【正确答案】可构成的循环码有以下几种:
(15,14)码:g(x)=x+1
(15,13)码:g(x)=x2+x+1
(15,12)码:g(x)=(x+1)(x2+x+1)=x3+1
(15,11)码:g(x)=x4+x+1
或g(x)=x4+x3+1
或g(x)=x15+x4+x3+x2+x4+1
(15,10)码:g(x)=(x+1)(x4+x+1)
=x5+x4+x2+1
或g(x)=(x+1)(x4+x3+1)
=x5+x3+1
或g(x)=(x+1)(x4+x3+x2+x+1)
=x5+1
(15,9)码: g(x)=(x2+x+1)(x4+x+1)
=x6+x5+x4+x3+1
或 g(x)=(x2+x+1)(x4+x3+1)
=x6+x3+x2+1
或 g(x)=(x2+x+1)(x4+x3+x2+x+1)
=x6+x4+x3+x2+1
(15,8)码: g(x)=(x+1)(x2+x+1)(x4+x+1)
=x7+x3+x+1
或 g(x)=(x+1)(x2+x+1)(x4+x3+1)
=x7+x6+x4+x2+x+1
或 g(x)=(x+1)(x2+x+1)(x4+x3+x2+x+1)
=x7+x6+x5+x2+x+1
(15,7)码: g(x)=(x4+x+1)(x4+x3+1)
=x8+x7+x5+x4+x3+1
或 g(x)=(x4+x+1)(x4+x3+x2+x+1)
=x8+x7+x6+x4+1
或 g(x)=(x4+x3+x2+x+1)(x4+x3+1)
=x8+x4+x2+x+1
(15,6)码: g(x)=(x+1)(x4+x+1)(x4+x3+1)
=x9+x7+x6+x3+x+1
或 g(x)=(x+1)(x4+x+1)(x4+x3+x2+x+1)
=x9+x6+x5+x4+x+1
或 g(x)=(x+1)(x4+x3+x2+x+1)(x4+x3+1)
=x9+x8+x5+x4+x3+1
(15,5)码: g(x)=(x2+x+1)(x4+x+1)(x4+x3+1)
=x10+x5+x3+x2+x+1
或 g(x)=(x2+x+1)(x4+x3+x2+x+1)(x4+x+1)
=x10+x8+x5+x4+x2+x+1
或 g(x)=(x2+x+1)(x4+x3+x2+x+1)(x4+x3+1)
=x10+x9+x8+x6+x2+1
(15,4)码: g(x)=(x+1)(x2+x+1)(x4+x+1)(x4+x3+1)
=x11+x10+x6+x5+x4+1
或 g(x)=(x+1)(x2+x+1)(x4+x+1)(x4+x3+x2+x+1)
=x11+x10+x9+x8+x6+x4+x3+1
或 g(x)=(x+1)(x2+x+1)(x4+x3+1)(x4+x3+x2+x+1)
=x11+x8+x7+x6+x3+x2+x+1
(15,3)码: g(x)=(x4+x3+1)(x4+x+1)(x4+x3+x2+x+1)
=x12+x9+x6+x3+1
(15,2)码: g(x)=(x+1)(x4+x3+1)(x4+x+1)(x4+x3+x2+x+1)
=x13+x12+x10+x9+x7+x6+x4+x3+x+1
(15,1)码: g(x)=(x2+x+1)(x4+x3+1)
(x4+x+1)(x4+x3+x2+x+1)
=x14+x13+x12+x11+x10+x9+x8+x7+x6+x5+x4+x3+x2+x+1
【答案解析】[知识点窍] 考查生成多项式的3个性质。
[逻辑推理] 根据g(x)的3个性质对x15+1的因子进行组合,从而得出所有生成多项式。