HK1108096B - Telephone with automatic switching between cellular and voip networks - Google Patents

Description

Telephone with automatic switching between cellular network and voice over internet protocol network

Cross Reference to Related Applications

This application claims benefit of the filing date of U.S. provisional patent application 60/534466 entitled "radiotelephone that automatically switches between cellular network and Wi-Fi network using Wi-Fi signal strength values", filed on 6.1.2004, according to 35 USC 119(e), the contents of which are incorporated herein by reference in their entirety.

Background

A small portion of the Radio Frequency (RF) spectrum is allocated to each communication carrier. The allocated spectrum must therefore be used efficiently in order to enable a maximum number of frequency users to use the spectrum. Multiple access modulation techniques have been developed to provide optimal use of the RF spectrum. Examples of such modulation techniques include Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), and Code Division Multiple Access (CDMA).

There are large differences in the performance of wireless networks. Conventional wireless cellular networks cover a large geographic area but provide a low bandwidth. Such wireless networks utilize a defined portion of the radio spectrum and are shared by many users. The infrastructure cost of a wireless network is high due to the size and complexity of cellular network devices.

Other wireless networks, such as CDMA2000-EV-DO/DV networks, offer higher bandwidth and enhanced data services (e.g., web browsing). However, these networks also crowd many users into a smaller range of the defined spectrum. Other types of radio networks are suitable for improving spectral efficiency with increased and smaller coverage areas. For example, an IEEE802.11x (or Wi-Fi) network can transmit at speeds up to 11Mbps using a Direct Sequence Spread Spectrum (DSSS) mode or up to 54Mbps using an Orthogonal Frequency Division Multiplexing (OFDM) mode.

An access point that conforms to an IEEE802.11x (e.g., IEEE802.11 b) network may cover an area several hundred feet in diameter. Each such access point is connected to a larger network (such as the internet). To cover a larger geographic area, a relatively large number of IEEE802.11x network access points and a relatively large number of wired backhaul networks are required. The resulting IEEE802.11 x-based networks may therefore be more expensive to build and operate than similarly-based wireless networks, due in part to backhaul costs. In other words, many tradeoffs often exist between and among the coverage areas, maximum bit rates, and costs associated with different types of wireless networks.

There is an increasing demand for high bandwidth and quality of service (QoS) associated with mobile communication devices having full roaming capabilities. One known communication device includes a cellular communication module adapted to communicate using a wireless cellular network and a Wi-Fi communication module adapted to communicate using a voice over IP (VoIP) protocol. In such devices, in order to change the communication mode from cellular to VoIP or vice versa, the user has to manually change the settings of the device by pressing one or more keys.

In still other known communication devices under development, to switch the communication mode from, for example, a cellular network to VoIP, the cellular network first detects the location of the mobile communication device to determine if the mobile communication device is within the Wi-Fi area. If it is detected that it is within the Wi-Fi zone, the cellular network sends a transition signal to the mobile communication device to enable the communication to continue communicating using the VoIP protocol. However, obtaining or maintaining the precise location of many mobile communication devices at the same time poses a challenging task. Thus, in such systems, the transition of a call from a cellular network to VoIP, or vice versa, may result in the call being lost.

Disclosure of Invention

In accordance with the present invention, a mobile communication device is configured to automatically switch an already ongoing communication to a voice over IP (VoIP) network or vice versa using a wireless cellular network (hereinafter also referred to as a cellular network). The mobile communication device is adapted to include, in part, a cellular communication module, a first antenna adapted to transceive data between the mobile communication module and a cellular network, a wireless fidelity (Wi-Fi) communication module, a second antenna adapted to transceive data between the Wi-Fi communication module and a VoIP network, a signal monitoring circuit, and a switching circuit adapted to switch an existing, ongoing communication between the cellular communication module and the Wi-Fi communication module. The second antenna and associated circuitry are continuously maintained in an on state to monitor and detect Wi-Fi signals.

If the mobile communication device is communicating via its cellular communication module and over the cellular network (i.e., pre-established) and the Wi-Fi antenna system detects a Wi-Fi signal having a first predetermined level (strength), a timer located within the mobile communication device is activated to establish a first time window of a first predetermined size. If the Wi-Fi signal level detected during the first time window remains equal to or greater than a first predetermined level, the switching circuit causes the ongoing communication to be switched from its cellular communication module to its Wi-Fi communication module and through the VoIP network upon expiration of the first time window without losing the ongoing communication.

In some embodiments, upon activation of the timer, the Wi-Fi communication module is caused to change state from a sleep mode during which the Wi-Fi communication module consumes a relatively small amount of power to a standby mode during which the Wi-Fi communication module consumes an intermediate amount of power. Subsequently, prior to the communication transitioning to the Wi-Fi communication module, the Wi-Fi communication module is caused to be placed in a fully active mode during which the Wi-Fi communication module consumes an amount of power greater than the intermediate amount of power.

If the mobile communication device is in a pre-established communication via its Wi-Fi communication module and over the VoIP network, and the Wi-Fi antenna system detects that the received Wi-Fi signal level is below a second predetermined value, the timer is activated to establish a second time window of a second predetermined size. If the Wi-Fi signal level detected during the second time window is equal to or greater than a third predetermined value, the pre-established communication via the Wi-Fi communication module is maintained without any change. If the Wi-Fi signal level detected during the second time window is less than a third predetermined value, the timer is reset and reactivated to establish a third time window of a third size. If the Wi-Fi signal level detected during the third time window is less than a third predetermined value, the switching circuit causes the ongoing communication to be switched from its Wi-Fi communication module to its cellular communication module and through the cellular network upon expiration of the third time window without losing the ongoing communication.

In some embodiments, upon activation of the timer to establish the second time window, the cellular communication module is caused to change state from a sleep mode during which the cellular communication module consumes a relatively small amount of power to a standby mode during which the cellular communication module consumes an intermediate amount of power. Subsequently, the cellular communication module is caused to be placed in a fully active mode during which the cellular communication module consumes an amount of power greater than the intermediate amount of power before the communication is switched to the Wi-Fi communication module.

In some embodiments, the Wi-Fi communication module is adapted to communicate with an access point of a Wi-Fi local area network using an 802.11x wireless protocol, and the cellular communication module is adapted to communicate with a base station of a wireless cellular network using any of a GSM, CDMA, or CDMA2000 protocol.

Drawings

Fig. 1 is a simplified high-level block diagram of a mobile communication device in accordance with one embodiment of the present invention.

Figure 2 illustrates Wi-Fi signal threshold levels and timing windows used to determine whether to transition a communication from a cellular communication module to a Wi-Fi communication module of the communication device of figure 1, in accordance with one embodiment.

Figure 3 illustrates Wi-Fi signal threshold levels and timing windows used to determine whether to transition a communication from the Wi-Fi communication module to the cellular communication module of the communication device of figure 1, in accordance with one embodiment.

Detailed Description

In accordance with the present invention, a mobile communication device is configured to automatically transition an existing communication from a wireless cellular network (hereinafter alternatively referred to as a cellular network) to a voice over wireless IP (VoIP) network or from a VoIP network to a cellular network. It should be appreciated that wireless fidelity (Wi-Fi) signals may be used to communicate with a voice over IP (VoIP) network, as defined, for example, in the IEEE802.11x standard or other equivalent standards. The mobile communication device is adapted to include, in part, a cellular communication module, a first antenna adapted to transceive data between the mobile communication module and a cellular network, a Wi-Fi communication module, a second antenna adapted to transceive data between the Wi-Fi communication module and a VoIP network, a signal monitoring circuit, and a switching circuit adapted to switch an existing ongoing communication between the cellular communication module and the Wi-Fi communication module. The second antenna and associated circuitry are continuously maintained in an on state to monitor and detect Wi-Fi signals.

It should be understood that a wireless cellular network includes, in part, many base stations. Each such base station is adapted to communicate with mobile communication devices via RF signals carried over a cellular network when the mobile communication devices are located within the coverage area of the base station. It should also be understood that each such coverage area is bounded by an area centered at the base station and having a radius of, for example, a few miles. It should also be understood that a Wi-Fi network may include, in part, many access points. Each such access point is adapted to communicate with the mobile communication device via VoIP packets when the mobile communication device is located within the coverage area of the access point. It should also be understood that the mobile communication device may also include blocks suitable for computation and thus be a communication/computing device.

If the mobile communication device is in an ongoing (i.e., pre-established) communication via its cellular communication module and through the cellular network, and the Wi-Fi antenna system detects a Wi-Fi signal having a first predetermined level (strength), a timer located within the mobile communication device is activated to establish a first time window of a first predetermined size. If the Wi-Fi signal level detected during the first time window remains equal to or greater than a first predetermined level, the switching circuit causes the communication in progress to be switched from its cellular communication module to its Wi-Fi communication module and through the VoIP network upon expiration of the first time window without losing the communication in progress.

In some embodiments, upon activation of the timer, the Wi-Fi communication module is caused to change state from a sleep mode during which the Wi-Fi communication module consumes a relatively small amount of power to a standby mode during which the Wi-Fi communication module consumes an intermediate amount of power. Subsequently, the Wi-Fi communication module is caused to be placed in a full active mode, during which the Wi-Fi communication module consumes an amount of power greater than the intermediate amount of power, before the communication is switched to the Wi-Fi communication module.

If the mobile communication device is in a pre-established communication via its Wi-Fi communication module and over the VoIP network, and the Wi-Fi antenna system detects that the received Wi-Fi signal level is below a second predetermined value, the timer is activated to establish a second time window of a second predetermined size. If the Wi-Fi signal level detected during the second time window is equal to or greater than a third predetermined value, pre-established communications via the Wi-Fi communication module are maintained without any change. If the Wi-Fi signal level detected during the second time window is less than a third predetermined value, the timer is reset and reactivated to establish a third time window of a third size. If the Wi-Fi signal level detected during the third time window is less than a third predetermined value, the switching circuit causes the ongoing communication to be switched from its Wi-Fi communication module to its cellular communication module and through the cellular network upon expiration of the third time window without losing the ongoing communication.

In some embodiments, upon activation of the timer to establish the second time window, the cellular communication module is caused to change state from a sleep mode during which the cellular communication module consumes a relatively small amount of power to a standby mode during which the cellular communication module consumes an intermediate amount of power. Subsequently, the cellular communication module is caused to be placed in a fully active mode during which the cellular communication module consumes an amount of power greater than the intermediate amount of power before the communication is switched to the Wi-Fi communication module.

Fig. 1 is a simplified high-level block diagram of a mobile communication device 100 in accordance with one embodiment of the present invention. A mobile communication device 100 suitable for automatically switching communications between a cellular network and a VoIP network is shown, which includes, in part, a cellular communication module (hereinafter alternatively referred to as a cellular module) 3 coupled to a cellular antenna 1, a Wi-Fi communication module (hereinafter alternatively referred to as a Wi-Fi module) 4 coupled to a Wi-Fi antenna 2, an audio/video amplifier 5, a network switching component 6, a timer component 7, a Wi-Fi signal level monitor 8, a microphone 20, a speaker 21, and a display monitor 22. Mobile communication device 100 is adapted to establish and maintain communication through a wireless network (not shown) via cellular module 3, and/or through a VoIP network (not shown) via Wi-Fi module 4. The cellular module 3 further comprises a transceiver 30 adapted to transmit and receive signals to and from a cellular network. Wi-Fi module 4 also includes a transceiver 32 adapted to transmit signals to and receive signals from a VoIP network. Depending on the detected level of Wi-Fi signals transmitted by the Wi-Fi access point, calls initially established via cellular module 3 may be switched to be processed by Wi-Fi module 4, or calls initially established via Wi-Fi module 4 may be switched to be processed by cellular module 3.

Assume that the mobile communication device 100 is communicating with a cellular network and is entering the coverage area of a Wi-Fi access point adapted to receive and transmit Wi-Fi signals. As is well known, Wi-Fi access points may be used to access VoIP networks. Wi-Fi antenna 2, along with Wi-Fi module 4 and Wi-Fi signal monitor 8, continuously monitors to detect Wi-Fi signals. If the detected Wi-Fi signal level is greater than a predetermined threshold V_th1Wi-Fi signal level monitor 8 activates timer 7 via signal line 10 and sends a wake-up signal to network transition unit 6 via signal line 12 causing network transition unit 6 to change state, thereby changing from a sleep mode during which the network transition unit consumes relatively little power to a standby mode during which the network transition unit cell consumes an intermediate amount of power. Network switch unit 6 in turn supplies a wake-up switch signal to cellular module 3 via signal line 15 and to Wi-Fi module 4 via signal line 13. This causes the cellular module 3 and Wi-Fi module 4 of the phone to activate their respective switching modules. The detected Wi-Fi signal level may be determined, for example, by taking a plurality of samples of the input Wi-Fi signal and calculating the signal levels of the samples. In one embodimentThe average of the amplitude/phase of the sampled signal can be used to detect the Wi-Fi signal level.

If the detected Wi-Fi signal level is greater than V, as shown in FIG. 2_th1The timer means 7 are activated to establish a first time window T of a first predetermined size₁. In a time window T₁During which Wi-Fi antenna 2, along with Wi-Fi module 4 and Wi-Fi signal monitor 8, continues to monitor and detect the level of received Wi-Fi signals. If in the time window T₁During which the detected Wi-Fi signal level remains equal to or greater than V_th1Then in the time window T₁Upon expiration, timer unit 7 sends a cellular tear down signal and a Wi-Fi link signal to network switch unit 6 via signal line 11. In response, network switch unit 6 sends a detach signal to cellular module 3 via signal line 15 and a link signal to Wi-Fi module 4 via signal line 13. The network switch unit 6 also instructs the audio/video amplifier 5 via a signal line 14 to generate an audio/video alarm signal. The generated audio alert signal is then replayed by the speaker 21 via the signal line 18, and the generated video alert signal is then replayed by the display monitor 22 via the signal line 23. The audio/video alert tone is adapted to notify the mobile communication device user of a network switch from cellular to Wi-Fi.

After receiving the teardown signal, the cellular module 3 is adapted to terminate the connection to the cellular network and to disconnect the connection to the audio/video amplifier 5. Upon receiving the Wi-Fi link signal, the Wi-Fi module 4 is adapted to activate a connection to the VoIP network and to switch on a connection to the audio/video amplifier 5 for passing voice signals to the audio amplifier 5 and video signals to the display monitor 22. The previously established communication link is thus continuously uninterrupted via the VoIP network and passes through the speaker 21, the microphone 20 and the display monitor 23.

Assume that mobile communication device 100 is communicating with a VoIP network and may be leaving the coverage area of a Wi-Fi access point. Wi-Fi antenna 2, along with Wi-Fi module 4 and Wi-Fi signal monitor 8, continuously monitors to detect Wi-Fi signals. If the detected Wi-Fi letterThe signal level being below a second predetermined threshold V_th2Wi-Fi signal level monitor 8 activates timer 7 and sends a wake-up signal to network switch unit 6 to change the state of network switch unit 6 from sleep mode to standby mode. Network switch unit 6 in turn supplies a wake-up switch signal to cellular module 3 and Wi-Fi module 4 to enable these modules to activate their respective switching processes.

As shown in FIG. 3, once activated, the timer means 7 establishes a second time window T of a second predetermined size₂. In a time window T₂During which Wi-Fi antenna 2, along with Wi-Fi module 4 and Wi-Fi signal monitor 8, continues to monitor and detect the level of received Wi-Fi signals. If in the time window T₂During which the detected Wi-Fi signal level is equal to or greater than a third predetermined threshold value V_th3In which V is_th3Less than V_th2The previously established VoIP communication continues without a transition.

If in the time window T₂During which the detected Wi-Fi signal level is less than V_th3Then in the time window T₂Upon expiry, the timer means 7 are reset and activated to establish a third time window T of a third predetermined size₃Wherein T is₃Less than T₂. If in the time window T₃During which the detected Wi-Fi signal level is equal to or greater than V_th3The previously established VoIP communication continues without a transition.

If in the time window T₃During which the detected Wi-Fi signal level is less than V_th3Then in the time window T₃Upon expiration, timer unit 7 sends a Wi-Fi detach signal and a cellular link signal to network switch unit 6. In response, network switch unit 6 sends a tear down signal to Wi-Fi module 3 and a link up signal to cellular module 4. The network switch unit 6 also instructs the audio/video amplifier 5 to generate an audio/video alarm signal. The generated audio alert signal is then played back by the speaker 21 and the generated video alert signal is then played back by the display monitor 22. Audio/video alert tone adapted to notify a mobile communication device user of Wi-Fi to cell for network switching.

Upon receiving the teardown signal, Wi-Fi module 4 is adapted to terminate the connection to the VoIP network and to cut off the connection to audio/video amplifier 5. After receiving the Wi-Fi link signal, the cellular module 4 is adapted to activate a connection to a cellular network and to switch on a connection to the audio/video amplifier 5. The previously established communication link is thus continuously uninterrupted and passes through the loudspeaker 21, the microphone 20 and the display monitor 23.

In accordance with certain embodiments, if the mobile communication device detects Wi-Fi signals from the access point and cellular signals from the mobile cellular base station before establishing the communication link, the mobile communication device first attempts to establish communication with the Wi-Fi access point using Wi-Fi module 4.

The above-described embodiments of the present invention are intended to be illustrative, not limiting. Various alternatives and equivalents are possible. It will be appreciated that the functionality associated with any of the blocks described above may be centralized or distributed, whether locally or remotely. It will also be understood that one or more blocks of each mobile communication device may be implemented in hardware, firmware, or software, or some combination thereof. The present invention is not limited by the type of cellular network (e.g., CDMA, GSM, or otherwise) that carries the communications. The present invention is also not limited by VoIP networks. The present invention is not limited by Wi-Fi signals (such as those defined by IEEE802.11x, where x may be a, b, g) or WiMAX that are used to carry VoIP communications. The invention is not limited by the type of integrated circuit in which the invention may be arranged. The invention is also not limited to any particular type of processing technology (e.g., CMOS, bipolar, or BICMOS) that may be used to fabricate the invention. Other additions, subtractions or modifications are obvious in view of the present disclosure and are therefore considered to be within the scope of the appended claims.

Claims (17)

1. A mobile communication device, comprising:

a cellular communication module adapted to communicate with a wireless cellular network;

a Wi-Fi communication module adapted to communicate with an access point associated with a Wi-Fi network that utilizes a VoIP protocol;

switching circuitry adapted to automatically switch operation between the cellular communication module and the Wi-Fi communication module,

a timer; and

Wi-Fi signal monitor, whereinIf the Wi-Fi signal monitor detects that a first Wi-Fi signal level is greater than a first predetermined threshold V_th1The timer is activated to establish a first time window T of a first predetermined size₁Wherein if at T₁During which the Wi-Fi signal monitor detects that a second Wi-Fi signal level is equal to or greater than V_th1Then, upon expiration of the first time window, the switching circuit sends a tear-down signal to the cellular communication module and a link signal to the Wi-Fi communication module, wherein the tear-down signal causes the cellular communication module to interrupt processing of a previously established cellular communication, and wherein the link signal causes the Wi-Fi communication module to process the previously established cellular communication via a VoIP network.

2. The mobile communication device of claim 1, wherein the wireless cellular network is selected from the group consisting of GSM, CDMA, and CDMA2000 wireless cellular networks.

3. The mobile communication device of claim 2, wherein the Wi-Fi network is selected from the group consisting of an IEEE802.11x, Wi-Fi, and WiMAX network.

4. The mobile communication device of claim 1, wherein the network switching circuitry causes the state of the Wi-Fi communication module to change from a sleep mode to an active mode upon activation of the timer.

5. The mobile communication device of claim 1, wherein the first and second Wi-Fi signal levels are each defined by a respective plurality of samples of the received Wi-Fi signal.

6. The mobile communication device of claim 1, wherein if the Wi-Fi signal monitor detects that the Wi-Fi signal level is below a second predetermined threshold V_th2Then the timer is activated to establish a second time of a second predetermined sizeMiddle window T₂Wherein if in the time window T₂During which the Wi-Fi signal monitor detects that the Wi-Fi signal level is equal to or greater than a third predetermined threshold V_th3The previously established VoIP communication continues without switching, where V_th3Less than V_th2。

7. The mobile communication device of claim 1, wherein the detach signal causes the cellular communication module to enter a sleep mode.

8. The mobile communication device of claim 1, wherein

The wireless cellular network is selected from the group consisting of GSM, CDMA, and CDMA2000 wireless cellular networks;

the Wi-Fi network is selected from the group consisting of an IEEE802.11x, Wi-Fi, and WiMAX network; and is

The detach signal causes the cellular communication module to enter a sleep mode.

9. The mobile communication device of claim 1, wherein

The wireless cellular network is selected from the group consisting of GSM, CDMA, and CDMA2000 wireless cellular networks;

the Wi-Fi network is selected from the group consisting of an IEEE802.11x, Wi-Fi, and WiMAX network; and is

Upon activation of the timer, the network switching circuitry causes the state of the Wi-Fi communication module to change from a sleep mode to an active mode.

10. The mobile communication device of claim 1, wherein

The wireless cellular network is selected from the group consisting of GSM, CDMA, and CDMA2000 wireless cellular networks;

the Wi-Fi network is selected from the group consisting of an IEEE802.11x, Wi-Fi, and WiMAX network; and is

The first and second Wi-Fi signal levels are each defined by a respective plurality of samples of the received Wi-Fi signal.

11. The mobile communication device of claim 1, wherein

The wireless cellular network is selected from the group consisting of GSM, CDMA, and CDMA2000 wireless cellular networks;

the Wi-Fi network is selected from the group consisting of an IEEE802.11x, Wi-Fi, and WiMAX network; and is

If the Wi-Fi signal monitor detects that the Wi-Fi signal level is below a second predetermined threshold V_th2Then the timer is activated to establish a second time window T of a second predetermined size₂Wherein if in the time window T₂During which the Wi-Fi signal monitor detects that the Wi-Fi signal level is equal to or greater than a third predetermined threshold V_th3The previously established VoIP communication continues without switching, where V_th3Less than V_th2。

12. The mobile communication device of claim 11, wherein if in time window T₂During the period, the Wi-Fi signal monitor detects that the Wi-Fi signal level is less than V_th3Then in the time window T₂Upon expiration, the timer component is activated to establish a third time window T of a third predetermined size₃Wherein T is₃Less than T₂Wherein if in the time window T₃During the period, the Wi-Fi signal monitor detects that the Wi-Fi signal level is less than V_th3The switching circuit sends a tear-down signal to the Wi-Fi communication module and a link signal to the cellular communication module, wherein the tear-down signal causes the Wi-Fi communication module to interrupt a previously established VoIP communication, and wherein the link signal causes the cellular communication module to process the previously established VoIP communication via a cellular network.

13. The mobile communication device of claim 12, wherein the predetermined period of time T₂At the time of expiration, theNetwork switching circuitry causes a change in state of the cellular communication module from a dormant mode to an active mode.

14. A method comprising the steps of:

detecting a first Wi-Fi signal level;

if the detected first Wi-Fi signal level is greater than a first predetermined threshold V_th1Then a first time window T of a first predetermined size is established₁；

Detecting a second Wi-Fi signal level during the first time window; and is

If the detected second Wi-Fi signal level is greater than V_th1Then the ongoing communication via the cellular wireless network is automatically switched to the communication via the VoIP network.

15. The method of claim 14, wherein the wireless cellular network is selected from the group consisting of GSM, CDMA, and CDMA2000 wireless cellular networks.

16. The method of claim 14, wherein the VoIP network communicates with a network selected from the group consisting of ieee802.11x, Wi-Fi, and WiMAX networks.

17. The method of claim 14, wherein the first and second Wi-Fi signal levels are each defined by a respective plurality of samples of the received Wi-Fi signal.