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basin extension replaced

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kdee committed 2026-10-11 16:39:46 -07:00
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commit 1e335d33be
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+78 -123
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@miSim/lesserSinkNeighbor.m
+70 -115
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@@ -1,11 +1,11 @@
function obj = lesserSinkNeighbor(obj)
% LESSERSINKNEIGHBOR Capacity-Aware Lesser Sink Neighbor algorithm (CALSN).
%
% Implements the algorithm specified in new/new_routing_algorithm.pdf as the
% selectable alternative to lesserNeighbor. UAVs 1 and N are base stations;
% every other UAV generates r = 1 unit of data per step, and all data must
% reach a base station. The algorithm outputs both a sparse maintained
% topology and a routing table.
% Implements the algorithm given in the CALSN algorithm description document
% (ADD; kept outside the repository) as the selectable alternative to
% lesserNeighbor. UAVs 1 and N are base stations; every other UAV generates
% r = 1 unit of data per step, and all data must reach a base station. The
% algorithm outputs both a sparse maintained topology and a routing table.
%
% 1. Base-station potentials phi via distributed Bellman-Ford over the
% current communication neighborhoods (obj.adjacency), with link cost
@@ -14,29 +14,31 @@ function obj = lesserSinkNeighbor(obj)
% 2. Lesser sink neighbors L_i replace LNA's "j < i" rule:
% L_i = { j in N_i : phi_j < phi_i, or phi_j == phi_i and j < i }.
% The equal-potential lexicographic tie-break is a documented deviation
% from the spec's strict inequality: at an exact potential watershed
% (e.g. a symmetric chain) the strict rule would split A_control into
% one tree per base station; the tie-break keeps the airborne graph
% connected, which the mission requires.
% from the ADD's strict inequality. It makes (phi, index) a total order,
% so every feasible link between two non-base UAVs has exactly one
% deciding endpoint (the uphill one).
% 3. LNA-style sparsity: one parent per connected component of the
% L_i-induced subgraph (only links with positive capacity in at least
% one direction count as edges), chosen by
% p = argmin_{j in C} ( phi_j + 1/(C_ij + eps) ).
% A_control(i,p) = A_control(p,i) = 1 (diagonal = I).
% BASIN EXTENSION (documented deviation): with two potential minima
% (the two bases), one-parent-per-component alone yields a spanning
% forest with up to two disjoint base-rooted trees whenever a UAV's
% lesser sink neighbors collapse into a single component (dense usable
% graphs). To restore LNA's global-connectivity property, each UAV
% selects one representative per component AND per base-station BASIN
% (the base a neighbor's potential descent terminates at). Interior
% UAVs are unaffected (their whole neighborhood shares one basin);
% watershed UAVs whose neighborhoods span both basins gain a second
% parent, which is exactly the bridge between the two trees. A final
% stitch guard covers degenerate geometries: if A_control still has
% multiple components, the lowest-cost feasible inter-component link
% is added (maintained for connectivity only; carries no flow).
% 4. Routing, children first (decreasing phi; equal phi processed in
% 4. Connectivity bridge (documented deviation; not in the ADD). Every UAV
% must stay connected to the whole fleet to exchange positions for
% guidance, so A_control must be one connected graph. LNA's grouping
% argument guarantees that whenever every feasible link has a deciding
% endpoint. The one exception is the base-to-base link: both bases have
% phi = 0 and select no parents, so nobody maintains it, yet it still
% merges groups when other UAVs form their components. Steps 1-3
% therefore leave A_control either connected or split into exactly two
% pieces, one containing each base. In the split case one bridge is
% added: of all feasible links between the two pieces (base-to-base
% included), the one whose weaker direction has the highest SINR, i.e.
% the most margin under the comms barrier. A warning is issued if even
% that link is inside the CBF maintenance band (sinrThreshold + 3 dB).
% The bridge is maintained for connectivity only and carries no flow,
% so when present it is the one maintained link outside the ADD's
% invariant A_control(i,j) = 1, i ~= j, iff F(i,j) > 0 or F(j,i) > 0.
% 5. Routing, children first (decreasing phi; equal phi processed in
% decreasing index order so tie-break children precede their parents):
% aggregate demand D_i = r + inflows, split capacity-proportionally
% over parents; saturated links are capped at capacity and the residual
@@ -72,13 +74,16 @@ function obj = lesserSinkNeighbor(obj)
positions(kk, :) = obj.agents{kk}.pos;
end
% Directed Shannon link capacities over the current communication
% neighborhoods: C(i, j) = capacity of sending from i to j (receiver j)
% Directed SINRs and Shannon link capacities over the current
% communication neighborhoods: S(i, j) and C(i, j) describe sending
% from i to j (receiver j)
S = zeros(nAgents);
C = zeros(nAgents);
for ii = 1:nAgents
for jj = 1:nAgents
if jj ~= ii && obj.adjacency(ii, jj)
C(ii, jj) = obj.bandwidth * log2(1 + obj.sinrLink(positions, jj, ii));
S(ii, jj) = obj.sinrLink(positions, jj, ii);
C(ii, jj) = obj.bandwidth * log2(1 + S(ii, jj));
end
end
end
@@ -109,42 +114,7 @@ function obj = lesserSinkNeighbor(obj)
end
end
% ---- Base-station basins (for the basin extension) -------------------
% Each finite-potential UAV descends its argmin neighbor chain; phi is
% strictly decreasing along it, so the chain terminates at a base. The
% basin label records which base that is.
descent = zeros(nAgents, 1);
for ii = 1:nAgents
if isBase(ii) || isinf(phi(ii))
continue;
end
bestMetric = inf;
for jj = 1:nAgents
if jj == ii || ~obj.adjacency(ii, jj)
continue;
end
metric = phi(jj) + 1 / (C(ii, jj) + EPS_CAP);
if metric < bestMetric
bestMetric = metric;
descent(ii) = jj;
end
end
end
basin = zeros(nAgents, 1);
basin(1) = 1;
basin(nAgents) = nAgents;
for ii = 1:nAgents
if isBase(ii) || isinf(phi(ii))
continue;
end
kk = ii;
while ~isBase(kk)
kk = descent(kk);
end
basin(ii) = kk;
end
% ---- Parent selection (one per lesser-sink component and basin) ------
% ---- Parent selection (one per lesser-sink component) ---------------
Acontrol = logical(eye(nAgents));
isParent = false(nAgents); % isParent(i, p): p is a selected parent of i
for ii = 1:nAgents
@@ -187,8 +157,7 @@ function obj = lesserSinkNeighbor(obj)
end
end
% One parent per connected component and per base-station basin
% present in it (basin extension), selected by capacity and
% One parent per connected component, selected by capacity and
% potential: p = argmin( phi_j + 1/(C_ij + eps) )
visited = false(1, lsnCount);
for aa = 1:lsnCount
@@ -198,72 +167,58 @@ function obj = lesserSinkNeighbor(obj)
component = bfs(subgraphAdjacency, aa);
visited(component) = true;
for bb = [1, nAgents] % the two possible basin labels
bestMetric = inf;
bestParent = 0;
for cc = 1:numel(component)
jj = lsn(component(cc));
if basin(jj) ~= bb
continue;
end
metric = phi(jj) + 1 / (C(ii, jj) + EPS_CAP);
if metric < bestMetric
bestMetric = metric;
bestParent = jj;
end
end
if bestParent > 0
isParent(ii, bestParent) = true;
Acontrol(ii, bestParent) = true;
Acontrol(bestParent, ii) = true;
bestMetric = inf;
bestParent = 0;
for cc = 1:numel(component)
jj = lsn(component(cc));
metric = phi(jj) + 1 / (C(ii, jj) + EPS_CAP);
if metric < bestMetric
bestMetric = metric;
bestParent = jj;
end
end
isParent(ii, bestParent) = true;
Acontrol(ii, bestParent) = true;
Acontrol(bestParent, ii) = true;
end
end
% ---- Connectivity stitch guard ---------------------------------------
% The basin extension bridges the two base-rooted trees through
% watershed UAVs whenever each base borders a routing basin. Degenerate
% geometries (e.g. a base whose only feasible neighbor is the other
% base) can still leave A_control split; add the lowest-cost feasible
% link between components until one remains. Stitched links are
% maintained for connectivity only and carry no routed flow. If the
% feasibility graph itself is disconnected no stitch exists; validate()
% ---- Connectivity bridge ---------------------------------------------
% The unmaintained base-to-base link is the only way steps 1-3 can
% leave A_control split, and then into exactly two pieces, one per
% base. Bridge them with the feasible cross link whose weaker direction
% has the highest SINR. If the pieces are not joined by any feasible
% link, the feasibility graph itself is disconnected; validate()
% reports that case.
while true
comp = zeros(1, nAgents);
nComp = 0;
for ii = 1:nAgents
if comp(ii) == 0
nComp = nComp + 1;
comp(bfs(Acontrol, ii)) = nComp;
end
end
if nComp <= 1
break;
end
bestMetric = inf;
pieceOfBase1 = false(1, nAgents);
pieceOfBase1(bfs(Acontrol, 1)) = true;
if ~pieceOfBase1(nAgents)
bestSinr = -inf;
bestU = 0;
bestV = 0;
for uu = 1:nAgents
for vv = (uu + 1):nAgents
if comp(uu) ~= comp(vv) && obj.adjacency(uu, vv)
% Bidirectional link cost (finite even for infinite
% potentials, so isolated islands remain stitchable)
metric = 1 / (C(uu, vv) + EPS_CAP) + 1 / (C(vv, uu) + EPS_CAP);
if metric < bestMetric
bestMetric = metric;
for uu = find(pieceOfBase1)
for vv = find(~pieceOfBase1)
if obj.adjacency(uu, vv)
sinrBinding = min(S(uu, vv), S(vv, uu));
if sinrBinding > bestSinr
bestSinr = sinrBinding;
bestU = uu;
bestV = vv;
end
end
end
end
if bestU == 0
break; % feasibility graph disconnected: nothing to stitch with
if bestU > 0
Acontrol(bestU, bestV) = true;
Acontrol(bestV, bestU) = true;
% CBF maintenance band: constrainMotion holds maintained links
% at sinrThreshold + 3 dB (paddingDb; keep in sync)
if bestSinr < 10^((obj.sinrThreshold + 3.0) / 10)
warning("miSim:bridgeInCbfBand", ...
"Connectivity bridge %d-%d has SINR %.1f dB, inside the CBF maintenance band (sinrThreshold %.1f dB + 3 dB)", ...
bestU, bestV, 10 * log10(bestSinr), obj.sinrThreshold);
end
end
Acontrol(bestU, bestV) = true;
Acontrol(bestV, bestU) = true;
end
% ---- Routing (children first: decreasing potential order) -----------
@miSim/miSim.m
+4 -4
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@@ -32,10 +32,10 @@ classdef miSim
bandwidth = 20e6; % channel bandwidth (Hz) for thermal noise N = k_B*T*B
% Topology-selection algorithm (requires useSinrComms; MATLAB sim only).
% false -> lesser-neighbor; true -> Capacity-Aware Lesser Sink Neighbor
% (CALSN, see new/new_routing_algorithm.pdf): base-station potentials
% replace the index-based "lesser" rule, and the maintained topology
% comes with a routing table (flows F, fractions R) that sends every
% UAV's data toward base stations 1 and N.
% (CALSN, see the algorithm description document, ADD): base-station
% potentials replace the index-based "lesser" rule, and the maintained
% topology comes with a routing table (flows F, fractions R) that sends
% every UAV's data toward base stations 1 and N.
useRoutingTopology = false;
routingAdjacencyMatrix = false(0, 0); % directed flow links (i, j) = child i sends to parent j (F > 0)
routingFlows = zeros(0, 0); % F: flow on each directed link (units of r = 1 per UAV per step)
@miSim/sinrLink.m
+1 -1
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@@ -60,7 +60,7 @@ function [sinr, grad] = sinrLink(obj, positions, rxIdx, txIdx)
S = P_t / (K * d_t^n);
% Interference I = sum of received powers from every other agent at r
I = 0.0;
I = 0;
for k = 1:nAgents
if k == r || k == t
continue;
@miSim/validate.m
+1 -1
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@@ -20,7 +20,7 @@ function validate(obj)
end
% In routing (CALSN) mode the MAINTAINED topology itself must form a
% single connected component (basin extension + stitch guard invariant)
% single connected component (guaranteed by the connectivity bridge)
if obj.useRoutingTopology && max(conncomp(graph(obj.constraintAdjacencyMatrix))) ~= 1
error("Maintained routing topology (A_control) is not connected");
end