GB2483700A - Siting an access point employing a plurality of antenna beam directions - Google Patents

Abstract

An access point (12, figure 1, 92, figure 5) is adapted to allow access from at least one user device (14, figures 1 and 4), wherein the access point comprises radio frequency transceiver circuitry for communicating over a wireless link with a base station selected from a plurality of available base stations (18, 20, 22, figures 1 and 4), and wherein the access point has a plurality of possible antenna beam directions. The access point determines an available data rate for each of the plurality of possible antenna beam directions; selects an antenna beam direction based on the available data rates 186; identifies the base station with which a wireless link is established using the selected antenna beam direction 196; detects a signal strength of a signal received from the identified base station using the selected antenna beam direction 198; detects a signal strength of a signal received from the identified base station using at least one other antenna beam direction of the plurality of possible antenna beam directions 200; determines a relationship between the detected signal strengths; determines whether the relationship between the detected signal strengths meets a predetermined criterion 202; and notifies a user if the relationship between the detected signal strengths does not meet the predetermined criterion 206. This can allow the user to be notified if it appears that a change in the location of the device would improve its performance.

Description

I

ACCESS POINT SITING

This invention relates to an access point, providing a wireless backhaul connection into a cellular network, and in particular to a method for allowing a user to obtain the best possible data throughput.

W02008/068495 discloses a wireless access point, which allows users of personal computers or other similar devices to establish a wireless connection with the access point. The access point then has a wireless connection into a cellular communications network, for example allowing the users of the personal computers to access the internet. The wireless access point has a controllable antenna beam direction, and suitable control of this beam direction can allow the wireless access point to establish a connection with a selected base station of the cellular communications network.

Specifically, the data rate that is achievable can be measured for various antenna beam directions. The wireless access point can then be operated using the beam direction that gives the highest data rate.

According to a first aspect of the present invention, there is provided a method of operating an access point, wherein the access point is adapted to allow access from at least one user device, wherein the access point comprises radio frequency transceiver circuitry for communicating over a wireless link with a base station selected from a plurality of available base stations, and wherein the access point has a plurality of possible antenna beam directions; the method comprising: determining an available data rate for each of the plurality of possible antenna beam directions; selecting an antenna beam direction based on the available data rates; identifying the base station with which a wireless link is established using the selected antenna beam direction; detecting a signal strength of a signal received from the identified base station using the selected antenna beam direction; detecting a signal strength of a signal received from the identified base station using at least one other antenna beam direction of the plurality of possible antenna beam directions; determining a relationship between the detected signal strengths; determining whether the relationship between the detected signal strengths meets a predetermined criterion; and notifying a user if the relationship between the detected signal strengths does not meet the predetermined criterion.

According to a second aspect of the present invention, there is provided a access point, comprising: radio frequency transceiver circuitry for communicating over a wireless link with a base station selected from a plurality of available base stations; and an antenna system, having a plurality of possible antenna beam directions; wherein the access point is adapted to operate in accordance with the method according to the first aspect of the invention.

This has the advantage that the user can be notified if it appears that the location of the access point could be changed to improve the performance of the device.

For a better understanding of the present invention, and to show how it can be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-Figure 1 is a block schematic diagram, illustrating a first wireless communication system in accordance with an aspect of the invention.

Figure 2 is a more detailed block schematic diagram of an access point in the system of Figure 1.

Figure 3 is a more detailed block schematic diagram of a part of the access point of Figure 2.

Figure 4 is a block schematic diagram, illustrating a second communication system in accordance with an aspect of the invention.

Figure 5 is a more detailed block schematic diagram of an access point in the system of Figure 4.

Figure 6 is a flow chart, illustrating a method of operation of the access point of Figure 2 or Figure 5.

Figure 7 is a flow chart, illustrating a method of operation of the access point of Figure 2 or Figure 5.

Figure 8 illustrates a possible deployment of an access point of Figure 2 or Figure 5.

Figure 1 shows a wireless communications environment 10, containing a wireless access point (AP) 12. The wireless access point 12 provides wireless access for a user of a suitably equipped mobile communications device 14, which may for example be a laptop computer, or another portable device. The wireless access point 12 can for example operate in accordance with one of the family of IEEE 802.11 standards, for example the standards commonly known as WiFi or WiMax. Alternatively, the wireless access point 12 can for example be a OSM pico base station, or any other base station or access point providing local area wireless coverage. For this purpose, the wireless access point 12 includes a first antenna 16, which may for example be an omnidirectional antenna.

The user of the mobile communications device 14, and other suitably equipped devices within the coverage area of the access point 12, can then transfer data to and from the access point 12. In order for the user of the mobile communications device 14 to be able to communicate with other users, or to be able to download data, for example from websites, the access point 12 needs to have a connection over a suitable network.

In the example shown in Figure 1, the wireless access point 12 is located in a wireless communications environment 10, which is typical of many urban areas, in that the wireless access point 12 is located in the coverage areas of a number of cellular base stations, in this case a first base station (BSI) 18, a second base station (BS2) 20 and a third base station (BS3) 22. As is well known, each of these cellular base stations 18, 20, 22 has a connection into the Public Switched Telephone Network (PSTN) (not shown), or into a packet data network, allowing it to establish voice and data calls to and from users of mobile phones and other suitably equipped mobile communications devices within their respective coverage areas.

In accordance with the invention, the access point 12 is provided with a suitable antenna 24, and radio frequency communications circuitry (not shown in Figure 1), allowing it to establish a connection with some or all of the cellular base stations 18, 20, 22. By establishing a connection with one of the cellular base stations, the access point 12 is able to transfer data between the user 14 and a location accessible over the PSTN. For example, the access point can establish a connection between the user 14 and a website to allow the user 14 to download content from the website. Thus, the access point 12 uses the respective cellular network to provide backhaul for its data.

As another illustrative example, the user device may be a VoIP (Voice over IP [Internet Protocol]) phone, establishing an IP connection through the access point 12, with backhaul over the cellular network, to another VoIP phone having an internet connection.

Figure 2 is a schematic diagram, illustrating in more detail the form of the access point 12. As mentioned previously, the access point 12 has a first antenna 16, for communication with users of suitably equipped mobile communications devices, in accordance with one of the family of IEEE 802.11 standards, and the antenna 16 may for example be an omnidirectional antenna to allow communication with suitably equipped mobile communications devices in the whole area around the access point 12.

The antenna 16 is connected to local area coverage RF circuitry 26, as would conventionally be found in an access point operating in accordance with that standard.

For example, where the access point 12 operates in accordance with one of the family of IEEE 802.11 standards, the local area coverage RF circuitry 26 is able to convert received signals into the appropriate data stream, and is able to convert incoming data into signals suitable for transmission over the wireless interface in accordance with that standard.

The local area coverage RF circuitry 26 is connected to cellular coverage RF circuitry 28, as would conventionally be found in a mobile communications device suitable for operating in accordance with the relevant standard or standards. For example, where the access point 12 is intended to establish a connection with a cellular base station (for example, one of the base stations 18, 20, 22) operating in accordance with the GSM standard, then the cellular coverage RF circuitry 28 includes appropriate GSM circuitry. Similarly, where the access point 12 is also intended to establish a connection with a cellular base station (for example, one of the base stations 18, 20, 22) operating in accordance with the UMTS standard, then the cellular coverage RF circuitry 28 also includes appropriate UMTS circuitry.

In this illustrated embodiment of the invention, the cellular coverage RF circuitry 28 is connected to power control circuitry 30, as will be described in more detail below.

The power control circuitry 30 is connected to antenna direction control circuitry 32, which in turn is connected to the cellular antenna 24.

The cellular coverage RF circuitry 28, the power control circuitry 30, and the antenna direction control circuitry 32 operate under the control of a controller 34.

The access point 12 receives electrical power from a power source 36. The power source 36 may be a mains electrical power source, or an electrochemical battery, or may be a power source deriving energy from its environment, such as a solar power source, or a wind power source, or combined wind/solar power source.

The access point 12 operates under the control of a management system 38. The management system 38 is typically contained in firmware running on a processor inside the access point, and can control the operation of the access point 12. It can alternatively be provided on a remote computer. For example, the management system 38 can be connected to the access point 12 over an existing local area network (LAN), or may be wirelessly connected to the access point 12, for example allowing the remote management system 38 to configure the link via ftp, or via a website provided for that purpose.

In addition, the access point has a user interface 40. For example, the user interface 40 may take the form of a display and a keypad provided on the access point itself.

Alternatively, the user interface 40 may be provided by means of a connection to the suitably equipped mobile communications device 14, such that messages to the user are displayed on a screen of the mobile communications device 14, while inputs by means of a keypad, touch screen or mouse of the mobile communications device 14 are accepted as inputs to the access point 12. In particular, the user interface 40 can be used to provide status information to the user, and to allow the user to set various configuration parameters of the device, as described in more detail below.

Figure 3 is a more detailed block schematic diagram of a part of the access point 12.

Specifically, Figure 3 shows in more detail the cellular coverage RF circuitry 28, the power control circuitry 30, the antenna direction control circuitry 32, and the cellular antenna 24.

As shown in Figure 3, the antenna 24 includes four antenna elements 24a, 24b, 24c, 24d, although it will be appreciated that any convenient number of antenna elements can be provided. In particular, an antenna with eight antenna elements may be particularly suitable for this implementation. Each of these antenna elements 24a, 24b, 24c, 24d is directional. That is, each of the antenna elements 24a, 24b, 24c, 24d transmits signals preferentially in one direction, in azimuth, and is most sensitive to received signals from the same direction. These preferential directions are preferably all different, and are equally spaced around the azimuth, such that the antenna 24 is essentially omnidirectional. However, it is also possible for the antenna 24 to be formed of antenna elements whose preferential directions are not equally spaced in this way, with the result that the antenna 24 will not be omnidirectional, but will be at least somewhat directional.

As mentioned above, the cellular coverage RF circuitry 28 is connected to power control circuitry 30, which is shown in more detail in Figure 3. For example, the power control circuitry 30 could include a duplexer 42, for separating and combining signals at the RF transmit and receive frequencies in the relevant cellular networks.

Thus, transmit signals from the cellular coverage RF circuitry 28 pass through the duplexer 42 to a power amplifier 44, before being passed to the antenna direction control circuitry 32. The power amplifier is provided in order to be able to amplify the signals more than would usually be the case in a cellular user equipment, thereby allowing the access point to establish a connection to a cellular base station (for example one of the base stations 18, 20, 22, shown in Figure 1)that is more distant than the base station that a cellular base station would conventionally access. The degree of amplification provided by the power amplifier 44 is determined by the controller 34 by means of a signal passed along a control line 46.

Somewhat similarly, received signals from the antenna 24 and the antenna direction control circuitry 32 pass through a low noise amplifier 48, before being passed through the duplexer 42 to the cellular coverage RF circuitry 28. The low noise amplifier 48 is provided in order to be able to amplify the signals more than would usually be the case in a cellular user equipment, thereby allowing the access point to establish a connection to a cellular base station (for example one of the base stations 18, 20, 22, shown in Figure 1) that is more distant than the base station that a cellular base station would conventionally access. The degree of amplification provided by the low noise amplifier 48 is determined by the controller 34 by means of a signal passed along a control line 50.

After passing through the power amplifier 44, the transmit signals are divided, and passed through respective gain control elements, in this case controllable attenuators 52a, 52b, 52c, 52d, and through respective duplexers 54a, 54b, 54c, 54d to the respective antenna elements 24a, 24b, 24c, 24d.

Somewhat similarly, received signals from the antenna elements 24a, 24b, 24c, 24d pass through the respective duplexers 54a, 54b, 54c, 54d to respective gain control elements, in this case controllable attenuators 56a, 56b, 56c, 56d, before being combined and passed to the low noise amplifier 48.

The degree of attenuation provided by each of the controllable attenuators 52a, 52b, 52c, 52d, and 56a, 56b, 56c, 56d is determined by the controller 34 by means of signals passed along a control line, or lines, 58.

Thus, by controlling the degree of attenuation in each of the signal paths to and from the antenna elements 24a, 24b, 24c, 24d, the effective beam shape of the antenna 24 can be altered. That is, if each of the controllable attenuators 52a, 52b, 52c, 52d, and 56a, 56b, 56c, 56d provides an equal degree of attenuation, or provides no attenuation at all, the antenna elements 24a, 24b, 24c, 24d transmit signals with equal amplitudes, and are equally sensitive to received signals, and so, depending on the respective preferred directions of the antenna elements 24a, 24b, 24c, 24d, the antenna 24 may be effectively omnidirectional.

By contrast, if the signals in the signal paths to and from one of the antenna elements 24a, 24b, 24c, 24d are not attenuated, or are only slightly attenuated, while the signals in the signal paths to and from the other antenna elements 24a, 24b, 24c, 24d are strongly attenuated, the effective beam shape of the antenna 24 strongly resembles the beam shape provided by the antenna element whose signals are not attenuated, or are only slightly attenuated.

That is, by suitable control of the controllable attenuators 52a, 52b, 52c, 52d, and 56a, 56b, 56c, 56d the antenna 24 can be made to be highly directional.

Usually, the controllable attenuators 52a, 52b, 52c, 52d, and 56a, 56b, 56c, 56d are controlled such that the attenuators of the pairs 52a, 56a; 52b, 56b; 52c, 56c; and 52d, 56d in the signal paths to and from the respective antenna elements 24a, 24b, 24c, 24d are controlled in the same way, such that the antenna 24 has the same beam shape and size in the uplink path as in the downlink path, but this need not necessarily be the case.

Although the invention is illustrated above with reference to an embodiment in which controllable attenuators are located in the signal paths to and from the antenna elements, it is equally possible to provide a beam switched antenna, with switches provided, for switching the respective antenna elements into and out of the signal paths. Thus, by switching only one or a small number of the antenna elements into the signal paths, the antenna 24 can be made highly directional.

Further, the antenna may alternatively include only a small number of antenna elements, such that they form a directional antenna, with means being provided (for example, a mechanical rotational device) for altering the direction of the antenna.

Controlling the antenna 24 such that it becomes somewhat directional has the further advantage that the transmission paths from the access point 12 to one of the cellular base stations, and from the cellular base station to the access point 12 become much less affected by multipath transmissions. For example, to illustrate this, if the antenna 24 of an access point 12 is made directional, with its preferred direction pointing towards the cellular base station with which it has established a connection, the access point is less likely to be affected by reflections of the signals transmitted from the cellular base station, because these reflections are likely to be arriving from a direction that is different from the preferred direction.

Figure 4 is a block schematic diagram of an alternative communications system in accordance with an aspect of the invention. In this system, there is again provided an access point 92 located in a wireless communications environment 10, and specifically located in the coverage areas of a first base station (BS1) 18, a second base station (BS2) 20 and a third base station (BS3) 22, forming part of one or more cellular telephone networks.

In accordance with the invention, the access point 12 is provided with a suitable antenna 24, and radio frequency communications circuitry allowing it to establish a connection with some or all of the cellular base stations 18, 20, 22.

Figure 5 is a more detailed block schematic diagram showing the form of the access point 92. Specifically, the access point 92 includes a local area network interface 94, which may for example be an Ethernet interface, allowing one or more computers 14 or other devices to establish a connection thereto. The connections of the computers may be wired or wireless. The local area network interface 94 is connected to cellular coverage RF circuitry 28, power control circuitry 30, antenna direction control circuitry 32, and a cellular antenna 24, all of which are as described above with reference to Figure 2 and Figure 3, and therefore will not be described in more detail. The access point 92 similarly includes a management system 38, which is as described above with reference to Figure 2 and Figure 3, and therefore will not be described in more detail.

In this case, the functionality of the access point 92 can simply be provided in a personal computer, for example the computer 14, which therefore may not be a

portable device.

In addition, the access point has a user interface 40. For example, the user interface may take the form of a display and a keypad provided on the access point itself.

Alternatively, the user interface 40 may be provided by means of a connection to the device 14, such that messages to the user are displayed on a screen of the device 14, while inputs by means of a keypad, touch screen or mouse of the device 14 are accepted as inputs to the access point 12. In particular, the user interface 40 can be used to provide status information to the user, and to allow the user to set various configuration parameters of the device, as described in more detail below.

In accordance with an aspect of the invention, the access point 92 provides backhaul for data that the user of the computer 14 wishes to communicate through the access point 92.

In a preferred embodiment, the cellular coverage RF circuitry 28 is provided on a data card, for example such as a so-called 3G data card. As is known, such a data card can conventionally be inserted into a mobile device, such as a portable computer, in order to allow a user of the portable computer to communicate over the relevant cellular network. In this case, the data card can be inserted into the access point 12, or the access point 92, in order to allow a user of a device having a wireless or wired connection into the access point to communicate over the relevant cellular network.

Figure 6 is a flow chart, illustrating a process in accordance with an aspect of the invention, which may be performed in, or under the control of, the controller 34 in the access point 12 or the access point 92.

The process starts at step 140, which may for example take place when the access point is first switched on, or at some subsequent time. In step 142, the controller 34 presents the user with a menu of configuration options. As discussed above, these may be presented by means of a display on the access point itself, or may be presented on a display of the device 14 after a connection has been established between the device 14 and the access point. The user of the device is then able to select options from the menu, or to provide his intended inputs, for example by means of a keypad on the device 14, or by highlighting and selecting the intended inputs by means of a mouse or other input device, as examples.

The configuration options presented to the user relate to the throughout measurements that are to be made, as part of the procedure for selecting a suitable beam direction.

The process shown in Figure 6 then involves reading the inputs provided by the user.

Thus, in step 144, the controller 34 reads a test duration selected and entered by the user. That is, the user is able to select the duration of each throughput measurement that is made. The duration can be expressed in terms of a fixed time period, with the throughput measurement then being a function of the amount of data that can be transferred in that period. It will be appreciated that a longer test duration will usually allow more accurately representative measurements of the available throughput to be made, while a shorter test duration allows a beam direction to be selected more quickly, and so making this duration selectable by the user allows the user to prioritise between these factors.

In step 146, the controller 34 reads a test direction selected and entered by the user.

That is, the user is able to select whether each throughput measurement is made on the uplink from the user to a remote site, or on the downlink to the user from a remote site, or on a combined measurement on the uplink and downlink. Again, this allows the user to set a configuration parameter for the throughput measurement so that the test reflects the user's intended usage of the access point, so that the results have the most effect in terms of improving the performance of the device. For example, if the user is planning primarily to download data, the test can be carried out on the basis of downlink measurements, while if the user is planning primarily to upload data, the test can be carried out on the basis of uplink measurements.

In step 148, the controller 34 reads a data throughput parameter selected and entered by the user. That is, the user is able to select whether the controller should select a beam direction on the basis of an average data rate during the test, or on the basis of a minimum data rate achieved at any point in the test, or on the basis of a maximum data rate achieved at any point in the test, or on the basis of any combination of these parameters. For example, the user might be able to select that the beam direction is selected based on a combination of an average data rate and a maximum data rate achieved during a test, or based on a combination of an average data rate, a minimum data rate and a maximum data rate achieved during a test.

In step 150, the controller 34 reads a test repeat interval selected and entered by the user. Thus, the user can select how often the throughput measurement should be repeated. Making the measurements more often will mean that the access point is able to react more quickly to changes in the radio environment, but each test involves using the available bandwidth resources of the network and of the access point itself, and so it is not desirable for the test to be repeated too often.

In step 152, the controller 34 reads a time of day selected and entered by the user.

Thus, the user can select when future throughput measurements are to be made. For example, if the controller 34 reads in step 150 that the throughput measurement is to be repeated every 24 hours, the user is able to select the time in each day when the measurement is to be made. Ideally, the user should select a time when they will not be using the access point, because the throughput measurements may impact on the normal use of the access point while they are being carried out. Thus, the user may select a time in the middle of the night for carrying out the measurements. However, the measurements should ideally be carried out at a time when the cellular network usage pattern is at least somewhat similar to the times when the user intends to use the access point.

That is, different basestations in the cellular network might be differently loaded at different times of day. Thus, basestations in cities might be most heavily loaded during working hours, while basestations in residential areas might be most heavily loaded during evenings, with the result that a higher throughput might be achieved from a basestation in a residential area during working hours, and from a basestation in a city during an evening. It is therefore advantageous for the user to schedule throughput measurements to take place at a time of day when the network usage pattern during a Having read this information provided by the user, the controller 34 is able to start the beam selection process, which is illustrated in more detail in Figure 7.

The process starts at step 170, and passes to step 172, in which it is determined whether the device is in its initial start up. If so, the process passes to step 174, in which a beam direction is selected. As discussed above, different beam directions can be selected by appropriate control of the controllable attenuators 52a, 52b, 52c, 52d, and 56a, 56b, 56c, 56d in the signal paths to and from the respective antenna elements 24a, 24b, 24c, 24d. For example, beam directions resembling the preferred directions of the antenna elements 24a, 24b, 24c, 24d can be selected in turn by choosing not to attenuate the signals in the signal paths to and from those antenna elements in turn.

Where the antenna is a beam switched antenna, different beam directions can be selected in turn by switching the different antenna elements into the signal paths in turn. Where the antenna is a rotatable directional antenna, different beam directions can be selected in turn by rotating the antenna.

Causing the antenna 24 of the access point 12 or 92 to become relatively highly directional constrains its ability to establish connections with the surrounding base stations. For each possible direction, the access point 12 or 92 may only be able to establish a connection with one of the surrounding base stations, and so the data rate over that connection can be measured.

In step 176, it is determined whether the access point 12 or 92 can establish a connection into a cellular network at the selected beam direction, with an acceptable signal quality, within a time period, such as 5 seconds.

If so, the process passes to step 178, in which the data rate available over that connection is measured and stored. For example, referring back to Figure 1, even though the three base stations 18, 20, 22 may all be provided by a single mobile network operator, they may be different types of base station. For example, one may be a GSM base station, one may be a UMTS base station, and one may be a UMTS base station that allows High Speed Uplink Packet Access (HSUPA), or High Speed Downlink Packet Access (HSDPA), or both. In that case, the UMTS base station allowing HSUPA or HSDPA will allow a higher data rate than the UMTS base station not allowing HSUPA or HSDPA, though the latter will still allow a higher data rate than the GSM base station.

It has been noted that, in the first few seconds after establishing a connection, an abnormally high data rate may be achieved. Therefore, in order to avoid this factor from making the measured throughput unrepresentative of the actual usage of the access point, this initial period of, say, 3 seconds or 5 seconds, is disregarded when monitoring the data rate.

The available data rate is measured by establishing a connection to a remote site. For example, a mobile network operator may establish a suitable site hosted at a particular server. Based on the selected test direction read by the processor 34 in step 146 of the process in Figure 6, it then attempts to upload data to the site, and/or download data from the site. The duration of this test is based on the selected test duration read by the processor 34 in step 144 of the process in Figure 6.

If it is determined in step 176 that no connection can be established within the specified time period, the process passes to step 180, in which it is determined whether this time period is at its maximum value. If so, it is determined that it will not be possible to establish a suitable connection, and the test of this beam direction is ended. If it is determined in step 180 that the time period has not reached its maximum value, the process passes to step 182, in which the time period is increased, following which the process returns to step 176, in which it is determined whether a connection can be established in this longer time period. For example, the time period may initially be set to 5 seconds, and it may then be increased to 10 seconds, and finally to a maximum value of 20 seconds.

After completing a test of a beam direction, the process passes to step 184, in which it is determined whether all of the possible beam directions have been tested. If not, the process returns to step 174, and continues until all of the possible beam directions have been tested. When this occurs, the process passes to step 186, in which one of the beam directions is selected. Alternatively, if all of the beam directions are tested, without any of them being able to establish a suitable connection into the cellular network through any base station, the controller 34 can arrange for a message to be presented to the user, for example by means of the display on the device 14, indicating that the location of the access point device needs to be changed. For example, if the access point device is located in a heavily screened location, it may not be able to establish a strong connection with any cellular base station, but this might be improved by, for example, moving the access point device close to a window in a building.

Having completed tests on multiple beam directions, with process having passed to step 186, the controller 34 then selects a beam direction based on these results, using the selected throughput parameter read by the controller 34 in step 148 of the process in Fi9ure 6. Thus, for example, the beam direction might be selected on the basis of an average data rate during the test, or on the basis of a minimum data rate achieved at any point in the test, or on the basis of a maximum data rate achieved at any point in the test, or on the basis of a combination of an average data rate and a maximum data rate achieved during a test, or on the basis of a combination of an average data rate, a minimum data rate and a maximum data rate achieved during a test.

The user can select an appropriate throughput parameter, depending on his intended usage of the access point. For example, the appropriate throughput parameter might differ, depending on whether the user is planning to use the access point for large file transfers, web browsing, or audio or video streaming.

The information about the available data rates might also be presented to the user, for example on a display of the device 14 as before, allowing the user to make a selection of the beam direction, based on this information.

The procedure described so far assumes that the access point has just been first powered on. However, if it is determined in step 172 that the access point is not in its initial start up, this full testing may be avoided, and so the process passes instead to step 188. In step 188, it is determined whether it is time to select a beam direction.

The access point is able to determine the date and time by suitable connection to a time server that is accessible over the internet, and is able to determine whether the current time matches the time for the next test, which is determined by the interval or the time selected by the user and read in steps 150 and 152 of the process shown in Figure 6.

If it is determined in step 188 that a time has been reached when a beam selection should be performed, the process can simply return to step 174, and the beam selection process described above can be performed in the same way. However, in this illustrated embodiment, steps might be taken to reduce the number of times that the beam selection is repeated. Specifically, in this illustrated embodiment, the process passes to step 190. In step 190, it is determined whether the orientation of the access point device has changed since the last beam selection was performed. The orientation can be determined by providing a compass in the access point or by some other method. If the orientation of the device has changed, the process can return immediately to step 174, as it will follow from this that the preferred beam direction will have changed. Similarly, the access point can be provided with accelerometers or other movement sensors, so that a new beam selection is performed whenever it is determined that the position of the access point device has changed.

If it is determined in step 190 that the orientation of the device has not changed, the process passes to step 192, in which a test is performed on the previously selected beam direction. The process then passes to step 194, in which it is determined whether the available throughput parameter is close to the previously obtained value.

For example, if the relevant parameter is the maximum available data rate, it might be determined whether the maximum available data rate is within 20% of the previously measured value. If so, it can be determined that there is no need to repeat the beam selection procedure, and the process can pass direct to step 186, in which the same beam direction is selected again.

Thus, by altering the beam direction, the access point 12 or 92 effectively forces the cellular network to establish a connection between the access point 12 or 92 and a particular cellular base station, based on the requirements of the access point 12 or 92.

In one embodiment of the invention, the controller 34 also selects an alternative beam direction, that can be used to provide a connection to an alternative cellular base station, for use in the event that the connection to the first selected base station fails for any reason.

This selection of an alternative beam direction can be performed in the case of a beam definable antenna, or in the case of a beam switched antenna. In either case, the alternative beam direction is kept active, even while the first selected beam direction is in use.

As mentioned above, the controller 34 can also boost the power of transmitted and received signals by means of the power control circuitry 30, in order to make it possible for the access point 12 or 92 to establish connections to cellular base stations, even though the access point 12 or 92 may not be within the normal coverage areas of those cells.

Having selected a preferred beam direction, on the basis that it provides the highest available data throughput, a further test is performed.

Figure 8 illustrates a typical situation in which the access point 12 or 92 might be deployed. Specifically, Figure 8 shows the deployment of an access point 92 (exactly the same description applies to an access point 12 of the type shown in Figures 1 and 2) in a premises having windows 212a, 212b, 212c, 212d, 212e, 212f on different walls thereof.

In such a situation, the quality of the connection between the access point 92 and the selected one of the base stations 18, 20, 22 will depend on the location of the antenna 24 of the access point 92 within the premises 210. The invention will be described below with reference to an example in which the antenna 24 has four possible preferred beam directions U, D, L, R, extending respectively up, down, to the left, and to the right, as shown in Figure 8.

Returning to Figure 7, once the preferred beam direction has been selected in step 186, the process passes to step 196.

When the preferred beam direction has been selected, the controller 34 can extract information from the signals received by the access point 92. For example, as the preferred beam direction is chosen on the basis of an examination of the available data rate through a specific one of the surrounding base stations 18, 20, 22, the controller 34 can detect signals transmitted by that specific base station that identify the base station itself.

Thus, in step 196, the controller 34 is able to identify a preferred base station, being the base station with which the connection is established to achieve the highest possible data throughput.

In step 198, the controller 34 measures the signal strength of the signals received from that preferred base station, with the antenna 24 configured such that the preferred beam direction is being used.

Having identified the base station, in step 200 the controller also measures the signal strength of the signals received from that preferred base station, with the antenna 24 configured such that other possible beam directions are being used.

Thus, as an illustration of this, in the example shown in Figure 8, the throughput test might reveal that the access point 92 can achieve the highest data throughput with the direction R selected as the preferred beam direction. For example, this might occur because the first and third base stations 18, 22 are more heavily loaded than the second base station 20, or because the second base station 20 has features that are not available in the first and third base stations 18, 22.

In such cases, it will typically follow that the highest data throughput can be achieved when the preferred beam direction of the antenna 24 is the direction that points most nearly towards the base station that can provide the highest data throughput.

Thus, in this example, the direction R is selected as the preferred beam direction, and in step 196 the second base station 20 can be identified from its transmissions as the preferred base station.

In step 198, the signal strength of the transmissions from the second base station 20 can be determined with the direction R set as the preferred beam direction of the antenna 24. Many mobile communications applications require the measurement of the signal strength of the transmissions from a cellular base station, and so the method of performing the required measurements need not be described in detail. In general terms, the controller 34 can request a signal strength measurement from the cellular coverage RF circuitry 28, and can use the reported value after waiting for a few second until the measurement has reached a steady state value.

While reference is made here to an explicit measurement of signal strength, the signal strength measurement can be any metric that allows the signal strength or quality to be derived or inferred.

In step 200, the signal strengths of the transmissions from the second base station 20 can be determined with the directions U, L and D set in turn as the preferred beam direction of the antenna 24. It will be apparent that, in any of these cases, the signal strengths of the transmissions from the second base station 20 might be lower than the signal strengths of the transmissions from one or more of the other base stations, so the transmissions from the second base station 20 must be separated out from the transmissions from the other base stations before the signal strength is measured.

Having measured the signal strengths of the transmissions from the preferred base station 20 with the preferred beam direction of the antenna 24 set to the four possible directions, these signal strengths are ranked, from strongest to weakest, as Si, S2, S3, S4. For example, it might be expected that the strongest signal will be achieved when the preferred beam direction of the antenna 24 is pointing as nearly as possible towards the preferred base station. In the case illustrated in Figure 8, the strongest signal might be achieved when the preferred beam direction of the antenna 24 is set to the direction R. In step 202, these signal strengths are compared. Specifically, it is determined whether the difference S -S4 between the strongest signal and the weakest signal is calculated, and it is determined whether this difference S -S4 exceeds a threshold value, which might for example be 5dB, 10dB, or similar.

The result of this comparison will depend on the position of the access point 92 within the premises 210. Referring to Figure 8, with the second base station 20 being the preferred base station and the direction R set as the preferred beam direction of the antenna 24, the best possible position for the access point 92 within the premises 210 might be close to the window 212c, so that the signals between the antenna 24 and the second base station 20 are subject to the minimum attenuation.

With the access point being close to the window 212c, it is highly likely that the highest detected signal strength S will be achieved with the direction R set as the preferred beam direction of the antenna 24, and it is also highly likely that this highest detected signal strength S will be considerably greater than the signal strengths 52, 53, and 54 detected with the other three directions set as the preferred beam direction of the antenna 24. Thus, it would be expected that the difference value (Si -34) would exceed the threshold value used in step 202.

If the difference value (Si -S4) exceeds the threshold value used in step 202, the process passes to step 204, and ends, it being assumed that the access point 92 is in an acceptable location.

However, if it is determined in step 202 that the difference value (Si -S4) does not exceed the threshold value, the process passes to step 206. For example, such a situation might arise with the access point being close to the window 212f, as shown in Figure 8. In such a situation, it is still likely that the highest detected signal strength S would be achieved with the direction R set as the preferred beam direction of the antenna 24, but this would be reduced compared with the situation in which the access point is close to the window 212c. At the same time, the signal strengths 32, S3, and S4 with the access point being close to the window 21 2f might be similar to, or even higher than, those detected with the access point being close to the window 212c. Thus, this could certainly result in the difference value (Si -S4) not exceeding the threshold value used in step 202.

As described here, the test applied in step 202 is whether or not the difference value (Si -S4) exceeds a predetermined threshold value, i.e. whether (Si -34) > T1. It will be apparent that other tests could be applied, in order to identify situations where the access point 92 is not optimally positioned. For example, the test could be whether the highest detected signal strength S exceeds the average of the other three signal strengths S2, S3, and S4 by a certain threshold value i.e. whether (Si -%[52 ÷ S3 ÷ S4]) > T2, or whether or not the average of the two highest detected signal strengths S, S2, exceeds the average of the other two signal strengths S, and S4 by a certain threshold value i.e. whether ([Si ÷ 32] -[33 ÷ 34]) > T3.

In another example, the signal strength might be measured with the antenna 24 configured such that the preferred beam direction is being used, and with the antenna 24 configured such that the direction opposite to the preferred beam direction is being used. If these measurements give results Sp and S respectively, then the test could be whether the difference between these measurements exceeds a certain threshold value, i.e. whether (S -So) > T. Similarly, the signal strength might be measured with the antenna 24 configured such that the preferred beam direction is being used, and with the antenna 24 configured such that a direction adjacent to the preferred beam direction is being used. If these measurements give results S and 5A respectively, then the test could be whether the difference between these measurements exceeds a certain threshold value, i.e. whether (S -SA) > T. These examples illustrate the possibility that the signal strength measurements might be made on only a subset of the available beam directions, especially when there are a larger number (e.g. eight or more) available beam directions.

In the case where the test is not satisfied, as mentioned above, the process passes to step 206. In step 206, a warning is provided to the user via the user interface 40, either on the access point 92 itself or on the device (such as the computer 14) connected thereto.

This warning notifies the user that an improved operation of the access point 92 might be achieved if the device is repositioned. For example, the access point 92 might be provided with operating instructions suggesting that the best performance might be achieved by locating it near a window, in which case the warning might suggest that the device should be repositioned to be near a different window (if a different window is available).

Depending on the measurements that have been made, more detailed warnings could be given. For example, in the illustrative situation described above, as it has been determined that setting the beam direction R as the preferred beam direction gives the highest data throughput, the controller 34 would be able to notify the user that repositioning the device to be to be near a window in the direction R might give the best results. For example, the access point 92 might have a number of lights around its periphery, and the controller 34 might cause one of these lights to flash, with the position of the light indicating the direction in which the device should be moved.

Thus, following the throughput test, signal strength measurements can be performed to determine whether a repositioning of the device might be able to achieve higher signal strength measurements in the preferred beam direction, as such improvements in the signal strength could be expected to allow the user of the access point to obtain a higher data rate service.

Claims (6)

1. CLAIMS1. A method of operating an access point, wherein the access point is adapted to allow access from at least one user device, wherein the access point comprises radio frequency transceiver circuitry for communicating over a wireless link with a base station selected from a plurality of available base stations, and wherein the access point has a plurality of possible antenna beam directions; the method comprising: determining an available data rate for each of the plurality of possible antenna beam directions; selecting an antenna beam direction based on the available data rates; identifying the base station with which a wireless link is established using the selected antenna beam direction; detecting a signal strength of a signal received from the identified base station using the selected antenna beam direction; detecting a signal strength of a signal received from the identified base station using at least one other antenna beam direction of the plurality of possible antenna beam directions; determining a relationship between the detected signal strengths; determining whether the relationship between the detected signal strengths meets a predetermined criterion; and notifying a user if the relationship between the detected signal strengths does not meet the predetermined criterion.
2. 2. A method as claimed in claim 1, wherein the step of detecting the signal strength of a signal received from the identified base station using at least one other antenna beam direction of the plurality of possible antenna beam directions comprises detecting the signal strengths of signals received from the identified base station using every other antenna beam direction of the plurality of possible antenna beam directions.
3. 3. A method as claimed in claim I or 2, wherein the relationship between the detected signal strengths comprises a difference between a highest signal strength and a lowest signal strength of the detected signal strengths, and wherein the step of determining whether the relationship between the detected signal strengths meets a predetermined criterion comprises determining whether the difference between the highest signal strength and the lowest signal strength of the detected signal strengths exceeds a threshold value.
4. 4. A method as claimed in any preceding claim, further comprising notifying the user of action that might be taken to cause the relationship between the detected signal strengths to meet the predetermined criterion.
5. 5. A method as claimed in claim 4, further comprising notifying the user of a direction in which the access point might be moved to cause the relationship between the detected signal strengths to meet the predetermined criterion.
6. 6. An access point, comprising: radio frequency transceiver circuitry for communicating over a wireless link with a base station selected from a plurality of available base stations; and an antenna system, having a plurality of possible antenna beam directions; wherein the access point is adapted to operate in accordance with a method as claimed in any of claims I to 5.