Simultaneous operation of wireless LAN and long-range wireless connections

1. A method for communication, comprising:

establishing a first connection between a wireless terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the wireless terminal and the base station;

sending a signal from the wireless terminal to the base station identifying an interval comprising one or more of the time frames during which the wireless terminal will not receive data from the base station; and

during the interval, establishing a second connection between the wireless terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein establishing the first connection comprises transmitting first data between the wireless terminal and the base station during the time frames outside the interval, and wherein establishing the second connection comprises transmitting second data between the wireless terminal and the access point during the interval.

2. The method according to claim 1 , wherein the long-range wireless data network is a WiMAX network.

3. The method according to claim 2 , wherein the WLAN operates in accordance with an IEEE 802.11 standard, and the WiMAX network operates in accordance with an IEEE 802.16 standard.

4. The method according to claim 2 , wherein sending the signal comprises using a reservation message in order to reserve first time frames for the transmission of the data between the wireless terminal and the base station and second time frames for inclusion in the interval during which the second connection is to be established.

5. The method according to claim claim 1 , wherein sending the signal comprises identifying a sequence of intervals, such that the second data are transmitted between the wireless terminal and the access point during the intervals, and the first data are transmitted between the wireless terminal and the base station during the time frames outside the intervals.

6. The method according to claim 5 , wherein establishing the second connection comprises suspending transmission of the first data over the first connection upon establishing the second connection, and resuming the transmission of the first data over the first connection when the second connection is lost.

7. The method according to claim 1 , wherein the terminal comprises a memory for holding both the first and the second data simultaneously.

8. The method according to claim 1 , wherein establishing the second connection comprises transmitting an uplink message from the wireless terminal to the access point during the interval using a terminal-initiated transmission mechanism.

9. The method according to claim 1 , wherein establishing the second connection comprises scanning periodically for available access points, wherein a rate of the scanning is determined by a measure of mobility of the wireless terminal.

10. A method for communication, comprising:

establishing a first connection between a wireless terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the wireless terminal and the base station;

sending a signal from the wireless terminal to the base station identifying an interval comprising one or more of the time frames during which the wireless terminal will not receive data from the base station; and

during the interval, establishing a second connection between the wireless terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein sending the signal comprises sensing periodic beacons transmitted by the access point, and adjusting the interval responsively to a transmission period of the beacons.

11. The method according to claim 10 , wherein adjusting the interval comprises selecting a start time of the interval so that one of the beacons occurs during an initial portion of the interval.

12. The method according to claim 10 , wherein establishing the second connection comprises transmitting a polling signal from the wireless terminal to the access point in response to one of the beacons during the interval.

13. A method for communication, comprising:

establishing a first connection between a wireless terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the wireless terminal and the base station;

sending a signal from the wireless terminal to the base station identifying an interval comprising one or more of the time frames during which the wireless terminal will not receive data from the base station;

during the interval, establishing a second connection between the wireless terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol; and

transmitting a bandwidth request from the wireless terminal to the base station in order to resume the transmission of the data between the wireless terminal and the base station over the first connection after conclusion of the sleep interval.

14. A method for communication, comprising:

establishing a first connection between a wireless terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the wireless terminal and the base station;

sending a signal from the wireless terminal to the base station identifying an interval comprising one or more of the time frames during which the wireless terminal will not receive data from the base station; and

during the interval, establishing a second connection between the wireless terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein the long-range wireless data network is a WiMAX network, and

wherein sending the signal comprises sending a reduced availability message indicating a starting time and a duration of the interval during which the second connection is to be established.

15. A method for communication, comprising:

establishing a first connection between a wireless terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the wireless terminal and the base station;

sending a signal from the wireless terminal to the base station identifying an interval comprising one or more of the time frames during which the wireless terminal will not receive data from the base station; and

during the interval, establishing a second connection between the wireless terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein establishing the first connection comprises assigning time slots within the time frames for communication between the base station and the wireless terminal, and comprising identifying periods within the time frames outside the interval that are not included in the assigned time slots, and transmitting the data over the second connection during the periods.

16. A method for communication, comprising:

establishing a first connection between a wireless terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the wireless terminal and the base station;

sending a signal from the wireless terminal to the base station identifying an interval comprising one or more of the time frames during which the wireless terminal will not receive data from the base station; and

during the interval, establishing a second connection between the wireless terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein establishing the second connection comprises transmitting a radio frequency (RF) probe signal from the wireless terminal requesting a response from the access point, and during a predetermined time period following the probe signal, intermittently switching a RF receiver of the wireless terminal on and off, and sampling radio signals received while the RF receiver is on so as to determine a probability that the radio signals comprise a response to the probe signal transmitted by the access point.

17. A wireless communication terminal, comprising:

a radio frequency (RF) transceiver; and

a baseband processing circuit, which is coupled to cause the RF transceiver to transmit and receive signals over the air so as to establish a first connection between the terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the terminal and the base station, and to send a signal to the base station identifying an interval comprising one or more of the time frames during which the terminal will not receive data from the base station, and to establish, during the interval, a second connection between the terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein the long-range wireless data network is a WiMAX network, and

wherein the signal comprises a reduced availability message indicating a starting time and a duration of the interval during which the second connection is to be established.

18. A wireless communication terminal, comprising:

a radio frequency (RF) transceiver; and

a baseband processing circuit, which is coupled to cause the RF transceiver to transmit and receive signals over the air so as to establish a first connection between the terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the terminal and the base station, and to send a signal to the base station identifying an interval comprising one or more of the time frames during which the terminal will not receive data from the base station, and to establish, during the interval, a second connection between the terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocols

wherein the baseband processing circuit is arranged to cause the terminal to exchange first data with the base station over the first connection during the time frames outside the interval, and to exchange second data with the access point over the second connection during the interval.

19. The terminal according to claim 18 , wherein the long-range wireless data network is a WiMAX network.

20. The terminal according to claim 19 , wherein the WLAIN operates in accordance with an IEEE 802.11 standard, and the WiMAX network operates in accordance with an IEEE 802.16 standard.

21. The terminal according to claim 19 , wherein the baseband processing circuit is arranged to send the signal using a reservation message in order to reserve first time frames for the transmission of the data between the wireless terminal and the base station and second time frames for inclusion in the interval during which the second connection is to be established.

22. The terminal according to claim 18 , wherein the signal identifies a sequence of intervals, such that the second data are transmitted between the wireless terminal and the access point during the intervals, and the first data are transmitted between the wireless terminal and the base station during the time frames outside the intervals.

23. The terminal according to claim 22 , wherein the baseband processing circuit is arranged to suspend transmission of the first data over the first connection upon establishing the second connection, and to resume the transmission of the first data over the first connection when the second connection is lost.

24. The terminal according to claim 18 , wherein the baseband processing circuit comprises a memory for holding both the first and the second data simultaneously.

25. The terminal according to claim 18 , wherein the baseband processing circuit is arranged to transmit an uplink message from the wireless terminal to the access point during the interval using a terminal-initiated transmission mechanism.

26. The terminal according to claim 18 , wherein the baseband processing circuit is arranged to scan periodically for available access points in order to establish the second connection, while determining a rate of the scanning responsively to a measure of mobility of the wireless terminal.

27. A wireless communication terminal, comprising:

a radio frequency (RF) transceiver; and

a baseband processing circuit, which is coupled to cause the RF transceiver to transmit and receive signals over the air so as to establish a first connection between the terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the terminal and the base station, and to send a signal to the base station identifying an interval comprising one or more of the time frames during which the terminal will not receive data from the base station, and to establish, during the interval, a second connection between the terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein the baseband processing circuit is arranged to sense periodic beacons transmitted by the access point, and to cause the base station to adjust the interval responsively to a transmission period of the beacons.

28. The terminal according to claim 27 , wherein the baseband processing circuit is arranged to adjust a start time of the interval so that one of the beacons occurs during an initial portion of the interval.

29. The terminal according to claim 28 , wherein the baseband processing circuit is arranged to transmit a polling signal to the access point in response to one of the beacons during the interval.

30. A wireless communication terminal, comprising:

a radio frequency (RF) transceiver; and

a baseband processing circuit, which is coupled to cause the RF transceiver to transmit and receive signals over the air so as to establish a first connection between the terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the terminal and the base station, and to send a signal to the base station identifying an interval comprising one or more of the time frames during which the terminal will not receive data from the base station, and to establish, during the interval, a second connection between the terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein the baseband processing circuit is arranged to transmit a bandwidth request to the base station in order to resume the transmission of the data between the terminal and the base station over the first connection after conclusion of the sleep interval.

31. A wireless communication terminal, comprising:

a radio frequency (RF) transceiver; and

a baseband processing circuit, which is coupled to cause the RF transceiver to transmit and receive signals over the air so as to establish a first connection between the terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the terminal and the base station, and to send a signal to the base station identifying an interval comprising one or more of the time frames during which the terminal will not receive data from the base station, and to establish, during the interval, a second connection between the terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein time slots are assigned by the base station within the time frames for communication between the base station and the terminal, and wherein the baseband processing circuit is arranged to identify periods within the time frames outside the interval that are not included in the assigned time slots, and to transmit the data over the second connection during the periods.

32. A wireless communication terminal, comprising:

a radio freciuency (RF) transceiver; and

a baseband processing circuit, which is coupled to cause the RF transceiver to transmit and receive signals over the air so as to establish a first connection between the terminal and a base station of a long-range wireless data network, which operates in accordance with a first protocol that defines a sequence of time frames for transmission of data between the terminal and the base station, and to send a signal to the base station identifying an interval comprising one or more of the time frames during which the terminal will not receive data from the base station, and to establish, during the interval, a second connection between the terminal and an access point of a wireless local area network (WLAN) in accordance with a second protocol, different from the first protocol,

wherein the RF transceiver is arranged to transmit a RF probe signal requesting a response from the access point, and to switch intermittently on and off during a predetermined time period following the probe signal, and wherein the baseband circuit is coupled to sample radio signals received while the RF transceiver is on so as to determine a probability that the radio signals comprise a response to the probe signal transmitted by the access point.