Signal transmission method from a local network node
View Patent ↗A transmitter is provided having transmission methods that minimize the power needed to ensure reliable reception in a coverage area. In one aspect, data that requires re-transmission as acknowledged mode data is re-transmitted when the power level of the transmission link is higher than a pre-determined level set for reliable reception. The data rate of the re-transmitted data is set according to the difference in the actual power and the pre-determined level. In a second aspect, two transmitting antennae are used to transmit the same signals with a frequency off-set. The frequency off-set can be used to determine the phase of the signals being received at the receiver, so that a phase off-set can be introduced to optimise the effect of interference at the receiver.
1. A transmitter comprising:
a memory for storing a first data that is to be transmitted, and a second data that has been transmitted;
a processor for receiving requests to re-transmit the second data from the memory;
a monitor for receiving, from user equipment, power control commands indicating a change in power to maintain, at a predetermined level, a power of a transmission link between the transmitter and a receiver associated with the user equipment and for separately summing a number of power control commands indicating that an increase in power is necessary and a number of power control commands indicating that a reduction in power is necessary over a predetermined period of time;
a power control unit electrically connected to the monitor, and configured to:
control the power of the transmission link such that the power is temporarily higher than the pre-determined level; and
maintain the power of the transmission link at a previous level after receiving a power control command from the user equipment that requests a reduction in power; and
a data control unit configured to schedule the second data for re-transmission in periods when the power of the transmission link is higher than the pre-determined level based at least in part on a difference in sums.
2. A transmitter according to claim 1 , wherein the data control unit is configured to control a data rate of the second data when the second data is re-transmitted based on a difference between the power level of the transmission link and the pre-determined level.
3. A transmitter according to claim 1 , wherein the data control unit is configured to control a data rate based on an amount of data that requires re-transmission.
4. A transmitter according to claim 1 , wherein the data control unit is configured to receive signal quality measurements of the transmission link between the transmitter to the receiver, and to schedule the second data for re-transmission based on an estimation of a channel state.
5. A transmitter according to claim 1 , wherein the power control unit is configured to transmit only the first data in periods wherein the power level of the transmission link is equal to the pre-determined level.
6. A transmitter according to claim 1 , wherein the power control unit is configured to increase the power of the transmission link when a power control command is received that instructs the power control unit to increase the power of the transmission link, but to maintain the power of the link at the previous level when a power control command is received indicating that a reduction in power is necessary.
7. A transmitter according to claim 1 , wherein the data control unit is configured to determine a data rate for the second data depending on the magnitude of the sum.
8. A transmitter according to claim 1 , wherein the predetermined period of time is a multiple of a transmission time interval (TTI) for the transmission link.
9. A transmitter according to claim 8 , wherein the predetermined period is approximately 10 ms.
10. A transmitter according to claim 1 , further comprising a housing accommodating a Physical Layer, a Medium Access Control Layer, and a Radio Link Layer according to an Open Systems Interface transmission model.
11. A transmitter according to claim 10 , wherein the memory comprises a buffer provided in the Radio Link Layer; the power control unit is provided in the Physical Layer, and the data control unit is configured to receive an indication of a quantity of second data for re-transmission from the Radio Link Layer, and to indicate to the Medium Access Control Layer what data is to be transmitted.
12. A transmitter according to claim 11 , wherein the housing also accommodates a Radio Resource Control layer, and the data control unit is configured to receive measurements of signal quality from a Radio Resource Controller.
13. A method of transmitting data from a transmitter to a receiver associated with an user equipment, the method comprising:
transmitting a first data from the transmitter to the receiver;
storing the first data that has been transmitted as a second data;
receiving requests from the receiver to re-transmit the second data;
receiving power control commands indicating a change in power to maintain, at a predetermined level, a power of a transmission link between the transmitter and the receiver;
separately summing a number of power control commands indicating that an increase in power is necessary and a number of power control commands indicating that a reduction in power is necessary over a predetermined period of time;
controlling the power of the transmission link such that the power is temporarily higher than the pre-determined level; and
scheduling the second data for re-transmission in periods when the power of the link is higher than the predetermined level based at least in part on a difference in sums;
wherein the power of the transmission link is controlled to be maintained at a previous level after receiving a power control command from the user equipment that requests a reduction in power.
14. The method of claim 13 , further comprising controlling a data rate of the second data when the second data is re-transmitted based on a difference between the power level of the transmission link and the pre-determined level.
15. The method of claim 13 , further comprising controlling a data rate based on an amount of data that requires re-transmission.
16. The method of claim 13 , further comprising receiving signal quality measurements of the link between the transmitter to the receiver, and re-transmitting the data based on an estimation of a channel state.
17. The method of claim 13 , further comprising transmitting only first data in periods where the power level of the transmission link is equal to the pre-determined level.
18. The method of claim 13 , further comprising increasing the power of the transmission link when a power control command is received indicating that this is necessary, but maintaining the power of the link at the previous level when a power control command is received indicating that a reduction in power is necessary.
19. The method of claim 13 , further comprising determining a data rate for the second data depending on a magnitude of the sum.
20. The method of claim 13 , wherein the predetermined period of time is a multiple of a transmission time interval (TTI) for the transmission link.
21. The method of claim 20 , wherein the pre-determined period is approximately 10 ms.