GB2258586A - Radio signal enhancer - Google Patents
Radio signal enhancer Download PDFInfo
- Publication number
- GB2258586A GB2258586A GB9116839A GB9116839A GB2258586A GB 2258586 A GB2258586 A GB 2258586A GB 9116839 A GB9116839 A GB 9116839A GB 9116839 A GB9116839 A GB 9116839A GB 2258586 A GB2258586 A GB 2258586A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- enhancer
- signal path
- amplifier
- level
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/155—Ground-based stations
- H04B7/15528—Control of operation parameters of a relay station to exploit the physical medium
- H04B7/15535—Control of relay amplifier gain
Abstract
An enhancer for radio signals transmitted over a radio telecommunications system comprises first and second antennas 1, 2 for transmitting and/or receiving radio signals and means 5, 6 defining within the enhancer a signal path between the two antennas. An amplifier 8 is connected in the signal path. The enhancer includes detector means 12, 13 for detecting a level of signal on the signal path above a predetermined threshold level, and control means 14 for preventing passage or amplification of the signal on the signal path 5, 6 or altering the gain of the amplifier 8 in the signal path in response to detection of a signal level above the threshold, indicator means 15, responsive to the level of signal on the signal path after action by the control means, indicates whether the above-threshold level of the signal was due to feedback between the two antennas 1, 2. The invention allows unskilled individuals to achieve a "good" installation (i.e. correct operation with little or no degradation in the performance of the telecommunications system) without intervention by the system operator. <IMAGE>
Description
RADIO SIGNAL ENHANCER
The present invention relates to an enhancer for radio signals transmitted over a radio telecommunications system.
Wide band enhancers, or "on frequency repeaters", are currently used in many radio telecommunications systems, such as point-to-point fixed link radio, point-tomultipoint fixed link radio, and cellular mobile radio systems, and will be used in the new personal communication network (PCN) systems. The function of enhancers is to extend the coverage or range of a radio system beyond the "normal" limits of the system or into radio "black spots" such as into the shadow of hills, into tunnels, or into buildings.
A simple enhancer comprises two amplifier chains connected between two antennas. In the case of a cellular mobile radio network for example, one antenna is positioned to transmit and receive radio signals to and from the network, and the other antenna is positioned to transmit and receive signals to and from a mobile transceiver in, for example, a radio black spot. The signals received from the network by the corresponding antenna are amplified by one amplifier chain, the "down link chain", for onward transmission by the other antenna. Similarly, signals received from a mobile transceiver by the corresponding antenna are amplified by the second amplifier chain, the "up link chain", for onward transmission to the network via the other antenna.More elaborate enhancers may have fault detectors, alarms, a mechanism for reporting to the network (for example for reporting amplifier failure), and test points for measuring the rf signal levels.
Enhancers require careful installation to ensure that they do not introduce significant interference into a radio system. Specifically, care must be taken to ensure that the antennas of the enhancer are sufficiently isolated from one another, since insufficient isolation may result in oscillation of the enhancer with consequent interference to the system. Interference may also result if amplifiers in the up or down link amplifier chains are driven into their non-linear operating regions, or into saturation, when one or other of the antennas is located too close to a source from which signals are received. This can give rise to unacceptably high levels of intermodulation distortion.
For example, in the case of a cellular mobile radio system, if the antenna "facing" the mobile transceivers is poorly sited such that a mobile transceiver can get too close to the antenna, the up link amplifier chain can be driven into saturation. Similarly, the down link amplifier chain may be driven into saturation if the antenna facing the network is too close to a network transmitter or another enhancer unit existing at the time of installation. These problems can also arise after installation if a new network transmitter is put into operation as the network evolves, or if a neighbouring enhancer is installed.
To avoid the problems of network interference discussed above, existing enhancers are currently installed and maintained by the network operator. By measuring the rf signal levels in the enhancer a skilled technician can assess whether these are sufficient to saturate the amplifiers, determine the cause of such high signal levels, and take appropriate action to resolve the problem. It will be appreciated that if installation of existing enhancers were left to private individuals, network interference may result from unnecessary, incompetent, or even malicious siting of enhancers.
According to the present invention there is provided an enhancer for radio signals transmitted over a radio telecommunications system, the enhancer comprising: first and second antennas for transmitting and/or receiving radio signals; means defining within the enhancer a signal path between the two antennas; an amplifier connected in the signal path; detector means for detecting a level of signal on the signal path above a predetermined threshold level; control means for preventing passage of the signal along the signal path or altering the gain of the amplifier in the signal path in response to detection of a signal level above the said threshold, and indicator means, responsive to the level of signal on the signal path after action by the control means, for indicating whether the abovethreshold level of the signal was due to feedback between the two antennas.
It will be understood that where the control means is adapted to alter the gain of the amplifier, the alteration may result in a fractional gain (and hence attenuation of the signal) or even zero gain.
When for use in a two-way telecommunications system, the enhancer preferably comprises means defining within the enhancer a first signal path for passage of signals from the first antenna to the second antenna, means defining within the enhancer a second signal path for passage of signals from the second antenna to the first antenna, and an amplifier connected in each of the first and second signal paths, wherein the detector means is arranged to detect a level of signal above a predetermined threshold on each signal path and the control means is adapted to prevent passage of the signal along each signal path or alter the gain of the amplifier in each signal path in response to detection of a signal level above the threshold on that path.
Depending on the point in the signal path at which the signal level is detected, the threshold level may be the level above which the amplifier will be driven into its non-linear region or into saturation. This will be the case where, as is preferred, the detector means is arranged to detect the level of signal on the or each signal path at a test point on the input side of the amplifier in the path. The term "amplifier" as used herein may mean either a single amplifier stage or a plurality of amplifierstages. In either case, the amplifier stage or stages may be connected with further stages either before or after the test point on the signal path.
It is preferred that the response of the indicator means is dependent upon whether or not a signal level above the said threshold is maintained on the or a signal path after action by the control means.
The control means may be adapted to interrupt the or a signal path when a signal level above the threshold is detected on the path. Since the signal is not then transmitted onwards by the antenna terminating the signal path, if a signal level above the threshold is maintained on the signal path at the test point, it can be deduced that the high signal level is caused by external influences on the receiving antenna, i.e. that this antenna is too close to a network transmitter or another enhancer.
Conversely, if the signal level is no longer above the threshold at the test point, it can be deduced that the high signal level was caused by insufficient antenna isolation resulting in feedback and oscillation of the enhancer. Thus, depending on the signal level detected by the detector means after action by the control means, different information will be provided by the indicator means.
It is preferred that the indicator means comprises a display. The display preferably gives direct information on the cause of the high signal level to enable appropriate action to be taken to resolve the problem, for example relocation of the antenna receiving the high level signal or further isolation of the two antennas. Alternatively, or in addition, the display may display information as to the steps to be taken to resolve the problem.
It will be appreciated that an enhancer according to the invention may be installed and maintained by a private individual, without intervention by the network operator, while ensuring that the enhancer does not introduce significant interference into the network. Thus, enhancers approved by a network operator may be used in their networks by private individuals without planning or recording by the network operator.
Where the control means interrupts the signal path on detection of a signal above the threshold level on the path, the control means is preferably adapted to do this by disabling the output of the amplifier in the path, for example by removing the dc power to the amplifier.
The enhancer may include means for manually resetting the enhancer, i.e. restoring passage of the signal on the signal path or the gain of the amplifier in the signal path. Thus, after appropriate adjustment of the antennas, normal operation of the enhancer can be restored by an individual. Alternatively, or in addition, the control means may be adapted to reset the enhancer automatically after a predetermined time period.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:
Figure 1 is a diagrammatic representation of a simple form of a known enhancer, and
Figure 2 is a diagrammatic representation of an enhancer embodying the invention.
In the following description, the terminology used is that consistent with use of the enhancers described in a
PCN.
Figure 1 shows a simple form of a known enhancer. Two antennas 1, 2 are connected to corresponding duplexers 3, 4. First and second signal paths are defined between the antennas 1, 2 by a down link amplifier chain 5 and an up link amplifier chain 6. Each amplifier chain 5, 6 includes a low noise amplifier 7, a power amplifier 8 and band pass filters 9 which pass only frequencies in the band in which the network operator has allowed.
The antenna 1 is the "base station facing antenna" which transmits and receives signals to and from the network. The antenna 2 is the "mobile facing antenna" which transmits and receives signals to and from mobile handsets compatible with the PCN. Signals transmitted by the network are received by the base station facing antenna 1, amplified by the down link amplifier chain 5 and transmitted onwards by the mobile facing antenna 2.
Similarly, signals transmitted by a mobile handset in the area covered by the mobile facing antenna 2 are received by this antenna, amplified by the up link amplifier chain 6, and transmitted onwards to the network by the base station facing antenna 1.
As previously described, if the base station facing antenna 1 is located too close to a base station or an existing enhancer, the level of the rf signal on the down link amplifier chain 5 may be sufficient to drive the power amplifier 8 into its non-linear region, or into saturation, with consequent interference to the network. Similarly, if the mobile facing antenna 2 is located such that mobile handsets can get too close to the antenna 2, the rf signal level on the up link amplifier chain 6 may be sufficient to drive the power amplifier 8 in that chain into its nonlinear region. Further, if the antennas 1, 2 are not sufficiently isolated from one another, the enhancer may be caused to oscillate.
Figure 2 is a diagrammatic representation of an enhancer embodying the invention. Equivalent components to those shown in the enhancer of Figure 1 are numbered accordingly. A direction coupler 10 is connected in each amplifier chain 5, 6 after the low noise amplifier 7. A signal detector 12 and a threshold detector 13 are connected to each of the direction couplers 10. Each direction coupler 10 thus defines a test point on a signal path defined by the up or down link amplifier chains.
The enhancer includes control means 14 connected to the detectors 13, and a display 15 connected to the control means 14. A switch 16, operable under the control of the control means 14, is connected in the dc power supply to each power amplifier 8. The amplifiers 7, 8 are Class A components, having highly linear characteristics, and the enhancer is designed for normal operation in the linear region of the amplifiers.
The enhancer of Figure 2 operates as follows.
The signal detectors 12 measure the rf signal levels in the up and down link amplifier chains 5, 6. Each threshold detector 13 compares the measured signal level with a threshold level to determine if the measured level is sufficient to drive the power amplifier 8 in that chain into its non-linear region.
When a signal above the threshold level is detected on one of the amplifier chains 5, 6, the control means 14 activates the appropriate switch 16 to disconnect the dc power to the power amplifier 8 in that chain. The output of the power amplifier is thus disabled. The corresponding detectors 12, 13 then determine whether a signal above the threshold level is maintained at the test point in the chain, and the control means 14 then activates the display 15 to indicate the cause of the high signal level in dependence upon whether the high signal level is maintained at the test point.If a signal above the threshold is detected on the down link amplifier chain 5, and the detected signal is still above the threshold level after the output of the amplifier 8 has been disabled, then the high signal level is caused by location of the base station facing antenna 1 too close to a base station, or another enhancer unit. This fact is indicated on the display 15, and the problem may be resolved by either relocating the antenna 1 or deactivating the enhancer unit if it is no longer required. Similarly, if a signal level above the threshold is detected on the up link amplifier chain 6, and the signal level is maintained after the amplifier 8 on that chain is disabled, then the cause of the high signal level is that the mobile facing antenna 2 is sited such that mobile handsets can get too close to this antenna.
This fact is indicated on the display 15 and the antenna 2 can be relocated. If the signal levels drop below the threshold after disabling of the amplifiers 8, then the high signal levels were due to insufficient antennas isolation, and the control means activates the display to indicate this fact.
The enhancer includes means (not shown) for manually resetting the enhancer after the problem has been solved.
The enhancer is reset by activating the relevant switch 16 to restore dc power to the amplifier 8. As an alternative, the control means could incorporate a "time-out" feature to reset the enhancer automatically after a period of time sufficient to allow a problem to be resolved.
It will be appreciated that the invention allows unskilled individuals to achieve a "good" installation (ie: correct operation with little or no degradation in the performance of the network). The invention thus enables a private individual to install and maintain the enhancer without intervention by the network operator.
It will be understood that the test point defined by the direction coupler 10 in each amplifier chain may be located at any stage in the chain before the final power amplifier output. In other embodiments, the test point may be located on the output side of the power amplifier and the detector means may be adapted to determine whether the amplifier is in saturation.
It will be appreciated that many other variations and modifications may be made to the specific embodiment described above without departing from the scope of the invention.
Claims (10)
1. An enhancer for radio signals transmitted over a radio telecommunications system, the enhancer comprising:
first and second antennas for transmitting and/or receiving radio signals;
means defining within the enhancer a signal path between the two antennas;
an amplifier connected in the signal path;
detector means for detecting a level of signal on the signal path above a predetermined threshold level;
control means for preventing passage of the signal along the signal path or altering the gain of the amplifier in the signal path in response to detection of a signal level above the said threshold, and
indicator means, responsive to the level of signal on the signal path after action by the control means, for indicating whether the above-threshold level of the signal was due to feedback between the two antennas.
2. An enhancer as claimed in Claim 1, comprising means defining within the enhancer a first signal path for passage of signals from the first antenna to the second antenna, means defining within the enhancer a second signal path for passage of signals from the second antenna to the first antenna, and an amplifier connected in each of the first and second signal paths, wherein the detector means is arranged to detect a level of signal above a predetermined threshold on each signal path and the control means is adapted to prevent passage of the signal along each signal path or alter the gain of the amplifier in each signal path in response to detection of a signal level above the threshold on that path.
3. An enhancer as claimed in Claim 1 or Claim 2, wherein the response of the indicator means is dependent upon whether or not a signal level above the said threshold is maintained on the or a said signal path after action by the control means.
4. An enhancer as claimed in any one of the preceding claims, wherein the detector means is arranged to detect the level of signal on the or each signal path at a test point on the input side of the amplifier in the path.
5. An enhancer as claimed in any one of the preceding claims wherein the control means is adapted to interrupt the or a said signal path when a signal level above the threshold is detected on the path.
6. An enhancer as claimed in Claim 5, wherein the control means is adapted to remove the dc power to the amplifier in the signal path when a signal level above the threshold is detected on the path.
7. An enhancer as claimed in any one of the preceding claims, wherein the control means is adapted to restore automatically passage of the signal along the signal path or the gain of the amplifier in the signal path after a predetermined time period.
8. An enhancer as claimed in any one of the preceding claims, including means for manually restoring passage of the signal along the signal path or the gain of the amplifier in the signal path.
9. An enhancer as claimed in any one of the preceding claims, wherein the indicator means comprises a display.
10. An enhancer for radio signals transmitted over a radio telecommunications system substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9116839A GB2258586B (en) | 1991-08-05 | 1991-08-05 | Radio signal enhancer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9116839A GB2258586B (en) | 1991-08-05 | 1991-08-05 | Radio signal enhancer |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9116839D0 GB9116839D0 (en) | 1991-09-18 |
| GB2258586A true GB2258586A (en) | 1993-02-10 |
| GB2258586B GB2258586B (en) | 1995-05-10 |
Family
ID=10699508
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9116839A Expired - Lifetime GB2258586B (en) | 1991-08-05 | 1991-08-05 | Radio signal enhancer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2258586B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1041832A2 (en) * | 1999-03-31 | 2000-10-04 | Harada Industry Co., Ltd. | Radio repeater device |
| EP1049251A2 (en) * | 1999-03-31 | 2000-11-02 | Harada Industry Co., Ltd. | Control device |
| EP1511193A2 (en) * | 1999-08-31 | 2005-03-02 | NTT DoCoMo, Inc. | System and method for boosting and monitoring |
| WO2005119936A2 (en) * | 2004-05-26 | 2005-12-15 | Wireless Extenders, Inc. | Wireless repeater for a duplex communication system implementing a protection based on oscillation detection |
| US7280799B1 (en) * | 2004-08-18 | 2007-10-09 | Broadlink Research Inc. | Mobile phone repeater |
| EP2839587B1 (en) * | 2012-05-04 | 2022-02-23 | Huawei Technologies Co., Ltd. | System and method for radio frequency repeating |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0227393A2 (en) * | 1985-12-16 | 1987-07-01 | Nippon Telegraph And Telephone Corporation | Radio repeater with spillover measurement |
-
1991
- 1991-08-05 GB GB9116839A patent/GB2258586B/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0227393A2 (en) * | 1985-12-16 | 1987-07-01 | Nippon Telegraph And Telephone Corporation | Radio repeater with spillover measurement |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1041832A2 (en) * | 1999-03-31 | 2000-10-04 | Harada Industry Co., Ltd. | Radio repeater device |
| EP1049251A2 (en) * | 1999-03-31 | 2000-11-02 | Harada Industry Co., Ltd. | Control device |
| EP1041832A3 (en) * | 1999-03-31 | 2000-12-20 | Harada Industry Co., Ltd. | Radio repeater device |
| US6493537B1 (en) | 1999-03-31 | 2002-12-10 | Harada Industry Co., Ltd. | Apparatus and method for preventing oscillations in a radio repeater device |
| CN1109458C (en) * | 1999-03-31 | 2003-05-21 | 原田工业株式会社 | Radio relay device |
| EP1049251A3 (en) * | 1999-03-31 | 2003-09-03 | Harada Industry Co., Ltd. | Control device |
| EP1511193A2 (en) * | 1999-08-31 | 2005-03-02 | NTT DoCoMo, Inc. | System and method for boosting and monitoring |
| EP1511193A3 (en) * | 1999-08-31 | 2005-07-20 | NTT DoCoMo, Inc. | System and method for boosting and monitoring |
| WO2005119936A2 (en) * | 2004-05-26 | 2005-12-15 | Wireless Extenders, Inc. | Wireless repeater for a duplex communication system implementing a protection based on oscillation detection |
| WO2005119936A3 (en) * | 2004-05-26 | 2006-04-20 | Wireless Extenders Inc | Wireless repeater for a duplex communication system implementing a protection based on oscillation detection |
| US7706744B2 (en) | 2004-05-26 | 2010-04-27 | Wireless Extenders, Inc. | Wireless repeater implementing low-level oscillation detection and protection for a duplex communication system |
| AU2005251169B2 (en) * | 2004-05-26 | 2010-07-15 | Zboost, Llc | Wireless repeater for a duplex communication system implementing a protection based on oscillation detection |
| US7280799B1 (en) * | 2004-08-18 | 2007-10-09 | Broadlink Research Inc. | Mobile phone repeater |
| EP2839587B1 (en) * | 2012-05-04 | 2022-02-23 | Huawei Technologies Co., Ltd. | System and method for radio frequency repeating |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2258586B (en) | 1995-05-10 |
| GB9116839D0 (en) | 1991-09-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) |
Free format text: REGISTERED BETWEEN 20100304 AND 20100310 |
|
| PE20 | Patent expired after termination of 20 years |
Expiry date: 20110804 |