Task: Network map discovery

Envisioned applications:
<ul>
<li>
Network management tool; graphical representation of
connectivity
<LI>Location discovery
</ul>

Assumptions:
<ul>
<LI>Local neighbor discovery collects localized link
   states to neighbors
<li> Some nodes may have GPS receivers
<LI>There is some other mechanism that can be used to
   assess relative distance to neighbors 
   <ul><LI> hop count? signal strength? 
      Potential problems: 
      <ul><li> signal strength is flaky wrt obstructions, etc.
        <LI> ORL people had problems getting a good reading at
          low power levels
      </ul><LI>Idea: send message twice, second time at reduced power.
      Nodes at the edge of transmission range will not hear
      second message
   <LI> time of flight? ultrasound?</ul>
</ul>

First order solution:
<ul><LI> Flood link state information to all neighbors
<LI> Program to generate data for testing purposes, for modelling
   larger numbers of nodes, initially very simplistic, later
   more accurate radio models, etc?
</UL>

Potential refinements:
<uL><LI> Limit flooding distance
<LI> Filter link state to remove transients and unimportant
   variations in distance measurements
   <UL><LI> can we make the link state/distance info converge for 
     fixed node networks?
   <LI> what is the incremental impact of mobility?
 </ul><LI> partition nodes into neighborhoods around gps nodes
 <LI> neighbors negotiate to disambiguate position information.  
   for example, suppose two nodes deduce their radial distances
   from different gps nodes.  if they can approximate their
   relative distance from each other they can reduce their 
   locus of possible positions from a circle to two points.
   (in 3-d it reduces from a sphere to some kind of oval)
 <LI> three non-colinear nodes that determine their relative locations 
   from each other determine a triangle with fixed angles.
   however, relative to absolute coordinates, rotation, and
   translation are unknown, and there is a mirror image 
   ambiguity.  However progressive determination of adjacent 
   triangles can determine relative distance between any two nodes.
</ul>

Input from Niru??