Spreading a response signal using a first set of orthogonal sequences and a reference signal using a second set of shorter orthogonal sequences
A radio communication apparatus includes spreading circuitry that spreads a response signal using a first set of orthogonal sequences to produce a spread response signal. Each orthogonal sequence in the first set has a first length. The spreading circuitry also spreads a reference signal using a second set of orthogonal sequences to produce a spread reference signal. Each orthogonal sequence in the second set has a second length that is shorter than the first length. A radio transmitter transmits the spread response signal and the spread reference signal.
1. A radio communication apparatus comprising:
first spreading circuitry configured to:
spread a response signal using a first sequence defined by an initial sequence and a first cyclic shift value among a plurality of cyclic shift values to generate an initially-spread response signal; and
provide the initially-spread response signal for subsequent processing by the first spreading circuitry,
wherein the first sequence forms a part of a first set of initial orthogonal sequences,
second spreading circuitry, located after the first spreading circuitry, configured to:
spread the initially-spread response signal using a second set of orthogonal sequences, to produce a spread response signal, each orthogonal sequence in the second set having a first length;
spread a reference signal using a third set of orthogonal sequences, to produce a spread reference signal, each orthogonal sequence in the third set having a second length that is shorter than the first length; and
a radio transmitter to transmit the spread response signal and the spread reference signal.
2. The radio communication apparatus in claim 1 , wherein the first length is four and the second length is three.
3. The radio communication apparatus in claim 1 , wherein the response signal is an acknowledgment/negative acknowledgment type of signal and the reference signal is a pilot signal.
4. The radio communication apparatus in claim 1 , wherein the first set of orthogonal sequences are Walsh sequences.
5. The radio communication apparatus in claim 1 , wherein the initial sequence is a Zadoff-Chu (ZC) sequence.
6. The radio communication apparatus in claim 1 , wherein the plurality of cyclic shift values is twelve.
7. A signal spreading method comprising:
spreading, using first spreading circuitry, a response signal using a first sequence defined by an initial sequence and a first cyclic shift value among a plurality of cyclic shift values to generate an initially-spread response signal; and
providing the initially-spread response signal for subsequent processing by the first spreading circuitry,
wherein the first sequence forms a part of a first set of initial orthogonal sequences,
spreading, using second spreading circuitry located after the first spreading circuitry, the initially-spread response signal using a second set of orthogonal sequences, to produce a spread response signal, each orthogonal sequence in the second set having a first length;
spreading, using the first spreading circuitry, a reference signal using a third set of orthogonal sequences, to produce a spread reference signal, each orthogonal sequence in the third set having a second length that is shorter than the first length;
transmitting, using a transmitter, the spread response signal and the spread reference signal.
8. The signal spreading method in claim 7 , wherein the number of sequences in the first set of orthogonal sequences is four and the number of sequences in the second set of orthogonal sequences is three.
9. The signal spreading method in claim 7 , wherein the response signal is an acknowledgment/negative acknowledgment type of signal and the reference signal is a pilot signal.
10. The signal spreading method in claim 7 , wherein the first set of orthogonal sequences are Walsh sequences.
11. The signal spreading method in claim 7 , wherein the initial sequence is a Zadoff-Chu (ZC) sequence.
12. The signal spreading method in claim 7 , wherein the plurality of cyclic shift values is twelve.