GB2513289A

GB2513289A - Determining the suitability of locations for devices in a wireless network

Info

Publication number: GB2513289A
Application number: GB1222898.7A
Authority: GB
Inventors: Marius Munder; Shoaib Javed; Jonathan Oliver Smith
Original assignee: Telegesis UK Ltd
Current assignee: Telegesis UK Ltd
Priority date: 2012-12-19
Filing date: 2012-12-19
Publication date: 2014-10-29
Anticipated expiration: 2032-12-19
Also published as: GB2513289B; GB201222898D0

Abstract

A hub unit (401) and satellite unit (402) are located in or near proposed locations for first and second devices of the wireless network. A first signal is transmitted on a channel of the wireless network from the hub unit (401) to the satellite unit (402) and a first test is performed on the first signal at the satellite unit (402). Results of the first test may be transmitted to the hub unit (401). It is then determined from the results of the first test (and second test, if present) whether the proposed locations of the first and second devices of the wireless network are suitable. The wireless network may be an IEEE standard 802.15.4 network, for example a Zigbee (RTM) Smart Energy network. The satellites are placed in proposed locations for devices in the smart energy network, e.g. the proposed location of the gas meter. The hub unit may be placed in a proposed location for a further device for the smart energy network e.g. the proposed location of the electricity meter. Embodiments of the invention include an apparatus for use as a hub unit, an apparatus for use as a satellite unit and an apparatus for use as a router unit.

Description

Determining the suitability of locations for devices in a wireless network

Field of the Invention

The invention relates to determining the suitability of locations for devices in a wireless network.

Background

ZigBee (RTM) is a specification for high level communication protocols using small, low powered digital radios, based on IEEE standard 802.15.4. The current ZigBee specification is based on the 2003 version of the IEEE standard.

There are three classes of ZigBee devices: * Coordinators form the root of the network, and may connect to external networks. There is one coordinator in each network, which stores information about the network, and can act as a Trust Centre and repository for security keys.

* Routers act as intermediate devices, passing on data from other devices.

Routers may also run an application function.

* End devices run only their own applications, and cannot act as routers. This allows them to remain in a low power state until activated.

It is important that when ZigBee devices are installed, they are capable of communication with each other, as the distance between the devices, objects between the devices, and noise on the signalling frequencies may degrade the connection. For the ZigBee network to function properly, all devices in the network must be able to communicate with each other, whether directly or via one or more routers.

A potential application for ZigBee devices is in smart metering systems. These are systems which monitor the usage of utilities, for example electricity, gas and water, to identify how the utility is being used. These systems include smart meters, which can automatically send consumption information to the utility provider; smart appliances, which can adjust their consumption based on feedback from the system, for example to reduce consumption during peak pricing times; and in home displays, which provide feedback to the consumer about their energy use. This feedback can include which appliances are drawing power during peak pricing periods, up to date metering information, or information from the utility supplier such as the proportion of power generated from renewable sources. The ZigBee Smart Energy specification describes the use of ZigBee devices in a smart metering system.

Summary

As the devices of the Smart Energy network may be large (e.g. a washing machine with Smart Appliance functionality), or difficult to move once installed (e.g. a Smart Meter), it would be useful for the locations for the devices to be determined before they are installed to ensure that they will be able to communicate with other devices in the network.

To this end, there is provided a method for determining the suitability of proposed locations tor devices of a wireless network. The method comprises locating a hub unit (401) in or near a proposed location for a first device of the wireless network (2.5) and locating a satellite unit (402) in or near a second proposed location for a second device of the wireless network (2.4). The method further comprises transmitting a first signal on a channel of the wireless network from the hub unit (401) to the satellite unit (402) (2.6) and performing a first test on the first signal on the channel at the satellite unit (402) (2.7). The method further comprises determining from the results of the test(s) whether the proposed locations of the first and second devices of the wireless network

are suitable (2.11).

The method may comprise transmitting results of the first test to the hub unit (401) (2.8), and/or transmitting a second signal on the channel from the satellite unit (402) to the hub unit (401) (2.9) and performing a second test on the second signal at the hub unit (401)(2.10).

The method may comprise locating a router unit (503) in or near a proposed location for a third device of the wireless network (3.5), with the first (and second, if present) signals being transmitted via the router unit (503) (3.8, 3.14), and optionally tests being performed on the signals at the router unit (503) (3.7, 3.12, 3.13). If the router unit (503) is included, then the suitability of the location for the third device is also determined (3.16).

A pie-test may be peifoimed before the above method. The pre-test comprises transmitting a pre-test signal from the hub unit (401) to the satellite unit (402) (and router unit (503), if present) on the channel to be tested (2.1, 3.1), and transmitting a confirmation signal from the satellite unit (402) (and the router unit (503), if present) to the hub unit (401) on the same channel (2.3, 3.3). The pre-test signal may include configuration information (2.2, 3.2), which may include one or more transmission characteristics of the devices of the wireless network.

The tests may comprise any of: * measuring the packet loss rate of any of the signals, wherein the signals comprise a plurality of data packets; * measuring a power of any of the signals; and * measuring a signal to noise ratio of any of the signals.

The proposed location may be considered unsuitable if the results of any of the tests show any of: * a signal strength below a signal strength threshold value; * a packet error rate above a packet error rate threshold value; and * a signal to noise ratio above a signal to noise ratio threshold value.

The threshold values may be determined by the characteristics of the devices of the If the location is unsuitable, a second channel may be selected, the second channel having a different frequency range to the channel, and the method may be repeated.

Each unit may transmit using the one or more transmission characteristics of a device of the wireless network.

The wireless network may be an IEEE standard 802.15.4 network, or more specifically a ZigBee network.

Further provided are apparatus and a system for use with the above method, and computer programs which cause a device to behave as such an apparatus.

Description of drawings

Figure 1 is example floor plan of a building, with potential locations of devices marked; Figure 2 is a flowchart of a method according to an embodiment; Figure 3 is a flowchart of a method according to an alternative embodiment; Figure 4 illustrates schematically a system suitable for performing the method according to an embodiment; and Figure 5 illustrates schematically a system suitable for performing the method according to an alternative embodiment.

Detailed Description

An object of the present invention is to provide a method and apparatus for determining the suitability of proposed locations for devices in a system of wireless devices such that they can communicate with each other. Embodiments of the invention are described with reference to a ZigBee Smart Energy system; however it will be appreciated by those skilled in the art that the invention applies equally to any system of wireless devices.

A first exemplary embodiment of the present invention will now be presented, with reference to the figures.

A testing system is provided, which includes a portable hub unit (401) and a portable satellite unit (402). The hub unit (401) and the satellite unit (402) communicate with each other over channels to be used by the devices to be installed. The hub unit (401) and satellite unit (402) may communicate using other elements of the wireless protocol used by the devices to be installed, such as the access control and physical layer processing specified by the protocol.

The system is used as illustrated in Figure 2. Note that the pie-test (2.1 to 2.3) does not occur in this embodiment.

2.4 The satellite (402) is placed in or near the proposed location for a first device of the 2.5 The hub (401) is placed in or near the proposed location for a second of the A network may use different channels that operate in different frequency ranges. Some channels may be more suitable than others, e.g. due to the presence of a greater amount of noise on one channel.

2.6 The hub (401) transmits a test signal on a selected channel. This signal may include a number of data packets.

2.7 The satellite (402), upon receiving the test signal, performs signal quality tests.

These tests may include measuring the power of the signal received, the packet loss rate, the signal to noise ratio, etc. 2.8 The satellite (402) transmits the results of these tests to the hub (401). This may be over the selected channel, or by a different communication means.

2.9 The satellite (402) sends a return test signal to the hub (401) over the selected channel. This signal may be a copy of the test signal received from the hub (401).

2.10 The hub (401) performs signal quality tests on the return test signal. These tests may include measuring the power of the signal received, the packet loss rate, the signal to noise ratio, etc. as before. If the return test signal was a copy of the received test signal, the hub (401) may also measure the "round trip" packet loss rate by comparing the test signal sent to the return test signal received.

2.11 The hub (401) uses the results of the signal quality tests at the hub (401) and satellite (402) to determine an overall signal quality for the channel. This signal quality may be a numeric value, a pass/fail rating, or some other measure.

The signal quality for the channel is used to determine if that channel is suitable for communication between devices positioned in the proposed locations, i.e. if the devices will be able to maintain a good connection to each other over the channel if placed in those locations. If the tested channel is found to be unsuitable, the method may be repeated for an alternative channel. If no suitable channel is found, the set of proposed locations is unsuitable.

If a proposed location is found to be unsuitable, it may be still be possible to place a device there and have it connect to a network via a router. The router relays all signalling to and from the device. The router may be a device which functions solely as a router, or another device on the network capable of acting as a router in addition to its normal function.

To determine whether a proposed location for the router is suitable, a system is provided which includes a portable hub unit (401) and portable satellite unit (402), as before, in addition to a portable router unit (503). The portable router unit (503) is configured to act as a router between the portable hub unit (401) and the portable satellite unit (402), and communicates using the same wireless protocol as the hub (401) and satellite units (402).

The system is used as illustrated in Figure 3, note that the pre-test (3.1 to 3.3, 2.2 and 2.3) does not occur in this embodiment. The following numbering corresponds to that of Figure 3.

2.4 The satellite (402) is placed in a proposed location for a first device of the wireless network.

2.5 The hub (401) is placed in a proposed location for a second device of the wireless network.

3.5 The router (503) is placed in a proposed location for a router of the wireless network, which should be between the proposed locations of the first and second devices.

3.6 The hub (401) transmits a test signal to the router (503) on a selected channel.

3.7 The router (503) may perform signal quality tests on the test signal.

3.8 The router (503) transmits the test signal to the satellite (402).

3.9 The satellite (402) performs signal quality tests on the test signal.

3.10 The satellite (402) transmits the results of the signal quality tests to the router (503). As before, this may be over the selected channel, or by a different communication means.

3.11 The satellite (402) transmits a return test signal to the router (503).

3.12 The router (503) may perform signal quality tests on the return test signal.

3.13 The router (503) transmits the results of the tests performed at the satellite (402) (and at the router (503) if carried out) to the hub (401). This may be over the selected channel or by a different communication means.

3.14 The router (503) transmits the return test signal to the hub (401).

3.15 The hub (401) performs signal quality tests on the return test signal.

3.16 The hub (401) calculates an overall signal quality for the channel using the results of all the tests. As before, this may be a numerical value, a pass/fail rating, or some other measure.

If tests are performed at the router (503) as in steps 3.7 and 3.12, this will make it easier to determine if a bad connection is due to the quality of the connection between the router (503) and the hub (401), or the quality of the connection between the router (503) and the satellite (402).

As before, if a channel is found to be unsuitable, then the method may be repeated using a different channel, and if no suitable channel is found for a set of proposed locations, that set of locations is deemed unsuitable.

The satellite (and router! if present) may not transmit the results of the tests back to the hub. Instead, each of the hub (401), satellite (402) and router (if present) (503) units may calculate a signal quality independently based on the test(s) performed at that unit, and the pioposed locations are consideied suitable only if all the calculated signal qualities indicate that the proposed locations are suitable.

The satellite (402) may not transmit a retuin signal, and the signal quality (and suitability of the pioposed locations) may be calculated based solely on the test(s) performed on the signal sent from the hub (401) to the satellite (402). This calculation may be performed eithei at the hub (401) or the satellite (402).

A second exemplary embodiment of the present invention will now be presented, with refeience to the figuies. It will be appreciated by those skilled in the alt that this example is illustiative only, and that not all features are essential foi the invention. For the second embodiment, the devices to be placed are taken to be devices of a ZigBee Smart Energy network, but it will be appreciated that devices using other communication protocols may be used.

A testing system is provided, which includes a hub unit (401) and multiple satellite units (402). The hub unit (401) and the satellite units (402) are configured to communicate according to IEEE standard 802.15.4. The hub unit (401) has a display to relay information to an operator, and inputs so that it can be controlled by the operator.

The operatoi fiist peiforms a pre-test to ensuie that the hub (401) and satellite units (402) can communicate. To perform the pre-test, the operator brings the units together, and selects the pre-test option on the hub unit (401). The hub unit (401)then transmits a signal to the satellite units (402) which contains configuration information for the satellite units (402) regarding further tests to be performed (2.1). This signal is transmitted on one of the channels to be tested. The configuration information may include information about devices which the satellite units (402) are to emulate, and/or signal quality indicators to use in the future tests. The satellite units (402), on receiving the pre-test signal, store the configuration information (2.2) and transmit a confirmation signal to the hub (401) (2.3). This confirmation signal may include data about the state of the satellites (402) such as their serial number, battery status, etc. The hub (401) displays a pass for the pre-test if it receives a confirmation signal from each satellite (402). and a fail if it does not receive a confirmation signal from each satellite (402).

The hub (401) may indicate the satellite(s) (402) from has not received a confirmation signal.

Once the pre-test is passed, the satellites (402) are placed in proposed locations for devices in the Smart Energy network (2.4). For example, with reference to Figure 1, one satellite unit (402) may be placed at the proposed location for the gas meter (104), and another may be placed at the proposed location for the In House Display (102).

The operator then starts the first test on the hub unit (401), which gives a short countdown to allow the hub unit (401) to be placed in a proposed location for a further device of the Smart Energy network (2.5). This may, for example, be the proposed location otthe electricity meter (101).

After the countdown, the hub unit (401) transmits a signal to the satellite units (402) on selected channels (2.6). This signal consists of a high number (e.g. 50) of data packets. The satellite units (402), upon receiving the signal, perform tests on the signal on each channel to determine signal quality (2.7). These tests may include the signal strength, the packet loss rate, the signal to noise ratio, etc. The satellites (402) then transmit a signal on each channel to the hub (401) which includes the packets transmitted from the hub (401) to the satellites (402) (2.9), and the results of the tests at the satellites (402) (2.8). The hub (401) then performs tests on the signals received from the satellites (402) (2.10). The transmission powers of the hub (401) and satellites (402) are specified in the configuration information, and set to emulate the devices that are to be placed at the proposed locations.

The signal strength can be measured by sampling the power of the received signal and taking an average over the samples. The satellites (402) may transmit only the average, or all of the measurements. The packet loss may be measured at the satellite (402) by including the expected packets in the configuration information transmitted in the pre-test, and comparing this to the packets received. The packet loss may be measured at the hub (401) by comparing the packets received from the satellites (402) to the packets transmitted to the satellites (402) (the "round trip" packet loss rate).

The hub (401) then determines a signal quality rating for each channel on which data was transmitted! from the results of the tests on that channel (2.11). This may be a numerical score, or a simple pass/tail rating. As an example, the hub (401) could report a failure for a channel based on it satisfying one of the following criteria: * The round trip packet loss rate is above 10% * The average signal strength at one or more units is below -85 dBm * More than 10% of the signal strength samples are below -85dBrn.

The signal quality for a channel is used to determine if that channel is suitable for communication between devices positioned in the proposed locations. The required signal strength may be adjusted based on the capabilities of the devices to be installed.

The hub (401) will also report a failure for a channel if no response is received from the satellite unit (402) within a specified time. The hub (401) may display the results of the tests for the operator. They may also be stored in memory on the hub (401) so that they can be later retrieved.

If one or more of the channels are found to be unsuitable, then the hub (401) could repeat the test on an alternative selection of channels. This may be done automatically, or require the user to initiate the testing on alternative channels. If a minimum number (e.g. 1) of suitable channels cannot be found for a proposed location, the proposed location is considered to be unsuitable, and either an alternative location should be found, or a router should be used.

To help in determining the ideal locations, the hub (401) may transmit multiple times (e.g. every second), with the satellites (402) echoing the signal as before, and performing the signal quality tests and transmitting the results to the hub (401) as before. The hub (401) may then display the signal quality information in real time, possibly as a moving average of the signal quality measures. This can then be used to find the ideal location for the devices of the Smart Energy Network, by determining the available locations which have the best signal quality. This can be used to select between possible locations for the devices of the wireless network by moving one or more of the testing units during the test. This allows multiple locations to be tested without the need to restart the testing each time a unit is moved.

If there are no suitable locations found, then a router may be necessary to connect the device to the network. The router may be a standalone router, or may be another device in the network which can act as a router in addition to its normal functions.

To test the routed connection, a pre-test is performed as before (3.1 to 3.3, 2.2, 2.3), and the configuration information sets one of the satellites (402) to "router mode" (3.2).

For the remainder of this example, "router' refers to the satellite in router mode (503), and "satellite" only to the other satellite(s) (402). The router (503) is then positioned in a proposed location for the router of the Smart Energy network (3.5), and the other satellite (402) in a proposed location for the device of the Smart Energy network (2.4).

For example, as shown in Figure 1, the router (503) may be positioned at location 103, and the satellite (402) at location 102.

The operator then selects a test to perform, and the hub (401) provides a countdown as before so that it can be positioned in a proposed location for the coordinator (101, 2.5).

Once the countdown is finished, the hub (401) transmits on one or more channels a signal containing a large number of data packets (e.g. 50) to the router (503) (3.6). The router (503) performs tests on the signal (3.7), and then transmits on each channel the same data packets to the satellite (402) (3.8). The satellite (402) then performs tests on the signal (3.9), and transmits on each channel the data packets (3.11) and the results of the tests at the satellite (402) to the router (503) (3.10). The router (503) performs tests on this signal (3.12), and then transmits on each channel the data packets to the hub (401) (3.14), along with the results of the tests on the signal sent from the hub (401) to the router (503), the results of the test on the signal sent from the router (503) to the satellite (402), and the results of the tests on the signal sent from the satellite (402) to the router (503) (3.13). The hub (401) then performs tests on the signal received from the router (503) (3.15).

The tests may include measurements of signal strength, packet loss, etc. as before.

The hub (401) then determines an overall signal quality from the results of the tests, which may be a pass/fail rating (3.16). The signal quality for a channel is used to determine if that channel is suitable for communication between devices positioned in the proposed locations. If no suitable channel is found for a set of proposed locations, then that set of proposed locations is unsuitable. A set of proposed locations may be considered suitable if there are a minimum number of suitable communication channels for devices in those locations.

A suitable location for the router may also be found by having the hub (401) transmit multiple times (e.g. every second) on the channel, and having the router (503) relay the signal between the hub (401) and the satellite (402). The hub (401), router (503) and satellite (402) perform signal quality tests as before, and the router (503) and satellite (402) transmit the results of the signal quality tests to the hub (401) as before. The hub (401) notifies the operator of the signal quality of the connection between the hub (401) and router (503), and the connection between the router (503) and satellite (402). This may be by a visual display, and/or an audio notification when the connection with the router/satellite falls below a certain signal quality threshold. This can be used to select between possible locations for the devices of the wireless network by moving one or more of the testing units during the test. This allows multiple locations to be tested without the need to restart the testing each time a unit is moved.

Figure 4 illustrates schematically a system suitable for use in the embodiments above which do not include a router. The system comprises a hub unit (401) and a satellite unit (402).

The hub unit comprises a transmitter (410) for transmitting a test signal to a satellite unit (402) on a channel and a receiver (411) for receiving a return test signal from the satellite unit (402) on the channel. The hub unit further comprises a processor (413) for performing a second test on the return test signal and a processor (414) for determining a signal quality for the channel using the results of the tests. The hub unit may comprise a receiver (412) for receiving the results of a first test from the satellite unit (402) and/or a display (415) for displaying the results of the tests, and/or the signal quality.

The satellite unit comprises a receiver (420) for receiving the test signal from a hub unit (401) on the channel and a processor (423) for performing a test on the test signal..

The satellite unit also comprises a transmitter (421) for transmitting the return test signal to the hub unit (401) on the channel.

The satellite may comprise a second processor (424) for determining a signal quality for the channel using results of the test! and/or a transmitter (422) for transmitting results of the test to the hub unit (401).

The transmitters (410, 421) of the satellite and hub units may be configured to transmit using transmission characteristics of devices of the wireless network.

Figure 5 illustrates schematically a system suitable for use in the embodiments above which include a router. The system comprises a hub unit (401) and satellite unit (402) as in the system of Figure 4. The system further comprises a router unit (503). The hub unit and satellite unit differ from those in Figure 4 only in that the transmitters and receivers are configured to communicate via the router unit (503).

The router unit (503) comprises a receiver (510) for receiving the test signal from the hub unit (402) on the channel, and a transmitter (520) for transmitting the test signal to the satellite unit (402) on the channel. The router unit (503) further comprises a receiver (521) for receiving the return test signal from the satellite unit (402) on the channel, and a transmitter (511) for transmitting the return test signal to the hub unit (401) on the channel. The router unit (503) further comprises a processor (523) for performing a third test on the test signal, and a processor (513) for performing a fourth test on the return test signal.

The router may also comprise a receiver (522) for receiving results of the first test from the satellite unit (402), and a transmitter (512) for transmitting the results of the first, second and third test to the hub unit (401).

The router may also comprise a processor (524) for calculating a signal quality from the results of the tests.

The transmitters (520, 511) of the router unit may be configured to transmit using transmission characteristics of devices of the wireless network.

Although the invention has been described in terms of exemplary embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the invention, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

Claims

CLAIMS: 1. A method for determining the suitability of proposed locations for devices in a wireless network, the method comprising: locating a hub unit (401) in or near a proposed location for a first device of the locating a satellite unit (402) in or near a second proposed location for a second device of the wireless network (2.4); transmitting a first signal on a channel of the wireless network from the hub unit (401) to the satellite unit (402) (2.6); performing a first test on the first signal on the channel at the satellite unit (402) (2.7); and determining from results of the first test whether the proposed locations of the first and second devices of the wireless network are suitable (2.11).
2. The method according to claim 1, and comprising: transmitting results of the first test to the hub unit.
3. The method according to claim 1 or 2, and comprising: transmitting a second signal on the channel from the satellite unit (402) to the hub unit (401) (2.9) performing a second test on the second signal at the hub unit (401) (2.10); determining from results of the second whether the proposed locations of the first and second devices of the wireless network are suitable
4. The method according to any of claims ito 3, further comprising: locating a router unit (503) in or near a proposed location for a third device of the wireless network (3.5); transmitting the first and second signals via the router unit (503) (3.8, 3.14).determining from the results of the tests whether the proposed locations of the first, second and third devices of the wireless network are suitable (3.16).
5. The method according to claim 4, and comprising: performing a third test on the first signal at the router unit (503) (3.7); performing a fourth test on the second signal at the router unit (503) (3.12).
6. The method according to claim 5, and comprising: transmitting the results of the third and fourth tests to the hub unit (401) (3.13).
7. The method according to any of claims 1 to 3, and comprising, prior to locating the hub unit (401) and the satellite unit (402): transmitting a pre-test signal from the hub unit (401) to the satellite unit (402) on a pre-test channel, the pre-test channel corresponding to the channel (2.1); and transmitting a confirmation signal from the satellite unit (402) to the hub unit (401) on the pre-test channel (2.3).
8. The method according to claim 4 or 5, and comprising, prior to locating the hub unit (401), the satellite unit (402), and the router unit (503): transmitting a pre-test signal from the hub unit (401) to the router unit (503) and the satellite unit (402) on a pre-test channel, the pre-test channel being one of the one or more channels (3.1); transmitting a first confirmation signal from the satellite unit (402) to the hub unit (401)on the pre-test channel (2.3); and transmitting a second confirmation signal from the router unit (503) to the hub unit (401) on the pre-test channel (3.3).
9. The method according to claim 7 or 8, wherein the pre-test signal includes configuration information (2.2, 3.2), the configuration information optionally including one or more transmission characteristics of the devices of the wireless network.
10. The method according to any of claims 1 to 9, wherein a tests comprises any of: measuring the packet loss rate of any of the signals, wherein the signals comprise a plurality of data packets; measuring a power of any of the signals; and measuring a signal to noise ratio of any of the signals.
11. The method according to any of claims ito 10, and comprising: in the event that the location is unsuitable, selecting a second channel, the second channel having a different frequency range to the channel, and repeating the method of any of claims 1 to 8 using the second channel.
12. The method according to any of claims ito 11, wherein the proposed location is considered unsuitable if the results of any of the tests show any of: a signal strength below a signal strength threshold value; a packet error rate above a packet error rate threshold value; and a signal to noise ratio above a signal to noise ratio threshold value.
13. The method according to claim 12, wherein the threshold values are determined by the characteristics of the devices of the wireless network.
14. The method according to any of claims 1 to 13, wherein each unit transmits using the one or more transmission characteristics of a device of the wireless network.
15. The method according to any of claims 1 to 14 wherein the wireless network is an IEEE standard 802.15.4 network.
16. An apparatus (401) for use as a hub unit in a system for determining the suitability of proposed locations for devices of a wireless network, the apparatus comprising: a first transmitter (410) for transmitting a first signal to a satellite unit (402) on a channel; a first receiver (411) for receiving a second signal from the satellite unit (402) on the channel; a first processor (413) for performing a second test on the second signal; and a second processor (414) for determining a signal quality for the channel using the results of the tests.
17. The apparatus according to claim 16, and comprising: a second receiver (412) for receiving results of a first test from the satellite unit (402).
18. The apparatus according to any of claims 16 or 17, wherein the first transmitter (410) is configured to transmit using one or more transmission characteristics of a device of the wireless network.
19. The apparatus according to any of claims 16 to 18, wherein the first transmitter (410) is configured to transmit to the satellite unit (402) via a router unit (503) (503), and the first (411) receiver is configured to receive from the satellite unit (402) via the router unit (503) (503).
20. The apparatus according to claim 19, wherein the second receiver (412) is additionally configured to receive results of a third and forth test from the router unit (503).
21. An apparatus (402) for use as a satellite unit in a system for determining the suitability of proposed locations for devices of a wireless network, the apparatus comprising: a first receiver (420) for receiving a first signal from a hub unit (401) on a channel; a first processor (423) for performing a first test on the first signal; a first transmitter (421) for transmitting a second signal to the hub unit (401) on the channel.
22. The apparatus of claim 21, and comprising: a second processor (424) for determining a signal quality for the channel using results of the first test.
23. The apparatus of claim 21 or 22, and comprising: a second transmitter (422) for transmitting results of the first test to the hub unit (401).
24. The apparatus according to any of claims 21 to 23, wherein the first transmitter (421) is configured to transmit using one or more transmission characteristics of a device of the wireless network.
25. The apparatus according to any of claims 21 to 24, wherein the first receiver (420) is configured to receive from the hub unit (401) via a router unit (503), and the first (421) transmitter is configured to transmit to the hub unit (401) via a router unit (503).
26. An apparatus (503) for use as a router unit in a system for determining the suitability of proposed locations for devices of a wireless network, the apparatus comprising: a first receiver (510) for receiving a first signal from a hub unit (402) on a channel; a first transmitter (520) for transmitting the first signal to the satellite unit (402) on the channel; a second receiver (521) for receiving a second signal from the satellite unit (402) on the channel; a second transmitter (511) for transmitting the second signal to the hub unit (401)on the channel; a first processor (523) for performing a first test on the first signal; and a second processor (513) for performing a second test on the second signal.
27. The apparatus of claim 26, and comprising: a third receiver (522) for receiving results of a third test from the satellite unit (402); and a third transmitter (512) for transmitting the results of the first, second and third tests to the hub unit (401).
28. The apparatus of claim 26 or 27, wherein the first (520) and second (511) transmitters are configured to transmit using one or more transmission characteristics of a device of the wireless network.
29. The apparatus of any of claims 26 to 28, and comprising: a third processor (524) for calculating a signal quality from results of the tests.
30. A system for determining the suitability of proposed locations for devices in a wireless network, the system comprising: a hub unit (401) according to any of claims 16 to 18; and a satellite unit (402) according to any of claims 21 to 24.
31. A system for determining the suitability of proposed locations for devices of a wireless network, the system comprising: a hub unit (401) according to claim 19 or2O a satellite unit (402) according to claim 25; and a router unit (403) according to any of claims 26 to 29.
32.A computer program comprising computer readable code, which when run on an apparatus causes it to behave as an apparatus according to any of claims 16 to 29.
33. A computer program product comprising a computer readable medium and a computer program according to claim 32, wherein the computer program is stored on the computer readable medium.