Kh. Hofmann, ON UNIFORM DISTANCE PROPERTY OF MULTILEVEL BLOCK 8-PSK MODULATION, European transactions on telecommunications and related technologies, 5(5), 1994, pp. 615-617
For upper bounding the word error probability of block codes by applic
ation of the union bound, in general the uniform distance property (di
stance invariance) of the code must be guaranteed. This property says
that the distance spectrum of a code is independent of the choice of t
he reference codeword. In the sequel new sufficient conditions for mul
tilevel block 8-PSK modulation codes to be distance invariant are deri
ved.