Arrangement for synchronizing access points in WLAN using direct-sequence spread spectrum signaling
An arrangement for providing synchronization between a number of overlapping area access points within a wireless LAN utilizes an Ethernet cable connection to transmit synchronization signals from a centralized hub/switch to each of the access points connected to the cable. The synchronization signal takes the form of a direct sequence spread spectrum (DS-SS) signal. At each access point, a filter is used to recover the synchronization signal, allowing for the group of access points to share a common beacon signal and allowing frequency re-use among the access points.
1. A method comprising:
generating a direct sequence spread spectrum synchronization signal at a network hub from a combination of a baseband data signal and a plurality of pseudo noise sequences including timing information for providing synchronization;
coupling the direct sequence spread spectrum synchronization signal onto at least one Ethernet cable, wherein the at least one Ethernet cable couples the network hub to a plurality of wireless access points of a wireless local area network; and
simultaneously transmitting the direct sequence spread spectrum synchronization signal from the network hub to the plurality of wireless access points over the at least one Ethernet cable.
2. The method of claim 1 , wherein the plurality of pseudo noise sequences includes a first pseudo noise sequence defining a precision phase signal, the precision phase signal utilized as a pilot tone to maintain synchronization between the plurality of wireless access points.
3. The method of claim 2 , wherein the plurality of pseudo noise sequences further includes a second pseudo noise sequence defining a time mark signal, the time mark signal utilized as a superframe/beacon synchronization signal between the plurality of wireless access points.
4. The method of claim 3 , wherein the plurality of pseudo noise sequences further includes a third pseudo noise sequence defining a time-of-day signal, the time-of-day signal usable within each access point of the plurality of wireless access points to provide a real-time clock signal.
5. The method of claim 1 , further comprising:
demodulating, at each wireless access point of the plurality of wireless access points, the direct sequence spread spectrum synchronization signal; and
extracting the timing information therefrom.
6. The method of claim 1 , wherein the direct sequence spread spectrum synchronization signal is generated using at least two independent pseudo noise sequences.
7. The method of claim 1 , further comprising transmitting a data signal from the network hub to the plurality of wireless access points over the at least one Ethernet cable simultaneously with transmitting the direct sequence spread spectrum synchronization signal and the power signal.
8. A network hub device comprising:
a power sourcing device responsive to a power supply to generate a power signal;
a direct sequence spread spectrum synchronization generator configured to generate a direct sequence spread spectrum synchronization signal based on a baseband data signal and a plurality of pseudo noise sequences including timing information; and
a circuit coupled to the power sourcing device and to the direct sequence spread spectrum synchronization generator, wherein the circuit is configured to send the power signal and the direct sequence spread spectrum synchronization signal to a plurality of wireless access points of a wireless local area network via at least one Ethernet cable.
9. The network hub device of claim 8 , further comprising an Ethernet line driver configured to send a data signal via the at least one Ethernet cable to the plurality of wireless access points concurrently with the power signal and the direct sequence spread spectrum synchronization signal.
10. The network hub device of claim 8 , wherein the circuit includes a power separation filter.
11. The network hub device of claim 8 , wherein the direct sequence spread spectrum synchronization signal is generated using at least two independent pseudo noise sequences.
12. The network hub device of claim 8 , wherein the direct sequence spread spectrum synchronization signal includes a precision phase signal, wherein the precision phase signal provides a pilot tone to maintain synchronization between the plurality of wireless access points.
13. The network hub device of claim 8 , wherein the direct sequence spread spectrum synchronization signal includes a time mark signal, wherein the time mark signal provides a superframe/beacon synchronization signal between the plurality of access points.
14. The network hub device of claim 8 , wherein the direct sequence spread spectrum synchronization signal includes a time-of-day signal, wherein the time-of-day signal is usable within each wireless access point of the plurality of wireless access points to provide a clock signal.
15. An access point device comprising:
a circuit configured to receive a signal from a network hub via at least one Ethernet cable, the signal including a power signal and a direct sequence spread spectrum synchronization signal, wherein the direct sequence spread spectrum synchronization signal includes a baseband data signal and a plurality of pseudo noise sequences;
a power sinking device coupled to the circuit, wherein the power sinking device is powered by the power signal; and
a direct sequence spread spectrum synchronization decoder coupled to the circuit, the direct sequence spread spectrum synchronization decoder configured to decode the direct sequence spread spectrum synchronization signal to determine timing information and to synchronize operation of the access point device with one or more other access point devices coupled to the network hub using the timing information.
16. The access point device of claim 15 , wherein the direct sequence spread spectrum synchronization signal is generated using at least two independent pseudo noise sequences.
17. The access point device of claim 15 , wherein the direct sequence spread spectrum synchronization signal includes a precision phase signal, wherein the precision phase signal provides a pilot tone to maintain synchronization of the access point device and the one or more other access point devices coupled to the network hub.
18. The access point device of claim 15 , wherein the direct sequence spread spectrum synchronization signal includes a time mark signal, wherein the time mark signal is used to align superframes or beacons of the access point device with superframes or beacons of the one or more other access point devices coupled to the network hub.
19. The access point device of claim 15 , wherein the direct sequence spread spectrum synchronization signal includes a time-of-day signal, wherein the time-of-day signal is used to provide a real-time clock signal.
20. The access point device of claim 15 , further comprising an Ethernet line receiver operable to receive a data signal via the at least one Ethernet cable concurrently with receipt of the power signal and the direct sequence spread spectrum synchronization signal.