Power detection in a spread spectrum system
This disclosure relates to method, device and system for selecting a device for communication in a communication system. A node receives a spread signal from a first transmitter and a second transmitter. The node despreads the spread signal with a first spreading code into a first frame and determines a first receive signal strength indicator (RSSI) from the first frame. The node despreads the spread signal with a second spreading code into a second frame and determines a second RSSI from the second frame. The node selects an access point based in part on the first RSSI and the second RSSI. The node transmits an uplink signal to the access point based on a slot start time and a random timing offset. The node transmits while a portion of a second signal is transmitted from a second node such that both the uplink signal and the second signal are received.
1. A method of measuring a receive signal strength indicator in a communication system, the method comprising:
receiving spread signals from a first transmitter and a second transmitter at a receiver;
despreading the spread signals with a first spreading code into a first frame;
determining a first receive signal strength indicator from the first frame;
despreading the spread signals with a second spreading code into a second frame;
determining a second receive signal strength indicator from the second frame;
selecting an access point based in part on the first receive signal strength indicator and the second receive signal strength indicator; and
transmitting an uplink signal to the access point at a first time based on a slot start time and a first random timing offset, wherein the uplink signal is transmitted while at least a portion of a second signal is transmitted from a second node such that both the uplink signal and the second signal are received, and wherein the second signal is transmitted at a second time based on the slot time and a second random timing offset.
2. The method of claim 1 , further comprising selecting the access point based in part on a first received access point interference signal power and a second received access point interference signal power.
3. The method of claim 1 , wherein the first spreading code is a first gold code and the second spreading code is a second gold code.
4. The method of claim 1 , wherein the first receive signal strength indicator is based on a signal-to-noise ratio determined while despreading the spread signals with the first spreading code and a total power measurement measured over a period of time where the spread signals are received.
5. The method of claim 1 , wherein the first transmitter and the second transmitter are synchronized by an outside time source.
6. The method of claim 5 , wherein variations in timing of the first transmitter is compensated for by despreading the spread signals with the first spreading code at a plurality of chip offsets.
7. A node comprising:
a processor;
a receiver operatively coupled to the processor and configured to receive spread signals from a first transmitter and a second transmitter;
despread the spread signals with a first spreading code into a first frame;
determine a first receive signal strength indicator from the first frame;
despread the spread signals with a second spreading code into a second frame;
determine a second receive signal strength indicator from the second frame; and
select an access point based in part on the first receive signal strength indicator and the second receive signal strength indicator; and
a transmitter operatively coupled to the processor and configured to transmit an uplink signal to the access point at a first time based on a slot start time and a first random timing offset, wherein the uplink signal is transmitted while at least a portion of a second signal is transmitted from a second node such that both the uplink signal and the second signal are received, and wherein the second signal is transmitted at a second time based on the slot time and a second random timing offset.
8. The node of claim 7 , wherein the first spreading code is a first gold code and the second spreading code is a second gold code.
9. The node of claim 7 , wherein the processor is configured to select the access point based in part on a first received access point interference signal power and a second received access point interference signal power.
10. The node of claim 7 , wherein the first receive signal strength indicator is based on a signal-to-noise ratio determined while despreading the spread signals with the first spreading code and a total power measurement measured over a period of time where the spread signals are received.
11. The node of claim 7 , wherein the first transmitter and the second transmitter are synchronized by an outside time source.
12. A system comprising:
a first access point comprising a first transmitter;
a second access point comprising a second transmitter; and
a node comprising a processor, and
a receiver operatively coupled to the processor and configured to
receive spread signals from the first transmitter and the second transmitter,
despread the spread signals with a first spreading code into a first frame,
determine a first receive signal strength indicator from the first frame,
despread the spread signals with a second spreading code into a second frame, and
determine a second receive signal strength indicator from the second frame;
the processor further configured to select a destination access point based in part on the first receive signal strength indicator and the second receive signal strength indicator; and
a third transmitter operatively coupled to the processor and configured to transmit an uplink signal to the destination access point at a first time based on a slot start time and a first random timing offset, wherein the uplink signal is transmitted while at least a portion of a second signal is transmitted from a second node such that both the uplink signal and the second signal are received, and wherein the second signal is transmitted at a second time based on the slot time and a second random timing offset.
13. The system of claim 12 , wherein the processor on the node is configured to select the destination access point based in part on a first received access point interference signal power and a second received access point interference signal power.
14. The system of claim 12 , wherein the first receive signal strength indicator is based on a signal-to-noise ratio determined while despreading the spread signals with the first spreading code and a total power measurement measured over a period of time where the spread signals are received.
15. The system of claim 12 , wherein the first transmitter and the second transmitter are synchronized by an outside time source.
16. The system of claim 15 , wherein the processor is further configured to despread the spread signals with the first spreading code at a plurality of chip offsets to compensate for variations in timing of the first transmitter.
17. The system of claim 12 , wherein the first spreading code is a first gold code and the second spreading code is a second gold code.
18. The node of claim 11 , wherein the processor is further configured to despread the spread signals with the first spreading code at a plurality of chip offsets to compensate for variations in timing of the first transmitter.