SE516977C2 - Method and means of a telecommunication system - Google Patents

Abstract

The present invention relates to a method and means for estimating the traffic load in a cell in a radio communication system. A base station measures (301) a first interference level in the cell. The base station transmits (302) a turn-off message to all radio units in the cell. The radio units in the cell determines (307) if they are in low power saturation, i.e. their output powers have been reduced to their minimum output power level and they still exceed the output power that is needed to comply with the SIR requirements in the system (e.g. by being very close to the base station). All radio units except those determined to be in low power saturation turn off their transmitters (308) while the base station measures (309) a second interference level in the cell. The base station estimates the traffic load (310) from the difference between the first and second interference level.

Description

20 25 »sia 977: _-: _ 2 = :: = - 2 The cell, associated with the particular base station with which a radio unit communicates, is usually called a service cell.

There are mainly two types of channels within cellular radio communication systems, the physical and the logical channel. A physical channel is a carrier of information via a radio link (a lagerl channel). A logical channel (a layer 2 channel) is a special kind of information, transmitted via a physical channel, for example speech via a traffic channel. A common expression is that the logical traction channel is mapped to the physical channel. WCDMA systems also have a third type of channel, the transport channels.

A transport channel is used for communication between a layer 1 and a layer 2 channel, i.e. a logical channel is mapped to the physical channel via a transport channel.

Channels mentioned in this text and which are not explicitly specified as physical or transport channels are mainly logical channels.

The cellular radio communication systems usually provide a broadcast channel, on which all radio units can listen to system information from the base stations, for example the Broadcast Control Channel (BCCH) in GSM and CDMA systems.

The BCCH is depicted on a Primary Common Control Physical Channel (P-CCPCH) in WCDMA.

The BCCH is an example of a common control signaling within a cellular radio communication system. Another example is paging signaling, which is used to wake and / or reach a radio device as an initial step, when someone in the radio system or in the usual exchange system in connection with the radio system or in the usual exchange system in connection with the radio system trying to reach a radio device. The search division is transmitted via the radio system (directly or in steps, local area by local area) to find the radio unit. There are search channels in both GSM and CDA systems, for example in WCDMA, where there is a search control channel 10 15 20 25 30 516 977 3 PCCH mapped to a secondary Common Control Physical Channel (S-CCPCH).

The number of radio units that can be used simultaneously in a CDMA system is limited.

This limitation is determined by the maximum allowable noise in the system. The radio units that are used, the more interference is generated in the system. An access control function will start rejecting devices, which seek access to the system, if the maximum number of concurrent users has been reached. This is to guarantee a certain minimum quality of radio traffic in the system.

The interference in a cellular radio communication system could be divided into interference from the same cell, called intracellular interference, and interference from adjacent cells, called intercellular interference. The disturbance, measured at the base station in a CDMA system, is often used by a traction load detector, in order to estimate the traction load within the cell as the disturbance increases with the traffic load. The base station usually has a power detector, which measures the total recorded power, for example the noise level. This means that the detector measures both intracellular and intercellular disruption. The measured disturbance is assumed to be largely proportional to the traction load within the cell during heavy traffic. This is a reasonable approximation if one can disregard the intercellular disruption compared to the intracellular disruption. However, this is often an overly optimistic approximation in a CDMA system. Especially when there are radio units in low power saturation near the base station.

These radio units use the lowest possible output power and still exceed the output power required to meet the requirements of the system on the signal-to-interference ratio (SIR- the Signal to Interference Ratio). This is due to the fast power control limitation in CDMA systems. Radio units in low power saturation generate higher intracellular disturbances than the other units within the cell. Radio units, which are located so close to the base station that their minimum power exceeds the required output power, are called radio units in low power saturation. 10 15 20 25 30 o: son 516 977 4 The noise from a radio unit in low power saturation can be equal to the noise from a number of radio units, which do not result in low power saturation, and the traction load detector will give a poor estimate of the actual traction load. (poor accuracy). Such a poor traffic load estimate can result in the system starting to reject radio devices, which seek access to the system, as the system believes that the maximum number of simultaneous users has been reached. This means that the system will lose capacity.

Therefore, there is a need for a method and means, which use noise measurements, to estimate the traffic load in a cell, with a higher accuracy than those used today.

PCT application WO 95/26598 comprises a CDMA system, set up to solve a problem concerning poor call quality due to many concurrent users in the system. This is solved by using a central control unit, which calculates average common disturbances, which are used in an optimization process to achieve an access control in different radio zones of the system. This means that the number of simultaneous users in each radio zone can be limited to a special maximum number, in order to maintain a good call quality in each radio zone. Noise measurements are performed in each radio zone to make it possible to calculate the average common disturbance in the system. In one embodiment, the radio base station and all mobiles in a specific radio zone are temporarily prevented from transmitting information for a short period, in order to measure the interference from the adjacent radio zones. This measurement, together with similar measurements from other radio zones, is then forwarded to the central control unit, which calculates the average common disturbances in the system.

US 5,774,814 comprises a method and system for detecting and receiving radio signals, using a modified macrodiversity scheme (base station diversity).

Multiple versions of a signal are registered by receivers and base stations and used by a decision algorithm to determine the information. At least three different signals are processed / combined to obtain the desired information. In order to determine some of the parameters of the algorithm, the signal / interference ratio for each mobile is estimated by ordering a mobile, which in the case is located within the cell, to switch off its transmitter for a short time, so that the interference from the other mobiles can be measured. When the mobile is switched on, the total noise level is measured, with which the interference level for the special mobile, which has been switched off, can be calculated. Some coordination is performed to avoid shutting down more than one mobile at a time.

As will be apparent from this, the systems and methods shown in 95/26598 and US 5,774,814 are of types other than the method and agent of the present invention.

SUMMARY The present invention addresses a problem which is related to tensile load estimation in a cell, based on interference measurements in a cellular radio communication system and in particular in a CDMA system, for example WCDMA.

The problem is that the traction load estimate, which is based on a disturbance measurement within the cell, is disturbed by interference from radio units in low power saturation, ie radio units which are close to the base station, as well as disturbances from radio units in adjacent cells and / or other types of equipment. generates disturbances. This means that the traction load estimate can have a rather poor accuracy in certain situations.

In light of the foregoing, a primary object of the present invention is to provide a method and means for improving the accuracy of traction load estimation, when interference measurements are used to estimate the traction load. Another object of the present invention is to provide a method and means for avoiding interference from low power saturation radio units interfering with the traffic load estimation.

With a method according to the present invention, a first disturbance level within the cell is measured. Transmitters in selected radio units within the cell are turned off, while a second noise level is measured. The traffic load is then estimated from the first and second disturbance value.

According to one embodiment of the method, the base station within the cell measures a first level of interference. Radio units within the cell, which are not in low power saturation, then temporarily turn off their transmitters while a second level of interference is measured by the base station. The traffic load is then estimated as the difference between the first and second disturbance value.

The method according to the invention is thus characterized by what appears in appended claim 1.

A system according to the present invention comprises means for measuring a first and second disturbance level, means for temporarily switching off the transmitters in specific radio units and means for estimating the traffic load from the first and second disturbance level.

An advantage of the present invention is that it is possible to exclude the disturbance from adjacent cells when estimating the tensile load.

Another advantage is that it is possible to exclude the interference from radio units in low-power saturation, when estimating the traction load. 10 15 20 25 30 51-6 977 7 An additional advantage is that it is possible to exclude the interference from equipment other than radio units when estimating the traction load.

Another advantage is that the same measuring unit can be used for all disturbance measurements, whereby measurement errors that occur are automatically suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a schematic view of a portion of a cellular radio communication system.

Figure 2 illustrates a schematic view of a cell in a cellular radio communication system.

Figure 3 illustrates a fate diagram of a first embodiment of a method according to the present invention.

Figure 4 illustrates a fate diagram of a fourth embodiment of a method according to the present invention.

Figure 5 illustrates a circuit diagram of a fifth embodiment of a method according to the present invention.

Figure 6 illustrates a circuit diagram of a sixth embodiment of a method according to the present invention.

Figure 7 illustrates a schematic block diagram of a system to enable the method of the present invention. DETAILED DESCRIPTION OF EMBODIMENTS The present invention relates to a method and means for estimating the traffic load in a cellular radio communication system and in particular in a CDMA system, for example WCDMA.

Figure 1 illustrates a schematic view of a part of a cellular radio communication system, comprising a number of cells 101-104, base stations 105-108 and radio units 109-114. The base stations 105-108 can be connected to one or more of your mobile radio stations, radio network controllers (RNCs), routers or similar nodes (not illustrated in Figure 1).

Figure 2 illustrates a schematic view of a cell 201 in a WCDMA system. A base station 202 serves a number of radio units 203-208 within the cell. The dashed circle 209 around the base station 202 illustrates the distance from the base station, within which the minimum power from the radio units can be used to reach the base station with a sufficient signal-to-interference ratio (SIR signal to interference ratio), i.e. SIR-Target. Both an internal control circuit (a fast power regulator) and an external control circuit regulate the output power. The radio unit output power can be set within a specified dynamics range, for example 70 dB, through the control circuits (ie between a maximum and minimum level). This means that there is a lower limit for the output power, ie the minimum level. A common value for the minimum power in a WCDMA system is -44dBm.

The dynamic range of the radio unit is a compromise between the resolution and the dynamic range of the power controller. A large dynamic range with high resolution requires fl your bits to control the power levels and this increases the power consumption of the radio units when the bits are processed. One reason for limiting the radio unit's dynamics range is to limit power consumption. Another reason is to make the test of the radio units in production quick and easy because it takes longer to test a large dynamic range. The radio units 207 and 208 within circle 209 are radio units in low power saturation.

Their output power was reduced to the minimum power of the inner control circuit as they passed the dashed circle 209 on their way to the base station 202. This means that these radio units are so close to the base station that their minimum power exceeds the output required to maintain SIRMaI. This also means that they cause a lot of interference at the base station 202. The fast power regulator can only increase the current output power and this will not happen as long as they are within circle 209. Consequently, radio units 207 and 208 are said to be in low power saturation. As mentioned earlier, the interference from a few radio units in low power saturation can cause an access control function in the system to reject new radio units, which seek access to the system long before the maximum permitted number of simultaneous users in the system is reached. Due to interference from a few radio units in low-power saturation, the traction load is estimated to be greater than it actually is.

The radio units 203-206, which are further away from the base station than the radio units 207 and 208, can still both increase and decrease their output powers (depending on their displacement within the cell), which means that they do not end up in low power saturation. .

As mentioned above, the system has at least two different ways of regulating the output power of the radio units and the base stations, i.e. the inner and outer control circuit.

The internal control circuit (fast power controller) on the uplink means that the base station measures the SIR from the radio units and compares these measured SIR values with referencing SIR values (SlRMaals). These SIR targets are minimum SIR values, selected to optimize system performance, for example in terms of capacity. If a measured SIR is higher than the SIRMM for a specific radio device, that radio device is instructed to reduce the output power by a predetermined value. If the measured SIR is 10 15 20 25 30 51 6 9 7 7 10 lower than SlRMâl, the radio unit is instructed to increase the output power by a predetermined value. This is done regularly, for example fl your times in each frame. The fast power regulator enables the base station to balance the power absorbed in the base station to a level which guarantees all uplink channels (radio unit to base station communication) the necessary signal in relation to interference (SlRMaals) ratio. The downlink works in a similar way.

The external power control circuit means that a control mode measures the quality, for example bit error rate (BER-Bit Error rate), frame error rate (PER-Frame Error Rate) or block error rate (BLER-Block Error Rate), on one or more uplink radio connections and compares it with a reference value (a quality target). If the quality of a radio connection is higher than the quality target, the control node instructs the base station to reduce SIRMH (for example in soft-hand-off in CDMA) to a lower value so that the quality target is reached. If the measured quality is worse than the quality target, the control node instructs the base station to increase SIRMåI. This is performed continuously with a time interval which is longer than that used for the internal control circuit. The external control circuit is usually regulated by a radio network controller (RNC-Radio Network Controller) or similar in the core network.

There is usually a third way to regulate the output power of the radio units and base stations, and that is the open one. The open power control circuit has a slower update of the radio unit output power than the internal and external power control circuits (closed loop power controllers). Radio units regulated by the open circuit and radio units regulated by the closed circuit behave in a similar manner.

The radio units use different types of S services, such as voice, data and real-time services such as video. These services have different SlRMaals depending on the quality goal and the service bit rate for each type of service S. 10 15 20 25 5 1 6- 9 7 7, 11 The total interference experienced by the base station could be divided into intracellular interference, intercellular interference, interference from radio units in low power saturation, thermal noise from the antenna connector and other interference.

The intracellular disruption is a result of the transfer from / to radio units within the cell.

A first part of the intracellular disruption within the cell is the disruption caused by radio units, which do not result in low-power saturation. These radio units can use one or fl your services S. If a first number of radio units NI uses a first kind of service S, with a SlRMaal SIRT] and a second number of radio units N; uses a second service S2 with a SIRMå; SIRTZ, the first part of the intracellular disturbance within the cell can be expressed as: I] = I * (N1 * SlRT1 + N2 * SIRT2) (equation 1) This means that if the number of radio units within the cell is Z, the recorded disturbance within cell 11 is written as: (equation 2) where SIRTfSIRMåI (C / I) for radio link number n, from radio unit number n.

A second part of the intracellular disturbance within the cell is the interference caused by radio units in low power saturation. As noted above, these radio devices can cause a lot of intracellular interference, as they are located near the base station and have a higher SIR than SlRMa. The recorded noise at the base station from radio units, which is based on low power saturation, is expressed as IPL. 10 15 20 25 516 977 12 Intercellular disruption is the disturbance a specific cell detects from other (mostly adjacent) cells. The intercellular disturbance depends on radio network planning parameters, such as cell distance (parameter a), the number of adjacent cells (parameter b) radio network environment (parameter c), traction load in adjacent cells (parameter d), etc. This means that the intercellular interference could be written as a function I (a, b, c, d, This tennis noise at the antenna connection is also a source of interference. This is expressed as Ibun fl.

The last part of the total disturbance is the disturbance generated by other systems and / or equipment, for example household equipment. This disturbance can be expressed as IM.

The total recorded noise I of the base station receiver can then be written as: ZI = I * 2 SIRTJ, + Ka, b, C, d, ----) + IPL + 1111514 'Ibunef n = 1 (equation 3) Where SIR = C This illustrates that the noise I, measured by a base station, is equal to the traction load within the cell plus a number of additional interference factors, such as I (a, B, c, d ...), IPL, Idist and Ibuller. According to the present invention, the tensile load within cell 201 is approximately equal to the interference caused by the fast power regulated radio units 203-206, i.e. all radio units used within cell 201 except those in low power saturation (207 and 208). Despite the fact that the radio units in low-power saturation contribute to the radio traffic within the cell, their exclusion does not affect the accuracy of the traffic load estimate to any great extent. This is because they are so few compared to the number of radio units (radio units that are not in low power saturation) within the cell. In fact, the exclusion of radio units in low power saturation increases the accuracy of the load load estimate compared to known methods, as they generate much more interference than corresponding radio units, which are not in low power saturation. The part of the noise within the cell, which originates from the radio units in low power saturation, is not in proportion to their part of the traction load, which applies to the other radio units within the cell.

Figure 3 illustrates a fate diagram of a first embodiment of a method according to the present invention. References to fi gur 2 will also be made in the text below.

According to a step 301 in Figure 3, the base station 202 within cell 201 measures a first interference level I (see equation 3) within cell 201.

According to a step 302, the base station sends a paging signal to all radio units 203-208 within the cell via a first channel, for example a paging control channel (PCCH-Paging Control Channel). The search signal may contain information concerning a second radio channel, for example the FACH-Forward Access Channel (which is a common transport channel in WCDMA), that the radio units should listen for further information. the search channel in this step is a first example of common signaling.

According to a step 303, the radio units 203 -208 begin to listen to the other radio channel.

According to step 304, the base station 202 sends a shutdown message to radio units via the second channel. The message contains information regarding in which time slot the radio units are to switch off their transmitters (a transmission in a WCDMA system is divided into frames, which include time slots). This time slot corresponds to a certain period of time, which is sufficient for the measurement in step 309 to be performed. The duration of this particular time period depends on the performance and embodiment of the communication system. This means that the specified time period can be increased to at least two or tid time slots or reduced to be only during a part of a time slot in some radio communication systems (ie the shutdown message will contain information concerning a part of a time slot or two or fl your time slots, during which the radio units must switch off their transmitters.

According to a step 305, the radio units receive the shutdown message from the base station and set their timers in accordance with the shutdown message. These timers (or counters) are set up in the radio units and are used to keep track of the shutdown time (or time slots) after receiving the shutdown message.

According to a step 306, the timers in the radio units begin to count down.

According to a step 307, each radio unit 203-208 determines if it is in low power saturation when the shutdown time is imminent. These low power saturation radio units, such as radio units 207 and 208, disregard the shutdown message (i.e. they skip the next step 308).

According to step 308, the radio units, which do not rely on low power saturation, turn off their transmitters during the time slot (or slots) indicated in the shutdown message, busy in accordance with step 304. These radio units are a selected number of radio units within the cell.

According to step 309, the base station 202 measures a second busy interference level Icon (Ik ° ,, = I (a, b, c, d, ...) + IPL + IdiS, + IbUUC,) during the transmitter shutdown in step 308. The second recorded interference level includes the second part of the intracellular interference IPL, since low power saturation radio units, for example 207 and 208, are not turned off during this measurement.

According to a step 310, the traction load within cell 201 in the base station is estimated by calculating the difference between the first disturbance level I, measured in step 301, and the second disturbance level IKORR, measured in step 309 (i.e. the traction load = I - Icon). The traction load estimation can alternatively be performed in a control mode (for example in a Radio Network Controller, RNC-Radio Network Controller), which means that the base station forwards the measured results in steps 301 and 309 to the control mode.

Any measurement errors are suppressed when both the first and second interference levels are measured by the same base station (and the same detector / measurement unit at the base station) and when the estimated traction load is calculated from the difference between these two levels.

The order in which these steps are performed can be changed, for example, the measurement of the second disturbance level in step 309 can be performed before the measurement of the first disturbance level in step 301, which means that steps 302-309 are performed before step 301.

In a second (not illustrated) embodiment of a method according to the present invention, a second example of common signaling is used. An est terrestrial broadcast channel, such as a Broadcast Control Channel (BCCH), is used instead of the paging signal, omitting steps 302-303 of Figure 3 and the base station transmits the shutdown message to the radio units via the BCCH channel in step 304. the second embodiment is similar to the corresponding steps in the first embodiment according to Figure 3.

In a third (not illustrated) embodiment of a method according to the present invention, the common signaling is replaced by allocated signaling (dedicated signaling). Steps 302-303 according to Figure 3 are omitted and the base station sends the shutdown message to all radio units in the cell via an allocated channel in step 304. The second steps in the third embodiment are similar to the corresponding steps in the first embodiment according to Figure 3. An example of an allocated signal is the DCCH-Dedicated Control Channel.

An example of where allocated signaling can be used in WCDMA is along with compressed mode. Compressed mode can be used to create the measured shutdown periods for the measurement in step 309. Compressed mode is specified by 3GPP (TS.25.215) and is intended for use in hard-hand-off, for example transmission to a carrier with a different frequency ( in another system or within the same system).

It is also possible, in the present invention, to use a specific channel for transmitting the shutdown messages between base stations and radio units.

Figure 4 illustrates a circuit diagram of a fourth embodiment of a method according to the present invention, in which all radio units, except those in low power saturation, receive the shutdown message transmitted from the base station.

According to step 401 in Figure 4, the base station 202 within cell 201 measures a first interference level I (see equation 3) within cell 201.

According to a step 402, the base station determines which radio units are in low power measurement by checking in a memory in which information concerning radio units which are known to be in low power saturation is stored. The base station continuously detects all neglected orders to reduce the output power, which are sent to various radio units. If, for example, 10 consecutive orders to reduce the output power have been neglected by a radio unit, it is determined that it is in low power saturation. 10 15 20 25 5 1 6 9 7 7 - l 7 According to a step 403, the base station sends the shutdown message via allocated control channels to the radio units, which are to switch off their transmitters, i.e. all radio units except those in low power saturation.

Steps 404-405 are the same as steps 305-306 and steps 406-408 are the same as steps 308-310 in the first embodiment according to Figure 3 and will not be described again for the sake of simplicity.

Figure 5 illustrates a circuit diagram of a fifth embodiment of a method according to the present invention, according to which radio units which use a specific service S but are not in low power saturation are switched off during the second disturbance measurement. This means that it is possible to estimate the traffic load for one or more of your more specified services within the cell.

According to a step 501 in Figure 5, the base station 202 within cell 201 measures a first interference level I (see Equation 3, p. 13) within cell 201.

According to a step 502, the base station transmits the shutdown message to radio units via an allocated channel, for example a DCCH. The shut-off message contains information regarding the time slot (or slots) the radio units are to switch off their transmitters and information regarding which service or services are to be switched off, for example all voice services. The shutdown message can also be sent by means of common signaling according to the first and second embodiments.

According to a step 503, the radio units receive shutdown messages from the base station and set their timers in accordance with the shutdown message.

According to a step 504, the timers in the radio units begin to count down. 10 15 20 25 30 516 977 18 According to a step 505, each radio unit 203-208 determines if it is in low power saturation. These low power saturation radio units, for example radio units 207 and 208, disregard the shutdown message (i.e. they skip the following two steps 506-507).

According to a step 506, each radio unit determines the type of service it uses. The radio units, which do not use the service or services according to the shutdown message recorded in step 502, ignore the shutdown message (i.e. they skip the next step 507).

According to a step 507, the radio units which use the service or services according to the shutdown message recorded in step 502 and do not end up in low power saturation during the time slot (or slots) indicated in the shutdown message recorded according to step 503, close their transmitters. during the time slot (or slots) indicated in the shutdown message recorded in accordance with step 503. These radio units, which are a selected number of radio units within the cell.

The last steps 508-509 in Figure 5 are the same as steps 309-310 of Figure 3 and will not be described again for simplicity.

Figure 6 illustrates a circuit diagram of a sixth embodiment of a method according to the present invention, in which a compensation of the propagation delay between the radio units and the base station is performed. References to Figure 2 will also be made in the text below.

The first steps 601-603 in Figure 6 are the same as steps 301-303 according to Figure 3 and will not be described again for the sake of simplicity.

According to a step 604, the base station 202 determines an uplink correction factor Ati for each radio unit within the cell (the uplink time correction factors At can also be determined in a control node, for example a radio network controller, which is connected with the base station).

According to a step 605, the base station 202 sends the shutdown message to the radio units. This transmission can be performed by means of one of the two common signaling examples according to the first and second embodiments or with allocated signaling according to the third embodiment. The message contains information regarding in which time slot (or slots) on the uplink the radio units are to switch off their transmitters and the correction factors Ati, determined in step 604.

According to a step 606, the radio units receive the shutdown message from the base station 202, set their timer in accordance with the shutdown message and the correction factors Ati.

Steps 607-611 are the same as steps 306-310 in the first embodiment according to Figure 3 and will not be described here again for the sake of simplicity.

The (uplink) correction factors Ati are time compensation factors, which are used to compensate for the different propagation delays between the radio units and the base station. This facilitates a more synchronized shutdown for all radio units within the cell. Each radio unit will receive a specific correction factor, which is determined in step 604 of the sixth embodiment. The radio units switch off their respective transmitter At, - before the given time slot (s) and the base station will experience it as if they are switched off simultaneously.

There are ways to use an Ati correction factor. One way is to simply turn off the transmitter at the time compensated by the Ati correction factor. Another way is to turn off the transmitter compensated with the Ati correction factor and to make an additional frame-time advance of the mobile uplink in phase to ensure a symbol-synchronized received shutdown at the base station receiver. 10 15 20 25 516 977 20 One way to determine the correction factors is to determine the distance Ad between the radio unit and the base station. The correction factors are then calculated as At, = (2 * Ad¿) / v, where v is the speed of the radio signal and Ad, the distance between the base station and the radio unit number i.

One way to determine the distance Ad between a radio unit and a base station is to use a positioning system to determine the position of the radio unit. The base station position is known, whereby the distance Ad is determined from these two positions. There are a number of well-known positioning systems that can be used, such as the Global Positioning System (GPS-Global Positioning System).

Another way to determine the distance Ad is to use the receiver delay spread in the base station receiver.

Due to path propagation, the transmitted signal from a radio unit will be recorded as a number of delayed copies in the base station receiver. All copies of the signal are received and combined into one receive signal in the base station receiver.

Since the radio unit is synchronized with the base station in the downlink, the position of the recorded collection of fl path signals gives the relative position of the radio unit.

A radio unit, which moves towards the cell edge, has a multipath cluster, which moves relative in time. The first busy road can be considered to take the shortest distance from the radio unit to the base station. The relative position of this path, compared to the delay of the first receiver path of a radio unit at the center of the cell, gives the shortest possible distance d, between the radio unit and the base station. This means that the distance Ad can be estimated to be equal to the distance dx. a v-.pøo o 10 15 20 25 30 516 977 21 If the coordination of radio unit transmitters to receivers is allowed to vary, for example as specified by 3GPP in TS 25.214 for WCDMA, the radio unit or control node (eg the RNC) could adjust the correction factor Ati with the time difference.

Other Ways to Determine At; is to use a round trip delay measurement or a round trip time measurement (RTT-Round Trip Time) (defined in the 3GPP specification TS 25.215).

The base station or control mode can alternatively determine (select) the specific time slot (s) or part of a time slot (within which the transmitters in the radio units are to be switched off) in such a way that this time compensation is made "automatically" when the transmitters are switched off. given the time slot (s), ie the time compensation is made in radio or control mode by time-forward shift change of the downlink. This means that no correction factors Ati need to be transmitted to the radio units.

Note that the radio units in the adjacent cells should preferably not be switched off at the same time as the radio units within the cell where the second interference measurement, for example step 309, is to be measured in order to obtain the best possible estimate of the tensile load. A control unit in the system can, for example, provide a planning or control function, which prevents surrounding base stations from sending their shutdown messages at the same time.

In the above-mentioned embodiments, the radio units in low power saturation are not considered to constitute a traction load, in order to avoid the error caused by their disproportionately large disturbance, and thereby improve the accuracy of the traction load estimate.

In a seventh (not illustrated) embodiment of a method according to the present invention, a tensile load compensation factor ARU is used to include also the small tensile loads which result from these few low power saturated radio units which are neglected in the units. the above-mentioned embodiments. Targets for these low power saturated radio units are known to the base station. Each radio unit that determines / senses that they are in low power saturation (for example according to step 307) sends a low power saturation sensing signal to the base station, which thus always knows how many radio units in low power saturation are within the cell (nLpS). The base station may alternatively determine the number of radio units in low power saturation nLpS according to step 402 of the fourth embodiment. The compensation factor for the radio unit distance load ARE is then estimated in the base station as: nLpS * SIRMå1. The base station (or RNC) estimates the traction load according to step 310 and adds the compensation factor for the radio unit traction load ARE to the calculation of the traction load, i.e. the traction load is estimated as: HARE- Ikorr- the time slot (s).

The switch-off parameter is then used by the respective radio unit to select a switch-off profile from a table or list, which is stored in the radio unit. The shut-off signal indicates within / during which time slot (s) the uplink channels from the transmitter in the selected number of radio units are to be switched off.

If a low power saturation in the traction load estimation is accepted, steps 307 and 308 according to the first embodiment (and the corresponding steps in the second embodiments) can be omitted, thereby excluding the noise from the low power saturation radio units in the second disturbance measurement in step 309.

Figure 7 illustrates a schematic block diagram of a portion of a cellular radio communication system for enabling the method of the present invention.

The system 700 comprises a radio unit 701, a base station 702 and a control mode 703 (for example a base station controller), a radio network controller (radio network controller) or an Internet access controller) in connection with 10 15 20 25 30 51 6 9 77 23 base station 702. The control mode 703 can be connected, for example, to a switching node, an intermediate network line or an extreme communication system (not illustrated). The radio unit 701 and the base station 702 comprise known circuits and functions for known operations as well as some further units for carrying out the present invention. These units can perform each process step by means of hardware components, a computer or processor programmed with appropriate software or by a combination of hardware and software.

The radio unit 701 comprises at least one timer unit 704, a low power saturation control unit 705, a transmitter shutdown unit 706, a transmitter 708, a power control unit 709, a receiver 710 and (if the fifth embodiment of the method is to be used) a control service unit 7.

The timer unit 704 stores the shutdown time and begins to count down, for example according to steps 305-306. In the sixth embodiment, this unit also adds the time compensation factor (in step 606), received from the base station before the countdown begins. The low power saturation control unit 705, which is coupled to the power control unit 709, determines if the radio unit is in the low power saturation according to step 307. The low power saturation control unit comprises a detector which senses the present output power level. The position power saturation control unit 705 compares the sensed present output power level with the minimum power level. The transmitter shut-off unit 706, which communicates with the power control unit 709, the timer unit 704, the transmitter 708 and / or the receiver 710, is arranged to switch off the transmitter 708, as in step 308, when the timer unit 704 has reached the time for shut-off, i.e. the correct time slot (s).

The control service unit 707, which is connected to the transmitter shut-off unit 706, the transmitter 708 and / or the receiver 710 is used in the fifth embodiment of the method, where the service or services the radio unit uses are determined, for example by controlling the channels used in the uplink. The base station 702 comprises at least one shut-off decision unit 711, a disturbance measuring unit 712, a traffic load estimating unit 713, a receiver 715 and (if the fourth embodiment is to be used) a low power saturation control unit 714.

The shut-off decision unit 711 determines when the shut-off message is to be sent, ie when the base station wants to measure the disturbance, for example according to step 309. The disturbance measuring unit 712, which is connected to the receiver 715, performs the disturbance measurements according to steps 301 and 309. 310, and includes a calculator unit (not illustrated) for calculating I - Icon and I + ARU - Icon. If the fourth embodiment is to be made possible, the base station also comprises a low-power saturation control unit 714, which determines whether radio units are in low-power measurement by continuously sensing all neglected orders to reduce the output power, which have been transmitted to the radio units. For example, if 10 consecutive orders to reduce the output power have been neglected by a radio unit (ie the SIR from the radio unit is still higher than the SIRW), it is considered to be in low power saturation.

The decision to turn off the radio units in each cell can alternatively be made in the control mode 703, instead of by the base station 702. This means that the shut-off decision unit 711 is set up in the control mode 703 (not illustrated). The traction load estimator 713 may also, as an alternative, be arranged in the control mode 703 (not illustrated). This means that the calculation of I - Icon or I + ARU - Icon is performed in control mode. The decision to turn off the radio units in each cell can also be an integral part of the normal system behavior, i.e. incorporated into the system, in such a way that there are certain predetermined time slots per cell, which are always used for the interference measurements according to the present invention. The invention methods can be fully or partially implemented as software in a cellular radio queue communication system, for example in radio units, base stations, radio network controllers, etc.

Claims (28)

10 15 20 25 30 _516 977 26 PATENT REQUIREMENTS A method for estimating the traction load in a specific region (101-104, 201) of a radio communication system, wherein at least one radio node (105-108, 202) is arranged to communicate with radio units (109-114, 203-208) in the specific region, wherein the method comprises the following steps: measuring a first noise level (301, 401,501,601) in the specific region at the at least one radio node; characterized in that the method further comprises the steps of: switching off (302-308, 402-406, 502-507, 602-609) the transmitters in a selected number of the radio units in the region for a certain period of time; measuring a second noise level (309, 407, 508, 610) in the specific region at the at least one radio node during the determined time period; and estimating the traction load (310, 408, 509, 611) from the first and second noise levels. The method of claim 1, wherein the step of shutting down the transmitters in a selected number of radio units comprises the following steps: transmitting a shutdown message (302-304, 602-605) from the at least one radio node to the radio units in the specific region; to determine in the radio units (307, 608) if they are in low power saturation, and to switch off the transmitters (308, 609) in all radio units in the specific region, except in the radio units for which it is determined that they is in low power saturation. The method of claim 1, wherein the step of turning off the transmitters in a selected number of radio units comprises the following steps: transmitting a shut-off message (502) from the at least one radio node to the radio units in the specific region , the suspension messages containing information concerning at least one specific service, which should be switched off; determining in the radio units (505) if they are in low power saturation; determining in the radio units (506) what kind of service the radio units use; and turning off the transmitters (507) in all radio units using the at least one specific service in the specific region, except in those radio units for which it is determined that they are in low power saturation. The method of claim 2 or 3, wherein the step of transmitting a shutdown message from the at least one radio node to the radio units in the specific region comprises the following steps: transmitting a common message (302, 602) from the at least one radio node to the radio units via a common channel, where the common message contains the shutdown message. The method of claim 4, wherein the common message is a fl destination broadcast message and wherein the common channel is a fl destination broadcast channel_ The method of claim 2 or 3, wherein the step of transmitting a shutdown message from the at least one radio node to the radio units in the specific region comprises the steps of: transmitting a paging signal (302, 602) from the at least one radio node to the radio units via a first channel, where the paging signal contains information, which instructs the radio units to temporarily switch to a second channel; and transmitting the shutdown message (304, 605) via the second channel to the radio units. The method of claim 2 or 3, wherein the step of transmitting a shutdown message from the at least one radio node to the radio units in the specific region comprises the steps of: transmitting the shutdown message (502) from the at least one radio node to the radio units via allocated channels. The method of claim 1, wherein the step of turning off the transmitters in a selected number of radio units comprises the steps of: determining in the at least one radio node (402) whether any radio units in the specific region are in low power saturation; transmitting a shutdown message (403) via allocated channels from the at least one radio node to the radio units in the specific region, except to the radio units for which it is determined that they are in low power saturation; and turning off the transmitter (406) in those of the radio units in the specific region which received the shutdown message. A method according to any one of claims 2-8, wherein the shut-off message contains information concerning the determined time period, within which the uplink channel from the transmitter in the selected number of radio units should be switched off. The method of claim 9, wherein the determined time period is specified as at least one time slot. A method according to claim 9, wherein the determined time period is specified as a specific part of a time slot. 10 15 20 25 516: 977 29 A method according to any one of claims 9-11, wherein the shut-off message contains a correction factor for each radio unit, which enables the selected number of radio units to synchronize the transmitter cut-off with respect to the at least one radio node, where the correction factors are used to compensate for the propagation delays. between the radio units and the at least one radio node. The method of claim 12, wherein the correction factor is calculated as twice the distance between the at least one radio node and the respective radio unit, divided by the speed of the radio signal, and wherein the distance is determined from position coordinates generated by a positioning system. The method of claim 12, wherein the correction factor is calculated as twice the distance between the at least one radio node and the respective radio unit, divided by the speed of the radio signal, and wherein the distance is determined from the receiver delay spread in the at least one radio node. A method according to any one of claims 2-8, wherein the shut-off message contains a specific shut-off parameter and wherein the shut-off parameter is used by the radio units to select a stored shut-off profile in the radio units and wherein the shut-off switch indicates when the uplink channels are switched off. A method according to any one of claims 2 to 15, wherein the step of estimating the traction load (310, 408, 509, 611) comprises the following steps: determining in the at least one radio node the number of radio units in low power saturation; to calculate a traction load compensation factor in the at least one radio node by multiplying the number of radio units for which it is determined that they are in low power saturation, by the first interference level and by the SIRMaI used by the radio units in the specific region; and estimating the traction load from the first noise level, the second noise level and the traffic load compensation factor by calculating the difference between the first and second noise levels and then adding the traction load compensation factor. A method according to any one of claims 1-16, wherein the estimation of the traffic load (310, 408, 509, 61 1) is performed in the at least one radio node (105-108, 202). A method according to any one of claims 1-16, wherein the estimation of the traffic load (310, 408, 509, 611) is performed in a control mode (703), which is connected to the radio node. A method according to any one of claims 1-18, wherein the measurement of a first disturbance level (301, 401, 501, 601) and the measurement of a second disturbance level (309, 407, 508, 610) are performed by the same disturbance measuring unit (712), arranged in the radio node (703). The method of claim 1, wherein the selected number of radio units are all active radio units in the region, thereby shutting down the transmitters of all active radio units with a shutdown message transmitted from the at least one radio node to the selected number of radio units. 21. Radio communication systems provided with means for estimating the traction load in a specific region (101-104, 201) of the system, where at least one radio node (105-108, 202) is arranged to communicate with radio units (109-114, 203). -208) in the specific region where the system comprises: 10 15 20 25 30 .S16 97? Means for measuring a first level of interference (712) in the specific region at the at least one radio node; characterized in that the system further comprises: means for switching off (704, 706, 711) the transmitters in a selected number of the radio units in the region for a certain period of time; means for measuring a second noise level (712) in the specific region at the at least one radio node during the determined time period; and means for estimating the traction load (713) from the first and second disturbance levels. The system of claim 21, wherein the system comprises means for determining (705, 714) whether the radio units are in low power saturation. The system of claim 22, wherein the means, for determining (705) whether the radio units are in low power saturation, are arranged in the radio units. The system of claim 22, wherein the means, for determining (714) whether the radio units are in low power saturation, are arranged in the radio node. A system according to any one of claims 21-24, wherein the radio units in the system comprise means for timing (704) the transmitter shutdown. A system according to any one of claims 21-25, wherein the radio units in the system comprise means for controlling the services they use (707). A system according to any one of claims 21-26, wherein the at least one radio node in the system comprises means for determining the number of radio units in low power measurement. 516 977 32 A system according to any one of claims 21-27, wherein the means for measuring a first noise level (712) and the means for measuring a second noise level (712) are the same means and the means for estimating the traction load (713) comprise calculating means for calculate a difference between the first and second level of disturbance.