JP2002526973A - Method and system for controlling co-channel interference in point-to-point communication - Google Patents

Abstract

A system and method for controlling a transmitter of a transmitter / receiver pair to provide a substantially constant radiating contour is described. According to a preferred embodiment of the present invention, a point-to-point link performance characteristic, such as a bit error rate received by the receiver, is set as a desired operating characteristic. However, since this operating characteristic requires a significant amount of time to measure, and other link attributes are measured for a faster determination of the required link coordination needed to obtain the desired performance characteristics. You. In a preferred embodiment, the lower quality bit error rate and received signal strength are measured and correlated with the link performance characteristics for a faster determination of the required link adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The invention is a point-to-point system
, And more particularly, co-channel interference in multiple such systems (
The present invention relates to a method and system for controlling [co-channel interference].

[0002]

BACKGROUND OF THE INVENTION

Transmission of wireless signals in the air in communication systems has many advantages over other transmission media. However, by its very nature, radio wave transmission cannot avoid co-channel interference when two or more receivers operating at the same frequency are located in close proximity. This co-channel interference degrades link performance. Thus, if a large number of receivers are located in a given area, system performance will be limited by interference.

[0003] Depending on the service requirements, unique solutions or organizational schemes for controlling co-channel interference have been used. For example, mobile service providers often utilize topographic, spatial radiant isolation structures to control co-channel interference through frequency reuse schemes. Generally, cellular phone service providers
Co-channel interference is resolved by using a frequency-separated cell structure in the zones (sectors and / or cells) and / or the time domain (time bursts of a time division multiple access (TDMA) system).

For mobile services using code division multiple access (CDMA), interface control techniques generally use intra- and inter-cell power control of active user transmit power instead of frequency reuse. Therefore,
At predetermined common points, such as base station receivers, the transmit powers of the mobile units are controlled to have a common input level, so that they interfere equally with each other and therefore each signal Recovered from the received composite signal.

[0005] Point-to-point typically uses micro or very high frequencies and is highly directional, for example, fixed rather than broadcast over a large area and received by a receiver operating in that area. A particular transmitter with a fixed location can be focused from a particular transmitter with a location. However, like other receivers, like radio, point-to-point systems do not interfere with each other in certain conditions, such as when multiple transmitter / receiver pairs operate near or along a common azimuth. There will be. Directional antennas can control transmission in any direction and can correct interference problems. However, such directional antennas do not control any possible interference propagation of the radio waves, such as those associated with side lobes of the antenna beam or over-radiation of the signal.

For example, transmission is a point-to-point application.
, It is easy to plot the contour of the resulting antenna beam. Each receiver, usually located in the antenna beam and aimed at the transmitter if directional, can receive the signal. Obviously, even with highly directional antennas, there will be areas covered by transmit antenna beams that are not needed to establish communication with the transmitter / receiver. These areas will involve the main beam extending beyond the intended receiver due to excessive transmit power, antenna beam sidelobes or the like. Accordingly, any second transmitter / receiver pairs located within the antenna beam contour of the first transmitter, including the side lobes or main beam shadows, will experience interference from the first transmitter.

In the past, point-to-point transmitter / receiver pairs
The radio arrangement of a ransmitter / receiver pair is a sparse arrangement, where each link is specially designed and affected by receivers located in the range of the antenna beam of a particular transmitter not related to the receiver Avoid that, or at least fix. However, there are situations in which there is a great deal of deployment to benefit from high frequency systems such as 20 to 40 GHz wireless systems and to service communication and data requests in urban areas. Therefore, relying on this sparsely populated configuration to resolve interference is unacceptable.

[0008] It should be taken into account that high-frequency propagation losses, such as the aforementioned 20 to 40 GHz system, vary greatly depending on environmental variations. For example, the change in signal attenuation or signal loss from sunny to rainy days is 40 dB per km. Thus, the transmitters of a transmitter / receiver pair are increased even during periods of low signal attenuation in order to be sufficiently received by the receivers of the transmitter / receiver pair during the maximum signal attenuation. May be sent at the power level you choose. This is because if the first transmitter / receiver pair is using a fixed transmit power level transmission, the antenna beam profile of the first transmitter / receiver pair has been expanded and this has less attenuation. During the period, interference will occur at the receiver associated with another transmitter / receiver pair.

In the prior art point-to-point, transmitter / receiver pairs are arranged to operate in the worst-case scenario expected and the transmitter's transmit power level is adjusted.
For example, depending on the distance between the transmitter and receiver and the expected signal attenuation for predictable phenomena such as precipitation, the transmission power may be less than required for proper signal quality in the receiver during periods of no precipitation. It is adjusted substantially substantially. This fixed power adjustment for the worst case situation is usually due to signal over-radiation, since precipitation in most areas where such point-to-point systems are typically located occurs less frequently than during periods of no precipitation. This results in an extension of the period. In this way, the fixed power level is adjusted to the worst case scenario when there is precipitation, so the transmit power will over-radiate the signal sufficiently high.

[0010] Accordingly, the desired level is maintained at a desired level, eg, the radio or radios involved in the transmission, while maintaining the quality of the transmission, while reducing the interference received by the non-participating radios. There is a need in the art for a system and method for adjusting the power level in such a manner.

Further, there is a need in the art for a system and method for maintaining a minimum antenna beam profile to allow for close placement of a communication system, eg, a transmitter / receiver pair. Thus, the available spectrum need not be unnecessarily broken by another communication link, and as a result, each link, even if placed in close proximity, will have a wider portion of the spectrum, and therefore have a greater Bandwidth available.

Further, there is a need for a system and method for dynamically adjusting communication parameters so that environmental changes are dynamically compensated. This dynamic adjustment of the communication parameters should preferentially consider the abnormal condition, and should avoid undesired adjustments to abnormal conditions with features that exhibit symptoms similar to those of the condition to be compensated. .

SUMMARY OF THE INVENTION These and other objects, features and technical advantages are achieved by systems and methods that provide for dynamic control of link parameters such as transmit power levels. In a preferred embodiment, the power control means generates an antenna beam profile and the received signal level received by the receiver of the transmitter / receiver pair is substantially constant. Thus, the transmit power is dynamically received to compensate for the propagation loss. Therefore, according to the present invention, the power amount is adjusted so that the received power level and / or other measured communication parameters, ie the contours, are constant, so that with respect to the main beam pattern, under any compensation conditions Also, the contour is constant.

A preferred embodiment of the present invention uses a closed feedback loop to provide information about the level of the communication parameter received and measured by the receiver of the transmitter / receiver pair. Thus, when communication parameters are measured by the receiver at a high level, the system adjusts to power down and feeds back to the transmitter. Similarly, when the received signal is measured at a low level by the receiver, the system adjusts and powers up the transmitter to provide feedback.

[0015] Desirably, the receiving system operates to make the desired measurements and determines the required power levels or other transmission characteristics, adjustments. Thus, a very low bandwidth return signal path is used by the feedback loop while providing the desired level of functionality. For example, the receiver concludes that a compensating adjustment is needed and communicates to the transmitter with very few reverse link control channel bits. Thus, the consumption of reverse channel bandwidth is avoided by not having a transmitter adjustment circuit with specific parameters or information on each measurement made from the parameters.

Also, the desired transmitting system operates to receive feedback regarding the power level adjustment from the receiving system, and determines the type, amount, and / or characteristics of the required adjustment. For example, with reference to a knowledge base that includes historical information about the operation of the communication link, the transmitter system determines that a particular power level adjustment should not be made. Thus, undesired power level adjustments in response to abnormal conditions are avoided.

The received signal or link characteristics are measured in a number of different ways at the receiver. For example, received signal strength (RSSI), signal-to-noise ratio (S / N), carrier-to-interference ratio (C / I), or similar measurements are used. However, since the present invention is expected to be used in high-speed transmission of data, the preferred embodiment measures the link performance of the transmitted information. Accordingly, link performance measurements such as bit error rate (BER) measurements are made, and the power levels are adjusted to maintain a constant level of these measurements. For example, by keeping the bit error rate constant,
The received signal is made constant.

[0018] Since this is a parameter of the product that is actually supplied to the subscriber or system user, the use of such measurements is in many cases ideal. Thus, the system of the present invention is not only employed to dynamically adjust link parameters, such as transmit power, to reduce interference experienced by other systems at large scale deployments, but also to the system. Can consistently provide a particular performance level to subscribers.

However, tuning based on performance characteristics does not include the complexities associated with simpler power level measurements. For example, if certain error rates are selected as acceptable, they will not be transferred immediately, as would counting errors that occur in a particular time span where these selected error rates are usually very low. Therefore, actually, it requires a substantial time to measure the error rate. Such a length measurement period may be too long for feedback useful in adjusting the transmit power level in a timely manner.

Therefore, the preferred embodiment of the present invention also measures parameters that are measured faster than measuring actual performance characteristics, and determines what the actual performance characteristics are. This allows the present invention to make decisions faster with respect to performance characteristics, so that communication before the measured parameters have had sufficient time to actually receive the performance characteristics dictated. Adjust the parameters. Measuring these communication parameters not only allows the communication parameters to be adjusted faster, but they also allow the parameters to be adjusted before the actual performance characteristics are degraded in the measurement.

In order to refer to the measured parameters relating to the desired actual performance characteristics, in addition to the aforementioned parameter measurements, a preferred embodiment of the present invention determines the actual performance characteristics in addition to the aforementioned parameter measurements. That is, a time intensity performance characteristic measurement is performed by measuring parameters during an immediate determination of power level adjustment. Therefore, the faster measurable parameters are correlated with the actual performance characteristics to determine or predict the actual performance characteristics.

Further, it is desirable to disable power level adjustment when the system enters an abnormal condition. For example, if the directional transmit antenna is not properly aligned with the corresponding receive antenna such that the measured performance characteristics typically behave poorly, exhibiting symptoms of the phenomenon being adjusted, feedback The information will cause an undesirable increase in the transmit power level.

Similarly, installation conditions require that power level adjustment be disabled. As mentioned above, the difference in signal attenuation according to precipitation or other conditions is on the order of 40 to 50 dB / km. However, for some directional radiation patterns, the side lob is just 2
5dB below. Therefore, during installation, when the main beam of the transmitting antenna aims and is locked to the main beam of the receiving antenna, if the system does not take control action to increase the power level during this time, There is a possibility that the main beam and the side lobe or the side lobe and the side lobe communication will be established.

Accordingly, a preferred embodiment of the present invention includes the analysis of feedback information to override power level adjustment when responding to other conditions than intended to be compensated. For example, the temporary, maximum power level is set for installation and / or antenna adjustment so that there is no power level adjustment sufficient to establish communications other than the main antenna beam.

Furthermore, during normal operation, the system has available information, such as a typical operating transmit power level, and may include information about the duration or percentage of operating time at which that level will be used. However, the system operates to detect an abnormal condition based on this information. Thus, if a high transmit power level occurs for a longer duration than that obtained historically in a particular measured characteristic, the system may be subject to potential abnormalities and / or excessive interference with nearby components. The technician can be notified to reduce the transmit power level to a pre-determined maximum so as not to cause

It should be understood that the ability to detect the cause of such anomalies offers significant advantages when operating in dense systems. For example, if a large number of point-to-point systems are deployed, the antenna of a particular transmitter may be out of alignment by a few degrees. However, the utilization of the performance of the monitored received signal of the present invention dynamically adjusts the transmitter power so that the associated receiver is not overly affected by slight shifts in the transmit antenna, but other resources in the network. The receiver may start to interfere. If it is not for the above historical measurement of the habitual power level of the transmitter whose antenna has not been correctly adjusted, the technician shall determine the affected receiver site, corresponding transmitter site, or area. At other transmitters, we will try to solve the problem without guidance on the specific transmitter that is actually causing the problem.

It should be understood that a technical advantage of the present invention is a system and method that is adapted to adjust a transmit power level to maintain a desired link performance level. Further, the system and method are adapted to allow such fast adjustment of link performance even when measuring performance levels requires a long time to make a decision.

In addition, technical advantages are realized because they can be used in providing a tight arrangement of communication systems by maintaining a minimum antenna beam profile at the transmitter / receiver pair. Thus, the available spectrum is available to provide additional bandwidth at each transmitter / receiver pair in avoiding co-channel interference.

Furthermore, a technical advantage is realized in that the present invention adjusts communication parameters so that environmental changes are dynamically compensated.

The foregoing features and technical advantages of the present invention are rather broadly outlined in order that the detailed description of the invention that follows may be better understood. The features and advantages of the invention, which form the subject of the claims of the invention, will be described hereinafter. It will be appreciated by those skilled in the art that the concepts and features of the disclosed embodiments can be used as a basis for modifications and designs that perform the same purpose as the present invention. It will be appreciated by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. For a more complete understanding of the present invention and its advantages, the following description is made with reference to the accompanying drawings.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

In a typical point-to-point system, a communication link is established between a transmitter and a receiver pair for transmitting signals and information between the transmitter and the receiver. For example, FIG.
Focusing on A, prior art point-to-point communication links have
The transmitter 101 and the receiver 102 constitute a transmitter / receiver pair. Here, the transmitter 101 emits a main beam 111a directed to the receiver 102 to establish an appropriate wireless communication link for transmitting signals and information to and from the receiver 102. Further, the transmitter 101 has an influence area 121a composed of side lobes, back lobes, and the like, in which signals transmitted from the transmitter 101 can be received outside the main beam 111a.

Therefore, a receiver placed in either the main beam 111a or the affected area 121a can establish communication with the transmitter 101. However, in point-to-point systems, it is usually desirable for only one receiver to establish communication with a particular transmitter. Therefore, the portion of the main beam 111a that extends beyond the receiver 102 (the shadow of the main beam) may cause interference in the communication link of another transmitter / receiver pair. Thus, the affected area 121a may cause interference in the communication links of other transmitter / receiver pairs.

Typically, there are dynamically changing situations in the environment in which such communication links are located, affecting the propagation of the emitted signal. For example, the difference in signal attenuation between a transmitter and a receiver from sunny to rain is as large as 40 dB per km. The effect of such a temporary situation is illustrated by the attenuated main beam 111b and the reduced area of influence 121b.

To provide a signal that can be adequately received by the receiver of a transmitter / receiver pair during periods of extreme signal attenuation, the system uses a fixed transmit signal power level,
The transmitters of a transmitter / receiver pair must transmit at increased power levels even during periods of signal attenuation. As such, another transmitter / receiver pair in such prior art systems must be removed from the area or use spectra that are sufficiently far away to avoid co-channel interference.

In addition, the conditions affecting link parameters are not constant over large areas, for example, the rate of rain is not uniform over many miles over a large area and cannot be completely predicted, so the system must provide a link separation. Usually designed with worst case scenarios that have the greatest overall effect. In that case, the credibility is simply that the link is maintained under all conditions. As such, the area in which another transmitter / receiver pair must be rejected is made unnecessarily large to ensure that the effects of co-channel interference are improved in every situation.

For example, consider two wireless links 151 and 152 where two receivers 161 and 171 are located close together as shown in FIG. 1B. For simplicity, it is assumed that the distance between one transmitter, transmitters 162 and 172, and both receivers is approximately equal. Therefore, the signal levels for the signals from both transmitters at the receiver's antenna input are almost the same, ie, the angles of incidence are different, but the link signal 151 and the interference signal 154 at the receiver 161 are almost at the same level; Also,
The link signal 152 and the interference signal 153 at the receiver 171 are almost the same. However, the received signal after being received by the antenna is different due to the antenna pattern having a different gain depending on the angle of incidence. The design of the link 151 must ensure that the ratio of the link signal 151 to the interference signal 154 is sufficient for the required performance.

For radio frequencies between 20 and 40 GHz, propagation losses vary over time due to air vapor, such as rain. A rain margin of 20 to 50 dB is required for normal flight distances. For systems without power control, the transmit power level is constant and always includes its rain margin. On a sunny day, the propagation loss is low, so the received signal is large and there is interference. However, the precipitation density is not always uniform over a large area, especially during heavy rains.
The propagation loss between and 152 varies over time.

FIG. 1C shows that when the difference in propagation loss is extreme, for example, some links have rain 180, while others have no effect. Assume that the signal-to-interference ratio at receiver 161 under normal conditions is XdB and the loss to rain is YdB, where Y is a large number such as 20 dB. The signal to interference ratio for the case shown in FIG. 1C is (XY) dB. This means that the link budget design must include the interference and propagation loss between the original path and the interference path.

The present invention uses automatic link parameter adjustments, such as power control adjustments, to maintain constant receive link characteristics when the propagation loss changes over time. Turning to FIG. 2, an embodiment of a communication system 200 having a transmitter / receiver pair operating in accordance with the present invention is shown. Here, the transmitter 201 radiates a main beam 211 directed to the receiver 202 and establishes a wireless communication link between them that is suitable for providing signals and information. The transmitter 201 also has an area of influence 221a, which is comprised of side lobes, back lobes, and the like, where signals emitted by the transmitter 201 can be received outside the main beam 211.

Therefore, any receiver placed in either the main beam 211 or the affected area 221 a can establish communication with the transmitter 101. However, it should be understood that the area associated with both the main beam 211 and the affected area 221 is significantly smaller than in FIG. 1A above. Thus, the further placed transmitter / receiver pairs are located closer to the transmitter / receiver pairs of FIG.

To avoid signal degradation or communication link failure during the occurrence of the dynamically changing conditions, the system of FIG. 2 measures link characteristics at receiver 202 and is measured at the receiver. The transmitter 201 operates to adjust the transmission so that the parameters become constant. This is because the main beam 211 remains at a substantially constant size.
, Ie, the main beam without attenuation is shown in the system of FIG. 1A.

However, since the communication parameters must be adjusted to compensate for the changing conditions, ie, the transmission power level of the transmitter 201 is increased to correct for the attenuation due to precipitation, and the affected area 221a is slightly reduced. Influence area 2 extended to
It is not constant as shown at 21b. For example, the transmission power compensates for the propagation loss in the main beam, and also compensates for the side lob area. Transmitter 201
Unwanted interference with coexisting transmitter / receiver pairs is of primary importance to maintain a communication link between the receiver and receiver 202, and if possible, to maintain consistent link performance characteristics. According to the present invention, which is not sufficiently shown or does not show undesired results, this variation of the affected area is tolerable.

When a system with power control is deployed according to the present invention, the received signal level is maintained at a substantially constant value. Therefore, the difference in propagation between the links is not significant, since the signal and interference levels are kept constant. Therefore, it is desirable to have a power control range that is greater than or equal to the rain margin.

From the above, in terms of system operation, the main differences between the prior art and the present invention are:
While the prior art constant transmit power system is limited in interference during low propagation losses (sunny days) and thermally limited during high propagation losses (rainy days), the present invention requires a fixed transmission power system. The received signal power system is thermally limited for the entire period. Furthermore, the transition from interference to thermal limitation is not uniform in prior art systems because the rate of rain is not uniform over many miles of large area. Thus, the overall network performance is very complex to analyze, and it is difficult to further deploy the transmitter / receiver pair without interference. Furthermore, it is unlikely that each link with a constant transmit power line will meet the performance required for some rain patterns.

On the contrary, the area change of the constant receiving power system of the present invention is small. Therefore, the performance management of the wireless network can be performed well.

Turning to FIG. 3, a block diagram of a transmitter / receiver pair employed in accordance with the present invention is shown. In accordance with the present invention, the control system includes maintaining a constant level of link parameters under all propagation loss conditions across the wireless link. Preferably, the control system utilizes a closed loop power control system in which the error level of the received signal is detected and used to adjust the transmission power.

As shown in FIG. 3, the preferred embodiment of the present invention includes two parts that operate to form a closed loop control system. Preferably, in communicating over link 300, portions of the control system
And other parts of the control system are located in or with the transmitter 201, as shown in FIG.

An advantage of having a control system at least in part of the reception is that it is at the receiver that the signal characteristics as actually experienced on the link can be measured most easily. The advantage of having a control system at least in the part of the transmitter is that not only can the controller regulate the transmission as required, but if any failure occurs in the system, the control system recognizes the condition of the failure and is adjusted The decision is whether to leave the transmitter in place or adjust the transmitter in response to a fault condition. For example, if, as a special case, the transmitter transmits a large power that does not attempt to improve the signal received by the receiver, the control system ignores the request to increase the power and rejects some detected faults. Instruct the transmitter to reduce the transmission power in the meantime.

In a preferred embodiment, a power request algorithm 320 operating in a processor-based system, such as having the CPU 302 of the receiver 202, receives a signal therefrom and attributes of the received signal above or below a predetermined level. It is coupled to a receiver circuit such as a demodulator 304 that determines whether The power change output request is sent to the other transmitter 201 of the wireless link, such as over the reverse channel of link 300.

In a typical point-to-point link, each site includes both a transmitter and a receiver, ie, a reverse link substantially identical to the forward link shown in FIG. 2 is provided for each transmitter / receiver pair. Exists. Generally, the reverse link operates at a different frequency than that of the forward link, for example, frequency division of the forward and reverse channels. Of course, the reverse link may be implemented via time division duplexing (TOD), CDMA, or other multi-access schemes if desired. The reverse link is generally used for the subscriber's payload, ie, the subscriber utilizes a two-way information link. However, often the control channel is included in this reverse channel link (the control channel can be included in the forward link). Thus, the present invention uses this control channel to link between the part of the control system located at the receiver and the one located at the transmitter.

The control channel may be an overhead bit of each packet of data to be transmitted,
Therefore, it is somewhat limited in bandwidth. Accordingly, the present invention is desirably operable to optimize the communication of control system information on the control channel.

However, it should be understood that the use of an existing bi-directional link between a transmitter / receiver pair is not required for operation of the present invention. For example, a reverse channel is established only for the control information communication of the present invention. For example, when a one-way wireless link is deployed, the control system of the present invention may provide a public switched telephone network (PSTN).
Other means are available for communication link parameter adjustment information, such as wide area networks, the Internet, cable systems, or the like. Furthermore, since the reverse channel required for operation of the preferred embodiment is optimized, the reverse link used can be provided with substantially less bandwidth than that of the forward link subscriber communication, and thus its cost And minimize complexity.
Further, the use of an external link to such a point-to-point system can be coordinated with the forward link control channel and ensure that there is no additional subscriber payload.

In a preferred embodiment, the power change algorithm 310 operating in a processor-based system, such as the CPU 301 of the transmitter 201, uses a radio frequency transmitter (Tx
RF) coupled to a transmitting circuit, such as module 303, and a power request algorithm 3
20 and the transmitter 201 should be tuned as requested,
Or decide not to. If it is determined that transmission 201 is to be adjusted, a command signal is provided by the power change algorithm 310 and the transmitter 2 such as an electronic control attenuator located in the TxRF module 303.
Adjust the 01 circuit.

Although the preferred embodiment described above uses the CPUs associated with the transmitter 201 and the receiver 202 to operate the power change algorithm 310 and the power change algorithm 320, respectively, this is not a limitation of the present invention. . For example, another embodiment of the present invention provides a central processing unit, INTEL80X86, having a memory for storing and executing the above algorithm and suitable for interfacing with the transmitter 201 or the receiver 202.
General purpose processor based systems based systems such as family based personal computer systems can be used.

As noted above, the receive demodulator is preferably the source for the receive side of link 300. When using demodulator 304, power request algorithm 320 can request information about link performance. For example, in the preferred embodiment, the power request algorithm 320 is provided with information about the bit error rate (BER) of the signal from the information provided by the demodulator 304 as well as receiving a received signal strength indicator. Based on this information, the power request algorithm 320 can determine whether the power should be adjusted from the current level and, if so, whether this adjustment should be increased or decreased.

Turning to FIG. 4, power request algorithm 3 according to a preferred embodiment of the present invention
A flow diagram of the operation of 20 is shown. In the preferred embodiment, the link performance obtained by the receiver is measured by adjusting the link parameters to compensate to change the link conditions. Therefore, the power change algorithm 320 uses the
Measure BER. Of course, another measurement of link performance is made according to the present invention if necessary. For example, another embodiment of the present invention measures the received signal level, the ratio of the received signal level to the noise level, or the like.

When a high-speed communication system is provided, reliability of data to be transmitted is desired.
It is desirable that recommunication data be avoided to avoid wasting bandwidth due to repeated transmissions. Therefore, the link error rate is desirably set as low as possible. For example, the BER that occurs for a particular link is of the order of magnitude 10-12, ie, one error is detected for every 1012 bits received. Therefore,
If a link is transmitting at 100 Mbit, it takes 2.78 hours to detect one error.

Preferably, the control system of the present invention substantially adjusts the communication system to a rate of environmental change, or another dynamic condition affecting link performance, to maintain desired link performance. Operate. However, in many cases, adapting to the rate of environmental change will require continuous and immediate measurement of link performance and adjustment of link parameters. Alternatively, such continuous and instantaneous measurements and adjustments may be made to select incremental measurements and / or adjustments, for example, to provide a margin for operation.

There is a trade-off between the adjustment step-off size and how often the adjustment is made. If the system adjusts slowly, then large adjustment steps are required to adapt to environmental changes. In order to maintain the minimum desired link quality with such a large tuning step, a large margin of link quality required by the receiver must be generously provided.

For example, if the link performance measurement is made with reference to the received signal strength, a particular power level is selected, eg XdB. If the adjustments are made in 1 dB increments even when the received power is strong, the system will use X + to allow the link extent to be reduced to a preselected X dB in preference to the lowest adjustment increase of 1 dB. It must operate at 1 dB. However, this will increase the exclusion area around this transmitter / receiver pair, as this will result in the transmitter constantly transmitting at a power level sufficient to compensate for the set large incremental adjustments.

Further, if the adjustment steps are too large, the receiver may not operate properly. For example, sudden changes in the transmit power level can cause problems with the receiver's AGC, locking loops, and the like. Accordingly, it is desirable to make the necessary decisions to adjust the transmission parameters to a desired and acceptable level of increase adjustment to be made.

However, such a fast decision is not always possible. For example, the preferred embodiment described above utilizing BER determination requires a sufficiently long time for the determination. It should be understood that environmental conditions will vary substantially over such a length of time.

Accordingly, the preferred embodiment of the present invention uses a multi-process to determine link quality, preferably using a slower, more accurate process and a faster, less accurate process. Ultimately, the information of the slow process is desired to be a link performance reference point because it is the quality that is actually carried, but the instantaneous linking of the link, through the correlation of low- and high-quality process decisions, is desired. Target or near-immediate determination of link information is made.

An accurate measurement of link performance, ie, a high quality BER measurement in the preferred embodiment, requires a long time to make an accurate measurement. In particular, the determination of high-quality BER is generally achieved by counting the number of bit errors in an interval. Measurement accuracy is based on the number of errors counted during the measurement interval. A good compromise solution is to record the interval at two consecutive errors, since it takes a long time to get some accuracy. Computation of high quality BER may utilize the average error interval of the last x errors, eg, the last 10 errors. The number of bits in the average error interval is twice the bit rate of the average error interval. The high quality BER is one greater than the number of bits in the average error interval. This measurement scheme allows the high quality BER to be updated for each detection error.

However, if measured earlier and used properly, very good indications of accurate link performance can be given, but there are inaccurate indications of link performance. In the preferred embodiment of FIG. 4, the two link parameters are measured very quickly, ie, substantially instantaneously and continuously. In particular, the received signal strength indicator (RSSI)
And low quality BER (Coarse BER) are measured to determine and use low quality link performance.

It will be appreciated that the transmitter / receiver pair information communication of the present invention uses some form of error correction coding. Therefore, many transmission errors are detected,
It is then modified prior to the information shown to the subscriber. The low-grade BER of the present invention uses (taps) the error rate before such an error correction code corrects the transmission error. Thus, by referring to the error rate given to the subscriber, errors are detected quickly.

However, as experienced by subscribers, there is no one-to-one correlation between low quality BER and BER. To that end, the preferred embodiment of the present invention utilizes the second link parameter in the case of a lower quality link parameter determination to more accurately correlate this information with a higher quality BER.

Furthermore, if the unidirectional link parameter measurement relies only on a fast determination of the link parameter adjustment, the hysteresis of the adjustment will be a problem. For example, depending on the noise and other phenomena affecting the communication link, if only the low quality BER is used to make the adjustment decision, since the low quality BER varies by only one bit, ie, the low quality BER There is a constant adjustment of the communication parameters, since is different every half-second when the adjustment is made. However, the transmitter must be configured such that it does not actually affect link performance.
It is usually undesirable to adjust continuously in response to rising, falling, rising, falling.

Thus, the preferred embodiment uses two measurements, both RSSI and low quality BER.
When both are better than the reference (exceeding the upper or lower threshold), the system is actually transmitting too much power and a low adjustment is desirable. However, when both are below the threshold (do not exceed the upper or lower threshold), the system is actually transmitting too weakly and it is desirable to adjust up. If one of the parameters is better (above the upper or lower threshold) and the other parameter is worse (does not exceed the upper or lower threshold), this does not affect the communication link and does not require adjustment of the link parameters Indicates slight environmental or other phenomena.

When using the same method as above related to high quality BER, average low quality BER and average
RSSI is calculated at each error interval. Therefore, the final low-grade average BER and R
SSI computations are based on the same intervals used for high-definition BER, although their average is updated more than for high-definition BER.

Preferably, the control system takes a plurality of samples of the RSSI and the low quality BER between two successive power change requests. In the preferred embodiment, the number of samples taken is based on the change from one sample to another. Thus, if the system is fairly stable, processing power is conserved by taking fewer samples and performing fewer calculations. However, if the system is undergoing faster fluctuations, the control system will react to make faster measurements so as to compensate for the fluctuations faster and more accurately.

As shown in FIG. 4, the preferred embodiment is the BE taken by the subscriber (box 401).
Calculate R, which takes several hours, and measures the measured RSSI and low quality BER simultaneously to set the reference (box 403). Measured RSSI and low quality
By recording the BER, the average of these measurements is correlated to the high quality BER measured for use eventually in making a more accurate and faster decision on link performance (box 402), ie, the link performance Slow measurements are moved to the reference point of the fast measurement of link performance.

The purpose of the correlation between BER and RSSI and low quality BER in the preferred embodiment is to determine what measured RSSI and low quality BER thresholds reach the desired high quality BER, ie, the BER defined by the system performance requirements Is to determine. High quality BER, average
Based on RSSI and low-grade BER measurements, either above or below the average RSSI and BER, depending on whether the high-quality BER at which the correlator is actually measured is lower or better than expected Set the RSSI and low-grade BER to.

Once this slow measurement of link performance has been moved to the fast measurement point,
The threshold is set for substantially immediate or real-time adjustment of link performance. This information is used to determine whether currently measured parameters, ie, low quality BER and RSSI, indicate that adjustment of the link parameters is desired.

In particular, if the low quality BER is less than the threshold associated with the desired high quality BER (box 4
04), and if the RSSI is greater than the reference threshold associated with the desired high quality BER (box
405) At that time, a decision is made to reduce the power level (box 407). Conversely, if the low quality BER is greater than the reference threshold associated with the desired BER (box 404) and the RSSI is greater than the reference threshold associated with the desired BER (box 406), then the decision to increase the power level is made. This is done (box 407). However, if the low quality BER is below the reference threshold associated with the desired high quality BER (box 404),
And if the RSSI is less than the reference threshold associated with the desired BER (box 405),
Alternatively, if the low quality BER is greater than the reference threshold associated with the desired high quality BER (
(box 404), and if the RSSI is greater than the reference threshold associated with the desired high quality BER (box 406), then a determination is made that the power levels should remain the same (box 407).

Thus, the decision algorithm decides what the next requirement related to the power level is, ie increase, decrease or no change. The power level change is based on a positive indication, ie, whether both RSSI and low-quality BER are better or worse than a threshold. A non-deterministic indication of a change when one of the two parameters is better than the threshold desirably is that there is no communication link adjustment.

Each decision made according to the power demand algorithm is desirably communicated to the part of the control system that actually operates to tune the transmitter (box 4).
08). However, if no coordination is desired, transmission of this decision will be omitted to avoid unnecessary use of the reverse link. Alternatively, if the decision is to be determined periodically and systematically through the use of the transmitter, such as to determine the continuous operation of the part of the control system located at the receiver, this "change" None "is desired.

Having described the preferred embodiment of the power request algorithm 320 of the present invention, reference is now made to FIG. 5, which shows a flow diagram of the preferred embodiment of the power change algorithm 310. Desirably, each link has a maximum and minimum power level associated therewith set to protect each radio and / or other communication link during the occurrence of an abnormal condition. In the preferred embodiment, this information is stored in box 50
1 is provided in a database associated with or accessible to the power change algorithm 310, or other knowledge base or look-up table.

In the preferred embodiment, the maximum power level is set as a function of link distance and performance requirements. The minimum power level is also desirably set as link distance and link performance, and is utilized primarily to ensure that the system does not degrade overall to minimize the startup process.

For example, consider two links, one wireless link has a longer link distance than the other. Longer distance links are typically in a relationship having higher maximum and minimum power levels than shorter ones. Other examples will have the same link distance but different effective performance requirements. Thus, a link with high link availability performance will have a higher maximum power level than a link with lower link availability requirements. here,
However, the minimum level is the same for each link.

The nominal power level shown in the embodiment of FIG. 5 is preferably the power level transmitted most of the time. This nominal level is computed from the link distance and / or from historical information related to the link. In a preferred embodiment of the present invention, the nominal power level determines whether the system is operating too long at excessive power levels and is a reference value that indicates a system fault, or other abnormal condition. Used as a reference level. Further, the nominal power level is used to set the minimum transmit power, for example,
The minimum power level is set as XdB below the nominal power level.

The setting of the link parameter range takes into account the occurrence of special conditions. For example, the minimum power level may be set to abnormal environmental conditions or another anomaly that causes the path to be less lossy. If such a phenomenon occurs, communication is maintained during this phenomenon, but it is undesirable to adjust the power level below a certain point because, when the phenomenon disappears, the undesired loss of the link Or, there is no way to adjust the communication parameters fast enough to avoid other communication problems.

Similarly, the maximum power level is set to avoid adjusting the power level upwards in response to a phenomenon where the power level adjustment is such that it does not maintain the desired link performance. For example, to set the lowest possible maximum attenuation as can be achieved by referencing the historical operating conditions for the calibration techniques and / or links described below, or to set the maximum level slightly higher. It will be appreciated that the system can compensate for such conditions, while not increasing to uncontrollable power in the event of a service outage.

The use of the above values to define a power range allows to be adjusted for various conditions as well as applying the present invention according to historical information or other sources of knowledge base. For example, in some cases it may be acceptable to have a link reliability of 99.999% ("five nines") or to lose a total of 5 minutes of transmitted data per year, such as due to rain attenuation. desired. This level of link reliability requires more power to compensate for the case of greater attenuation. Therefore, the maximum power associated with the power range of the power change algorithm 310 will be set higher. However, in some cases, 99.99% ("foanain") link reliability, or a total of 15 minutes of transmission data error loss per year is acceptable. At that time, the maximum power level related to the power range is set to a lower level.

Further, the use of these tunable parameters in the algorithm allows the unidirectional algorithm to be designed to change in time or configuration without the need for an independent algorithm or function to operate a particular state or condition. It should be understood that it is possible to operate the system with a range of parameters. Instead, a one-way algorithm can easily determine whether the required adjustment is within the range of acceptable parameters, and without actually determining under what conditions the system will operate. That change is possible. Thus, the present invention provides a simple and effective method in which the standard system is improved and deployed, and the operating environment of each link is adjusted initially based on the deployment and later in response to historical operational information. .

As shown in FIG. 5, the power change algorithm 310 of the preferred embodiment comprises:
It operates to receive a power level change request generated by the power request algorithm 320. Thereafter, the algorithm uses the aforementioned power range information (box 50).
With reference to 1), it is determined whether the requested power change is within this range (box 502). If the requested change is within the power range,
Changes are performed as requested. However, if the change is not within the power range, the request will not be fulfilled. For example, if a request to increase power is received, but the system is already operating at a maximum power level that is not within the allowable range for the requested power change, then the request is not accepted.

If the decision is to change the transmit power, a message or control signal is sent from the power change algorithm 310 to the TxRF to change the attenuation value. In the preferred embodiment, the adjustment of the power level is a consistent increase.
For example, if the power change algorithm 310 instructs the attenuator to increase the transmitted power level, the single unit of power level increase is incremented. Thus, if the power change algorithm 31
If a 0 indicates to the attenuator to decrease the transmitted power level, the single unit of power level increase is decremented.

However, in another embodiment, the link parameter adjustment is non-linear. For example, when increasing power, the system increases in larger steps, but when decreasing power, the system decreases in smaller steps. In this way, the system can determine the frequency of parameter adjustment requests, i.e., constantly increasing power, and when those requests are repeated, make slightly larger adjustments rather than smaller adjustments. For example, once the threshold is exceeded, the system adjusts the link parameters by one step. However, if the threshold is exceeded a second time, the system adjusts the parameters by two steps. Alternatively, two sets of thresholds are provided, and if the first threshold is exceeded, the system adjusts the link parameters by one step, but if the second threshold is exceeded, the system adjusts the link parameters by two steps. To adjust. These embodiments are such that a small incremental step of power increase is substantially inadequate to compensate for temporary attenuation.
It is desirable when attenuation is caused by "cloud burst" type precipitation.

It is understood that the size of these incremental adjustments and the conditions under which additional incremental adjustments are used are provided in a database, or other knowledge base, or information table as used by the power ranges described above. Should be. Thus, the incremental adjustment is made to the specific environment in which the system is to be placed by the power range.
This information is actually stored in the same database as the power range,
It is illustrated as 1. Alternatively, a separate database is provided for storing this information (not shown).

When initially powered up, it is desirable that the system does not wait for a high quality BER measurement before the start operation according to the invention. Therefore, default values, such as those loaded at the factory, are used to start the system. These default values are substantially arbitrary depending on the particular link configured and are based on parameters known at the time of establishment, such as, for example, link distance.

A system calibration is preferably performed when the system is operating but cannot measure high quality BER, eg, when no errors are detected or immediately after power-up. This system calibration is used to set thresholds for determining link parameter adjustments, and preferably also includes adjusting the default values of the power range information.

For example, if the magnitude of the error is of the order of 10-12, measuring a particular desired error rate can take a long time. Therefore, after measuring the error over a long time, there may be substantially no error. At first, it will be clear that the conclusion of the error is not desired. However, if the system does not know exactly what the error rate is, the system may transmit too much power, so that even if it has a virtually error-free link, Interference can occur.

According to the preferred embodiment, the calibration is a three parameter, high quality BE
Implemented by reducing the values of R, low-grade BER and RSSI, which causes the power request algorithm to operate to reduce the transmitted power. Decreasing these values is repeated until some measurable error is detected. Once some errors are detected, these values, or some of these values, are readjusted or increased to achieve the desired link performance level.

In many cases, it is desirable to design the power control system to operate slightly above the required performance to allow for some degradation between adjustments.
Accordingly, a margin is required between the actually measured communication parameters and the required communication parameters that is appropriate for the required link performance. Therefore, the correlator of the preferred embodiment inserts a system margin. For example, a correlator may be
In combination with the BER, it determines that a particular RSSI is appropriate to provide the desired link performance, but the correlator provides a system margin for this determined value of RSSI. Thus, the correlator introduces or increases the system margin by increasing the threshold.

One of the tasks during the installation and commissioning of a point-to-point transmitter / receiver pair is to place the two antennas in the correct relationship, ie with each antenna facing the other. It is to arrange. However, since large distances are taken in such systems, one or both antennas will be aligned on the side lobes, due to the physical misalignment of the antenna only a few degrees, i.e. Instead of beams, they may face each other to side lobes that produce sufficient transmit power.

The preferred embodiment of the present invention sets the maximum power level of the power range to a nominal level (
Alternatively, by reducing the maximum power level in the power range just above (the level expected for communication of a particular length link by the main antenna beam), avoiding the establishment of communication over these unwanted links. is there. Under these conditions,
The system operates only when the antenna is pointing at each of the main beams. Furthermore, this technique will reduce the interference of the installed base radio due to the alignment process by pointing the radio in the wrong direction.

The preferred embodiment of the present invention recognizes and reacts to system anomalies, and in particular, to adjust link parameters such that interference is introduced to other links. FIG.
Focusing on, a flow diagram of a preferred embodiment of the power change algorithm 310 is shown with a decision box (box 601) for determining system anomalies.

Thus, in this embodiment, the requirement for power level depends not only on the determination that the required change is within the limits of the system as in FIG. 5, but also on the determination that the system is not abnormal. There will be. If the system is determined to be abnormal, the system is closed and the operator is notified. Alternatively, if the system is determined to be abnormal, the system may not be at the desired link performance level, but in advance, such as at the nominal or maximum power level described above, to allow communication. Continue to transmit at some determined level.

[0099] System anomalies are determined by means of measuring while the system operates at a height above the nominal power level. For example, if a substantial decay period is recognized to be short and the system is historically recognized and operates at an increased power level over a period of time, then the system is concluded to be abnormal.

Similarly, the system determines an abnormal condition from the number, type, and / or frequency of power change requests. For example, the system continues to receive only requests to increase power levels for a long period of time. This represents a misalignment of the antenna alignment, rather than environmental conditions should be compensated. Therefore, the system
It is determined that such an increase is not insignificant and informs the operator of the possibility of an abnormal condition.

While the invention and its advantages have been described in detail, it will be understood that various changes, substitutions, and modifications may be made without departing from the spirit and scope as defined by the appended claims. Should.

[Brief explanation of the figure]

FIG. 1A shows a prior art point-to-point communication system wireless radiation pattern contour. 1B and 1C are diagrams illustrating information input between closely arranged transmitter / receiver pairs.

FIG. 2 illustrates a radiation pattern contour of a point-to-point communication system configured according to the present invention.

FIG. 3 shows a block diagram of a preferred embodiment of the control system according to the present invention.

4 is a diagram showing a flowchart of a power request algorithm of the control system of FIG. 3;

FIG. 5 shows a flow diagram of a power change algorithm of the control system of FIG. 3;

FIG. 6 shows a flowchart of another embodiment of the power change algorithm of the control system of FIG. 3;

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZWF terms (reference) 5K014 AA01 CA04 CA05 GA02 GA06 5K046 AA05 DD01 DD14 DD20 DD29 PP06 5K067 AA03 CC04 CC10 DD27 HH22 HH26 KK01

Claims (44)

[Claims] 1. A transmitter having a main antenna beam profile for point-to-point communication, a receiver communicating with the transmitter over the link created by the main antenna beam, and a link attribute recognized by the receiver. And a controller for controlling the transmitter to maintain the main antenna beam substantially constant. 2. The system of claim 1, wherein the attributes measured by the controller include performance characteristics of the link and at least one additional attribute. 3. The control device correlates the performance characteristic with at least one of the additional attributes, wherein the measurement of the performance characteristic requires a longer measurement time than the additional attribute, and The system according to claim 2, wherein the additional attributes are used to determine the current execution performance by the correlation. 4. The system of claim 3, wherein the performance characteristic is a high definition bit error rate, and the at least one additional attribute includes a low definition bit error rate. 5. The system of claim 1, wherein the controller includes link attribute range information for the controller to control so that the transmitter does not operate outside of the attribute. . 6. The system according to claim 5, wherein said attribute range includes a maximum power and a minimum power. 7. The system of claim 6, wherein the maximum power is set slightly above a nominal power level during a setup phase of the link. 8. The system of claim 7, wherein the maximum power is set in the operational phase of the link to be slightly above a power level sufficient for worst case attenuation conditions. 9. The system of claim 1, wherein the controller is at least partially co-located with the transmitter. 10. The system according to claim 9, wherein the controller is at least partially co-located with the receiver. 11. A monitor located at least partially on the receiver for monitoring performance characteristics and at least one link attribute in addition to the performance characteristics.
The monitor correlates the at least one monitored additional attribute with the monitored performance characteristic to obtain correlation information thereof, and the monitor determines the at least one attribute currently monitored and the at least one attribute. Providing correlation information and a link manipulation control signal, wherein the manipulator has a function of determining the manipulation in response to the manipulation control signal between the links and the link manipulator control signal within predetermined operating parameters; A system for manipulating said link, said system being at least partially located at said transmitter, comprising substantially consistent performance characteristics in a link between a transmitter / receiver pair of a communication network. . 12. The system of claim 11, wherein at least one of the additional attributes includes received signal strength and low quality error rate. 13. The system of claim 11, wherein the performance characteristic is a high quality bit error rate. 14. The system of claim 11, wherein the at least one additional attribute includes at least two additional attributes. 15. The correlation information according to claim 15, wherein the correlation information includes a first threshold value related to a first attribute of the at least two attributes and a second threshold value related to a second attribute of the at least two attributes. 15. The system according to 14. 16. The control signal is a first value when both the first attribute and the second attribute do not exceed respective thresholds, and both the first attribute and the second attribute are respective When the threshold is exceeded, the control signal is a second value, and one of the first attribute and the second attribute does not exceed a respective threshold and the first attribute and the second attribute are not changed. The system of claim 15, wherein the control signal is a third value when the other exceeds a respective threshold. 17. The method of claim 17, wherein the first threshold is a power increase of the transmitter, the second threshold is a power decrease of the transmitter, and the third threshold is a power maintenance of the transmitter. 17. The system of claim 16, wherein: 18. The system according to claim 11, wherein the predetermined operating parameter comprises a first power range. 19. The system of claim 18, wherein said first power range includes maximum, minimum and nominal power values. 20. The manipulation of the link by the manipulator,
The system of claim 19, wherein the system is a function for determining the presence of an abnormal condition. 21. The system of claim 20, wherein the determination of the presence of an abnormal condition is made at least in a portion that references the nominal power value. 22. The predetermined operating parameter includes a second power range, wherein the first power range relates to a first operating condition, and wherein the second power range corresponds to a second operating condition. 19. The system of claim 18, wherein the system is related. 23. The system according to claim 22, wherein the first operating condition is a set operating condition, and the second operating condition is an arrangement operating condition. 24. The system of claim 18, wherein a value related to the first power range is updated with reference to history information related to the link. 25. measuring a first attribute of the received signal; measuring a second measurement of the received signal; measuring a third attribute of the received signal; Correlating the measurement of the three attributes with the measurement of the first and second attributes, setting a first threshold for the first attribute, wherein the first threshold at least partially refers to the correlation information Setting the second threshold for the second attribute, wherein the second threshold is determined at least in part from the correlation information. The function of comparing the measured first attribute to the first threshold, and comparing the measured second attribute to the second threshold. Generating the received signal control signal as a function. And maintaining a desired received signal quality. 26. The method of claim 25, wherein the third attribute is a high quality bit error. 27. The method of claim 25, wherein the first attribute is a low quality bit error rate. 28. The apparatus according to claim 25, wherein the second attribute is received signal strength.
The method described in. 29. Receiving information regarding comparing the measured first attribute to a first threshold and comparing the measured second attribute to a second threshold, wherein the first and second thresholds are Determining whether the signal transmission characteristics are to be adjusted with reference to the received information, wherein the determining is performed in a part referring to the third attribute; A method comprising controlling a signal transmission to maintain a desired received signal quality, comprising a step of including a reference to a predetermined range of characteristics. 30. The method according to claim 29, wherein the third attribute is a high-quality bit error rate and the second attribute is a received signal strength. 31. The method of claim 29, wherein the first attribute is a low quality bit error rate and the second attribute is a received signal strength. 32. The method of claim 29, further comprising adjusting the predetermined range from a first range to a second range. 33. The method according to claim 32, wherein the second range is at least a portion based on history information. 34. The system of claim 32, wherein the first range is set to an initially acceptable range for a transmitter / receiver pair configuration associated with the transmitted signal.
The method described in. 35. measuring a first attribute of the link; measuring a second attribute of the link; measuring a third attribute of the link; the first attribute to provide attribute correlation information. Correlating the measurement of the second attribute with the measurement of the second attribute, and setting a second threshold value for the second attribute related to a state in which the first attribute can be accepted from the correlation information. Setting a third threshold value for the third attribute associated with a state in which the first attribute is acceptable from the correlation information; comparing the measured second attribute to the second threshold value; and Generating a received signal control signal as a function of comparing the third attribute to the third threshold value, determining whether link characteristics consistent with operation are in a selected range according to the link control signal, and , The link feature Adjusting the link attribute if is within the selected range, the transmitter / receiver pair communicating over a wireless link and the co-channel associated with the transmitter / receiver pair of the communication network. How to reduce interference. 36. The system according to claim 3, wherein said first attribute is a link performance characteristic.
5. The method according to 5. 37. The method of claim 36, wherein said performance characteristic is a high quality bit error rate. 38. The method of claim 37, wherein said second attribute is a low quality bit error, and said third attribute is received signal strength. 39. The method of claim 35, further comprising adjusting a selected range from a first range to a second range. 40. The method of claim 39, wherein the second range is based at least in part on history information of the link operation. 41. The method of claim 39, wherein the first range is set as an initially acceptable range for the transmitter / receiver pair arrangement. 42. The method of claim 35, wherein the adjusting step for determining the presence of an abnormal condition further comprises comparing a nominal attribute of the link to the attribute of the link for adjustment. Method. 43. Measuring a high quality bit error in the receiver; measuring a low quality bit error in the receiver; measuring a received signal strength in the receiver; and providing correlation information. Measuring the correlation between the low-quality bit error rate and the received signal strength and the high-quality bit error rate; and setting a threshold value for the low-quality bit error rate related to a desired high-quality bit error rate from the correlation information. Setting a threshold for the received signal strength related to a desired bit error rate from the correlation information; as a function of comparing the measured low quality bit error rate to a low quality bit error rate threshold; and Generating a link control signal as a function of comparing the received signal strength with the received signal strength threshold Determining whether the transmitter's transmit power, consistent with operation in accordance with the link control signal, is in a selected range; and, if the link characteristics are in a selected range, the transmitter's Adjusting the transmit power to reduce co-channel interference associated with a transmitter / receiver pair of the communication network. 44. The method of claim 43, wherein referring to the nominal power level and the link control signal, determine whether an abnormal condition exists.