] Dynamic Quality of Service for Mobile Ad-Hoc Networks, M. Mirhakkak, N. Schult, D. Thomson, The MITRE Corporation  [9] Network Architecture to Support QoS in Mobile Ad Hoc Networks, Lei Chen and Wendi Heizelman, University of Rochester

Assignment #10  Write note on the topics highlighted in Yellow.

Q&A ??