System and method for modulation scheme changes
View Patent ↗A system and method are disclosed that allow changes of a modulation and coding scheme (MCS) without overhead signaling. A priori, a network device and a user device know the manner in which the MCS will be changed. In one embodiment, the network device indicates the MCS to be used to decode a second portion of a message in a first portion of the message. In another embodiment, the user device blind detects the MCS used over a sub-set of MCSs.
1. A method for changing modulation and coding schemes (MCSs) comprising:
storing, by a user equipment, a set of N MCS values and an increment value k, where k is less than N;
receiving a first message encoded with a first MCS index i;
decoding the first message using the first MCS index i;
receiving a second message encoded with a second MCS index;
attempting to decode the second message using the first MCS index i;
choosing a first attempt MCS index, the first attempt MCS index being greater than or equal to i−k and less than or equal to i+k; and
attempting to decode the second message using the first attempt MCS index.
2. The method of claim 1 further comprising receiving the increment value k.
3. The method of claim 1 further comprising:
when decoding the second message fails using the first attempt MCS index, attempting to decode the second message using a second attempt MCS index.
4. The method of claim 3 further comprising:
when decoding the second message fails using the second attempt MCS index, attempting to decide the second message using another attempt MCS index from the set of N MCS values.
5. The method of claim 4 further comprising:
when decoding the second message fails N times, wherein N different attempt MCS indexes are used, sending a message indicating that a proper MCS could not be determined.
6. The method of claim 1 , wherein a maximum number of attempt MCS indexes is equal to N.
7. A user equipment comprising:
a memory configured to store a set of N modulation and coding scheme (MCS) values and an increment value k, where k is less than N;
a receiver configured to:
receive a first message encoded with a first MCS index i;
receive a second message encoded with a second MCS index j; and
a decoder configured to:
decode the first message using the first MCS index i;
attempt to decode the second message using the first MCS index i;
choose a first attempt MCS index from the set of N modulation and coding schemes, the first attempt MCS index being greater than or equal to i−k and less than or equal to i+k; and
decode the second message using the first attempt MCS index.
8. The user equipment of claim 7 wherein the receiver is further configured to receive the increment value k.
9. The user equipment of claim 7 wherein the decoder is further configured to:
when decoding the second message fails using the first attempt MCS index, attempt to decode the second message using a second attempt MCS index.
10. The user equipment of claim 9 , wherein the decoder is further configured to:
when decoding the second message fails using the second attempt MCS index, attempting to decode the second message using another attempt MCS index from the set of N MCS values.
11. The user equipment of claim 9 further comprising:
a transmitter configured to, when decoding the second message fails N times, using N different attempt MCS indexes, send a message indicating that a proper MCS could not be determined.
12. The user equipment of claim 7 , wherein a maximum number of attempt MCS indexes is equal to N.