Method and apparatus for random access channel probe initialization using transmit diversity
View Patent ↗Embodiments of the present invention extend the benefits of mobile transmit diversity to the initialization phase of communication with a base station over a random access channel. According to a method of the invention, the transmitter may attempt to initiate communication with a receiver by varying a transmit diversity parameter, for example, phase difference, in addition to or instead of varying power settings.
1. A method of initiating communication between a first communication device and a second communication device comprising:
transmitting from the first communication device a first probe signal on a random access channel using at least two antennas, wherein transmissions of the first probe signal on the two antennas differ by a first value of a transmit diversity parameter; and
if acknowledgement is not received from the second communication device, then transmitting from the first communication device a second probe signal on a random access channel using at least two antennas, wherein transmissions of the second probe signal on the two antennas differ by a second value of the transmit diversity parameter.
2. The method of claim 1 , comprising
transmitting from the first communication device a first sequence of probe signals on a random access channel using at least two antennas, said first sequence including the first probe signal,
wherein for the first sequence, transmissions of each the probe signals on the two antennas differ by the first value of the transmit diversity parameter, and
wherein each subsequent probe signal in the first sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the first sequence until a maximum allowed transmission power is reached; and
if acknowledgement is not received from the second communication device, then transmitting from the first communication device a second sequence of probe signals on a random access channel using at least two antennas, said second sequence including the second probe signal,
wherein for the second sequence, transmissions of each the probe signals on the two antennas differ by the second value of the transmit diversity parameter, and
wherein each subsequent probe signal in the second sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the second sequence until the maximum allowed transmission power is reached.
3. The method of claim 2 , wherein a transmission power of a last probe signal in the first sequence is greater than a transmission power of a first probe signal in the second sequence.
4. The method of claim 2 , wherein said transmit diversity parameter is a phase difference, said method comprising transmitting a plurality of sequences of probe signals each of said sequences using a single respective phase difference until an end condition is attained.
5. The method of claim 1 , wherein a transmission power of said second probe signal is greater than a transmission power of said first signal.
6. The method of claim 1 , comprising
transmitting from the first communication device a first sequence of probe signals on a random access channel using at least two antennas, said first sequence including the first probe signal,
wherein for the first sequence, transmissions of each the probe signals on the two antennas differ by respectively different values of the transmit diversity parameter, and
wherein each subsequent probe signal in the first sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the first sequence until a maximum allowed transmission power is reached; and
if acknowledgement is not received from the second communication device, then transmitting from the first communication device a second sequence of probe signals on a random access channel using at least two antennas, said second sequence including the second probe signal,
wherein for the second sequence, transmissions of each the probe signals on the two antennas differ by respectively different values of the transmit diversity parameter, and
wherein each subsequent probe signal in the second sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the second sequence until the maximum allowed transmission power is reached.
7. The method of claim 6 , wherein probe signals having corresponding transmission power in said first and second sequences have different transmit diversity parameters.
8. The method of claim 1 , comprising
transmitting from the first communication device a first sequence of probe signals on a random access channel using at least two antennas, said first sequence including the first probe signal,
wherein for the first sequence, transmissions of each the probe signals on the two antennas have different values of the transmit diversity parameter, and
wherein each probe signal in the first sequence is transmitted with a first transmission power; and
if acknowledgement is not received from the second communication device, then transmitting from the first communication device a second sequence of probe signals on a random access channel using at least two antennas, said second sequence including the second probe signal,
wherein for the second sequence, transmissions of each the probe signals on the two antennas have different values of the transmit diversity parameter, and
wherein each probe signal in the second sequence is transmitted with a second transmission power.
9. The method of claim 8 , comprising transmitting a plurality of sequences until a maximum transmission power is reached.
10. The method of claim 1 , comprising transmitting a plurality of probe signals until a maximum allowed number of probe signals is reached.
11. A mobile communication device comprising:
first and second antennas; and
a processor to:
transmit on the first and second antennas a first probe signal on a random access channel, wherein transmissions of the first probe signal on the first and second antennas differ by a first value of a transmit diversity parameter, and
if acknowledgement is not received from a second communication device, transmit on the first and second antennas a second probe signal on a random access channel, wherein transmissions of the second probe signal on the first and second antennas differ by a second value of the transmit diversity parameter.
12. The mobile communication device of claim 11 , wherein said processor is to:
transmit a first sequence of probe signals on a random access channel using said first and second antennas, said first sequence including the first probe signal,
wherein for the first sequence, transmissions of each the probe signals on the two antennas differ by the first value of the transmit diversity parameter, and
wherein each subsequent probe signal in the first sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the first sequence until a maximum allowed transmission power is reached; and
if acknowledgement is not received from the second communication device, transmit a second sequence of probe signals on a random access channel using said first and second antennas, said second sequence including the second probe signal,
wherein for the second sequence, transmissions of each the probe signals on the two antennas differ by the second value of the transmit diversity parameter, and
wherein each subsequent probe signal in the second sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the second sequence until the maximum allowed transmission power is reached.
13. The mobile communication device of claim 12 , wherein a transmission power of a last probe signal in the first sequence is greater than a transmission power of a first probe signal in the second sequence.
14. The mobile communication device of claim 12 , wherein said transmit diversity parameter is a phase difference, said processor adapted to transmit a plurality of sequences of probe signals each of said sequences using a single respective phase difference until an end condition is attained.
15. The mobile communication device of claim 11 , wherein a transmission power of said second probe signal is greater than a transmission power of said first signal.
16. The mobile communication device of claim 11 , wherein said processor is to:
transmit on said first and second antennas a first sequence of probe signals on a random access channel, said first sequence including the first probe signal,
wherein for the first sequence, transmissions of each the probe signals on the two antennas differ by respectively different values of the transmit diversity parameter, and
wherein each subsequent probe signal in the first sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the first sequence until a maximum allowed transmission power is reached; and
if acknowledgement is not received from the second communication device, transmit on said first and second antennas a second sequence of probe signals on a random access channel, said second sequence including the second probe signal,
wherein for the second sequence, transmissions of each the probe signals on the two antennas differ by respectively different values of the transmit diversity parameter, and
wherein each subsequent probe signal in the second sequence is transmitted with a transmission power greater than a transmission power of the previous probe signal in the second sequence until the maximum transmission power is reached.
17. The mobile communication device of claim 16 , wherein probe signals having corresponding transmission power in said first and second sequences have different transmit diversity parameters.
18. The mobile communication device of claim 11 , wherein said processor is to:
transmit on said first and second antennas a first sequence of probe signals on a random access channel, said first sequence including the first probe signal,
wherein for the first sequence, transmissions of each the probe signals on the two antennas have different values of the transmit diversity parameter, and
wherein each probe signal in the first sequence is transmitted with a first transmission power; and
if acknowledgement is not received from the second communication device, transmit on said first and second antennas a second sequence of probe signals on a random access channel, said second sequence including the second probe signal,
wherein for the second sequence, transmissions of each the probe signals on the two antennas have different values of the transmit diversity parameter, and
wherein each probe signal in the second sequence is transmitted with a second transmission power.
19. The mobile communication device of claim 18 , wherein said processor is to transmit a plurality of sequences until a maximum transmission power is reached.
20. The mobile communication device of claim 11 , wherein said processor is to transmit a plurality of probe signals until a maximum allowed number of probe signals is reached.