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Service Discovery Architecture for TGaq

This document presents a service architecture for TGaq, detailing service indication from AP, network discovery, and service information query. Various options and issues are discussed in depth.

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Service Discovery Architecture for TGaq

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  1. Service discovery architecture for TGaq Date: 2013-11-05 Authors: Ping FANG, Huawei

  2. Abstract This document presents a service architecture for TGaq. Service indication from AP, network discovery and detailed service information query are described. Possible options and issues are further discussed. Ping FANG, Huawei

  3. Background In 13/501r0, a architecture with service registration and service discovery is registered. Per the meeting discussion, the registration can be done in MAC layer or upper layer after association. In 13/796r0, the procedure on how a STA discovers necessary service information before association is described with a high level 2-step service discovery procedure proposed. In 13/796r1, more details on service indication are further discussed. In 13/893r0, different service hash values proposed to be carried in service discovery request and response with public action frame for privacy and security Ping FANG, Huawei

  4. Overall picture of 11aq Ping FANG, Huawei

  5. Service Indication from AP • Option 1 : new Service Indication IE in Beacon/ Probe Response • Carried in Beacon or Probe Response, no extra overhead • Good for passive scanning to indicate which services are provided or not • Option 2: new Public Action frame • Extra load for AP to broadcast besides Beacon • STA doesn’t know when to receive, broadcast periodically • Assumption: • Proxy in AP caches general service information • Good for scenarios when lots of STA queries • Good to indicate what kind of services are provided or not Ping FANG, Huawei

  6. Service Indication IE • Service Indication IE in Beacon/ Probe Response • Service Indication Bitmap • Protocol Part: fixed bits to indicate protocols for services • Service Information Part: Bits used to indicate available services, each bit corresponds to a service/services with hash value Part 1: Protocol Part 2: Service Information UPnP Bonjour … … 1 0 0 1 1 0 0 0 … … Bit 1 Bit 2 Bit 3 Hash(“UPnP:Printer”), then set bit 1 value to be 1. Ping FANG, Huawei

  7. General Service Query • General Service Query • To decide whether a service can be provide via AP • Query and response can be relatively shorter • Option 1 : Combine with AP/Network discovery • Carry service hash IE in Probe Request/Response • Different Service hash values can be carried in Probe request/response for privacy • Option 2: New Public Action frame [4] • Carry service hash values in PAM request/response • Different Service hash values be in Probe request/response for privacy Option 1 Option2 Ping FANG, Huawei

  8. Public Action Frame vs. Service IE • Option 1: Service IE in Probe Req/Resp • Option 2:New Public Action Frame • Option1 vs. option 2 Ping FANG, Huawei

  9. Detailed Service Query • DetailedService Query (Different from general query) • Can provide detailed service information • The query response can be much bigger than that of general query • Option 1 : GAS mechanism for further information query • Mechanism similar to ANQP as carried in GAS • Option 2: new PAM (public action frame)[5] • Carry detailed service query information in PAM between STA and AP • AP may forward the query to backhaul or associated STAs for further detailed information Option 1 Option2 Ping FANG, Huawei

  10. New protocol in GAS vs. new Public Action Frame • Option 1: New advertisement protocol ID in GAS • Option 2: new Public Action Frame • New advertisement protocol vs. new Public Action Frame Ping FANG, Huawei

  11. Discussion on Practice • Service bitmap • For scenario with lots of STAs queries, service bitmap can help to reduce STAs’ queries with passive scanning • When the number of services provided by AP is far less than the length of bitmap, the bitmap can provide useful information to indicate which services are not provided • General service query vs. detailed service query • When there are quite some APs and STAs around, general service query should be used first to reduce channel time • For sparse environment, detailed service query can be used directly to query for detailed service information Ping FANG, Huawei

  12. Summary • Overall picture for TGaq is recaptured with service indication from AP, general service query and detailed service query • Service bitmap IE in Beacon/Probe Resp for indication from AP • New Public Action frame carries different service hash values in general service query/response • New Public Action frame carries detailed service query or response of upper layer for detailed service query Ping FANG, Huawei

  13. References • IEEE Std 802.11™-2012 • 11-13-0057-02-00aq-design-options • 11-13-0501-00-00aq-service-registration-of-sta-to-an-ap • 11-13-0893-00-00aq-service-discovery-proposal • 11-13-0788-01-00aq-transaction-protocol Ping FANG, Huawei

  14. Service Indication Performance Analysis • Assumption • Number of total service number: k = 5000 • Length of Service Hash bitmap: m= 128 bit • Number of services supported by AP: n = 16, 32, 48, 64, 80 • Algorithm • Service names are randomly generated with alphabets , digits and phonetic symbols • Services supported by AP are randomly chosen from 5000 services • Service hash values are calculated with SHA256, and then mod(128) to set a corresponding bit in bitmap • Bit value 0 indicate there are no corresponding services • The result is to indicate how many percent of services are not supported by the AP, with the 128 bit service indication bitmap and given the n kind of services supported by the AP Percentage of no service n Ping FANG, Huawei

  15. Straw Polls Ping FANG, Huawei

  16. Straw Polls on Proposed Text to SFD • Straw Poll-1: add the following sentence to section 5 Frame Formats of TGaq SFD, 11-13-0300r1 • 802.11aq shall define a IE with service hash bitmap for service indication. • Result • Yes • No • Need more info Ping FANG, Huawei

  17. Straw Polls on Proposed Text to SFD – con’t • Straw Poll-2: add the following sentence to section 5 Frame Formats of TGaq SFD, 11-13-0300r1 • 802.11aq shall define a new public action frame for service query. • Result • Yes • No • Need more info Ping FANG, Huawei

  18. Straw Polls on Proposed Text to SFD – con’t • Straw Poll-3: add the following sentence to section 7 MLME of TGaq SFD, 11-13-0300r1 • 802.11aq shall define mechanism to provide service indication from AP with service hash bitmap and service protocol bitmap in Beacon and Probe Response • Result • Yes • No • Need more info Ping FANG, Huawei

  19. Straw Polls on Proposed Text to SFD – con’t • Straw Poll-4: add the following sentence to section 7 MLME of TGaq SFD, 11-13-0300r1 • 802.11aq shall define mechanism to provide general service query for a STA to decide the availability of a service from AP before association. • Result • Yes • No • Need more info Ping FANG, Huawei

  20. Straw Polls on Proposed Text to SFD – con’t • Straw Poll-5: add the following sentence to section 7 MLME of TGaq SFD, 11-13-0300r1 • 802.11aq shall define mechanism to provide detailed service query for a STA to get the detailed information of a service from AP before association. • Result • Yes • No • Need more info Ping FANG, Huawei

  21. Straw Polls on Proposed Text to SFD – con’t • Straw Poll-6: add the following sentence to section 8 Security of TGaq SFD, 11-13-0300r1 • 802.11aq shall define mechanism to provide privacy for pre association service queries with different hash values for a service in service query request and response. • Result • Yes • No • Need more info Ping FANG, Huawei

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