Internet DRAFT - draft-jobert-iccrg-ip-aware-ap

draft-jobert-iccrg-ip-aware-ap



Internet Draft                                                S. Jobert
Intended status: Informational                             I. Hamchaoui
Expires: January 2014                                          W. Diego
                                                                 Orange
                                                          July 11, 2013



      Packet-oriented QoS management model for a wireless Access Point
                   draft-jobert-iccrg-ip-aware-ap-00.txt


Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008. The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on January 11, 2014.





Jobert                Expires January 11, 2014                [Page 1]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with
   respect to this document.

Abstract

   This document introduces a packet-oriented QoS management model
   applicable to a wireless Access Point, referred to as "IP aware
   Access Point". This model may be used in addition, or as a
   substitute to the connection-oriented traditional QoS model defined
   for cellular mobile networks, based on the notion of bearer.

Table of Contents

   1. Introduction ................................................. 2
   2. Conventions used in this documen ............................. 4
   3. Concepts and architecture .................................... 4
   4. IP aware wireless Access Point behavior ...................... 6
   5. Extension to upstream traffic ................................ 7
   6. Examples of possible models .................................. 8
      6.1. Model for intra-bearer arrangement ...................... 8
      6.2. Models for inter-bearer arrangement ..................... 9
   7. Security Considerations ...................................... 9
   8. IANA Considerations .......................................... 9
   9. References ................................................... 9
      9.1. Normative References .................................... 9
      9.2. Informative References ................................. 10
   10. Acknowledgments ............................................ 10



1. Introduction

   The management of QoS in cellular mobile networks remains
   connection-oriented in many cases: when QoS differentiation is
   targeted, the general solution proposed by most existing cellular
   mobile standards consists in establishing several tunnels (e.g.
   bearers), one per class of service, between the mobile terminal
   (e.g. UE) and the wireless Access Point (e.g. NodeB, eNB).


Jobert                Expires January 11, 2014                [Page 2]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

   The packets are then positioned into the various tunnels, depending
   on various criteria, for instance on the required QoS of the
   corresponding application. Adapted QoS treatments are then applied
   on the overall tunnels, according to the characteristics of the
   established bearers, but not at the packet level. In other words:
   even if an IP packet is marked (e.g. using DSCP marking) as being of
   high priority, this information inside the packet is not taken into
   account to schedule the packet over the radio interface, only the
   bearer that the packet belongs to matters.

   These tunnels are moreover in general extended up to an aggregation
   point in the network (e.g. GGSN, PDN-GW). Packet-oriented QoS
   management may however be applied over the fixed portion of the
   network, although tunnels are present.

   This connection-oriented model was inherited from TDM-based
   transport, and it was well adapted to early mobile data services
   deployments when the amount of data exchanged was low. It now raises
   important questions considering the high volumes and variability of
   mobile data traffic to be handled by most of mobile network
   operators generated by smartphones applications.

   In addition, managing the QoS of mobile networks using a connection-
   oriented model has clearly some drawbacks, such as: problems of
   scalability of the architecture due to the number of tunnels to be
   maintained simultaneously, additional signaling traffic required to
   establish or modify the parameters of the tunnels, time to establish
   or modify a tunnel, etc.

   In this draft, we introduce the concepts of a packet-oriented QoS
   management model applicable to a wireless Access Point, referred to
   as "IP aware Access Point", which can be considered as an
   alternative approach to the existing connection-oriented model. Note
   however that both models could be simultaneously deployed: a
   connection-oriented model could be used for managed ISP services
   when signaling traffic is exchanged prior to starting the service (a
   typical example might be managed VoLTE), while a packet-oriented
   model could be suitable to differentiate among the other services
   (e.g. Internet services), thanks to proper DSCP marking/remarking
   (according to the QoS policy enforced in the ISP-operated DiffServ
   domain).

   It is expected that this model be applicable to both licensed and
   unlicensed wireless networks (such as Wi-Fi).





Jobert                Expires January 11, 2014                [Page 3]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

2. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [RFC2119].

   In this document, these words will appear with that interpretation
   only when in ALL CAPS. Lower case uses of these words are not to be
   interpreted as carrying RFC-2119 significance.

   AP: Access Point

   CQI: Channel Quality Indicator

   DSCP: Differentiated Services Code Point

   eNB: evolved NodeB

   GGSN: Gateway GPRS Support Node

   Mifi: Mobile Wi-Fi

   NB: NodeB

   PDN-GW: Packet Data Network Gateway

   PF: Proportional Fair

   RB: Resource Block

   TTI: Transmission Time Interval

   UE: User Equipment

   VoLTE: Voice over LTE



3. Concepts and architecture

   Introducing a packet-oriented model in mobile networks is expected
   to simplify QoS management by leveraging the experience and current
   practice in fixed IP networks and permitting consistent operations
   over all network segments. Indeed, it simply reuses proven (and
   standard) mechanisms of fixed IP networks. It also solves most of
   the drawbacks of the connection-oriented approach. Finally, it



Jobert                Expires January 11, 2014                [Page 4]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

   allows for global seamless offers over various wireline and wireless
   accesses.

   The proposed packet-oriented QoS management model consists in the
   following main principles (the description below applies mainly to
   the downstream direction, i.e. from the wireless AP to the terminal,
   but can be extended to the upstream direction, i.e. from the
   terminal to the wireless AP):

   o There is no need for establishing several tunnels to allow
      differentiated QoS treatments; multiple classes of service are
      defined for this purpose independently of the tunnels, allowing
      differentiated QoS treatments inside the same tunnel, which may
      be maintained for mobility purposes if needed.

   o The packets SHOULD be marked or re-marked properly at the ingress
      of the DiffServ domain corresponding to the mobile network,
      according to the applicable criteria (which may depend on the
      type of service, agreement between parties, etc.). The DSCP field
      in the header of the IP packets MUST be used for this purpose.
      This marking SHOULD be maintained transparently up to the IP
      aware Access Point. Depending on the applicable scenario, the
      DSCP marking function MAY be located in any upstream point from
      the IP aware access point, including the traffic source.

   o The IP aware wireless Access Point MUST classify the packets
      based on the marking indicated in each packet and differentiated
      treatments are applied on a packet-per-packet basis. The packets
      with the highest priority SHOULD for instance be positioned in a
      high priority queue, which is served first when radio resources
      are allocated to the terminal.

   Figure 1 below illustrates the proposed packet-oriented QoS
   management model, with an example where 3 classes have been
   configured in the IP aware Access Point (e.g. one for traffic
   requiring low delay/jitter, one for traffic requiring low packet
   loss, and one for Best Effort traffic). Note that the IP layer at
   the IP aware Access Point MAY NOT implement a full IP layer (e.g.
   only the DSCP marking in the IP header MUST be analyzed to classify
   the packets into the relevant queues, but the forwarding of the
   packets MAY be based on traditional relaying functions between the
   tunnel on fixed network and the radio layers).







Jobert                Expires January 11, 2014                [Page 5]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point


   +-----------------------------------------------------------------+
   |      ++     |                       #: Voice packet             |
   | .----++     |    +------------+     *: Video packet             |
   | | .-. |   Radio  |   +------+ |     @: Email packet     +-----+ |
   | | |#| |Scheduling|   |####  | |                        #|Voice| |
   | | '-' |     |    | | +------+ |                         '-----' |
   | | .-. |==========| |  Queue1  |                      #          |
   | | |*| | +------+ | | +------+ |====================     +-----+ |
   | | '-' | |##*@  | | | |***** | |@ # * @ #  *  @  *  # * *|Video| |
   | | .-. | +------+ | | +------+ |==================== @   '-----' |
   | | |@| |==========| |  Queue2  |    Fixed network                |
   | | '-' |     |    | v +------+ | (backbone/backhaul)  @  +-----+ |
   | '-----'     |    |   |@@@   | |                        @|Email| |
   |  Mobile     |    |   +------+ |                         '-----' |
   | Terminal    V    |    Queue3  |                                 |
   |                  +------------+                                 |
   | +-------+     IP Aware Wireless AP                    +-------+ |
   | |  App  |---------------------------------------------|  App  | |
   | |-------|                                             |-------| |
   | |TCP/UDP|---------------------------------------------|TCP/UDP| |
   | |-------|          +-------+      +-------+   DSCP    |-------| |
   | |  IP   |----------|  IP   |------|  IP   |--Marking--|  IP   | |
   | |-------|          |-------|      |-------|           |-------| |
   | |  L2   |----------|  L2   |------|  L2   |-----------|  L2   | |
   | |-------|          |-------|      |-------|           |-------| |
   | |  L1   |----------|  L1   |------|  L1   |-----------|  L1   | |
   | +-------+          +-------+      +-------+           +-------+ |
   | '---------v-----------' '------------------v------------------' |
   |       Radio segment                  Wireline segment           |
   +-----------------------------------------------------------------+

     Figure 1 - Packet-oriented QoS management model in mobile networks



4. IP aware wireless Access Point behavior

   The IP aware Access Point MUST take into account the DSCP/ToS field
   of each packet prior to the transmission over the radio segment. For
   this purpose, an IP multiplexing stage (i.e. an IP queuing system)
   is added before the radio scheduler. This two-level scheduling
   process can be implemented through various algorithms. In some
   cases, it is relevant to consider a model which associates one set
   of IP queues to each terminal (see for instance the model in section
   6.1).



Jobert                Expires January 11, 2014                [Page 6]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

   In this draft, we distinguish two main types of behavior for the IP
   aware Access Point:

   o Intra-bearer arrangements: the allocation of radio resources is
      independent of the traffic mix waiting for transmission; in this
      case, radio resources allocated to a given user are determined by
      a basic radio scheduler which generally takes into account the
      radio conditions (e.g. algorithm based on Proportional Fairness).
      The addition of an IP priority queuing system per user before the
      radio scheduler (without influencing it) allows prioritizing the
      sensitive flows of a given user against his own other flows when
      populating the radio frame.

   o Inter-bearer arrangements: the allocation of the radio resources
      depends on the traffic mix waiting for transmission; in this
      case, the radio resources allocated to one UE not only depend on
      the radio conditions of the UE, but also on the traffic mix
      offered to the IP queuing system. This traffic mix is defined
      through the DSCP of its constitutive packets. Several approaches
      are possible (e.g. weighting the allocation according to the
      prioritized traffic volume / priority queue backlog, ensuring a
      maximum latency for certain classes, etc.)

   The first case (intra-bearer arrangement) is expected to be useful
   for multi-tasking users (e.g. user running several applications
   simultaneously, for instance in case of tethering terminals or
   acting as Mifi access point). This model is further detailed in
   section 6.1 of this document.

   The second case (inter-bearer arrangement) targets real time
   applications with stringent QoS constraints. This model is further
   detailed in section 6.2 of this document.



5. Extension to upstream traffic

   A future version of this draft will provide some details on the
   usage of the mechanism for upstream traffic.

   Note that some solutions, such as the model described in section 6.1
   of this document, are already applicable to upstream traffic without
   changes in the mobile terminal.






Jobert                Expires January 11, 2014                [Page 7]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

6. Examples of possible models

   The following sections provide examples of applicable models for
   intra-bearer and inter-bearer arrangements. It should be noted that
   these models are considered as examples only (mainly as references
   for simulation activity), and that actual implementations may differ
   from them.

6.1. Model for intra-bearer arrangement

   In this section, we describe the intra-bearer arrangement model. The
   aim of this model is to prioritize the sensitive flows of one UE
   against its own other flows without modifying the radio resources
   allocated to this UE. As a consequence, the good properties of the
   scheduling algorithm are preserved (e.g. trade-off between UE
   fairness and cell throughput), thus preserving the cell throughput
   capacity.

   As mentioned before, the "IP aware Access Point" MUST take into
   account the DSCP/ToS field, therefore an IP layer MUST be added on
   the eNB side, which is not the current practice in most existing
   cellular networks. In the present model, it is assumed that the
   marking procedure is performed upstream from the eNB.

   On the "IP aware Access Point" side, a two-level scheduler is
   implemented when considering an intra-bearer arrangement:

   The first level consists in an IP priority queuing system composed of
   "n" finite queues per UE (DiffServ model - one queue per level of
   QoS). These queues are operated according to a non-preemptive service
   policy. This means that if one or more high priority packets arrive
   when a packet of lower priority is served, the high priority packets
   will be served only after the current service of a low priority
   packet is complete. For the sake of simplicity, we propose the use of
   a strict priority policy between queues, but other policies are also
   possible, such as weighted fair queuing/weighted round robin. The
   service rate of this IP queuing system is constant during each TTI
   (Transmission Time Interval). It is calculated for each UE at each
   TTI by the second level described hereafter.

   The second level is a radio scheduler which shares the available
   radio resources (e.g. RB - Resources Block in LTE) between the UEs.


Jobert                Expires January 11, 2014                [Page 8]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

   Different scheduling algorithms are possible for the allocation of
   radio resources depending on the optimization criteria (delay,
   throughput, etc., or trade-off between some of these criteria). On
   the present model, Proportional Fair (PF) scheduler, without any
   modification, is suggested because it offers a good trade-off between
   cell throughput and fairness between UEs, and because it is the basis
   of many scheduler implementations in base stations. PF assigns the
   available radio resources to UEs every TTI (Transmission Time
   Interval), regardless of the first level queuing process described
   above. The PF scheduler algorithm takes into account the radio
   conditions (e.g. CQI - Channel Quality Indicator in LTE) provided by
   each UE.

6.2. Models for inter-bearer arrangement

   A future version of this draft will provide some details on the
   applicable models for inter-bearer arrangements.



7. Security Considerations

   <Add any security considerations>



8. IANA Considerations

   <Add any IANA considerations>



9. References

9.1. Normative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate
         Requirement Levels", BCP 14, RFC 2119, March 1997.

   [2]  Crocker, D. and Overell, P.(Editors), "Augmented BNF for
         Syntax Specifications: ABNF", RFC 2234, Internet Mail
         Consortium and Demon Internet Ltd., November 1997.

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.


Jobert                Expires January 11, 2014                [Page 9]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

   [RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
             Syntax Specifications: ABNF", RFC 2234, Internet Mail
             Consortium and Demon Internet Ltd., November 1997.



9.2. Informative References

   [3]  Faber, T., Touch, J. and W. Yue, "The TIME-WAIT state in TCP
         and Its Effect on Busy Servers", Proc. Infocom 1999 pp. 1573-
         1583.

   [4]  Hamchaoui, I., Jobert, S., Boufelja, S., "IP aware radio
         scheduling - Introducing IP QoS management in LTE networks",
         IEEE ICC'13, June 2013



10. Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.



























Jobert                Expires January 11, 2014               [Page 10]

Internet-Draft  Packet-oriented QoS management model         July 2013
                   for a wireless Access Point

Authors' Addresses

   Sébastien Jobert
   Orange
   2 avenue Pierre Marzin
   22300 LANNION, FRANCE

   Email: sebastien.jobert@orange.com


   Isabelle Hamchaoui
   Orange
   2 avenue Pierre Marzin
   22300 LANNION, FRANCE

   Email: isabelle.hamchaoui@orange.com


   William Diego
   Orange
   2 avenue Pierre Marzin
   22300 LANNION, FRANCE

   Email: william.diego@orange.com
























Jobert                Expires January 11, 2014               [Page 11]