Method and apparatus for encoding and decoding
View Patent ↗A method of encoding a bit sequence over a Physical Downlink Control Channel (PDCCH) having Downlink Control Information (DCI) including: determining DCI bits to provide a DCI bit sequence; performing a CRC calculation on the DCI bit sequence to provide a CRC parity bit sequence; scrambling the CRC parity bit sequence to provide a scrambled CRC bit sequence; if the DCI format is LTE-A, further scrambling the DCI together with the attached scrambled CRC bit sequence to provide a LTE-A scrambled bit sequence; channel coding either the DCI attached scrambled CRC bit sequence or LTE-A scrambled bit sequence to provide a channel coded bit sequence; modulating the channel coded bit sequence to provide a modulated symbol sequence; layer mapping the modulated symbol sequence to one or more antennas associated with a transmitter to provide one or more layers having a symbol sequence; and precoding the layered symbol sequences.
1. A method of encoding a bit sequence over a Physical Downlink Control Channel (PDCCH) having Downlink Control Information (DCI) including:
(a) determining DCI bits to provide a DCI bit sequence;
(b) performing a CRC calculation on the DCI bit sequence to provide a CRC parity bit sequence;
(c) scrambling the CRC parity bit sequence to provide a scrambled CRC bit sequence;
(d) if the DCI format is LTE-A, further scrambling the DCI together with the attached scrambled CRC bit sequence to provide a LTE-A scrambled bit sequence;
(e) channel coding either the DCI attached scrambled CRC bit sequence or LTE-A scrambled bit sequence to provide a channel coded bit sequence;
(f) modulating the channel coded bit sequence to provide a modulated symbol sequence;
(g) layer mapping the modulated symbol sequence to one or more antennas associated with a transmitter to provide one or more layers having a symbol sequence; and
(h) precoding the layered symbol sequences.
2. The method of claim 1 , wherein the DCI bit sequence is represented by α l , of length D here the index i ranges from 0 to D−1.
3. The method of claim 1 , wherein the CRC parity bit sequence is represented by p 1 , which has a length of L bits and whose index l ranges from 0 to L−1.
4. The method of claim 3 , wherein scrambling the CRC parity bit sequence includes:
(a) performing a bitwise modulo-2 summation on the CRC parity bit sequence with a first predetermined sequence; and
(b) concatenating the CRC parity bit sequence with the DCI bit sequence to provide the scrambled CRC bit sequence.
5. The method of claim 4 , wherein the modulo two summation is a bitwise XOR operation on the CRC parity bit sequence given by the expression:
b l =( p l +x l )mod2 l= 0,1,..., L−1 where x is the first predetermined sequence.
6. The method of claim 5 , wherein the first predetermined sequence is the Radio Network Temporary Identifier (RNTI) sequence of 16 bits.
7. The method of claim 5 , wherein the first predetermined sequence is any sequence having the same bit length as the CRC parity bit sequence.
8. The method of claim 4 , wherein at step (b) the scrambled CRC bit sequence is denoted c k which is given by:
c
k
=
{
a
k
for
k
=
0
,
1
,
2
,
…
,
D
-
1
b
k
for
k
=
D
,
D
+
1
,
…
,
D
+
L
and where the length of c is denoted by K=D+L.
9. The method of claim 1 , wherein at step (d), the further scrambling is performed by scrambling the scrambled CRC bit sequence with a second predetermined sequence to provide the LTE-A scrambled bit sequence.
10. The method of claim 9 , wherein the second predetermined sequence is equal to the total number of bits K .
11. The method of claim 10 , wherein the second predetermined sequence is a repeated version of the RNTI or cell ID bit sequence.
12. The method of claim 11 , wherein the sequence of RNTI bits is manipulated so as not to undo the scrambling of the CRC parity bit sequence.
13. The method of claim 12 , wherein the manipulation includes reversing or permuting the sequence.
14. The method of claim 1 , wherein at step (h), the precoding complies with the LTE-A specification when available.
15. An encoder for encoding a bit sequence over a Physical Downlink Control Channel (PDCCH) having Downlink Control Information (DCI) including:
a DCI bit module for providing a DCI bit sequence;
a CRC calculation module for computing a CRC calculation on the DCI bit sequence to provide a CRC parity bit sequence;
a CRC scramble module for scrambling the CRC parity bit sequence to provide a scrambled CRC sequence;
an LTE-A bit scrambler module for further scrambling the scrambled CRC bit sequence to provide a LTE-A scrambled bit sequence if the DCI bit module determined the DCI format to be LTE-A;
a channel coding module for further channel encoding the scrambled CRC bit sequence or LTE-A scrambled bit sequence to provide a channel coded bit sequence;
a modulation module for modulating the channel coded symbol sequence to provide a modulated symbol sequence;
a layer mapping module for modulating the symbol sequence to one or more antennas associated with a transmitter to provide one or more layers having a symbol sequence; and
a precoding module for precoding the layered symbol sequences.
16. A decoder for decoding an encoded bit sequence including:
a demodulation and demapping module for demodulating and demapping the received symbol sequence to provide a demodulated bit sequence;
a channel decoding module for channel decoding the demapped bit sequence to provide a channel decoded bit sequence;
a LTE-A descrambler module to descrambling the channel decoded bit sequence and provide a LTE-A descrambled bit sequence if the bit sequence is an LTE-A sequence;
a CRC descrambler module for CRC descrambling either the LTE-A descrambled bit sequence or channel decoded bit sequence to provide a DCI bit sequence such that the DCI format is detected.