wdiff draft-ietf-rmcat-wireless-tests-02.txt draft-ietf-rmcat-wireless-tests-03.txt

Network Working Group Z. Sarker
Internet-Draft I. Johansson
Intended status: Informational Ericsson AB
Expires: November 8, 2016 May 18, 2017 X. Zhu
J. Fu
W. Tan
M. Ramalho
Cisco Systems
May 7,
November 14, 2016

Evaluation Test Cases for Interactive Real-Time Media over Wireless
Networks
draft-ietf-rmcat-wireless-tests-02
draft-ietf-rmcat-wireless-tests-03

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 adaptation algorithm(s) to be used in the for real-time interactive communication.
In this
To ensure seamless and robust user experience, the proposed rate
adaptation algorithm(s) should work well across all access network
types. This document describes test cases are described to evaluate the for evaluating
performances of the proposed endpoint rate adaptation solutions in over LTE
networks and
Wi-Fi networks. The proposed 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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This Internet-Draft will expire on November 8, 2016. May 18, 2017.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Cellular Network Specific Test Cases . . . . . . . . . . . . 3
3.1. Varying Network Load . . . . . . . . . . . . . . . . . . 6
3.1.1. Network Connection . . . . . . . . . . . . . . . . . 6
3.1.2. Simulation Setup . . . . . . . . . . . . . . . . . . 7
3.2. Bad Radio Coverage . . . . . . . . . . . . . . . . . . . 8
3.2.1. Network connection . . . . . . . . . . . . . . . . . 9
3.2.2. Simulation Setup . . . . . . . . . . . . . . . . . . 9
3.3. Desired Evaluation Metrics for cellular test cases . . . 10
4. Wi-Fi Networks Specific Test Cases . . . . . . . . . . . . . 10
4.1. Bottleneck in Wired Network . . . . . . . . . . . . . . . 12
4.1.1. Network topology . . . . . . . . . . . . . . . . . . 12
4.1.2. Test setup . . . . . . . . . . . . . . . . . . . . . 13
4.1.3. Typical test scenarios . . . . . . . . . . . . . . . 14
4.1.4. Expected behavior . . . . . . . . . . . . . . . . . . 14
4.2. Bottleneck in Wi-Fi Network . . . . . . . . . . . . . . . 15
4.2.1. Network topology . . . . . . . . . . . . . . . . . . 15
4.2.2. Test setup . . . . . . . . . . . . . . . . . . . . . 15
4.2.3. Typical test scenarios . . . . . . . . . . . . . . . 16
4.2.4. Expected behavior . . . . . . . . . . . . . . . . . . 17
4.3. Potential Potential Test Cases . . . . . . . . . . . . . 18
4.3.1. EDCA/WMM usage . . . . . . . . . . . . . . . . . . . 18
4.3.2. Legacy 802.11b Effects . . . . . . . . . . . . . . . 18
5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 18
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 19
8. Security Considerations . . . . . . . . . . . . . . . . . . . 18 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 20
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 generate huge amount of media
traffic in the Internet. They covers the Application scenarios of range from users
having a video call in the bus to media consumption by someone
sitting on a couch in a living
room. room couch. It is a well known fact that the characteristic
characteristics and technical challenges for offering service multimedia
services over wireless network are very different than from those of providing the
same service over a wired network. Even though RMCAT basic test
cases defines number of test cases that covers lots of as defined in [I-D.ietf-rmcat-eval-test] have covered many
effects of the impairments also visible in the wireless networks but networks, there are
remains characteristics and dynamics those are unique to particular a given wireless
environment. For example, in the LTE networks the base station maintains
queues per radio bearer per user hence it gives leads to a different nature
of interaction
when all from that over the wired network, where traffic from user
all users share the same queue. Again, the Furthermore, user mobility in a
cellular network is different than the user mobility in a Wi-Fi network. Thus,
Therefore, It is important to evaluate the performance of the proposed
RMCAT candidates candidate solutions separately in the over cellular mobile networks
and over Wi-Fi local networks (IEEE (i.e., IEEE 802.11xx protocol family ).

RMCAT evaluation criteria [I-D.ietf-rmcat-eval-criteria] document
provides the guideline to perform the evaluation on for evaluating candidate algorithms and
recognizes the importance of testing over wireless networks to be important access
link. networks.
However, it does not provides particular describe any specific test cases to
evaluate the for evaluating
performance of the candidate algorithm. In this This document we describe describes 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 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 period. At
the beginning of the simulation there should be enough amount of time
to warm-up the network. This is to avoid running the evaluation 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
stability in terms of rate variations, lowest possible end to 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 a fixed user. The connection
between the mobile user and fixed user consists of a LTE radio
access, an Evolved Packet Core (EPC) and an Internet connection. The
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 wired connection
in this setup does not add any network impairments to the test, it
only adds 10ms of one-way transport propagation delay.

The path from the fixed user to mobile user is defines as "Downlink"
and the path from mobile user to the fixed user is defined as
"Uplink". We assume that only uplink or downlink is congested for
the mobile users. Hence, we recommend that the uplink and downlink
simulations are 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 notion set in [I-D.ietf-rmcat-eval-test]. The
desired simulation setup as follows-

1. Radio environment

A. Deployment and propagation model : 3GPP case 1[Deployment]

B. Antenna: Multiple-Input 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) * 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:

* 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}

* 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 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 Type : Audio

a. Media direction: Uplink and Downlink

b. Number of Media source per 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:

* Downlink simulation: Maximum of 4Mbps/cell (web browsing or
FTP traffic)

* Unlink simulation: Maximum of 2Mbps/cell (web browsing or FTP
traffic)

3.2. Bad Radio Coverage

The goal of this test is to evaluate the performance of candidate
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 test case. In this test case each of the
user/UE in the 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 period. At
the beginning of the simulation there should be enough amount of time
to warm-up the network. This is to avoid running the evaluation 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 same kind of flows (with same
adaptation algorithms) . The investigated congestion control
algorithms should show maximum possible network utilization and
stability in terms of rate variations, lowest possible end to end
frame latency, network latency 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 Varying Network Load test
case defined in 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

RMCAT evaluation criteria document [I-D.ietf-rmcat-eval-criteria]
defines metrics to be used to evaluate candidate algorithms.
However, looking at the nature and distinction of cellular networks
we recommend at minimum following metrics to be used to evaluate the
performance of the candidate algorithms for the 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 to end Media frame delay. For video, this means the 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 solutions
over Wi-Fi test cases. cases that include Wi-Fi access lines. Such evaluations
should also highlight the inherent different characteristics of Wi-Fi
networks in contrast to
Wired wired networks:

o The wireless radio channel is subject to interference from nearby
transmitters, multipath fading, and shadowing, causing
fluctuations in link throughput and sometimes an error-prone
communication environment

o Available network bandwidth is not only shared over the air
between cocurrent users, but also between uplink and downlink
traffic due to the half duplex nature of wireless transmission
medium.

o Packet transmessions transmissions over Wi-Fi are susceptible to contentions and
collisions over the air. Consequently, traffic load beyond a
certain utilization level over a Wi-Fi network can introduce
frequent collisions and significant network overhead. This, in
turn, leads to excessive delay, retransmission, loss retransmissions, packet losses 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 most
appropriate modulation scheme for a given received singal
strength. A different choice of Physical-layer physical-layer rate will lead leads to
different application-layer throughput.

o Presence of legancy 802.11b networks can significantly slow down
the the rest of a modern Wi-Fi Network, since it takes longer to
transmit the same 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 lead to
packet delay and loss. losses during the process.

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,

In summary, presence of Wi-Fi network access links in different network
topologies and traffic arrival can exert different impact on the network performance in
terms of video transport rate, application-layer effective throughput, packet loss rate,
and
delay that, packet delivery delay. These, in turn, effect influence the behavior of
end-to-end real-time multimedia congestion control.

Throughout this draft, unless otherwise mentioned, test cases are
described using 802.11n due to its wide availability in real-world
networks. Statistics collected from enterprise Wi-Fi networks show
that the dominant physical modes are 802.11n and 802.11ac, accounting
for 73.6% and 22.5% of enterprise network users, respectively.

Since

Typically, a Wi-Fi access network normally connects to a wired infrastructure,
either infrastructure.
Either the wired network or the Wi-Fi segment of the network could be the
bottleneck. In the following section, sections, we describe basic test cases
for both scenarios separately. The 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 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 pros and cons of simulation-
based vs. testbed-based evaluations. Will be good to provide
recommended testbed configurations. ]

4.1. Bottleneck in Wired Network

The test scenarios below are intended to mimic the set up of video
conferencing over Wi-Fi connections from the home. Typically, the
Wi-Fi home network is not congested and the bottleneck is present
over the wired home access link. Although it is expected that 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 nodes (MNs) connected to a common Wi-Fi
access point (AP) and 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
+----------------->+
+------+ +------+
| MN_1 |)))) /=====| FN_1 |
+------+ )) // +------+
. )) // .
. )) // .
. )) // .
+------+ +----+ +-----+ +------+
| MN_N | ))))))) | | | |========| FN_N |
+------+ | | | | +------+
| AP |=========| FN0 |
+----------+ | | | | +----------+
| MN_tcp_1 | )))) | | | |======| MN_tcp_1 |
+----------+ +----+ +-----+ +----------+
. )) \\ .
. )) \\ .
. )) \\ .
+----------+ )) \\ +----------+
| MN_tcp_M |))) \=====| MN_tcp_M |
+----------+ +----------+
+<-----------------+
downlink

Figure 2: Network topology for Wi-Fi test cases

4.1.2. 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 802.11n

* MCS Index at 11: 16-QAM 1/2, Raw Data Rate@52Mbps

o Wired path characteristics:

* 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:

* Media Traffic:

+ Media type: Video

+ Media direction: See Section 4.1.3

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

+ Media timeline:

- Start time: 0s.

- End time: 119s.

* Competing traffic:

+ Type of sources: long-lived TCP or CBR over UDP

+ Traffic direction: See Section 4.1.3
+ Number of sources (M): See Section 4.1.3

+ Congestion control: Default TCP congestion control [TBD] or
CBR over UDP

+ Traffic timeline: See Section 4.1.3

4.1.3. Typical test scenarios

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

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

o One pair of bi-directional RMCAT flows, one on-off CBR over UDP
flow on uplink : N=2 (with one uplink flow and one downlink flow);
M=1 (uplink). CBR flow on time at 0s-60s, off time at 60s-119s

o One pair of bi-directional RMCAT flows, one off-on CBR over UDP
flow on uplink : N=2 (with one uplink flow and one downlink flow);
M=1 (uplink). UDP off time: 0s-60s, on time: 60s-119s

o One RMCAT flow competing against one long-live TCP flow over
uplink: N=1 (uplink) and M = 1(uplink), TCP start time: 0s, end
time: 119s.

4.1.4. Expected behavior

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

o Bi-directional RMCAT flows: It is expected that the candidate
algorithms
algorithm is able to converge to the bottleneck capacity of the
wired path on both directions despite presense presence of measurment noise
over the Wi-Fi connection. In the presence of background TCP or
CBR over UDP traffic, the rate of RMCAT flows should adapt in a
timely manner to changes in the available bottleneck bandwidth.

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

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 well-provisioned whereas the Wi-Fi network bottleneck exists over
wireless. the Wi-Fi
access network. This is to mimic the enterprise/coffee-house scenarios. application scenarios typically
encountered by users in an enterprise environment or at a coffee
house.

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 802.11n

* MCS Index at 11: 16-QAM 1/2, Raw Data Rate at 52Mbps

o Wired path characteristics:

* Path capacity: 100Mbps

* 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:

* Media Traffic:

+ Media type: Video

+ Media direction: See Section 4.2.3

+ Number of media sources (N): See Section 4.2.3
+ Media timeline:

- Start time: 0s.

- End time: 119s.

* Competing traffic:

+ Type of sources: long-lived TCP or CBR over UDP

+ Number of sources (M): See Section 4.2.3

+ Traffic direction: See Section 4.2.3

+ Congestion control: Default TCP congestion control [TBD] or
CBR over UDP

+ Traffic timeline: See Section 4.2.3

4.2.3. Typical test scenarios

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

o Multiple RMCAT Flows Sharing the Wireless Downlink: N=16 (all
downlink); M = 0; 0. This test case is for studying the impact of
contention on competing RMCAT flows. Specifications for IEEE
802.11n, For an 802.11n network,
given the MCS Index at 11: 16-QAM 1/2, Raw Data Rate at 52Mbps is
chosen. Note that retransmissions, MAC-layer headers, of 11 and control
packets may be sent at a lower link speed. The the corresponding raw data rate of
52Mbps, the total application-
layer application-layer throughput (reasonable (assuming
reasonable distance, low interference and small
number of contention stations) for 802.11n infrequent contentions
caused by competing streams) is around 20 Mbps. 20Mbps. Consequently, a
total of N=16 RMCAT flows are needed for
saturating to saturate the wireless
interface in this experiment. Evaluation of a given candidate
solution should focus on whether downlink RMCAT flows can stablize
at a fair share of bandwidth. total application-layer throughput.

o Multiple RMCAT Flows Sharing the Wireless Uplink: N = 16 (all
downlink); M = 0; 0. When multiple clients attempt to transmit video
packets uplink over the wireless interface, they introduce more
frequent contentions and potentially potential collisions. Per-flow
throughput is expected to be lower than that in the previous
downlink-only scenario. Evaluation of a given candidate solution
should focus on whether uplink flows can stablize at a fair share
of bandwidth. application-layer throughput.

o Multiple Bi-directional RMCAT Flows: N = 16 (8 uplink and 8
downlink); M = 0. the The goal of this test is to evaluate
performance of the candidate solution in terms of bandwidth
fairness between uplink and downlink flow.

o Multiple Bi-directional RMCAT Flows with on-off CBR traffic: N =
16 (8 uplink and 8 downlink); M = 5(uplink). The goal of this
test is to evaluate upgrading performance adaptation behavior of the candidate solution in terms of
when its available bandwidth changes caused by the CBR
uplink flow over UDP. CBR over UDP due to departure of
background traffic. The background traffic consists of several
(e.g., M=5) CBR flows have on time
0s-60s, transported over UDP, which are ON at times
t=0-60s and off time 60s-119s are OFF at times t=61-120s.

o Multiple Bi-directional RMCAT Flows with off-on CBR traffic: N =
16 (8 uplink and 8 downlink); M = 5(uplink). The goal of this
test is to evaluate upgrading performance adaptation behavior of the candidate solution in terms of
when its available bandwidth changes caused by the CBR
uplink flow over UDP. CBR over UDP due to arrival of background
traffic. The background traffic consists of several (e.g., M=5)
parallel CBR flows have off time
0s-60s, transported over UDP, which are OFF at times
t=0-60s and on time 60s-119s. are ON at times t=61-120s.

o Multiple RMCAT flows in the presence of background TCP traffic:
the traffic.
The goal of this test is to evaluate how RMCAT flows compete
against TCP over a congested Wi-Fi network for a given candidate
solution. TCP start time: 0s, end time: 119s. [Editor's Note:
more detailed description will be added in
need to add the next version in
terms of directoin/number number of recommended RMCAT and TCP flows. ] flows]

o Varying number of RMCAT flows: the flows. The goal of this test 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 the next version
in terms of need to specify recommended arrival/departure pattern of the flows.]
RMCAT flows]

4.2.4. Expected behavior

o Multiple downlink RMCAT flows: All each RMCAT flows flow should get its fair
share of the total bottleneck link bandwidth. Overall bandwidth
usage should not be no less significantly lower than that experienced by
the same case with number of concurrent downlink TCP flows (using flows. In other words,
the performance of multiple concurrent TCP flows will be used as a
performance
benchmark). benchmark for this test scenario. The end-to-end
delay and packet loss ratio experienced by each flow should be
within acceptable range for real-time multimedia flow. applications.

o Multiple uplink RMCAT flows: overall bandwidth usage shared by all
RMCAT flows should not be no less significantly lower than those shared that
experienced by the same number of concurrent uplink TCP flows (i.e., benchmark flows. In
other words, the performance using of multiple concurrent TCP flows). flows will
be used as a performance benchmark for this test scenario.

o Multiple bi-directional RMCAT flows with dynamic background
traffic carry CBR flows over UDP traffic: UDP: RMCAT flows should adapt in a
timely fashion to the resulting changes in available bandwidth.

o Multiple bi-directional RMCAT flows with TCP traffic: overall
bandwidth usage shared by all RMCAT flows should not be no less
significantly lower than those shared achieved by the same number of bi-
directional TCP flows (i.e., benchmark flows. In other words, the performance using of
multiple concurrent TCP flows). flows will be used as a performance
benchmark for this test scenario. 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 flows should have achieve
better performance (lower (i.e., lower delay, less loss) fewer packet losses) with
EDCA/WMM enabled when competing against non-interactive background
traffic (e.g., file transfers). When most of the traffic over Wi-Fi
is dominated by media, however, turning on WMM may actually degrade performance.
performance since all media flows now attempt to access the wireless
transmission medium more aggressively, thereby causing more frequent
collisions and collision-induced losses. 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 can be added to evaluate the affects of legancy devices on the
performance of RMCAT congestion control algorithm.

5. Conclusion

This document defines a collection of test cases that are considered
important for cellular and Wi-Fi networks. Moreover, this document
also provides a framework for defining additional test cases 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]
Varun,
Singh, V., Ott, J., and S. Holmer, "Evaluating Congestion
Control for Interactive Real-time Media", draft-ietf-
rmcat-eval-criteria-05
rmcat-eval-criteria-06 (work in progress), March September 2016.

[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,
<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., Varun, Singh, V., Zhu, X., and M. Ramalho, "Test
Cases for Evaluating RMCAT Proposals", draft-ietf-rmcat-
eval-test-03
eval-test-04 (work in progress), March October 2016.

[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