New Upper Bound for $(m, k, \lambda )$-IRSs With $\lambda \geq 2$

Impulse radio sequences were first introduced by Chu and Colbourn in 2004. A better upper bound for
(m
,
k
, 1)-IRS was given by Gao and Chang in 2006. In this paper, we present an upper bound for
(m
,
k
, lambda)-IRS with
lambda

ges

2
, which improves the known Johnson bound.