Hi Gyan,
Thanks a lot for your very thorough review of this draft, and for your valuable
comments. We have uploaded the revised version (-09) to address some of the
concerns and suggestions you've raised.
Please also see our replies below inline, tagged [authors]. Let us know if you
have any further thoughts or comments __
Best Regards,
Xiaoqing, on behalf of all authors.
On 1/21/20, 3:46 PM, "Gyan Mishra via Datatracker" <nore...@ietf.org> wrote:
Reviewer: Gyan Mishra
Review result: Ready with Issues
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Reviewer: Gyan Mishra
Review result: Ready with Minor Issues
Document: draft-ietf-rmcat-wireless-tests-08
Reviewer: Gyan Mishra
Review Date: 2020-01-17
IETF LC End Date: 2020-01-21
IESG Telechat date: Not scheduled for a telechat
Summary: Ready, but with nits and minor issues that should be addressed.
Major issues: None
Minor issues: This document describes test cases for evaluating
performance of
RTP congestion control algorithms over LTE & WIFI networks.
Section 1 It is mentioned a number of instance where “wired” is mentioned
where
I believe “wireless” or “WIFI” is what is meant to be stated. Please check.
[authors] Thanks for raising this concern. We’ve doubled checked on the usage
of “wired” in all three instances in the introduction section, and believe it
is intended as such. Our intention was to contrast the characteristics of
wireless networks from those of wired networks, as a motivation of the need for
this draft. We have, however, taken the opportunity to revise those sentences
to make them less wordy.
I would recommend to use WIFI to refer to local LAN WIFI and use cellular
to
refer to a mobile handset, and not use the term “wireless” as that could be
confusing.
[authors] We agree with the suggestion that it is preferable to refer
specifically to WiFi or cellular whenever possible and have mostly edited out
the word “wireless”. In a few places, however, it is rather cumbersome to
always say “cellular and WiFi networks” when our intention is to simply
contrast the difference between wireless and wired communication. We have
therefore stuck with the term “wireless” in those cases.
I would recommend not using LTE to refer to Cellular from a general mobile
handset point of view, since LTE refers to 4G and Cellular could be any -
2G,3G,4G,5G etc
[authors] We agree with this proposed change. The text has been updated
accordingly with a few exceptions: a) mentioning LTE/5G as an example of
operational cellular network; b) pointing to the LTE simulator in NS-3; and c)
referencing the corresponding 3GPP standard documents.
Section 3 This section also mentioned “wired” where I think the goal of the
document is test cases of WIFI & Cellular and adding in wired does confuse
the
reader as we are talking about quality degradation issues with wireless
technologies - WIFI & Cellular. Please check the verbiage.
[authors] Thanks for pointing this out. We have checked all three previous
usage of the word in this section and have eliminated the mention of it in the
introductory discussions. The remaining two uses, however, are needed for
describing the proposed test case topology so we left them as is.
Section 3 In this sentence you mention 3G support of high bandwidth. My
experience with 3G has not been very slow page loading and that multimedia
would suffer.
[authors] This is a fair complaint. To avoid controversy, we have revised the
sentence to now state: “… it is evident that only the more recent radio
technologies can support the high bandwidth requirements …”
Section 3 Bottom of page 5 it is mentioned that 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. Please explain why as
the reader would believe it would be in scope as that is the main topic.
[authors] When some of the users are on LTE and some of the users are on
Wi-Fi, it is only interesting to investigate the test case when the bottleneck
of the system is on the wired hop. Whereas the main focus of this draft is to
evaluate how congestion control schemes interactive over the wireless
interface. We have added the following statement in the draft to explain why it
is out of scope:
“It should be noted that the goal of the following test cases is to
evaluate the performance
of candidate algorithms over the 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 introduce any extra congestion along the path.
Consequently, this draft has kept
as out of scope the combination of multiple access technologies
involving both cellular and Wi-Fi users.”
Section 3 Top of page 6 - I am wondering if there is a better explanation of
why you need a test simulator due to unpredictable nature or cellular other
than underground mines.
[authors] The unpredictable nature of the cellular networks makes test results
unrepeatable. Therefore our recommendation of carrying out tests using
simulators.
Section 3.1.1 Here the fixed user is on a wired LAN connected to mobile
user.
You mention wireless interface which makes me wonder is the fixed user
actually
a WIFI user connected to broadband WIFI router wired to the internet. See in
quotes which makes me wonder "The fixed user is connected to the Internet
via
wired connection with sufficiently high bandwidth, for instance, 10 Gbps, so
that the system is resource limited on the {wireless?} interface"
[authors] Thanks for raising this point of confusion. The proposed test case
comprise of both cellular users and fixed users. They share the wired backhaul
link with sufficiently high bandwidth. As such, the bottleneck of the system
is over the cellular radio access link. We have revised the sentence as below
to avoid further confusion:
“… so that the system bottleneck is on the cellular radio access interface … “
Section 4.1 Please explain in why the home access link represents a
bottleneck
due to its bandwidth. It is not obvious as these days Gigabit and above
broadband speeds are available at home.
[authors] We agree that the scenario where the wired hop remains the bottleneck
is becoming less common. This subsection describes test cases to reflect
DSL-like home Internet access that's less common but still present especially
in other parts of the world. As acknowledged in this section, these test
cases are proposed mainly as a sanity check. Over time, we can perhaps get rid
of this section completely.
Nits/editorial comments:
Draft Date should to be updated.
[authors] Done
Section 3.1.2 1-B Antenna- [2D, 3D] should be defined
[authors] The cited reference of the 3GPP test plan contains information for
the above terminology. For this round of revision we have not gathered input
from authors familiar with the cellular technology terminologies. We will try
to update the definition directly in the text in a later revision.
Section 3.1.2 RTT [40, 150] , should define a unit millisecond
[authors] Done.
Section 3.1.2 4. User Intensity, should define what the values in brackets
mean
and unit of measure.
[authors] The cited reference of the 3GPP test plan contains information for
the above terminology. For this round of revision we have not gathered input
from authors familiar with the cellular technology terminologies. We will try
to update the definition directly in the text in a later revision.
Section 3.1.2 7.2.a Media direction: Uplink and Downlink, should define what
is meant by Uplink and Downlink
[authors] The definition has been provided in the second paragraph of Section
3.1.1 as well as in the illustration in Fig. 1.
Section 4.2.3 g N= [4, 8, 12, 16, 20], should define what N is and any unit of
measure
[authors] The variables N and M indicate the number of real-time media flows
and competing TCP streams, respectively, as illustrated in Fig. 2. We added a
sentence in Sec. 4.1.1 to explicitly explain this
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