On Thu, Apr 08, 2004 at 03:29:58PM -0400, R. A. Hettinga wrote:
At 11:28 AM -0700 4/8/04, Major Variola (ret) wrote:
Geodesic means shortest path, and you'll note if you play with tracert that the shortest path (as seen on Earth's surface) is rarely taken.
A pretty densely distributed radio mesh with good (geographic routing) algorithms would tend to use the shortest path. Very small cells based on current WiFi or ultrawideband/digital pulse radio might have to route around obstacles (large high buildings, flow along the nodes with aerials dangling into the streets). MobileMesh doesn't seen to be the single solution, at least one contender exists. Both are being used in practice, alas not yet in your $100 garden-variety WiFi routers (these do bridging already, though). Internet is mostly a tree (if you look at the connectivity maps). Wires over long distances will tend to follow geodesics (because cables are expensive, and an enterprise will try to minimize the costs). Current flow is mostly dictated by frozen chance, politics (peering arrangements). Automating peering arrangments and using agoric load levelling in the infrastructure will tend to erode that over time. Over time, physical lines will tend to be densest along densest traffic flow. American cities are orthogonal, European usually radial. The cities are connected with traffic ducts (rail, highway) which is typically loosely geodesic (but for obstacles in the landscape). Fiber typically follows railway or highway. Easiest is a cloud of satellites with mutual time of flight triangulation, and line of sight laser signalling.
Measure the path in time?
UWB gives you realtime location in each node down to cm scale. No idea how difficult to ToF triangulate with multipath. The higher device density, the less confusion. Intel's pushing UWB as wireless USB substitute. No reason why it couldn't cover 10 miles of open terrain with enough power and proper aerials. Anyone knows how UWB handles directional aeriales? Does it prefer fractal emitters, or are there specific optimal radiator geometries? -- Eugen* Leitl <a href="http://leitl.org">leitl</a> ______________________________________________________________ ICBM: 48.07078, 11.61144 http://www.leitl.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE http://moleculardevices.org http://nanomachines.net [demime 1.01d removed an attachment of type application/pgp-signature]