QoS mechanisms in IEEE 802 Bin Zhen, Huan-band Li and Ryuji Kohno January 2007 doc.: IEEE 802.15-07-0564 July/2007 QoS mechanisms in IEEE 802 Bin Zhen, Huan-band Li and Ryuji Kohno National Institute of Information and Communications Technology (NICT) Zhen, Li and Kohno Carlos Cordeiro, Philips

Submission Title: [QoS mechanisms of IEEE 802] January 2007 doc.: IEEE 802.15-07-0564 July/2007 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [QoS mechanisms of IEEE 802] Date Submitted: [July, 2007] Source: [Bin Zhen, Huan-Bang Li and Ryuji Kohno] Company [National Institute of Information and Communications Technology (NICT)] Contact: Bin Zhen Voice:[+81 46 847 5445, E-Mail: zhen.bin@nict.go.jp] Abstract: [review of QoS mechanisms in IEEE 802 framework] Purpose: [for discussion in MBAN] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Zhen, Li and Kohno Carlos Cordeiro, Philips

Motivations Distinguished features of MBAN from other 802.15 standards January 2007 doc.: IEEE 802.15-07-0564 July/2007 Motivations Distinguished features of MBAN from other 802.15 standards QoS for life critical applications Extreme low power wireless Review of QoS mechanism of IEEE 802 802.11e: QoS enhancements 802.11k: radio resource measurement enhancements 802.11v: wireless network management 802.15 Zhen, Li and Kohno Carlos Cordeiro, Philips

QoS Limitations of 802.11 Distributed Coordination Function January 2007 doc.: IEEE 802.15-07-0564 July/2007 QoS Limitations of 802.11 Distributed Coordination Function Only support best-effort services No guarantee in bandwidth, packet delay and jitter Point Coordination Function Unpredictable beacon frame delay due to incompatible cooperation between CP and CFP modes Transmission time of the polled stations is unknown Point Coordinator does not know the QoS requirement of traffic Basic elements for QoS Traffic Differentiation Concept of Transmission Opportunity (TXOP) Zhen, Li and Kohno Carlos Cordeiro, Philips

Hybrid Coordination Function of 802.11e January 2007 doc.: IEEE 802.15-07-0564 July/2007 Hybrid Coordination Function of 802.11e Hybrid Coordinator Function (HCF) Enhanced distributed channel access (EDCA) Contention-Based channel access Provides service differentiation 8 different traffic classes 4 access categories in each station HCF controlled channel access (HCCA) Hybrid coordinator to coordinate contention free media To provides Guaranteed Services with a much higher probability than EDCA Operates in CFP and CP Coordinates the traffic in any fashion not just round-robin Zhen, Li and Kohno Carlos Cordeiro, Philips

Enhanced distributed channel access January 2007 doc.: IEEE 802.15-07-0564 July/2007 Enhanced distributed channel access 8 User priorities mapping to 4 Access Categories Scheduler (resolves virtual collisions by granting TXOP to highest priority 8 User priorities per QSTA Pri 0 Pri 1 Pri 7 Backoff (AIFSN3) (AIFSN2) (AIFSN1) (AIFSN0) AC0 AC1 AC2 AC3 Transmission Attempt Zhen, Li and Kohno Carlos Cordeiro, Philips

Enhanced distributed channel access (cont.) January 2007 doc.: IEEE 802.15-07-0564 July/2007 Enhanced distributed channel access (cont.) Priority Access Category (AC) Designation (Informative) Best Effort 1 2 3 Video Probe 4 Video 5 6 Voice 7 Zhen, Li and Kohno Carlos Cordeiro, Philips

Transmission Opportunities January 2007 doc.: IEEE 802.15-07-0564 July/2007 Transmission Opportunities TXOP is the time interval of a QSTA to transmit frame(s) In TXOP, frames exchange sequences are separated by SIFS When will a QSTA get a TXOP ? Win a contention in EDCA during CP Receive a QoS ControlField-poll (“polled TXOP”) from hybrid coordinator TXOPs will increase RTS/CTS use Unlike with short, single frame, transmissions, use of RTS/CTS is efficient with TXOPs Zhen, Li and Kohno Carlos Cordeiro, Philips

HCF controlled channel access January 2007 doc.: IEEE 802.15-07-0564 July/2007 HCF controlled channel access The time is divided into repeated Superframes HC starts a CAP during which only polled and granted QSTAs are allowed to transmit for TXOPs Superframe TCA Beacon Frame Beacon Frame EDCA EDCA CAP (HCCA) CAP QoS CF-Poll QoS CF-Poll PCF HC … ACK ACK … … … … PIFS SIFS PIFS SIFS DIFS PIFS DIFS … RTS DATA DATA … … Stations … … … AIFS SIFS SIFS TXOP ( Station n ) TXOP ( Station m ) time backoff time Zhen, Li and Kohno Carlos Cordeiro, Philips

Admission control Admission control January 2007 doc.: IEEE 802.15-07-0564 July/2007 Admission control Admission control To limit the level where appropriate QoS can be guaranteed for all the admitted traffic stream Admission control can be mandated per access control Admission control algorithm is not specified Dynamic behavior of the radio link To adjust operation according to changing conditions Zhen, Li and Kohno Carlos Cordeiro, Philips

Other mechanisms Block Ack: by aggregating several Acks into one frame January 2007 doc.: IEEE 802.15-07-0564 July/2007 Other mechanisms Block Ack: by aggregating several Acks into one frame Immediate Block Ack Delayed Block Ack Support for higher layer synchronization Broadcast Sync packet containing time stamp and sequence number Direct link Directly send frames from one QSTA to another in QBSS Zhen, Li and Kohno Carlos Cordeiro, Philips

Automatic power-save delivery January 2007 doc.: IEEE 802.15-07-0564 July/2007 Automatic power-save delivery Automatic power-save delivery (APSD) QAP deliver downlink frames, which belong to some specified AC, to power saving stations automatically Unscheduled APSD (U-APSD) Power-saving QSTA wakes up and send a “trigger” data frame belonging to “trigger-enabled” AC to QAP After receiving “trigger” frame, a service period is started QAP send frames belonging to “delivery-enabled” AC to QSTA Scheduled APSD (S-APSD) QSTA negotiate a APSD Schedule with QAP QAP start transmitting the frames of the specified traffic stream at Service Start Time and the following periods QSTA must wake up at Service Start Time and the following periods to receive frames Zhen, Li and Kohno Carlos Cordeiro, Philips

802.11k: radio resource management January 2007 doc.: IEEE 802.15-07-0564 July/2007 802.11k: radio resource management Scope of 11k To enhance the MAC of 802.11 standards to provide mechanisms to higher layers for radio and network measurements Purpose of 11k To define measurements and develop mechanisms to provide 802.11 wireless network measurement information to higher layers and new applications Radio measurements enable STA to understand the radio environments in which they exist STA to observe and gather data on radio link Local measurement or remote measurement Standard measurement across venders and interface to upper layer message inside a STA Zhen, Li and Kohno Carlos Cordeiro, Philips

802.11k measurements AP related measurements January 2007 doc.: IEEE 802.15-07-0564 July/2007 802.11k measurements AP related measurements Beacon Backup AP tables on a specified channel Can be done by active mode, passive mode, or beacon table mode Measurement pilot a minimum set of compact beacon with a smaller interval To reduce duty cycle of beacon and provide timely information Neighbor report Known neighbor AP that are candidates for handover Traffic related measurements Channel load Channel utilization Frame Picture of all the channel traffic and a counter Zhen, Li and Kohno Carlos Cordeiro, Philips

802.11k measurements (cont.) Channel related measurements January 2007 doc.: IEEE 802.15-07-0564 July/2007 802.11k measurements (cont.) Channel related measurements Link measurement An RF ping Link path loss and link margin Noise histogram A power histogram measurement of non-802.11 noise power when CCA indicates idle QoS related measurements STA statistics A groups of values for STA counter and for BSS average access delay Transmit stream measurement Transmit-side performance metrics for the measured traffic stream Zhen, Li and Kohno Carlos Cordeiro, Philips

802.11v: wireless link management January 2007 doc.: IEEE 802.15-07-0564 July/2007 802.11v: wireless link management Scope of 11v “to extend prior work in radio measurement to effect a complete and coherent upper layer interface for managing 802.11 device” Purpose of 11v “enable management of attached STA in a centralized or in a distributed fashion through a L2 mechanism” Message format exchanged between station and AP to configure STA Zhen, Li and Kohno Carlos Cordeiro, Philips

802. 11v mechanisms AP collaboration BSS load balancing Power saving January 2007 doc.: IEEE 802.15-07-0564 July/2007 802. 11v mechanisms AP collaboration Virtual AP A logical entity that exists within a physical AP To use a single beacon to efficiently advertise multiple BSSIDs and SSIDs Time and power collaboration BSS load balancing geographically non-uniformly distributed traffic in indoor applications Handover of STA from one AP to another AP triggered by load considerations; not by mobility Station centric or AP centric? Power saving Idle and paging mode Zhen, Li and Kohno Carlos Cordeiro, Philips

802. 11v mechanisms (cont.) Dynamic channel selection January 2007 doc.: IEEE 802.15-07-0564 July/2007 802. 11v mechanisms (cont.) Dynamic channel selection Change the operating channel for the entire BSS during live system operation seamlessly with no loss of connectivity both when idle and in a session Channel quality index Deferral management Control of transmission power by transmitter and energy detection threshold (EDT) by receiver to allow for higher channel reuse and higher system capacity Flexible broadcast/multicast service Co-located interference reporting Admission control Zhen, Li and Kohno Carlos Cordeiro, Philips

January 2007 doc.: IEEE 802.15-07-0564 July/2007 802.15 Bluetooth (802.15.1) TDMA Round-robin scheduling 802.15.3 and 802.15.4 Guarantee time slot (GTS) Polling Zhen, Li and Kohno Carlos Cordeiro, Philips

Comments Main focus and limitation Useful features January 2007 doc.: IEEE 802.15-07-0564 July/2007 Comments Main focus and limitation 802.11 and 802.15.3: to maximize data throughout 802.15.4 simple and battery-powered device MBAN life critical applications and periodical medical data Limited power Useful features Measurement pilot, idle mode, power-save delivery Dynamic channel switch, traffic priorities, block ACK Admission control, direct link Location indicator Zhen, Li and Kohno Carlos Cordeiro, Philips

Conclusions Review of QoS mechanisms in IEEE 802 January 2007 doc.: IEEE 802.15-07-0564 July/2007 Conclusions Review of QoS mechanisms in IEEE 802 802.11e 802.11k 802.11v 802.15 Comments on applying these mechanisms to MBAN Zhen, Li and Kohno Carlos Cordeiro, Philips