Network Working Group                                          Z. Sarker
Internet-Draft                                              I. Johansson
Intended status: Informational                               Ericsson AB
Expires: December 13, 2015                                 June 11, May 8, 2016                                              X. Zhu
                                                                   J. Fu
                                                                  W. Tan
                                                              M. Ramalho
                                                           Cisco Systems
                                                        November 5, 2015

  Evaluation Test Cases for Interactive Real-Time Media over Wireless
                                Networks
                   draft-ietf-rmcat-wireless-tests-00
                   draft-ietf-rmcat-wireless-tests-01

Abstract

   It is evident that to ensure seamless and robust user experience
   across all type of access networks multimedia communication suits
   should adapt to the changing network conditions.  There is an ongoing
   effort in IETF RMCAT working group to standardize rate adaptive
   algorithm(s) to be used in the real-time interactive communication.
   In this document test cases are described to evaluate the
   performances of the proposed endpoint adaptation solutions in LTE
   networks and Wi-Fi networks.  It is aimed that the  The proposed solutions algorithms should be
   evaluated using the test cases defined in this document to select
   most optimal solutions.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on December 13, 2015. May 8, 2016.

Copyright Notice

   Copyright (c) 2015 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2   3
   2.  Terminologies . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Cellular Network Specific Test Cases  . . . . . . . . . . . .   3
     3.1.  Varying Network Load  . . . . . . . . . . . . . . . . . .   5   6
       3.1.1.  Network Connection  . . . . . . . . . . . . . . . . .   6
       3.1.2.  Simulation Setup  . . . . . . . . . . . . . . . . . .   6   7
     3.2.  Bad Radio Coverage  . . . . . . . . . . . . . . . . . . .   8
       3.2.1.  Network connection  . . . . . . . . . . . . . . . . .   8   9
       3.2.2.  Simulation Setup  . . . . . . . . . . . . . . . . . .   8   9
     3.3.  Desired Evaluation Metrics for cellular test cases  . . .   9  10
   4.  Wi-Fi Networks Specific Test Cases  . . . . . . . . . . . . .   9
   5.  Conclusion  10
     4.1.  Bottleneck in Wired Network . . . . . . . . . . . . . . .  12
       4.1.1.  Network topology  . . . . . . . . . .  10
   6.  Acknowledgements . . . . . . . .  12
       4.1.2.  Test setup  . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . .  13
       4.1.3.  Typical test scenarios  . . . . . . . . . . . . . .  10
   8.  Security Considerations .  14
       4.1.4.  Expected behavior . . . . . . . . . . . . . . . . . .  10
   9.  References  14
     4.2.  Bottleneck in Wi-Fi Network . . . . . . . . . . . . . . .  14
       4.2.1.  Network topology  . . . . . . . . . .  10
     9.1.  Normative References . . . . . . . .  15
       4.2.2.  Test setup  . . . . . . . . . .  10
     9.2.  Informative References . . . . . . . . . . .  15
       4.2.3.  Typical test scenarios  . . . . . .  11
   Authors' Addresses . . . . . . . . .  16
       4.2.4.  Expected behavior . . . . . . . . . . . . . .  11

1.  Introduction

   Wireless networks (both cellular and Wi-Fi [IEEE802.11] local area
   network) are an integral part of the Internet.  Mobile devices
   connected to the wireless networks produces huge amount of media
   traffic in the Internet.  They covers the scenarios of having a video
   call in the bus to media consumption sitting on a couch in a living
   room.  It is a well known fact that the characteristic and challenges
   for offering service over wireless network are very different than
   providing the same over a wired network.  Even though RMCAT basic
   test cases defines number of test cases that covers lots of effects
   of the impairments visible in the wireless networks but there are
   characteristics and dynamics those are unique to particular wireless
   environment.  For example, in the LTE the base station maintains
   queues per radio bearer per user hence it gives different interaction
   when all traffic from user share the same queue.  Again, the user
   mobility in a cellular network is different than the user mobility in
   a Wi-Fi network.  Thus, It is important to evaluate the performance
   of the proposed RMCAT candidates separately . . . .  17
     4.3.  Potential Potential Test Cases  . . . . . . . . . . . . .  17
       4.3.1.  EDCA/WMM usage  . . . . . . . . . . . . . . . . . . .  17
       4.3.2.  Legacy 802.11b Effects  . . . . . . . . . . . . . . .  17
   5.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .  18
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  18
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  18
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  19

   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   Wireless networks (both cellular and Wi-Fi [IEEE802.11] local area
   network) are an integral part of the Internet.  Mobile devices
   connected to the wireless networks produces huge amount of media
   traffic in the Internet.  They covers the scenarios of having a video
   call in the bus to media consumption sitting on a couch in a living
   room.  It is a well known fact that the characteristic and challenges
   for offering service over wireless network are very different than
   providing the same over a wired network.  Even though RMCAT basic
   test cases defines number of test cases that covers lots of effects
   of the impairments visible in the wireless networks but there are
   characteristics and dynamics those are unique to particular wireless
   environment.  For example, in the LTE the base station maintains
   queues per radio bearer per user hence it gives different interaction
   when all traffic from user share the same queue.  Again, the user
   mobility in a cellular network is different than the user mobility in
   a Wi-Fi network.  Thus, It is important to evaluate the performance
   of the proposed RMCAT candidates separately in the cellular mobile
   networks and Wi-Fi local networks (IEEE 802.11xx protocol family ).

   RMCAT evaluation criteria [I-D.ietf-rmcat-eval-criteria] document
   provides the guideline to perform the evaluation on candidate
   algorithms and recognizes wireless networks to be important access
   link.  However, it does not provides particular test cases to
   evaluate the performance of the candidate algorithm.  In this
   document we describe test cases specifically targeting cellular
   networks such as LTE networks and Wi-Fi local networks.

2.  Terminologies

   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 RFC2119 [RFC2119]

3.  Cellular Network Specific Test Cases

   A cellular environment is more complicated than a wireline ditto
   since it seeks to provide services in the context of variable
   available bandwidth, location dependencies and user mobilities at
   different speeds.  In a cellular network the user may reach the cell
   edge which may lead to a significant amount of retransmissions to
   deliver the data from the base station to the destination and vice
   versa.  These network links or radio links will often act as a
   bottleneck for the rest of the network which will eventually lead to
   excessive delays or packet drops.  An efficient retransmission or
   link adaptation mechanism can reduce the packet loss probability but
   there will still be some packet losses and delay variations.
   Moreover, with increased cell load or handover to a congested cell,
   congestion in transport network will become even worse.  Besides,
   there are certain characteristics which make the cellular network
   different and challenging than other types of access network such as
   Wi-Fi and wired network.  In a cellular network -

   o  The bottleneck is often a shared link with relatively few users.

      *  The cost per bit over the shared link varies over time and is
         different for different users.

      *  Left over/ unused resource can be grabbed by other greedy
         users.

   o  Queues are always per radio bearer hence each user can have many
      of such queues.

   o  Users can experience both Inter and Intra Radio Access Technology
      (RAT) handovers ("handover" definition in [HO-def-3GPP] ).

   o  Handover between cells, or change of serving cells (see in
      [HO-LTE-3GPP] and [HO-UMTS-3GPP] ) might cause user plane
      interruptions which can lead to bursts of packet losses, delay
      and/or jitter.  The exact behavior depends on the type of radio
      bearer.  Typically, the default best effort bearers do not
      generate packet loss, instead packets are queued up and
      transmitted once the handover is completed.

   o  The network part decides how much the user can transmit.

   o  The cellular network has variable link capacity per user

      *  Can vary as fast as a period of milliseconds.

      *  Depends on lots of facts (such as distance, speed,
         interference, different flows).

      *  Uses complex and smart link adaptation which makes the link
         behavior ever more dynamic.

      *  The scheduling priority depends on the estimated throughput.

   o  Both Quality of Service (QoS) and non-QoS radio bearers can be
      used.

   Hence, a real-time communication application operating in such a
   cellular network need to cope with shared bottleneck link and
   variable link capacity, event likes handover, non-congestion related
   loss, abrupt change in bandwidth (both short term and long term) due
   to handover, network load and bad radio coverage.  Even though 3GPP
   define QoS bearers [QoS-3GPP] to ensure high quality user experience,
   adaptive real-time applications are desired.

   Different mobile operators deploy their own cellular network with
   their own set of network functionalities and policies.  Usually, a
   mobile operator network includes 2G, EDGE, 3G and 4G radio access
   technologies.  Looking at the specifications of such radio
   technologies it is evident that only 3G and 4G radio technologies can
   support the high bandwidth requirements from real-time interactive
   video applications.  The future real-time interactive application
   will impose even greater demand on cellular network performance which
   makes 4G (and beyond radio technologies) more suitable access
   technology for such genre of application.

   The key factors to define test cases for cellular network are

   o  Shared and varying link capacity

   o  Mobility

   o  Handover

   However, for cellular network it is very hard to separate such events
   from one another as these events are heavily related.  Hence instead
   of devising separate test cases for all those important events we
   have divided the test case in two categories.  It should be noted
   that in the following test cases the goal is to evaluate the
   performance of candidate algorithms over radio interface of the
   cellular network.  Hence it is assumed that the radio interface is
   the bottleneck link between the communicating peers and that the core
   network does not add any extra congestion in the path.  Also the
   combination of multiple access technologies such as one user has LTE
   connection and another has Wi-Fi connection is kept out of the scope
   of this document.  However, later those additional scenarios can also
   be added in this list of test cases.  While defining the test cases
   we assumed a typical real-time telephony scenario over cellular
   networks where one real-time session consists of one voice stream and
   one video stream.  We recommend that an LTE network simulator is used
   for the test cases defined in this document, for example-NS-3 LTE
   simulator [LTE-simulator].

3.1.  Varying Network Load

   The goal of this test is to evaluate the performance of the candidate
   congestion control algorithm under varying network load.  The network
   load variation is created by adding and removing network users a.k.a.
   User Equipments (UEs) during the simulation.  In this test case, each
   of the user/UE in the cellular mobile
   networks and Wi-Fi local networks (IEEE 802.11xx protocol family ).

   RMCAT media session is an RMCAT compliant endpoint.
   The arrival of users follows a Poisson distribution, which is
   proportional to the length of the call, so that the number of users
   per cell is kept fairly constant during the evaluation criteria [I-D.ietf-rmcat-eval-criteria] document
   provides period.  At
   the guideline beginning of the simulation there should be enough amount of time
   to perform warm-up the network.  This is to avoid running the evaluation on candidate in
   an empty network where network nodes are having empty buffers, low
   interference at the beginning of the simulation.  This network
   initialization period is therefore excluded from the evaluation
   period.

   This test case also includes user mobility and competing traffic.
   The competing traffics includes both same kind of flows (with same
   adaptation algorithms) and different kind of flows (with different
   service and congestion control).  The investigated congestion control
   algorithms should show maximum possible network utilization and recognizes wireless networks
   stability in terms of rate variations, lowest possible end to be important access
   link.  However, it does not provides particular test cases end
   frame latency, network latency and Packet Loss Rate (PLR) at
   different cell load level.

3.1.1.  Network Connection

   Each mobile user is connected to
   evaluate a fixed user.  The connection
   between the performance mobile user and fixed user consists of the candidate algorithm.  In this
   document we device test cases specifically targeting cellular
   networks such as a LTE networks radio
   access, an Evolved Packet Core (EPC) and Wi-Fi local networks.

2.  Terminologies an Internet connection.  The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   mobile user is connected to the EPC using LTE radio access technology
   which is further connected to the Internet.  The fixed user is
   connected to the Internet via wired connection with no bottleneck
   (practically infinite bandwidth).  The Internet and "OPTIONAL" wired connection
   in this
   document are to be interpreted as described in RFC2119 [RFC2119]

3.  Cellular Network Specific Test Cases

   A cellular environment is more complicated than a wireline ditto
   since it seeks setup does not add any network impairments to provide services in the context test, it
   only adds 10ms of variable
   available bandwidth, location dependencies and user mobilities at
   different speeds.  In a cellular network one-way transport propagation delay.

   The path from the fixed user may reach the cell
   edge which may lead to a significant amount of retransmissions to
   deliver mobile user is defines as "Downlink"
   and the data path from the base station mobile user to the destination and vice
   versa.  These network links or radio links will often act fixed user is defined as a
   bottleneck
   "Uplink".  We assume that only uplink or downlink is congested for
   the rest of the network which will eventually lead to
   excessive delays or packet drops.  An efficient retransmission or
   link adaptation mechanism can reduce mobile users.  Hence, we recommend that the packet loss probability but
   there will still be some packet losses uplink and delay variations.
   Moreover, with increased cell load or handover to a congested cell,
   congestion in transport network will become even worse.  Besides,
   there downlink
   simulations are certain characteristics which make run separately.

                             uplink
            ++)))        +-------------------------->
            ++-+      ((o))
            |  |       / \     +-------+     +------+    +---+
            +--+      /   \----+       +-----+      +----+   |
                     /     \   +-------+     +------+    +---+
             UE         BS        EPC        Internet    fixed
                         <--------------------------+
                                  downlink

                       Figure 1: Simulation Topology

3.1.2.  Simulation Setup

   The values enclosed within " [ ] " for the following simulation
   attributes follow the cellular network
   different and challenging than other types of access network such notion set in [I-D.ietf-rmcat-eval-test].  The
   desired simulation setup as
   Wi-Fi follows-

   1.  Radio environment

       A.  Deployment and wired network.  In a cellular network -

   o  The bottleneck is often a shared link with relatively few users.

      *  The cost per bit over the shared link varies over time propagation model : 3GPP case 1[Deployment]

       B.  Antenna: Multiple-Input and is
         different for different users.

      *  Left over/ unused resource can be grabbed by other greedy
         users.

   o  Queues are always Multiple-Output (MIMO), [2D, 3D]

       C.  Mobility: [3km/h, 30km/h]

       D.  Transmission bandwidth: 10Mhz

       E.  Number of cells: multi cell deployment (3 Cells per radio Base
           Station (BS) * 7 BS) = 21 cells

       F.  Cell radius: 166.666 Meters

       G.  Scheduler: Proportional fair with no priority

       H.  Bearer: Default bearer hence each for all traffic.

       I.  Active Queue Management (AQM) settings: AQM [on,off]

   2.  End to end Round Trip Time (RTT): [ 40, 150]

   3.  User arrival model: Poisson arrival model

   4.  User intensity:

       *  Downlink user can have many
      of such queues.

   o  Users can experience both Inter and Intra Radio Access Technology
      (RAT) handovers ("handover" definition in [HO-def-3GPP] ).

   o  Handover between cells, or change intensity: {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9,
          5.6, 6.3, 7.0, 7.7, 8.4, 9,1, 9.8, 10.5}

       *  Uplink user intercity : {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9,
          5.6, 6.3, 7.0}

   5.  Simulation duration: 91s

   6.  Evaluation period : 30s-60s

   7.  Media traffic

       1.  Media type: Video

           a.  Media direction: [Uplink, Downlink]

           b.  Number of serving cells (see Media source per user: One (1)

           c.  Media duration per user: 30s

           d.  Media source: same as define in
      [HO-LTE-3GPP] and [HO-UMTS-3GPP] ) might cause user plane
      interruptions which can lead to bursts of packet losses, delay
      and/or jitter.  The exact behavior depends on the type section 4.3 of radio
      bearer.  Typically, the default best effort bearers do not
      generate packet loss, instead packets are queued up
               [I-D.ietf-rmcat-eval-test]

       2.  Media Type : Audio

           a.  Media direction: Uplink and
      transmitted once the handover is completed.

   o  The network part decides how much the user can transmit.

   o  The cellular network has variable link capacity Downlink

           b.  Number of Media source per user user: One (1)

           c.  Media duration per user: 30s

           d.  Media codec: Constant BitRate (CBR)

           e.  Media bitrate : 20 Kbps

           f.  Adaptation: off

   8.  Other traffic model:

       *  Can vary as fast as a period  Downlink simulation: Maximum of milliseconds. 4Mbps/cell (web browsing or
          FTP traffic)

       *  Depends on lots  Unlink simulation: Maximum of facts (such as distance, speed,
         interference, different flows).

      *  Uses complex and smart link adaptation which makes the link
         behavior ever more dynamic.

      * 2Mbps/cell (web browsing or FTP
          traffic)

3.2.  Bad Radio Coverage

   The scheduling priority depends on the estimated throughput.

   o  Both Quality goal of Service (QoS) and non-QoS radio bearers can be
      used.

   Hence, a real-time communication application operating in such a
   cellular network need to cope with shared bottleneck link and
   variable link capacity, event likes handover, non-congestion related
   loss, abrupt change in bandwidth (both short term and long term) due this test is to handover, evaluate the performance of candidate
   congestion control algorithm when users visit part of the network load and
   with bad radio coverage.  Even though 3GPP
   define QoS bearers [QoS-3GPP] to ensure high quality user experience,
   adaptive real-time applications are desired.

   Different mobile operators deploy their own cellular network with
   their own set  The scenario is created by using larger
   cell radius than previous test case.  In this test case each of network functionalities and policies.  Usually, a
   mobile operator network includes 2G, EDGE, 3G and 4G radio access
   technologies.  Looking at the specifications of such radio
   technologies it is evident that only 3G and 4G radio technologies can
   support
   user/UE in the high bandwidth requirements from real-time interactive
   video applications. media session is an RMCAT compliant endpoint.  The future real-time interactive application
   will impose even greater demand on cellular network performance which
   makes 4G (and beyond radio technologies) more suitable access
   technology for such genre
   arrival of application.

   The key factors to define test cases for cellular network are
   o  Shared and varying link capacity

   o  Mobility

   o  Handover

   However, for cellular network it users follows a Poisson distribution, which is very hard
   proportional to separate such events
   from one another as these events are heavily related.  Hence instead the length of devising separate test cases for all those important events we
   have divided the test case in two categories.  It should be noted call, so that in the following test cases the goal number of users
   per cell is to evaluate kept fairly constant during the
   performance evaluation period.  At
   the beginning of candidate algorithms over radio interface the simulation there should be enough amount of time
   to warm-up the
   cellular network.  Hence it is assumed that the radio interface  This is to avoid running the bottleneck link between evaluation in
   an empty network where network nodes are having empty buffers, low
   interference at the communicating peers and that beginning of the core simulation.  This network does not add any extra
   initialization period is therefore excluded from the evaluation
   period.

   This test case also includes user mobility and competing traffic.
   The competing traffics includes same kind of flows (with same
   adaptation algorithms) . The investigated congestion control
   algorithms should show maximum possible network utilization and
   stability in the path.  Also the
   combination terms of multiple access technologies such as one user has LTE
   connection rate variations, lowest possible end to end
   frame latency, network latency and another has Wi-Fi Packet Loss Rate (PLR) at
   different cell load level.

3.2.1.  Network connection

   Same as defined in Section 3.1.1

3.2.2.  Simulation Setup

   The desired simulation setup is kept out of the scope
   of this document.  However, later those additional scenarios can also
   be added same as Varying Network Load test
   case defined in this list of Section 3.1 except following changes-

   1.  Radio environment : Same as defined in Section 3.1.2 except
       followings

       A.  Deployment and propagation model : 3GPP case 3[Deployment]

       B.  Cell radius: 577.3333 Meters

       C.  Mobility: 3km/h

   2.  User intensity = {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6, 6.3,
       7.0}

   3.  Media traffic model: Same as defined in Section 3.1.2

   4.  Other traffic model: None

3.3.  Desired Evaluation Metrics for cellular test cases.  While defining cases

   RMCAT evaluation criteria document [I-D.ietf-rmcat-eval-criteria]
   defines metrics to be used to evaluate candidate algorithms.
   However, looking at the test cases
   we assumed a typical real-time telephony scenario over nature and distinction of cellular networks where one real-time session consists of one voice stream and
   one video stream.  We
   we recommend that an LTE network simulator is at minimum following metrics to be used to evaluate the
   performance of the candidate algorithms for the test cases defined in
   this document, for example-NS-3 LTE
   simulator [LTE-simulator].

3.1.  Varying Network Load document.

   The goal of this test is desired metrics are-

   o  Average cell throughput (for all cells), shows cell utilizations.

   o  Application sending and receiving bitrate, goodput.

   o  Packet Loss Rate (PLR).

   o  End to evaluate end Media frame delay.  For video, this means the performance delay
      from capture to display.

   o  Transport delay.

   o  Algorithm stability in terms of rate variation.

4.  Wi-Fi Networks Specific Test Cases

   Given the prevalence of Internet access links over Wi-Fi, it is
   important to evaluate candidate RMCAT congestion control algorithm under varying network load.  The network
   load variation is created by adding and removing network users a.k.a.
   User Equipments (UEs) during the simulation.  In this solutions
   over Wi-Fi test case, each
   of cases.  Such evaluations should also highlight the user/UE
   inherent different characteristics of Wi-Fi networks in the media session is an RMCAT compliant endpoint. contrast to
   Wired networks:

   o  The arrival of users follows a Poisson distribution, which wireless radio channel is
   proportional subject to the length of the call, so that the number of users
   per cell interference from nearby
      transmitters, multi-path fading, and shadowing, causing
      fluctuations in link throughput and sometimes an error-prone
      communication environment

   o  Available network bandwidth is kept fairly constant during the evaluation period.  At
   the beginning of the simulation there should be enough amount of time not only shared over the air
      between concurrent users, but also between uplink and downlink
      traffic due to warm-up the network.  This is half duplex nature of wireless transmission
      medium.

   o  Packet transmissions over Wi-Fi are susceptible to avoid running contentions and
      collisions over the evaluation in
   an empty air.  Consequently, traffic load beyond a
      certain utilization level over a Wi-Fi network where can introduce
      frequent collisions and significant network nodes are having empty buffers, low
   interference at overhead.  This, in
      turn, leads to excessive delay, retransmission, loss and lower
      effective bandwidth for applications.

   o  The IEEE 802.11 standard (i.e., Wi-Fi) supports multi-rate
      transmission capabilities by dynamically choosing the beginning most
      appropriate modulation scheme for a given received signal
      strength.  A different choice of Physical-layer rate will lead to
      different application-layer throughput.

   o  Presence of legacy 802.11b networks can significantly slow down
      the simulation.  This network
   initialization period is therefore excluded from the evaluation
   period.

   This test case also includes user mobility and competing traffic.
   The competing traffics includes both same kind rest of flows (with a modern Wi-Fi Network, since it takes longer to
      transmit the same
   adaptation algorithms) packet over a slower link than over a faster
      link.  [Editor's note: maybe include a reference here instead.]

   o  Handover from one Wi-Fi Access Point (AP) to another may cause
      packet delay and different kind loss.

   o  IEEE 802.11e defined EDCA/WMM (Enhanced DCF Channel Access/Wi-Fi
      Multi-Media) to give voice and video streams higher priority over
      pure data applications (e.g., file transfers).

   As we can see here, presence of flows (with Wi-Fi network in different
   service and congestion control).  The investigated congestion control
   algorithms should show maximum possible network utilization
   topologies and
   stability traffic arrival can exert different impact on the
   network performance in terms of rate variations, lowest possible end to end
   frame latency, network latency video transport rate, packet loss and Packet Loss Rate (PLR) at
   different cell load level.

3.1.1.  Network Connection

   Each mobile user is connected
   delay that, in turn, effect end-to-end real-time multimedia
   congestion control.

   Throughout this draft, unless otherwise mentioned, test cases are
   described using 802.11g due to a fixed user.  The connection
   between the mobile user and fixed user consists of a LTE radio
   access, an Evolved Packet Core (EPC) its wide availability in network
   simulation platform.  In practice, however, statistics collected from
   enterprise networks show that the dominant physical modes are 802.11n
   and an Internet connection.  The
   mobile user 802.11ac, accounting for 73.6% and 22.5% of enterprise network
   users, respectively.  Whenever possible, it is connected recommended to extend
   some of the EPC using LTE radio access technology
   which is further connected experiments to 802.11n and 802.11ac, so as to reflect a
   more modern Wi-Fi network setting.

   Since Wi-Fi network normally connects to a wired infrastructure,
   either the Internet. wired network or the Wi-Fi network could be the
   bottleneck.  In the following section, we describe basic test cases
   for both scenarios separately.  The fixed user same set of performance metrics
   as in [I-D.ietf-rmcat-eval-test]) should be collected for each test
   case.

   While all test cases described below can be carried out using
   simulations, e.g. based on [ns-2] or [ns-3], it is
   connected also recommended
   to perform testbed-based evaluations using Wi-Fi access points and
   endpoints running up-to-date IEEE 802.11 protocols.  [Editor's Note:
   need to add some more discussions on the Internet via wired connection with no bottleneck
   (practically infinite bandwidth).  The Internet pros and wired connection cons of simulation-
   based vs. testbed-based evaluations.  It will be good to provide
   recommended testbed configurations. ]

4.1.  Bottleneck in this setup does not add any network impairments Wired Network

   The test scenarios below are intended to mimic the test, it
   only adds 10ms set up of one-way transport propagation delay.

   The path video
   conferencing over Wi-Fi connections from the fixed user to mobile user home.  Typically, the
   Wi-Fi home network is defines as "Downlink" not congested and the path from mobile user to bottleneck is present
   over the fixed user wired home access link.  Although it is defined as
   "Uplink".  We assume expected that only uplink or downlink is congested test
   evaluation results from this section are similar to those from test
   cases defined for wired networks (see [I-D.ietf-rmcat-eval-test]), it
   is worthwhile to run through these tests as sanity checks.

4.1.1.  Network topology

   Figure 2 shows topology of the network for Wi-Fi test cases.  The
   test contains multiple mobile users.  Hence, we recommend that the uplink nodes (MNs) connected to a common Wi-Fi
   access point (AP) and downlink
   simulations are run separately. their corresponding wired clients on fixed
   nodes (FNs).  Each connection carries either RMCAT or TCP traffic
   flow.  Directions of the flows can be uplink, downlink, or bi-
   directional.

                                   uplink
            ++)))        +-------------------------->
            ++-+      ((o))
                             +----------------->+
            +------+                                       +------+
            | MN_1 |))))                             /=====| FN_1 |       / \     +-------+
            +------+    +---+
            +--+      /   \----+       +-----+    ))                          //     +------+
                .        ))                        //         .
                .         ))                      //          .
                .          ))                    //           .
            +------+         +----+         +-----+        +------+
            | MN_N | ))))))) |    |         |     |========| FN_N |
                     /     \   +-------+
            +------+    +---+
             UE         BS        EPC        Internet    fixed
                         <--------------------------+         |    |         |     |        +------+
                             | AP |=========| FN0 |
           +----------+      |    |         |     |      +----------+
           | MN_tcp_1 | )))) |    |         |     |======| MN_tcp_1 |
           +----------+      +----+         +-----+      +----------+
                 .          ))                 \\             .
                 .         ))                   \\            .
                 .        ))                     \\           .
           +----------+  ))                       \\     +----------+
           | MN_tcp_M |)))                         \=====| MN_tcp_M |
           +----------+                                  +----------+
                            +<-----------------+
                                    downlink

              Figure 1: Simulation Topology

3.1.2.  Simulation Setup

   The values enclosed within " [ ] " 2: Network topology for the following simulation
   attributes follow the notion set in [I-D.ietf-rmcat-eval-test].  The
   desired simulation Wi-Fi test cases

4.1.2.  Test setup as follows-

   1.

   o  Test duration: 120s

   o  Wi-Fi network characteristics:

      *  Radio environment

       A.  Deployment and propagation model: Log-distance path loss propagation
         model : 3GPP case 1[Deployment]

       B.  Antenna: Multiple-Input [NS3WiFi]

      *  PHY- and Multiple-Output (MIMO), [2D, 3D]

       C.  Mobility: [3km/h, 30km/h]

       D.  Transmission bandwidth: 10Mhz
       E.  Number of cells: multi cell deployment (3 Cells per Base
           Station (BS) MAC-layer configuration: IEEE 802.11g

      * 7 BS) = 21 cells

       F.  Cell radius: 166.666 Meters

       G.  Scheduler: Proportional fair with no priority

       H.  Bearer: Default bearer for all traffic.

       I.  Active Queue Management (AQM) settings: AQM [on,off]

   2.  End to end Round Trip Time (RTT): [ 40, 150]

   3.  User arrival model: Poisson arrival model

   4.  User intensity:  PHY-layer link rate: 54 Mbps

   o  Wired path characteristics:

      *  Downlink user intensity: {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9,
          5.6, 6.3, 7.0, 7.7, 8.4, 9,1, 9.8, 10.5}  Path capacity: 1Mbps

      *  One-Way propagation delay: 50ms.

      *  Maximum end-to-end jitter: 30ms

      *  Bottleneck queue type: Drop tail.

      *  Bottleneck queue size: 300ms.

      *  Path loss ratio: 0%.

   o  Application characteristics:

      *  Uplink user intercity : {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9,
          5.6, 6.3, 7.0}

   5.  Simulation duration: 91s

   6.  Evaluation period : 30s-60s

   7.  Media traffic

       1. Traffic:

         +  Media type: Video

           a.

         +  Media direction: [Uplink, Downlink]

           b. See Section 4.1.3

         +  Number of media sources (N): See Section 4.1.3

         +  Media source per user: One (1)

           c.  Media duration per user: 30s

           d.  Media source: same as define in section 4.3 of
               [I-D.ietf-rmcat-eval-test]

       2.  Media timeline:

            -  Start time: 0s.

            -  End time: 119s.

      *  Competing traffic:

         +  Type : Audio

           a.  Media of sources: long-lived TCP

         +  Traffic direction: Uplink and Downlink

           b. See Section 4.1.3
         +  Number of Media source per user: sources (M): See Section 4.1.3

         +  Congestion control: Default TCP congestion control [TBD]

         +  Traffic timeline:

            -  Start time: 0s

            -  End time: 119s

4.1.3.  Typical test scenarios

   o  Single uplink RMCAT flow: N=1 with uplink direction and M=0.

   o  One (1)

           c.  Media duration per user: 30s
           d.  Media codec: Constant BitRate (CBR)

           e.  Media bitrate : 20 Kbps

           f.  Adaptation: off

   8.  Other traffic pair of bi-directional RMCAT flows: N=2 (with one uplink flow
      and one downlink flow); M=0.

   o  One RMCAT flow competing against one long-live TCP flow over
      uplink: N=1 (uplink) and M = 1(uplink).

4.1.4.  Expected behavior

   o  Single uplink RMCAT flow: the candidate algorithm is expected to
      detect the path capacity constraint, converges to bottleneck
      link's capacity and adapt the flow to avoid unwanted oscillation
      when the sending bit rate is approaching the bottleneck link's
      capacity.  No excessive rate oscillations.

   o  Bi-directional RMCAT flows: It is expected that the candidate
      algorithms is able to converge to the bottleneck capacity of the
      wired path on both directions despite of the presence of
      measurement noise over the Wi-Fi connection.

   o  One RMCAT flow competing with long-live TCP flow over uplink: the
      candidate algorithm should be able to avoid congestion collapse,
      and stabilize at a fair share of the bottleneck capacity over the
      wired path.

4.2.  Bottleneck in Wi-Fi Network

   These test cases assume that the wired portion along the media path
   are well-provisioned.  The bottleneck is in the Wi-Fi network over
   wireless.  This is to mimic the enterprise/coffee-house scenarios.

4.2.1.  Network topology

   Same as defined in Section 4.1.1

4.2.2.  Test setup

   o  Test duration: 120s

   o  Wi-Fi network characteristics:

      *  Radio propagation model: Log-distance path loss propagation
         model [NS3WiFi]

      *  PHY- and MAC-layer configuration: IEEE 802.11g

      *  PHY-layer link rate: 54 Mbps

   o  Wired path characteristics:

      *  Path capacity: 100Mbps

      *  Downlink simulation: Maximum of 4Mbps/cell (web browsing or
          FTP traffic)  One-Way propagation delay: 50ms.

      *  Unlink simulation:  Maximum end-to-end jitter: 30ms

      *  Bottleneck queue type: Drop tail.

      *  Bottleneck queue size: 300ms.

      *  Path loss ratio: 0%.

   o  Application characteristics:

      *  Media Traffic:

         +  Media type: Video

         +  Media direction: See Section 4.2.3

         +  Number of 2Mbps/cell (web browsing or FTP
          traffic)

3.2.  Bad Radio Coverage

   The goal media sources (N): See Section 4.2.3

         +  Media timeline:

            -  Start time: 0s.

            -  End time: 119s.

      *  Competing traffic:

         +  Type of this test is to evaluate the performance sources: long-lived TCP

         +  Number of candidate sources (M): See Section 4.2.3

         +  Traffic direction: See Section 4.2.3

         +  Congestion control: Default TCP congestion control algorithm when users visit part of the network
   with bad radio coverage.  The scenario is created by using larger
   cell radius than previous [TBD]

         +  Traffic timeline:

            -  Start time: 0s

            -  End time: 119s

4.2.3.  Typical test case.  In this scenarios

   This sections describes a few specific test case each scenarios that are deemed
   as important for understanding behavior of a RMCAT candidate solution
   over a Wi-Fi network.

   o  Multiple RMCAT Flows Sharing the
   user/UE in the media session Wireless Downlink: N=16 (all
      downlink); M = 0; This test case is an for studying the impact of
      contention on competing RMCAT compliant endpoint.  The
   arrival flows.  Specifications for IEEE
      802.11g with a physical-layer transmission rate of users follows 54 Mbps is
      chosen.  Note that retransmission and MAC-layer headers and
      control packets may be sent at a Poisson distribution, which lower link speed.  The total
      application-layer throughput (reasonable distance, low
      interference and small number of contention stations) for 802.11g
      is
   proportional to around 20 Mbps.  Consequently, a total of N=16 RMCAT flows are
      needed for saturating the length wireless interface in this experiment.
      Evaluation of a given candidate solution should focus on whether
      downlink RMCAT flows can stabilize at a fair share of bandwidth.

   o  Multiple RMCAT Flows Sharing the call, so that Wireless Uplink: N = 16 (all
      downlink); M = 0; When multiple clients attempt to transmit video
      packets uplink over the number of users
   per cell wireless interface, they introduce more
      frequent contentions and potentially collisions.  Per-flow
      throughput is kept fairly constant during the evaluation period.  At expected to be lower than that in the beginning previous
      downlink-only scenario.  Evaluation of the simulation there a given candidate solution
      should be enough amount focus on whether uplink flows can stabilize at a fair share
      of bandwidth.

   o  Multiple Bi-directional RMCAT Flows: N = 16 (8 uplink and 8
      downlink); M = 0.  The goal of time
   to warm-up the network.  This this test is to avoid running evaluate
      performance of the evaluation candidate solution in
   an empty network where network nodes are having empty buffers, low
   interference at the beginning terms of bandwidth
      fairness between uplink and downlink flow.

   o  Multiple RMCAT flows in the simulation.  This network
   initialization period is therefore excluded from presence of background TCP traffic:
      the evaluation
   period.

   This test case also includes user mobility and competing traffic.
   The competing traffics includes same kind goal of this test is to evaluate how RMCAT flows (with same
   adaptation algorithms) . The investigated congestion control
   algorithms should show maximum possible compete
      against TCP over a congested Wi-Fi network utilization and
   stability for a given candidate
      solution.  [Editor's Note: more detailed description will be added
      in the next version in terms of rate variations, lowest possible end to end
   frame latency, network latency directoin/number of RMCAT and Packet Loss Rate (PLR) at
   different cell load level.

3.2.1.  Network connection

   Same as defined in Section 3.1.1

3.2.2.  Simulation Setup

   The desired simulation setup is same as TCP
      flows. ]

   o  Varying Network Load number of RMCAT flows: the goal of this test
   case defined is to
      evaluate how a candidate RMCAT solution responds to varying
      traffic load/demand over a congested Wi-Fi network.  [Editor's
      Note: more detailed description will be added in Section 3.1 except following changes-
   1.  Radio environment : Same as defined the next version
      in Section 3.1.2 except
       followings

       A.  Deployment and propagation model : 3GPP terms of arrival/departure pattern of the flows.]

4.2.4.  Expected behavior

   o  Multiple downlink RMCAT flows: All RMCAT flows should get fair
      share of the bandwidth.  Overall bandwidth usage should be no less
      than same case 3[Deployment]

       B.  Cell radius: 577.3333 Meters

       C.  Mobility: 3km/h

   2.  User intensity = {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6, 6.3,
       7.0}

   3.  Media traffic model: Same with TCP flows (using TCP as defined in Section 3.1.2

   4.  Other traffic model: None

3.3.  Desired Evaluation Metrics performance
      benchmark).  The delay and loss should be within acceptable range
      for cellular test cases real-time multimedia flow.

   o  Multiple uplink RMCAT evaluation criteria document [I-D.ietf-rmcat-eval-criteria]
   defines metrics to flows: overall bandwidth usage shared by all
      RMCAT flows should be used to evaluate candidate algorithms.
   However, looking at no less than those shared by the nature and distinction same number
      of cellular networks
   we recommend at minimum following metrics to TCP flows (i.e., benchmark performance using TCP flows).

   o  Multiple bi-directional RMCAT flows: overall bandwidth usage
      shared by all RMCAT flows should be used to evaluate no less than those shared by
      the same number of TCP flows (i.e., benchmark performance using
      TCP flows).  All downlink RMCAT flows are expected to obtain
      similar bandwidth with respect to each other.

4.3.  Potential Potential Test Cases

4.3.1.  EDCA/WMM usage

   EDCA/WMM is prioritized QoS with four traffic classes (or Access
   Categories) with differing priorities.  RMCAT flow should have better
   performance (lower delay, less loss) with EDCA/WMM enabled when
   competing against non-interactive background traffic (e.g., file
   transfers).  When most of the candidate algorithms for traffic over Wi-Fi is dominated by
   media, however, turning on WMM may actually degrade performance.
   This is a topic worthy of further investigation.

4.3.2.  Legacy 802.11b Effects

   When there is 802.11b devices connected to modern 802.11 network, it
   may affect the performance of the whole network.  Additional test
   cases defined in
   this document.

   The desired metrics are-

   o  Average cell throughput (for all cells), shows cell utilizations.

   o  Application sending and receiving bitrate, goodput.

   o  Packet Loss Rate (PLR).

   o  End can be added to end Media frame delay.  For video, this means evaluate the delay
      from capture to display.

   o  Transport delay.

   o  Algorithm stability in terms affects of rate variation.

4.  Wi-Fi Networks Specific Test Cases

   TBD legacy devices on the
   performance of RMCAT congestion control algorithm.

5.  Conclusion

   This document defines two a collection of test cases that are considered
   important for cellular and Wi-Fi networks.  Moreover, this document
   also provides a framework to define more for defining additional test cases for cellular network. over
   wireless cellular/Wi-Fi networks.

6.  Acknowledgements

   We would like to thank Tomas Frankkila, Magnus Westerlund, Kristofer
   Sandlund for their valuable comments while writing this draft.

7.  IANA Considerations

   This memo includes no request to IANA.

8.  Security Considerations

   Security issues have not been discussed in this memo.

9.  References

9.1.  Normative References

   [Deployment]
              TS 25.814, 3GPP., "Physical layer aspects for evolved
              Universal Terrestrial Radio Access (UTRA)", October 2006,
              <http://www.3gpp.org/ftp/specs/
              archive/25_series/25.814/25814-710.zip>.

   [HO-def-3GPP]
              TR 21.905, 3GPP., "Vocabulary for 3GPP Specifications",
              December 2009, <http://www.3gpp.org/ftp/specs/
              archive/21_series/21.905/21905-940.zip>.

   [HO-LTE-3GPP]
              TS 36.331, 3GPP., "E-UTRA- Radio Resource Control (RRC);
              Protocol specification", December 2011,
              <http://www.3gpp.org/ftp/specs/
              archive/36_series/36.331/36331-990.zip>.

   [HO-UMTS-3GPP]
              TS 25.331, 3GPP., "Radio Resource Control (RRC); Protocol
              specification", December 2011,
              <http://www.3gpp.org/ftp/specs/
              archive/25_series/25.331/25331-990.zip>.

   [I-D.ietf-rmcat-eval-criteria]
              Singh, V. and J. Ott, "Evaluating Congestion Control for
              Interactive Real-time Media", draft-ietf-rmcat-eval-
              criteria-03
              criteria-04 (work in progress), March October 2015.

   [NS3WiFi]  "Wi-Fi Channel Model in NS3 Simulator",
              <https://www.nsnam.org/doxygen/
              classns3_1_1_yans_wifi_channel.html>.

   [QoS-3GPP]
              TS 23.203, 3GPP., "Policy and charging control
              architecture", June 2011, <http://www.3gpp.org/ftp/specs/
              archive/23_series/23.203/23203-990.zip>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997. 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

9.2.  Informative References

   [I-D.ietf-rmcat-cc-requirements]
              Jesup, R. and Z. Sarker, "Congestion Control Requirements
              for Interactive Real-Time Media", draft-ietf-rmcat-cc-
              requirements-09 (work in progress), December 2014.

   [I-D.ietf-rmcat-eval-test]
              Sarker, Z., Singh, V., Zhu, X., and M. Ramalho, "Test
              Cases for Evaluating RMCAT Proposals", draft-ietf-rmcat-
              eval-test-01
              eval-test-02 (work in progress), March September 2015.

   [IEEE802.11]
              "Standard for Information technology--Telecommunications
              and information exchange between systems Local and
              metropolitan area networks--Specific requirements Part 11:
              Wireless LAN Medium Access Control (MAC) and Physical
              Layer (PHY) Specifications", 2012.

   [LTE-simulator]
              "NS-3, A discrete-Event Network Simulator",
              <https://www.nsnam.org/docs/release/3.23/manual/html/
              index.html>.

   [ns-2]     "The Network Simulator - ns-2",
              <http://www.isi.edu/nsnam/ns/>.

   [ns-3]     "The Network Simulator - ns-3", <https://www.nsnam.org/>.

Authors' Addresses

   Zaheduzzaman Sarker
   Ericsson AB
   Laboratoriegraend 11
   Luleae  97753
   Sweden

   Phone: +46 107173743
   Email: zaheduzzaman.sarker@ericsson.com

   Ingemar Johansson
   Ericsson AB
   Laboratoriegraend 11
   Luleae  97753
   Sweden

   Phone: +46 10 7143042
   Email: ingemar.s.johansson@ericsson.com

   Xiaoqing Zhu
   Cisco Systems
   12515 Research Blvd., Building 4
   Austin, TX  78759
   USA

   Email: xiaoqzhu@cisco.com

   Jiantao Fu
   Cisco Systems
   707 Tasman Drive
   Milpitas, CA  95035
   USA

   Email: jianfu@cisco.com
   Wei-Tian Tan
   Cisco Systems
   725 Alder Drive
   Milpitas, CA  95035
   USA

   Email: dtan2@cisco.com

   Michael A. Ramalho
   Cisco Systems
   8000 Hawkins Road
   Sarasota, FL  34241
   USA

   Phone: +1 919 476 2038
   Email: mramalho@cisco.com