Method for data transmission within a wireless local area network

• US 20060045053A1
• Filed: 09/11/2003
• Published: 03/02/2006
• Est. Priority Date: 09/11/2003
• Status: Active Grant

• Current Assignee: Tahoe Research Limited (f/k/a Learndale Limited) (Vector Capital Corporation)
• Original Assignee: Lantiq Deutschland GMBH (Intel Corporation)
• Inventors: Rashi, Yaron, Erlich, Yossi
• Granted Patent: US 7,551,591 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04B 2001/7154 with means for preventing interference
• CPC Class Codes: H04J 3/0658 Clock or time synchronisation among packet nodes
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Method for data transmission within a wireless local area network (WLAN) which is operable simultaneously with other wireless local area networks (WLANs) in the same local area, wherein each wireless local area network (WLAN) comprises at least one transceiver, wherein a transmitting transceiver of a wireless local area network (WLAN) transmits a signal that conveys data to a receiving transceiver of the same wireless local area network (WLAN) during data transmission intervals with changing frequency bands, wherein the frequency band is changed with each data transmission interval in a cyclical order according to a predetermined frequency hopping sequence which is identical for all simultaneously operated wireless local area networks (WLANs), wherein the transmitting transceivers of different wireless local area networks (WLANs) start the respective data transmissions at shifted times to establish different data transmission channels for the wireless local area networks (WLANs).

Claims

1. A method for data transmission within a wireless local area network (WLAN) which is operable simultaneously with other wireless local area networks (WLANs) in the same local area, wherein each wireless local area network (WLAN) comprises at least one transceiver, the method comprising the steps of:

transmitting a signal using a transmitting transceiver of a wireless local area network (WLAN) that conveys data to a receiving transceiver of the same wireless local area network (WLAN) during data transmission intervals with changing frequency bands;

changing the frequency band with each data transmission interval in a cyclical order according to a predetermined frequency hopping sequence which is identical for all simultaneously operated wireless local area networks (WLANs); and

,

wherein the transmitting transceivers of different wireless local area networks (WLANs) use different time shifts for the frequency hopping cycle with reference to a local time point that each transceiver holds, to establish different data transmission channels for the wireless local area networks (WLANs).

2. The method according to claim 1, wherein each wireless local area network (WLAN) comprises a coordinating transceiver (PNC) for managing the data traffic within the wireless local area network (WLAN).

3. The method according to claim 2, wherein the transceivers transmit or receive a predetermined synchronization signal (sync) during a periodic synchronization time window according to a first synchronization policy sequence.

4. The method according to claim 3, and further comprising the step of providing a predetermined synchronization policy sequence for each data transmission channel.

5. The method according to claim 3, wherein the start time of the synchronization time window is the local reference time for alignment of the frequency hopping sequence.

6. The method according to claim 4, further comprising the step of transmitting the synchronizing signal within the synchronization time window at a fixed point with respect to the beginning of the synchronization time window during synchronization transmission intervals with changing frequency bands.

7. The method according to claim 6, further comprising the step of changing a frequency band with each synchronization transmission interval in a predetermined cyclical order according to a synchronization frequency hopping sequence.

8. The method according to claim 7, wherein the order of frequency bands of the synchronization frequency hopping sequence is the same or reversed to the order of frequency bands of the frequency hopping sequence for the data transmission.

9. The method according to claim 5, wherein the coordinating transceiver (PNC) of a wireless local area network (WLAN) receives synchronization signals during uplink synchronization time windows depending on the synchronization policy sequence provided for the respective data transmission channel of the wireless local area network (WLAN) and wherein the other transceivers of the wireless local area network (WLAN) receive a synchronization signal during downlink synchronization time windows according to the synchronization policy sequence provided for the respective data transmission channel of the wireless local area network (WLAN).

10. The method according to claim 9, wherein a transceiver receiving a signal during a synchronization window detects the arrival time of synchronization signal.

11. The method according to claim 10, wherein a transceiver receiving a signal during a synchronization time window correlates the received signal with an expected synchronization signal to generate the correlation signal.

12. The method according to claim 11, wherein the transceiver detects the time of the first signal peak of the generated correlation signal as the arrival time of the synchronization signal and compares the detected arrival time with an expected time of reception for a synchronization signal sent by said transceiver.

13. The method according to claim 12, wherein the transceiver aligns its synchronization period to match the detected arrival time of the synchronization signal if the arrival time is earlier than the expected time of reception.

14. The method according to claim 6, wherein an autocorrelation function of the synchronization signal within a synchronization transmission interval approximates an impulse function.

15. The method according to claim 1, wherein the data transmission intervals have a predetermined time length.

29. The method according to claim 2, wherein the transceivers transmit and receive a predetermined synchronization signal (sync) sequentially in the same periodic time window according to a second synchronization policy sequence.

16. A method for data transmission within a wireless local area network (WLAN) which is operable simultaneously with other wireless local area networks (WLANs) in the same local area, wherein each wireless local area network (WLAN) comprises at least one transceiver the method comprising the steps of:

transmitting a signal using a transmitting transceiver of a wireless local area network (WLAN) that conveys data to a receiving transceiver of the same wireless local area network (WLAN) during data transmission intervals with changing frequency bands;

changing the frequency band with each data transmission interval in a cyclical order according to a predetermined frequency hopping sequence;

wherein the transmitting transceivers of different wireless local area networks (WLANs) use different time shifts for the frequency hopping cycle with reference to a local time point to establish different data transmission channels for the wireless local area networks (WLANs); and

,

wherein the time difference between data transmission channel of different wireless local area networks (WLANs) is the sum of the time length of a transmission interval and a predetermined guard time.

17. The method according to claim 16, wherein any two transceivers, belonging or not belonging to the same wireless local area network, are directly synchronized if the synchronization signal transmitted from one transceiver is received inside the synchronization window of the other transceiver.

19. A method for data transmission within a wireless local area network (WLAN) which is operable simultaneously with other wireless local area networks (WLANs) in the same local area, wherein each wireless local area network (WLAN) comprises at least one transceiver and a Piconet Coordinator (PNC), the method comprising the steps of:

transmitting a signal using a transmitting transceiver of a wireless local area network (WLAN) that conveys data to a receiving transceiver of the same wireless local area network (WLAN) during data transmission intervals with changing frequency bands;

changing the frequency band with each data transmission interval in a cyclical order according to a predetermined frequency hopping sequence;

wherein the transmitting transceivers of different wireless local area networks (WLANs) use different time shifts for the frequency hopping cycle with reference to a local time point, to establish different data transmission channels for the wireless local area networks (WLANs); and

,

wherein a group of transceivers are all synchronized and form a cluster if any two transceivers in the group can be connected via a virtual chain of directly synchronized transceivers.

20. The method according to claim 19, wherein any Piconet coordinator (PNC) increases the synchronization frequency at random times, for a predetermined acceleration period, thus increasing the average synchronization frequency of all transceivers in its cluster, to enable merging of that cluster with other clusters.

21. The method according to claim 20, wherein a first process to generate random acceleration times is for the PNC to identify acceleration periods, generated by itself or other PNCs, and at the end of any of these periods to start a timer that will count from zero to a random time, which is selected according to the following cumulative distribution function (CDF):

22. The method according to claim 21, wherein when using the first process to generate the random acceleration periods, any PNC will increase the synchronization frequency when the timer reaches the selected random time.

23. The method according to claim 22, wherein when using the first process to generate random acceleration periods and when a coordinating transceiver (PNC) of a wireless local area network (WLAN) within a cluster detects that the synchronization frequency has already been increased by another coordinating transceiver (PNC) of another wireless local area network (WLAN) within the same cluster it resets its timer and waits for the end of the acceleration period.

24. The method according to claim 20, wherein in a second process to generate random acceleration times the coordinating transceiver (PNC) operates either in an acceleration initiator mode or in a non-acceleration initiator mode.

25. The method according to claim 24, wherein in the non-acceleration initiator mode, any PNC that is in acceleration initiator mode starts a timer immediately after it finishes an acceleration period, wherein the timer counts from zero to a random time, selected according to a distribution function that generates a number between TAccMin and TAccMax, wherein when the timer reaches the selected random time the PNC starts a new acceleration period.

26. The method according to claim 24, wherein in the non-acceleration initiator mode, any PNC that is in acceleration initiator mode and identifies an acceleration period generated by another PNC, switches to the non-initiator acceleration mode.

27. The method according to claim 24, wherein any PNC that is in non acceleration initiator mode will identify acceleration periods and start a counter after each such period, wherein when the counter reaches TaccSwitch (which is higher than TaccMax) the PNC generates an acceleration period and switches to the acceleration initiator mode.

28. The method according to claim 20, wherein when a first cluster having a first synchronization frequency and a second cluster having a second synchronization frequency approach each other they merge to form a united cluster when a synchronization frequency of the first or second cluster has been increased for the predetermined acceleration period, so that at least one synchronization time window of the periodic synchronizing time windows of the first and the second clusters overlap each other.

19-1. The method according to claim 18, wherein the average synchronization period of any transceiver in a cluster will be equal to the period of the fastest transceiver in the cluster.