Voice over 802.11, 802.16 and 3G/WCDMA D93944005 賴啟屏 R94922068 廖承賦 2018/11/23

Outline IEEE 802.11 IEEE 802.16(WiMAX) 3G/WCDMA 2018/11/23

Agenda 802.11 MAC layer QoS 802.11e MAC layer QoS 802.11e EDCA performance analysis 2018/11/23

Reference “Analysis of IEEE 802.11e for QoS Support in Wireless LANs”, IEEE Wireless Communication, Dec. 2003 “Performance Analysis of IEEE 802.11e Contention-Based Channel Access”, IEEE Communication, vol. 22, NO. 10, Dec.2004 “Performance Analysis and Enhancements for IEEE 802.11e Wireless Networks”, IEEE Network, July/August 2005 2018/11/23

802.11 with QoS (PCF + DCF) Support for time-bound services Coordinated by Point Coordinator (PC) Typically the AP A superframe Beacon Contention Free Period (CFP) Contention Period (CP) B CFP CP 2018/11/23

Contention Period (CP) CTS ACK AP RTS DATA Station 1 RTS Station 2 2018/11/23

Contention Free Period (CFP) B Data and CF-Poll Data and CF-Poll CF end AP Data Station 1 DATA Station 2 Contention Period (CP) Contention Free Period (CFP) Contention Period (CP) 2018/11/23

Problems in the 802.11 MAC Time-bounded application (ex: VoIP) Bandwidth, delay, and jitter is considered PCF problems Unpredictable Beacon delay Result in frame delay Variable transmission time Delay and jitter can not be guaranteed DCF problems All frames contention channel with the same priority No QoS label in MAC frame 2018/11/23

QoS Support Mechanisms of 802.11e Medium access mechanisms HCCA : Solve PCF problem in 802.11 PCF Unpredictable Beacon delay : Transmission exceed next beacon arrival is not allowed Variable transmission time : TXOPlimit to bound transmission time EDCA : Solve DCF problem in 802.11 DCF All frames contention channel with the same priority : Four access categories with different QoS priority CFP (polling) CP (contention) CFP (polling) superframe 2018/11/23

HCCA A B AP TXOP Station A TXOP Station B QoS CF-POLL QoS CF-POLL CF-end Ask for : Admitted_time Used_time A B AP TXOP Station A TXOP Station B 2018/11/23 Contention Period (CP) Contention Free Period (CFP)

EDCA : four access categories 802.11e station Voice Video Best Effort Background Backoff: AIFS[AC_VO] CWmin[AC_VO] CWmax[AC_VO] Backoff: AIFS[AC_VI] CWmin[AC_VI] CWmax[AC_VI] Backoff: AIFS[AC_BE] CWmin[AC_BE] CWmax[AC_BE] Backoff: AIFS[AC_BK] CWmin[AC_BK] CWmax[AC_BK] Contention to transmit 2018/11/23 Transmission

EDCA control AIFS, CWmin and CWmax can be decided by AP ACK RTS DATA AIFS[AC_BK] Background AIFS[AC_BE] Best Effort AIFS[AC_VI] Video AIFS[AC_VO] ACK RTS DATA Voice CTS DIFS 2018/11/23

EDCA channel access procedure random backoff 3 slots random backoff 5 slots AIFS[0] AIFS[0] RTS DATA Freeze Station A CTS ACK AP random backoff 3 slots Remaining Backoff 2 slots AIFS[3] AIFS[3] Freeze counter, set NAV RTS Station B 2018/11/23

EDCA performance analysis Analytical model for EDCA Some assumptions Fixed number of station (M) Each station has multiple access categories Each access category always has a packet to transmit. Ideal channel environment without errors 2018/11/23

2018/11/23

One step transition ( j , k , d ) j : j-th trying to transmit packet j = -2 represent packet is now transmitting j = -1 represent the state before the first transmission k : backoff counter (range : [0,Wj]) d : (1) remaining frozen time (2) remaining time for transmission (3) remaining time for collision period 2018/11/23

Delay 2018/11/23

Beacon delay Unpredictable beacon delays Result in frame delay transmitted in CFP Contention Period Contention Free Period ACK B Data and CF-Poll Data CTS RTS DATA DATA Contention Period Contention Free Period 2018/11/23 BACK

TXOP A time duration TXOPlimit : maximum value of a TXOP During TXOP a station is allowed to transmit a burst of data frames TXOPlimit : maximum value of a TXOP 2018/11/23 BACK

Agenda Introduce to IEEE 802.16 Uplink request/grant scheduling algorithm for real-time service Unsolicited grant service Real-time polling service Proposed algorithm NUMERICAL ANALYSIS && Simulation results 2018/11/23

Reference IEEE Standard 802.16: A Technical Overview of the WirelessMAN™ Air Interface of BWA A Quality of Service Architecture for IEEE 802.16 Standards An Efficient Uplink Scheduling Algorithm Based on Voice Activity for VoIP Services in IEEE 802.16d/e System 2018/11/23

Overview Standard for wireless metropolitan area networks (WirelessMAN™) Goal: Provide high-speed Internet access to home and business subscribers, without wires. Base stations (BS) can handle thousands of subscriber stations (SS) Supports A variety of services such as IP, voice over IP, and streaming video ATM & packet based protocols Applications with different QoS requirements. 2018/11/23

Wireless Metropolitan Area Networks (MANs) 2018/11/23

IEEE 802.16 MAC layer(1/2) 2018/11/23

IEEE 802.16 MAC layer(2/2) The Service-Specific Convergence Sublayer (CS) provides any transformation or mapping of external network data, received through the CS service access point (SAP). The MAC CPS provides the core MAC functionality of system access, bandwidth allocation, connection establishment, and connection maintenance. The MAC security sublayer providing authentication, secure key exchange, and encryption. 2018/11/23

The Downlink and Uplink subframe Ranging Contention 2018/11/23

Uplink request/grant scheduling Uplink request/grant scheduling is performed by the BS with the intent of providing each subordinate SS with bandwidth for uplink transmissions or opportunities to request bandwidth. By specifying a scheduling service type and its associated QoS parameters, the BS scheduler can anticipate the throughput and latency needs of the uplink traffic and provide polls and/or grants at the appropriate times. 2018/11/23

Voice traffic Model ON OFF Assume that using a voice codec with a voice activity detector (VAD) or silence detector (SD), the SS can know whether its state is on or off by using a VAD or SD in the higher layer. 2018/11/23

Unsolicited grant service(1/2) The UGS is designed to support real-time service flows that generate fixed size data packets periodically. The BS periodically assigns fixed size grants to the SS. 2018/11/23

Unsolicited grant service(2/2) Advantage: These grant size and period are negotiated in the initialization. It can minimize a MAC overhead and uplink access delay Disadvantage: It causes a waste of uplink resource because of silence duration. 2018/11/23

Real-time polling service(1/2) The rtPS is designed to support real-time service flows that generate variable size data packets periodically. The BS assigns uplink resources which are sufficient for unicast bandwidth request to the SS 2018/11/23

Real-time polling service(2/2) Advantage: It has more optimum data transport efficiency than the UGS algorithm. Disadvantage: It has more MAC overhead and more access delay than the UGS algorithm. 2018/11/23

Other The non-real time polling service is designed to support delay-tolerant data streams consisting of variable-sized data packets for which a minimum data rate is required. The Basic Effort (BE) service is designed to support data streams for which no minimum service level is required and therefore may be handled on a space-available basis. 2018/11/23

Using Rule Fixed-size grants on a real-time periodic UGS VoIP without silence mode Fixed-size grants on a real-time periodic rtPS MPEG, VoIP with silence mode Periodic unicast request opportunities nrtPS FTP Timely unicast request opportunities Contention request opportuniities BE WWW, E-mail, instant message 2018/11/23

Proposed Algorithm(1/3) In our proposed algorithm, the BS has to know the voice state transitions of the SSs. This higher layer information can be known in the MAC layer by using primitives of Convergence Sublayer. the SS has to inform the BS of its voice state transitions, it requires a method for relaying its voice status information. We define this reserved bit as a Grant-Me (GM) bit. When the voice state of the SS is ‘on’, the SS sets the GM bit to ‘1’, otherwise it sets the GM bit to ‘0’. 2018/11/23

Proposed Algorithm(2/3) Operation of theBS: GM bit is ‘0’: The BS assigns the minimum grant size to the SS. GM bit is changed, ‘1’ into ‘0’, the BS once assigns maximum grant size to the SS whose voice state is ‘off’ GM bit is ‘1’: The BS assigns the maximum grant size to the SS. GM bit is changed, ‘0’ into ‘1’, the BS once assigns minimum grant size to the SS whose voice state is ‘on’. 2018/11/23

Proposed Algorithm(3/3) Advantage: It causes a little waste of uplink resources, which could be negligible. It doesn’t modify IEEE 802.16 BWA 2018/11/23

NUMERICAL ANALYSIS TVC= the voice codec frame duration each state denotes the number of the voice users in the on-state. TVC= the voice codec frame duration LVC= information bit per voice codec frame LHU= compressed RTP/UDP/IP header size 2018/11/23

SIMULATION RESULTS 2018/11/23

3G packet scheduling 2018/11/23

Reference Jin Yuan Sun, Lian Zhao and Alagan Anpalagan, “A Unified Framework for Adaptively Scheduling Hybrid Voice/Data Traffic in 3G Cellular CDMA Downlinks,” IEEE International Conference on Wireless Networks, Communications and Mobile Computing, 2005, p751-756. J. Laiho, A. Wacker, and T. Novosad, Radio Network Planning and Optimisation for UMTS, Wiley, 2002. 2018/11/23

PCS system Architecture 2018/11/23

UMTS QoS(1/2) Congestion control QoS Admission control : enter sys or not Load control : drop or distribute Packet scheduling QoS 2018/11/23

UMTS QoS(2/2) Packet scheduling WCDMA Time division, code division Traffic classes Conversational class Streaming class Interactive class Background class Delay sensitive Real time Nonreal time Non-delay sensitive 2018/11/23

Example: Packet scheduling A Unified Framework for Adaptively Scheduling Hybrid Voice/Data Traffic in 3G Cellular CDMA Downlinks Downlink scheduling RNC MS voice data voice 2018/11/23

Example: Packet scheduling Motivation Existing scheduling algorithms fall into one of four categories: (a) scheduling only one class without coordinating multi-classes (b) coordinating multi-classes with no scheduling for single classes (c) scheduling individual classes with completely distinct schemes, resulting in implementation complexity at base stations (d) scheduling individual classes with absolutely the same scheme, failing to exploit distinguishing performance optimizing manners of the two classes. We want : Simple & performance optimization for multi-classes 2018/11/23

address method consistency of the framework distinctions of voice and data scheduling processes method adaptive priority profile is designed in the scheduling algorithm based on queuing delay required transmission power available transmission rate 2018/11/23

result system performance enhancement as a whole while retaining separate performance features without degradation. 2018/11/23

CDMA characteristics Interference control is important Downlink Specially in uplink Power control Smaller Rate, smaller powerl Downlink smaller power, higher downlink capacity Power control is an important issue. 2018/11/23

Scheduling framework(1/2) first after sort 2018/11/23

Scheduling framework(2/2) Unified voice/data scheduling framework Discrepancy of voice/data scheduling within framework 2018/11/23

Voice/data : different a,b,c better channel AP Higher, better sort first the largest AP first after sort Voice/data : different a,b,c 2018/11/23

Different state, different calculation sort data normal moderate urgent Delay=0 0 < Delay < D D < Delay AP=b/power AP=a*delay + b/power AP=a*delay + b/rate Different state, different calculation 2018/11/23

voice sort normal urgent 0 < Delay < V V < Delay AP=b/power AP=a*delay + b/power 2018/11/23

Comparison & conclusion --QoS services: * WiMAX(802.16) : voice --Voice + data : Simple & performance optimization for multi-classes --On-off traffic : efficient resource usage --HSDPA(High speed downlink packet access) HSUPA --Cross layer mechanism *routing, phy *CDMA packet scheduling : queue delay, power control, rate control *802.16, 802.11 : no CDMA 2018/11/23