I understand that you are trying to perform Binary Polynomial Division (Modulo Division of Polynomials). To get the expected result, gfdeconv command should be used instead of deconv with some modifications in writing polynomials as shown
g = x^3 + x + 1 = 1 + x + x^3 = [1 1 0 1]
The following code snippet helps you for better understanding of using the command
g = [1 1 0 1] % g = 1 + x + x^3
gfpretty(g)
x1 = [0 0 0 1] % x1 = x^3
gfpretty(x1)
u1 = [0 0 0 1] % u1 = x^3
gfpretty(u1)
[q,r] = gfdeconv(conv(x1,u1) ,g) %q -> queotient, r -> remainder
gfpretty(q)
gfpretty(r)
Refer to the below documentation link for more information on gfdeconv and gfpretty
Hope the query is resolved.
