Communication Technology

Communication Technology

m Sequence (MLS : Maximum Length Sequence)

m-Sequence is a kind of (special kind of) LFSR sequence. So in order for you to understand m-sequence, first you need to understand the concept of LFSR sequence.

What is so special about m-sequence comparing to typical LFSR ? If you generate a sequence with LFSR, the output eventually repeats itself. But in most of the application, the purpose is to generate the longest possible non-repeating sequence with a given number of shift registers (Taps). m-Squence is a special type of LFSR which gives the longest non-repeating sequence for each give number of taps. The well-known m-sequence for various taps is shown in the following table.

No of Taps	Generator Polynomial
2	[2 1 0]
3	[3 2 0]
4	[4 3 0]
5	[5 3 0]
6	[6 5 0]
7	[7 6 0]
8	[8 6 5 4 0]
9	[9 5 0]
10	[10 7 0]
11	[11 9 0]
12	[12 11 8 6 0]
13	[13 12 10 9 0]
14	[14 13 8 4 0]
15	[15 14 0]
16	[16 15 13 4 0]
17	[17 14 0]
18	[18 11 0]
19	[19 18 17 14 0]
20	[20 17 0]
21	[21 19 0]
22	[22 21 0]
23	[23 18 0]
24	[24 23 22 17 0]
25	[25 22 0]
26	[26 25 24 20 0]
27	[27 26 25 22 0]
28	[28 25 0]
29	[29 27 0]
30	[30 29 28 7 0]
31	[31 28 0]
32	[32 31 30 10 0]
33	[33 20 0]
34	[34 15 14 1 0]
35	[35 2 0]
36	[36 11 0]
37	[37 12 10 2 0]
38	[38 6 5 1 0]
39	[39 8 0]
40	[40 5 4 3 0]
41	[41 3 0]
42	[42 23 22 1 0]
43	[43 6 4 3 0]
44	[44 6 5 2 0]
45	[45 4 3 1 0]
46	[46 21 10 1 0]
47	[47 14 0]
48	[48 28 27 1 0]
49	[49 9 0]
50	[50 4 3 2 0]
51	[51 6 3 1 0]
52	[52 3 0]
53	[53 6 2 1 0]