Re: [802.19] WhiteSpace Coexistence Use Cases
Richard, Mark, Alex,
I propose the following wording for the third paragraph of Section 1. Introduction:
The purpose of this document is to identify and examine potential limitations on operation and use of the White Space spectrum when more than one radio technology is attempting to use a band. A goal is to lay the foundation for further investigations into the feasibility and effort required to operate devices more efficiently in such coexistence situations in the White Space. Such future work enabled by this document may include investigation of modifications of base standards to achieve efficient White Space use, or development of mechanisms that can be used by industry in White Space spectrum to improve efficiency.
As reference, the current wording in Document 26r1 IS:
The purpose of this document is to lay the foundation for developing mechanisms that can be used by industry in White Space spectrum to prevent the type of problems suffered by the Citizen Band (CB). In the CB bands, interference became such an issue that wide spread use ceased and low cost widely available equipment became uneconomic.
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DISCUSSION
Firstly, the proposed wording change addresses correctly (I believe) what the purpose and goals of this document are as decided by the Study Group decisions/polls. I believe this proposed wording is not contentious, but time will determine that.
Secondly, I would like more discussion before the group sets in stone the reference to "the type of problems suffered by the Citizen Band (CB)." I believe the CB reference is a very effective statement for use informally within our Study Group, as we try to explain concepts and get at the heart of problems as we grapple with them, but upon reflection I am questioning this wording and analogy in an official document from our Study Group. The CB reference misses the mark for our study, in my opinion, on several key points:
1) CBs are entirely one technology attempting to share bands, and the CB technology is not separate technologies attempting to coexist, which is what we are dealing with in TV Whitespace.
2) The "type of problem encountered" by CBs in the '70s, which is what I believe is being referenced in the existing text, has a name in networking --- "congestion collapse." This happened with CBs, owing to CBs' own brief, boom for a period of a few years. This exact problem has occurred with many different technologies in their early generations. However, CB technology has not addressed pushing a higher point of efficiency for onset of "congestion collapse", whereas other technologies have. CB technology "has chosen" --- in a sense --- to remain what it was. CBs are still in use today, serving their core users; the technology is what it is. The core CB users are probably very glad that the bulk of the fad users have moved on to other technologies, and that their CB technology has remained simple. The economy of the technology may not be suitable to the fad users, but it very well may be suitable to the core users. If not, something will change. That is the market.
3) This exact same issue of "congestion collapse" which occured with CB also occurred with Ethernet, and Aloha, and perhaps other technologies --- the simplicity of the technology led to a limitation --- a threshold of "congestion collapse" which was lower than could be provided by more advanced (and more complicated) sharing techniques. However, in these technologies, unlike with CB, more advanced sharing techniques were developed. For example, Ethernet and ultimately 802.11 and many other technologies, eventually developed techniques that pushed up to higher efficiency (throughput as a fraction of dedicated channel capacity) the onset of "congestion collapse" in their networks. These are better examples to use in our report, since these are examples where techniques were developed and adopted to push up the onset of "congestion collapse," enabling higher efficiency on their networks.
4) CBs are still in use today. Although the advancement in other technologies over the last 30 years has almost certainly had an impact on the CB business, it is not correct (I believe) to characterize the CB business as a failure, which is a "take away" I get from the existing wording. It serves its core users and it is what it is. It may eventually be "mothballed", as is probably the fate of all technology. Bottom line, citing a technology which had its heyday over 30 years ago, but is still serving a purpose today, does not deliver our message most effectively (my opinion). I think we can make the same point but with more fitting examples or references.
I hope this isn't overkill for making the case for my simple suggestion.
Later, tjk
-----Original Message-----
From: Gerald Chouinard [mailto:gerald.chouinard@xxxxxx]
Sent: Tuesday, June 09, 2009 5:59 AM
To: STDS-802-19@xxxxxxxxxxxxxxxxx
Subject: [802.19] WhiteSpace Coexistence Use Cases
Richard, Mark, Alex,
Thank's for the effort in putting this white paper together. See my
comments in 'track change' in the attached copy. I guess this could be
discussed on the teleconference calls if time permits.
Gerald