Tracing many users with almost no rate penalty
For integers n, r >= 2 and 1   0 such that min ((c1)/(r), (c3)/(k2)) <= log (h(n,r,k))/(n) <= min (c2)/(r), (c4logk)/(k2) In particular, for all k <= root r, log (h(n,r,k))/(n). This improves an estimate of Laczay and Ruszinko.
multiple-user tracing codes probabilistic construction of codes superimposed codes