A journal version of this paper exists and is recommended:



Journal Version:
"Capacity and Delay Tradeoffs for Ad-Hoc Mobile Networks," IEEE Transactions on Information Theory, June 2005.



Conference Versions:
1. Original CISS 2003 version demonstrating exact capacity and delay analysis, with achievable tradeoff via redundant packet transfers:
M. J. Neely and E. Modiano, "Improving Delay in Ad-Hoc Mobile Networks Via Redundant Packet Transfers," Proceedings of the Conference on Information Sciences and Systems, Johns Hopkins University March 2003. SLIDES
2. Invited paper extending CISS 2003 and proving optimality of the tradeoff delay/rate >= O(N):
M. J. Neely and E. Modiano, "Capacity and Delay Tradeoffs for Ad-Hoc Mobile Networks," (Invited Paper) IEEE BroadNets 2004, San Jose, CA, Oct. 2004. [PowerPoint Slides]



This work can also be found in Chapter 6 of my Ph.D. thesis [M. J. Neely, Dynamic Power Allocation and Routing for Satellite and Wireless Networks with Time Varying Channels, Ph. D. Dissertation, Massachusetts Institute of Technology, LIDS, November 2003.]

Abbreviated History: The theory of Capacity/Delay tradeoffs is becoming somewhat of a hot-topic, and several interesting results of this type are emerging. Here is a shortened history of my own "Capacity and Delay Tradeoffs" paper: My original CISS 2003 paper (March 2003) proved the capacity results and demonstrated achievability of the tradeoff Delay/Rate = O(N) (for the simplified iid mobility model). Shortly after, I submitted the full version of the paper (which contained the proof of _necessity_ of this tradeoff) to IEEE Infocom 2004, listing the CISS 2003 reference in my bibliography. This work was also Chapter 6 of my thesis (MIT 2003). In my own (admittedly biased) opinion, it was a truly beautiful result that I had full certainty would be accepted at Infocom. =) So, in the summer of 2003 I advertised the result widely and posted the Infocom submission on my webpage even before hearing back about whether or not it was accepted.

Surprisingly, the Infocom paper was rejected, due mainly b/c of perceived simiarity between it and the CISS 2003 paper (one reviewer also, incorrectly, said the result was wrong). Baffled, I just decided to submit it as a journal to IEEE Transactions on Information Theory (October 2003). Having not formally presented the necessity part at any conference, I also submitted to the ISIT 2004 conference. But that was again surprisingly rejected for unclear reasons. Eventually, the IEEE Information Theory paper got accepted (getting all good reviews that recommended only minimal changes). Eytan and I also got invited to present at Broadnets 2004, so I eventually presented the necessity results at that conference.

The current journal version of the paper is basically the same as the original infocom submission. However, the journal version contains more details on stochastic coupling. Also, while the journal version was being reviewed, some other conference results by El Gammal-Mammen-Prabhakar-Shah, Toumpis-Goldsmith, Lin-Shroff came out. Thus, a year later when I was revising my accepted journal paper, I took the opportunity to write a new section (Section VI.A), which briefly comments on these new related works and their context to my own formulation. I think this section is interesting, and I encourage those interested in this field to read that section as well as all of these related works.


NOTE: The original printed and bound journal version of this paper contained a reference error that shifted all references after [13] by one (due to a compiling mistake just before printing). The majority of these references were located in the 4th paragraph of the left hand side of page 1918. The PDF file given here on my webpage is the electronic version of the paper, and does not have this reference error.


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