Device and method for performing non-orthogonal multiplexing
View Patent ↗A device includes circuitry configured to spread one or more symbols with one or more orthogonal codes into spread signals having a predetermined number of bits. The amplitude of the spread signals is modified via one or more layer coefficients and the spread signals are multiplexed into a layered transmit signal.
1. A device comprising:
circuitry configured to
spread symbols with orthogonal codes into spread signals having a predetermined number of bits,
modify an amplitude of the spread signals via layer coefficients, and
multiplex the amplitude modified spread signals into a layered transmit signal; and
a communication interface configured to transmit the layered transmit signal, wherein the circuitry is configured to
determine the layer coefficients based on a coefficient difference factor that is less than one, and
determine a highest layer coefficient to be greater than a sum of a plurality of remaining lower layer coefficients.
2. The device of claim 1 , wherein the circuitry is further configured to allocate the layered transmit signal to a predetermined number of subcarriers.
3. The device of claim 2 , wherein the predetermined number of subcarriers corresponds to the predetermined number of bits of the spread signal.
4. The device of claim 1 , wherein the orthogonal codes are Walsh codes.
5. The device of claim 1 , wherein the circuitry is further configured to reduce a physical layer bit error rate by increasing the coefficient difference factor.
6. The device of claim 1 , wherein the circuitry is further configured to modify a total transmit power by modifying at least one of a sum of the layer coefficients or the predetermined number of bits of the spread signal.
7. The device of claim 1 , wherein the circuitry is further configured to reduce a total transmit power for the layered transmit signal by adding an offset to at least one of the layer coefficients.
8. The device of claim 7 , wherein the circuitry is further configured to add the offset to alternating layers of the layered transmit signal.
9. The device of claim 8 , wherein the offset is equal to 45 degrees.
10. The device of claim 1 , wherein the layered transmit signal includes non-orthogonal signal layers.
11. The device of claim 10 , wherein the circuitry is further configured to reduce interference between the non-orthogonal signal layers by modifying the amplitude of the spread signals with the layer coefficients.
12. The device of claim 1 , wherein the circuitry is further configured to implement quadrature amplitude modulation for a first layer and phase-shift keying modulation for second and higher layers of the layered transmit signal.
13. The device of claim 1 , wherein the circuitry is further configured to allocate signals from one terminal device to four subcarriers of a twelve-subcarrier resource block.
14. The device of claim 1 , wherein the circuitry is further configured to recover a highest received signal layers by reverse spreading a received signal with the orthogonal codes.
15. A device comprising:
circuitry configured to
spread symbols with orthogonal codes into spread signals having a predetermined number of bits,
modify an amplitude of the spread signals via layer coefficients, and
multiplex the amplitude modified spread signals into a layered transmit signal; and
a communication interface configured to transmit the layered transmit signal, wherein the circuitry is configured to
recover a highest received signal layer by reverse spreading a received signal with the orthogonal codes, and
re-spread the highest received signal layer with the orthogonal codes and multiply a corresponding spread signal by an associated layer coefficient.
16. The device of claim 15 , wherein the circuitry is further configured to subtract a re-spread signal from the received signal to recover one or more lower received signal layers.
17. A method comprising:
spreading symbols with orthogonal codes into spread signals having a predetermined number of bits;
modifying an amplitude of the spread signals via layer coefficients; and
multiplexing the amplitude modified spread signals into a layered transmit signal;
transmitting the layered transmit signal,
wherein the layer coefficients are determined based on a coefficient difference factor that is less than one, and a highest layer coefficient to be greater than a sum of a plurality of remaining lower layer coefficients.