WNP-MPR-qos 1 Wireless Networks and Protocols MAP-Tele Manuel P. Ricardo Faculdade de Engenharia da Universidade do Porto
WNP-MPR-qos 2 Topics Scheduled for Today … Quality of Service » Characterization and models » Case studies » Research issues …
WNP-MPR-qos 3 Review of QoS basic concepts QoS in wireless networks » 3GPP-QoS » IEEE-wireless-QoS
WNP-MPR-qos 4 Quality of Service From a user’s point of view » level of satisfaction experienced by the user of an application whose traffic is delivered through a network. Depends on – User’s subjective evaluation and expectations – Terminal capabilities – Performance of networks From a network point of view » ability of providing differentiated treatment to traffic flows or traffic classes » provide them with different levels of delivery guarantees – bandwidth, delay, loss » network behaviour characterizable by a set of performance parameters
WNP-MPR-qos 5 QoS principles The provisioning of QoS requires » cooperation of various communications layers » cooperation of network elements in the end-to-end chain QoS requirements of users/applications must be mapped into values of network service attributes Attributes of a network service » may be described by a set of performance (QoS) parameters » which must be observable, measurable and controllable Networks and users must negotiate contracts, which are described by means of offered traffic and QoS parameters
WNP-MPR-qos 6 QoS QoS is an end-to-end problem, handled at several communication layers Application control (e.g. SIP) Application Application node Application node Application Application App. node-backbone control plane interface app. control app. control Transport Inter-domain interface IP layer IP layer IP control plane IP control plane Control Control IP user plane IP user plane Network IP IP IP IP Quality of Service Multicast Mobility Security IP Backbone Data link App. node-backbone user plane (IP) interface Physical
WNP-MPR-qos 7 QoS building blocks in a packet network • network Data plane (traffic flows/packets) – Shaping, Policing – Classification & Marking – Queuing and Scheduling (service discipline) – Congestion control and Queue management • Control plane – QoS mapping – Admission control – QoS routing – Resource reservation/allocation • Management plane – Resource provisioning – Policy management Traffic source/ packet switch feed-back based, end-to-end (TCO, RTP+RTCP) (router, switch) previous network element inter-network element
WNP-MPR-qos 8 IP QoS Models 2 service models » IntServ - oriented towards the support of QoS per flow » DiffServ - oriented towards the provisioning of QoS to traffic classes Differentiated Services Integrated Services (IntServ) model (DiffServ) model » Resource ReSerVation Protocol » DS field (RSVP) » Per-Hop Behaviours (PHB) » FlowSpec » Assured Forwarding (AF) » Controlled load » Expedited Forwarding (EF) » Guaranteed service (maximum delay) » Bandwidth broker
WNP-MPR-qos 9 IntServ - RSVP Resource ReSerVation Protocol (RSVP)
WNP-MPR-qos 10 IntServ – Tspec, FlowSpec The FlowSpec - information that characterizes » the traffic to submit to the network (TSpec) » the service requested from the network (RSpec) TSpec includes the following parameters » p – peak rate » r – mean rate » b – bucket size » M – maximum datagram size » m – minimum policed unit RSpec is specified only for the Guaranteed service and includes » R – service rate (must be > r) » S – delay slack (acceptable delay in addition to the delay obtained with R
WNP-MPR-qos 11 IntServ – QoS Services Guaranteed Service » hard guarantees provided to real-time applications – Guaranteed bandwidth – Bound on end-to-end delay – No losses of conforming packets on the routers » Resources reserved per flow, based on a Flowspec (TSpec and RSpec) Controlled-Load Service » emulates the service provided by a moderately loaded best-effort network » only qualitative guarantees – Very high percentage of transmitted packets are successfully delivered – Delay of the majority of the packets will not greatly exceed the minimum delay of a packet » The sender does not specify RSpec
WNP-MPR-qos 12 DiffServ – DSCP field 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | DSCP | CU | +---+---+---+---+---+---+---+---+ DSCP: differentiated services codepoint CU: currently unused
WNP-MPR-qos 13 Diff Serv – PHB, AF, EF Per-Hop Behaviours (PHB) » Packets marked with the same DSCP, receive similar treatment 3 PHBs defined » Best effort » Assured Forwarding (AF) – Service provides qualitative guarantees, based on priorities – Service characterized by a high probability of packet delivery – may be used to implement the Olympic service (gold, silver, and bronze classes) » Expedited Forwarding (EF) – aimed at building services characterized by low packet loss ratio, low latency and low jitter
WNP-MPR-qos 14 DiffServ - Bandwidth broker
WNP-MPR-qos 15 QoS in UMTS
WNP-MPR-qos 16 Quality of Service in UMTS UMTS CN TE MT RAN TE CN Gateway EDGE NODE End-to-End Service TE/MT Local External Bearer UMTS Bearer Service UMTS Bearer Service Bearer Service Service CN Bearer Radio Access Bearer Service Service Radio Bearer RAN Access Backbone Bearer Service Service Bearer Service Physical Radio Physical Bearer Service Bearer Service
WNP-MPR-qos 17 QoS management functions, UMTS bearer service, user plane TE MT RAN CN EDGE Gateway Ext. Netw. Class if. Class if. Cond. Cond. Cond. Mapper Mapper Mapper Resource Resource Resource Resource Resource Resource Local BS External BS Manager Manager Manager Manager Manager Manager RAN phys. BS work service BB netw ork service RAN Access net data f low with indication of direction
WNP-MPR-qos 18 TE MT RAN CN EDGE Gateway Ext. Netw. Class if. Class if. Cond. Cond. Cond. Mapper Mapper Mapper Resource Resource Resource Resource Resource Resource Local BS External BS Manager Manager Manager Manager Manager Manager Class RAN phys. BS work service BB netw ork service RAN Access net data f low with indication of direction » Classifies and marks packet » At the entry of network (downlink GGSN, uplink terminal) Cond – Traffic conditioner » Enforces compliance of flow with QoS attributes » At the entry of the network and radio segment Mapper » marks packet with QoS information related to bearer service below Resource manager » Decides when to send the packet so that QoS is satisfied » Manages the resources it sees – Packet queues, ARQ mechanisms, modulations and codes, power, spreading codes
WNP-MPR-qos 19 UMTS QoS Classes Traffic class Conversational class Streaming class Interactive class Background Fundamental Preserve time relation Preserve time Request-response Destination is characteristics (variation) between relation (variation) pattern not expecting information entities of between the data within a the stream information entities certain time Preserve payload of the stream content Conversational pattern Preserve (stringent and low payload content delay) Example of the voice streaming video Web browsing Background application download of emails
WNP-MPR-qos 20 UMTS Bearer Service Attributes – Examples Traffic class ('conversational', 'streaming', 'interactive', 'background') Maximum bitrate (kbit/s) » compliance enforced by token-bucket (Maximum-bitrate , Maximum-SDU-size) » used to reserve codes in WCDMA radio interface - downlink Guaranteed bitrate (kbit/s) » traffic compliance enforced by token-bucket (Guaranteed-bitrate , Maximum-SDU-size) » Delay/ reliability attributes guaranteed only for traffic up to the Guaranteed bitrate » Used for admission control and resource allocation Maximum SDU size (octets) SDU error ratio » fraction of SDUs lost or detected as erroneous Residual bit error ratio » Undetected bit error ratio in the delivered SDUs Transfer delay (ms) » 95th percentile of the statistical delay distribution
WNP-MPR-qos 21 Token Bucket OK OK Non-compliant TBC L1<TBC L2<TBC L3>TBC b b-L1+r* T b-L1 Time Token Bucket Counter (TBC) - number of remaining tokens at any time
WNP-MPR-qos 22 QoS attributes versus traffic classes Conversational Streaming class Interactive class Background class Traffic class class Maximum bit rate X X X X Delivery order X X X X Maximum SDU size X X X X SDU format X X information SDU error ratio X X X X Residual bit error X X X X ratio Delivery of X X X X erroneous SDUs Transfer delay X X Guaranteed bit rate X X Traffic handling X priority Allocation/ X X X X Retention priority Source statistics X X descriptor Signalling Indication X
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