GB2364618A

GB2364618A - Measuring received signal strength for the installation of a wireless fixed subscriber unit

Info

Publication number: GB2364618A
Application number: GB0016913A
Authority: GB
Inventors: Joaquin Goui
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2000-07-10
Filing date: 2000-07-10
Publication date: 2002-01-30
Also published as: WO2002005584A1; GB0016913D0; AU2001289634A1

Abstract

A portable communication device 10 may be operated so as to indicate the signal strength received directly from a network, or the signal strength received by a fixed subscriber unit 50 from the same network when the two devices are connected together. The arrangement allows possible locations for the fixed portion of a wireless local loop system to be checked with a portable handset before installation.

Description

2364618 COMMMCATIONS DEVIQE

TECHNICAL FIELD OF THE INVENTION

This invention relates to a communications device, and in particular to a device which can be used in the 5 installation of a fixed subscriber unit in a wireless local loop of a telecommunications system. The invention relates also to a method of installation of the fixed subscriber unit.

BACKGROUND OF THE INVE=ION

10 W099113659 describes an interface un:it, which allows a fixed subscriber, using a standard telephone, to gain access to a satellite or cellular radio telephone system. The advantage of such a fixed subscriber unit is that it allows the provision of a is telephone service to the subscriber, without the need to establish a fixed link. For subscribers iti remote areas, therefore, it can be economically advantaqeous to provide the telephone service by means of a fixed subscriber unit of this type.

20 Such a unit is typically installed on a wall of the subscriber's premises, and it is necessary to select a location where signals from the radio telephone network can be received with a high.signal strength, since the signal strength can vary 25 consider-ably from one location to another, over short distances.

Thus, installation of a fixed subscriber unit typically includes moving the unit around the.premises, to find a suitable location. At each location, the 30 received signal strength can be measured. This measurement can be made in different ways. For example, the fixed subscriber unit itself can-be provided with a visual output which indicates:the strength of a signal received through its antenna.

35 Alternatively, a separate device can be connected to the fixed subscriber unit, the separate device being able to provide a display which indicates the strength of the signal received through the antenna of the fixed subscriber unit.

5 However, these methods have the disadvantage that it is necessary to carry the fixed subscriber unit to all of the possible locations around the premises, which is inconvenient since the unit is relatively heavy.

10 SUMMARY OF THE IM10

According to the invention, there is provided a portable communications device, operating in the same network as a fixed subscriber unit, which can provide an indication as to a received signal strength. In a 15 first mode of operation, the portable device can indicate the signal strength which it receives directly from the network. In a second mode of operation, the portable device can be connected to the fixed subscriber unit, and can indicate the signal strength 20 which the fixed subscriber unit receives from the network.

The portable device can be made relatively small and light. Therefore, this has the advantage that the best location for the fixed subscriber unit, in terms 25 of the available received signal strength, can be found without needing to carry the fixed subscriber unit to different locations.

There is therefore also provided a method of installation of a fixed subscriber unit. The method 30 comprises using the portable device in its first mode of operation at various locations and selecting a suitable location for the fixed subscriber unit on the basis of signal strength measurements made thereby.

The method then comprises using the portable device in 35 its second mode of operation to determine the signal strength received by the fixed subscriber unit at the selected location.

BRIEF DESCRIPTION OF DRAWINGS

Figure I is a block schematic diagram of a 5 portable communications device in accordance with the invention.

Figure 2 shows the device of Figure I in use in the installation of a fixed subscriber unit.

DETAILED DESCRIPTIM OF PREFERRED EMBODIMENTS 10 Figure I shows a portable communications device 10. The portable communications device can operate as a conventional handheld communications device, such as a mobile phone. Therefore, the device 10 has all of the components and features of a mobile phone. Those is features, and others, will only be described further below to the extent that such description is necessary for an understanding of the present invention.

The device 10 has a radio antenna 14 for receiving and transmitting radio signals. The antenna is 20 connected to radio transceiver circuitry 18. The transceiver circuitry IS receives radio frequency signals from the antenna 14, and downconverts and demodulates them into a suitable format, and then passes them to a processor 22. The processor 22 25 controls the operation of the device 10. It will be apparent to the person skilled in the art that the processor 22 is a simplified representation of various signal processing, memory, microprocessor and other devices, as is generally conventional. The transceiver 30. circuitry IS further receives signals from the processor 22, modulates and upconverts them, and then passes them to the antenna 14 for transmission.

The device 10 operates in accordance with the same standards, and on the same network, as the fixed 35 subscriber units with which it is to be used. Thus, it can operate on any suitable cellular or satellite radio telecommunications network.

The processor is connected to receive inputs from a keypad 26, and to provide visual outputs on a screen 5 display 30, as is generally conventional.

Further, the processor 22 is connected to an interface. unit 34, which is adapted to be physically connected to a fixed subscriber unit (not shown). A fixed subscriber unit typically has a serial line 10 interface that can be used for connection to an external device, for example such as a personal computer, for monitoring and maintenance purposes.

The interface 34 can be connected to the serial line interface of the fixed subscriber unit, and can is pass information from the processor 22 to the fixed subscriber unit, as well as pass information from the fixed subscriber unit to the processor 22.

Figure 2 shows the operation of the device of Figure 1, in the installation of a fixed subscriber 20 unit, Figure 2(a) showing its operation in a first mode, and Figure 2(b) showing its operation in a second mode.

Thus, Figure 2(a) shows the portable device 10 in a first, standalone mode.

25 In this mode, the device 10 receives radio signals from a radiocommunications network, through its antenna 14. Also, the display 30 can provide an indication of the strength of the received signals, as well as information conventionally available on the display of 30 a mobile phone. For example, the display 30 can provide an indication that the phone has found an available control channel, and can show dialled digits which have been entered through the keypad 26.

However, in accordance with the invention, the 35 display can provide an accurate indication of the received signal strength. While it is common for mobile phones to provide an indication as to the strength of a received signal, these typically differentiate between about four signal strength 5 levels, covering the whole range from no signal to maximum signal strength.

The display according to the illustrated embodiment of the invention provides a numerical indication of the signal strength, for example to the 10 nearest SdBm, or to the nearest 2dBm. Moreover, in the illustrated embodiment, the display also indicates the channel number on which this measurement is taken.

Thus, the display screen 30 may contain the alphanumeric message:

15 0323 -95 to indicate that, on channel 323, the received signal strength is -95dBm.

The signal strength indication can be available on the display whenever the phone is in the first mode, or 20 can be available for selection as a menu option, or can be made available by pressing a specific key sequence on the keypad 26. In the illustrated embodiment, the signal strength indication is displayed when the key sequence 9,,,,,,MENU,MENU is pressed, although of 25 course, the processor 22 can be programmed such that it provides the display on receipt of any desired sequence.

Thus, when it is desired to install a fixed subscriber unit in a customer's premises, it is only 30 necessary to carry the device 10 around the premises, while it is in the first mode of operation, and monitor the displayed received signal strength indication.

This is convenient because of the small size of the device 10. When a suitable location is found, at which 35 the signal strength is as high as possible, while also meeting other desirable criteria, that location can be selected for the fixed subscriber unit.

Figure 2(b) shows the fixed subscriber unit 50 placed approximately in the selected location, with a 5 conventional fixed line telephone 60 connected thereto.

The portable device 10 is connected through its fixed subscriber unit interface 34 to the serial line interface 52 of the fixed subscriber unit So.

When connected to the fixed subscriber unit 50, 10 the device 10 can operate in a second mode. The switch from the first mode can be made automatically, as soon as the processor 22 detects that the device is connected to the fixed subscriber unit, or can be activated manually, for example when the processor 22 15 detects a specific key sequence pressed on the keypad 26.

In the second mode, the device 10 shows on its display 30 information which is received from the fixed subscriber unit 50. Further, in the second mode, 20 signals are set to the fixed subscriber unit 50, corresponding to keypresses on the keypad 26.

Thus, returning to the installation of the fixed subscriber unit 50, once the unit has been placed approximately in the selected location, the device 10 can be connected thereto, and operated in the second mode. In this mode, the display 30 of the device 10 shows the actual received signal strength. This allows an accurate measurement to be made because the display can provide an accurate indication, while still 30 allowing fine adjustments of the position of the fixed subscriber unit 50. This is important because the actual signal strength received by the fixed subscriber unit 50 through its antenna 54 can still vary noticea.bly over small distances.

35 It will be noted that the received signal strength measured by the device 10 when connected to the fixed subscriber unit 50 will often be greater than the received signal strength measured by the device 10 from the same position when in its first mode. This is 5 because the antenna 54 of a fixed subscriber unit is typically more efficient than the antenna 14 of a mobile phone. However, any difference between the measured values will tend to be relatively constant at different locations, and so the measurements made in 10 the first mode will still validly indicate the preferred location for the fixed subscriber unit.

When the location of the fixed subscriber unit 50 has been finalised, the device 10 can be used in the second mode for testing and maintenance purposes.

is Thus, a fixed subscriber unit typically has operational features such as testing procedures, which are activated by sending specific signals to the fixed subscriber unit over the serial line interface 52.

Specific keypresses on the device 10 are converted in 20 the processor 22 and interface 34 to appropriate signals which can be sent to the fixed subscriber unit to activate these features or procedures.

When any necessary testing procedures have been completed, the device 10 can be disconnected from the 25 serial line interface 52 of the fixed subscriber unit 50. The device 10 detects that it is no longer connected, and returns from the second mode of operation to the first mode. Alternatively, the device can return from the second mode of operation to the 30 first mode in response to a user input of a specific key sequence.

in the first mode of operation, the device 10 can be used as a conventional mobile phone. Thus, the device 10 can be used to place a call to the fixed 35 subscriber unit over the radio communications network to which both are connected. This can be used to provide a further check on the operation of the fixed subscriber unit.

There is thus provided a device which can be used conveniently to find a preferred location for a fixed subscriber unit.

Claims

1. A portable communications device, having:

a first mode of operation, in which the device is connectable to a radiocommunications network and in 5 which the device is operable to indicate a received signal strength; and a second mode of operation, in which the device can be physically connected to a fixed subscriber unit for data transfer.

10

2. A portable communications device as claimed in claim 1, having a display, the display being operable in the first mode to provide a numerical indication of received signal strength.

3. A portable communications device as claimed is in claim 1, having a display, the display being operable in the second mode to provide a numerical indication of the strength of a signal received by a fixed subscriber unit to which the device is connected.

4. A portable communications device as claimed 20 in claim 1, having a keypad, wherein, in the second mode, signals are sent to a fixed subscriber unit to which the device is connected, corresponding to keypresses on the keypad.

5. A portable communications device as claimed 25 in claim 1, wherein the device can be switched from the first mode to the second mode of operation by means of user inputs via a keypad.

6. A portable communications device as claimed in claim 1, wherein the device can he switched from the 30 second mode to the first mode of operation by means of user inputs via a keypad.

7. A portable communications device as claimed in claim 1, wherein the device switches automatically to the second mode of operation when the device is 35 physically connected to a fixed subscriber unit.

-io- A portable communications device as claimed in claim 7, wherein the device switches automatically from the second mode of operation to the first mode of operation when the device becomes disconnected from the fixed subscriber unit.

9. A portable communications device, operable in the same radiocommunications network as a fixed subscriber unit, the portable device having a first mode of operation in which it indicates the signal 10 strength which it receives directly from the network, and a second mode of operation, in which it can be connected to the fixed subscriber unit, and can indicate the signal strength which the fixed subscriber unit receives from the network.

15

10. A method of installation of a fixed subscriber unit, the method comprising:

using a portable device at various locations in a first mode of operation in which it measures its received signal strength; 20 selecting a suitable location for the fixed subscriber unit on the basis of signal strength measurements made thereby; and using the portable device in a second mode of operation in which it is physically connected to the 25 fixed subscriber unit to measure the signal strength received by the fixed subscriber unit at the selected location.