JP2011502380A - Method for providing interference measurement result, mobile station for providing interference measurement result, method for setting radio resource allocation, OFDMA cellular system, and method for scheduling mobile station - Google Patents

Abstract

Under adaptive frequency reuse techniques, mobile stations in a cellular orthogonal frequency division multiple access (OFDMA) system are served by different radio resource regions with appropriate frequency reuse patterns to reduce intercell interference. Reduce and improve system capacity. In the first novel aspect, the mobile station measures interference statistics and obtains interference measurement results. The mobile station reports the obtained interference measurement result to the serving base station. The serving base station determines an adaptive frequency reuse pattern based on the received interference measurement result. In the second novel aspect, the radio resource control element receives the interference measurement result, determines a frequency reuse pattern, and sets radio resource allocation based on the received interference measurement result. In a third novel aspect, the base station obtains interference measurement results and arranges for the mobile station to be served with an appropriate radio resource region.

Description

  This application is a US Provisional Application No. 60/980 entitled “A Measurement Mechanism for Adaptive Frequency Reuse in Cellular OFDMA System” filed on October 16, 2007, the subject matter of which is incorporated herein by reference. From 413, we claim priority under 35 USC 119.

  The present invention relates to an orthogonal frequency division multiple access (OFDMA) cellular system, and more particularly to an interference measurement mechanism for adaptive frequency reuse.

  In mobile radio systems, frequency reuse is an important technique that improves overall system capacity by reusing less radio spectrum resources, but increases interference and results in loss of link performance. In OFDMA cellular systems, there is no intra-cell interference because the user maintains orthogonality. However, since the same frequency band is reused by base stations supplying neighboring cells, the reuse of radio spectrum causes intercell interference.

  FIG. 1 (Prior Art) is a diagram showing a cell structure of an OFDMA cellular system 1. The OFDMA cellular system 1 has a cell structure with a frequency reuse factor 1 / K equal to 1/4. The frequency reuse factor 1 / K indicates the number of cells that cannot share the same frequency band during transmission. In the example of FIG. 1, the entire licensed spectrum is divided into four frequency bands, each four adjacent cells forming a cluster of four cells, and each cell is served by a different frequency band. In one embodiment, the base station BS4 and the base station BS5 share the same frequency band # 1, serve the mobile station MS6 located in the cell 2, and serve the mobile station MS7 located in the cell 3, respectively. To do. As a result, when the BS 4 transmits a desired data signal and communicates with the MS 6, an undesired interference signal is transmitted to the MS 7. Such an interference signal reduces the signal to interference-plus-noise ratio (SINR) of the mobile station MS7, thus reducing the overall quality of service. Smaller frequency reuse factor 1 / K usually results in greater isolation from interference sources (eg SQRT (3K) * R, where R is the cell radius), but the available radio resources in each cell Lower (eg 1 / K of the licensed spectrum).

  Other technologies such as Fractional Frequency Reuse (FFR) have been proposed for OFDMA cellular systems to achieve a good balance between system capacity and quality of service. FIG. 2 (Prior Art) is a diagram showing the FFR used in the OFDMA cellular system 10. The OFDMA cellular system 10 includes a cell 11 divided into a cell region 1 and a cell region 2. The cell area 1 is located in a geographical area close to the serving base station BS12, and the cell area 2 is located in a geographical area far from the serving base station BS12. Further, the radio spectrum of the OFDMA system 10 is divided into a first frame zone and a second frame zone in the time domain. Under adaptive frequency reuse technology, different frame zones and different frequency reuse factors are applied to serve mobile stations located in different cell regions. In the example of FIG. 2, the first frame zone has a high frequency reuse factor of 1 / K = 1, serves cell region 1, and the second frame zone has a low frequency reuse of 1 / K = 1/3. Serve cell region 2 with a factor. The mobile station MS17 located in the cell region 1 is served by the BS 12 from the first frame zone of 1 / K = 1, and the mobile station MS18 located in the cell region 2 is served in the second frame of 1 / K = 1/3. Served by the BS 12 from the zone. Since the mobile station MS17 is located near the center of the cell 11, it is estimated that it receives a relatively strong data signal from the BS 12 and a relatively weak interference signal from a nearby interference source. On the other hand, the mobile station MS18 is located near the boundary of the cell 11, and is estimated to receive a relatively weak data signal from the BS 12 and a relatively strong interference signal from a nearby interference source. This achieves a good balance between system capacity and service quality by serving MS1 with a high reuse factor (1 / K) and serving MS2 with a low reuse factor (1 / K) Is done.

  Unfortunately, FFR technology based on geographic regions is not always effective. As shown in FIG. 2, the physical structure 14 is located between the mobile station MS18 and the interfering base station BS13. Therefore, the interference of the base station BS13 transmits a relatively strong interference signal 15 to the MS 17 and a relatively weak interference signal 16 to the MS 18. Under the frequency reuse pattern that exists based on the cell area described above, the MS 17 located in the cell area 1 suffers strong interference from the BS 13 but is served at a high 1 / K = 1 and the MS 18 located in the cell area 2. Enjoys good service quality but is served at a low 1 / K = 1/3. As a result, FFR technology based on geographical area is not suitable under dynamic network conditions. The challenge is to be able to dynamically measure interference, determine frequency reuse patterns, and configure radio resource allocation to maintain a balance between mobile radio system link performance and system capacity. .

  Interferometry mechanisms are incorporated into various mobile radio systems. For example, in known cellular FDMA (eg, GSM) or CDMA systems, narrowband signals are transmitted and received by the transceiver. The narrowband feature allows an FDMA system to measure signal power or interference only on a single signal time-frequency domain at a given time. Since the RF center frequency of an FDMA system needs to be adjusted, such an FDMA system cannot be freely measured in different time-frequency domains. In contrast, in OFDMA systems, wideband signals are transmitted and received by transceivers with Fast Fourier Transfer (FFT) functionality. Such OFDMA systems can easily transmit and receive signals over any specified time-frequency domain with a wide channel bandwidth. Thereby, the transceiver of the OFDMA system can freely measure signal power and interference in a time-frequency region different from the time-frequency region of data reception without changing the RF center frequency. This is a distinguishing feature of OFDMA systems compared to other known cellular FDMA and CDMA systems.

  Under adaptive frequency reuse techniques, mobile stations in OFDMA cellular systems are served by different radio resource regions with appropriate frequency reuse patterns to reduce intercell interference and improve system capacity. In addition, adaptive frequency reuse further uses system resources more actively in conjunction with radio resource allocation, scheduling, power allocation, antenna placement, and channelization format, and can be used together to improve system performance. Optimize.

  In the first novel aspect, the mobile station measures interference statistics and obtains interference measurement results. Billing, unsolicited, or automatic interference measurement mechanisms can be used to measure interference statistics. The interference measurement results can then be obtained directly from the interference statistics or can be obtained indirectly from the interference statistics. Interference measurement results include interference power, signal to interference ratio (SIR), signal to interference-plus-noise ratio (SINR), index index of interfering station, preferable, or Other radio frequency domain index indicators or other SIR / SINR formats may be included. In one embodiment, each mobile station measures its interference statistics over a specified time-frequency domain, and the serving base station does not transmit a signal over the specified time-frequency domain. In another embodiment, each mobile station measures its interference statistic over a designated time-frequency domain, and the serving base station transmits a signal over the designated time-frequency domain. The serving base station transmits a signal on a specified time-frequency region, the serving base station and the interfering base station transmit signals in that region, and the mobile station is a serving transmitted by the interfering base station. Identify signals transmitted by the base station. The mobile station then reports the obtained interference measurement results to the serving base station or the centralized network control element. The serving base station and the control element determine an adaptive frequency reuse pattern based on the received interference measurement result.

  In a second novel aspect, adaptive frequency reuse in an OFDMA cellular system is achieved at the base station by centralized network control elements or internal BS coordination based on the interference measurement results. In one embodiment, a radio resource control element receives an interference measurement result, determines a frequency reuse pattern, and sets a radio resource allocation based on the received interference measurement result. In another embodiment, the base station obtains an interference measurement result and communicates with the interference measurement result between adjacent base stations. Thereafter, the base station determines a frequency reuse pattern based on the interference measurement result obtained by the internal BS adjustment, and sets radio resource allocation.

  In a third novel aspect, the base station obtains interference measurement results and arranges for the mobile station to serve the radio resource region with an appropriate frequency reuse pattern. In downlink frequency reuse control, the base station receives an interference measurement result from the mobile station. In uplink frequency reuse control, the base station measures the interference statistics and obtains interference measurement results. The base station then arranges for the mobile station to serve the appropriate radio resource area to optimize system performance.

  Other embodiments and features are described in the detailed description. This summary does not claim to define the invention. The invention is defined by the claims.

The accompanying drawings illustrate embodiments of the invention, with like numerals indicating like elements.
It is a figure which shows the cell structure of the OFDMA cellular system of a well-known technique. FIG. 2 is a diagram illustrating fractional frequency repetition in a known OFDMA cellular system. 1 shows an OFDMA cellular system according to a first novel aspect. FIG. It is a flowchart of the measurement of the interference statistic value in OFDMA cellular system, and the report of the interference measurement result. FIG. 6 is a diagram showing a billing type or non-billing type interference measurement mechanism. It is a figure which shows an automatic interference measurement mechanism. It is a figure which shows the example of a measurement of an interference statistic value. FIG. 2 is a diagram illustrating a first embodiment of an OFDMA cellular system according to a second novel aspect. FIG. 6 shows a second embodiment of an OFDMA cellular system according to a second novel aspect. It is a flowchart which determines a frequency reuse pattern based on an interference measurement result, and sets radio | wireless resource allocation. It is a figure which shows one Embodiment which determines antenna arrangement | positioning based on an interference measurement result. FIG. 6 illustrates an embodiment for determining a channelization format based on interference measurement results. FIG. 6 shows an OFDMA cellular system according to a third novel aspect. It is a flowchart which schedules a mobile station based on an interference measurement result. It is a figure which shows the example which schedules a mobile station based on an interference measurement result. It is FIG. (1) which shows the example which applies fractional frequency reuse with uplink power supply control. It is FIG. (2) which shows the example which applies fractional frequency reuse with uplink power control.

  Reference will now be made in detail to several embodiments of the invention, examples of which are illustrated in the accompanying drawings.

  FIG. 3 is a diagram illustrating an OFDMA cellular system 20 according to a first novel aspect. The OFDMA cellular system 20 includes a cell 21, a serving base station BS22, and a plurality of mobile stations including mobile stations MS23, MS24, and MS25 located in the cell 21. Each mobile station includes a transceiver 26, a measurement module 27, an analog baseband circuit 28, a digital baseband circuit 29, and a memory 30. The OFDMA cellular system 20 mitigates intercell interference using adaptive frequency reuse (also referred to as fractional frequency reuse (FFR)) techniques. In the example of FIG. 3, the total frequency channel obtained in the OFDMA cellular system 20 is divided into three different radio resource regions # 1, # 2, and # 3. The radio resource area is divided into a time domain, a frequency domain, or a combination of the time domain and the frequency domain. Each radio frequency region serves a mobile station located in the cell 21 using a corresponding frequency reuse factor. According to the first novel aspect, each mobile station located in the cell 21 is served by an appropriate frequency reuse factor based on the interference measurement result obtained by each mobile station. As shown in FIG. 3, for downlink FFR control, each mobile station first measures its interference statistic on a designated time-frequency domain to obtain an interference measurement result. The interference statistics are shown in the form of interference power, signal-to-interference ratio (SIR), signal-to-interference plus noise ratio (SINR), or other interference information. Interference measurement results can be obtained directly from interference statistics or indirectly by calculating from interference statistics. For example, the interference measurement result is indicated by interference power, SIR, SINR, an index index of an interference station, an index index of a radio resource region that is preferable or not, or other SIR / SINR derivatives. Each mobile station then reports the interference measurement result to the serving base station BS22. Based on the received interference measurement results, the serving base station BS22 arranges each mobile station to be served by a radio resource area that matches the corresponding radio resource area, thereby optimizing the link performance, Maximize system capacity.

  FIG. 4 is a flowchart showing measurement of interference statistics and reporting of interference measurement results in an OFDMA cellular system. There are different interference measurement mechanisms. Under the billing interference measurement mechanism, the mobile station first transmits an interference measurement request to the serving base station (step 31). After charging, the mobile station receives an interference measurement command from the serving base station (step 32). In step 34, the mobile station measures interference statistics on the designated time-frequency domain, thereby obtaining interference measurement results. The specified time-frequency domain is provided by the interference measurement command. In the final step 35, the mobile station reports the interference measurement result to the serving base station. Under the unsolicited interference measurement mechanism, the mobile station does not transmit the interference measurement result. Instead, the serving base station directly instructs the mobile station to perform interference measurement. The mobile station then performs the same steps 34 and 35, measures its interference statistics, and reports the interference measurement results to the serving base station. Under the automatic interference measurement mechanism, there is no interference measurement request and no interference measurement command to communicate between the mobile station and the serving base station. Instead, the mobile station receives a resource allocation map transmitted by the serving base station. By decoding the resource allocation map, the mobile station obtains a specified time-frequency domain that is used to perform interference measurements. The mobile station then proceeds to the same steps 34 and 35, measures its interference statistics, and reports the interference measurement results to the serving base station.

  FIG. 5 is a diagram showing a solicited and unsolicited interference measurement mechanism used in the cell 40 of the OFDMA cellular system. The mobile stations MS42, MS43 and MS44 are located in the cell 40 served by the serving base station BS41. In the example of FIG. 5, the downlink (DL) frame of the cell 40 is divided into N different frame zones (ZONE # 1- # N) in the time domain. Under the billing interference measurement mechanism, the mobile stations MS42, MS43 and MS44 first request the serving base station BS41 to instruct the mobile station to measure their interference statistics. Serving base station BS41, after receiving such a request, instructs each mobile station to perform interference measurements on the specified time-frequency domain in each frame zone. Under the unsolicited interference measurement mechanism, the serving base station BS41 directly starts interference measurement without receiving a request from the mobile station.

  In one embodiment, the mobile station cannot identify whether the received signal is from a serving base station or from another interfering station. In order to facilitate interference measurement for the mobile station, the serving base station BS41 does not transmit a data signal on a designated time-frequency region. As a result, the total signal power received by each mobile station on the designated time-frequency domain is equivalent to the total received interference power, and therefore, measurement is easy. In other embodiments, the mobile station can identify an interference signal from the data signal, and thus can measure and calculate the total received interference power, SIR, or SINR. For example, in a wireless communication system such as WiMAX, a pilot signal transmitted from each base station is encoded into a unique code. Thereby, the mobile station obtains interference power received from the interference base station using the pilot power received from the serving base station.

  FIG. 6 is a diagram showing an automatic interference measurement mechanism used in the cell 40 of the OFDMA cellular system. The serving base station BS41 periodically transmits a resource allocation map to all mobile stations located in the cell 40. In one embodiment, the mobile stations MS42, MS43, and MS44 decode the resource allocation map to obtain a decoded time-frequency domain in each frame zone where the serving base station BS22 does not transmit a signal. Each mobile station then assigns a designated time-frequency region in each frame zone and automatically performs interference measurements. For example, the specified time-frequency domain is a subset of the decoded time-frequency domain on the serving base station BS41 that does not transmit signals. In another embodiment (not shown in FIG. 6), each mobile proposes to the serving base station BS41 which time-frequency domain to designate and perform interference measurements.

  In the OFDMA cellular system, there are various means for measuring interference statistics of mobile stations using a measurement module. In the present invention, the measurement module (for example, the measurement module 27 in FIG. 3) is a programmable or non-programmable hard wafer that measures interference statistics, or software embedded in a mobile station.

  FIG. 7 is a diagram illustrating an example of measurement of interference statistics of the mobile station MS 42 located in the cell 40 of the OFDMA cellular system. In the example of FIG. 7, the mobile station MS42 is served by the serving base station BS41 and is within a range that a nearby interference station BS45 can reach. As shown in FIG. 7, if the mobile station MS42 can identify a data signal from the interference signal, then the interfering station BS45 transmits the interference signal 46 to the MS42 and at the same time the serving base station BS41 also receives the data signal. 47 is transmitted to MS42. In the first example, the mobile station MS42 obtains interference power by measuring the reference signal power (for example, pilot signal power) of each base station, and the reference signal power is proportional to the total received signal power. In the second example, the mobile station MS42 receives the interference signal 46 and identifies the procode matrix indicator (PMI) used by the interference station BS45. In the third example, the mobile station MS 42 identifies the data signal 47 from the interference signal 46 and measures the SIR or SINR received by the MS 42.

  After the mobile station measures the interference statistic selection format, an interference measurement result is obtained. The interference measurement result is the same as the measured interference statistic. Interference measurement results can also be calculated indirectly from interference statistics. In one embodiment, the interference measurement result is indicated by an index value that identifies the interfering base station. If the mobile station identifies the signal of a particular interfering base station from the total received interference signal, then it reports an indicator associated with at least one interfering station having the most significant interference. For example, the indicator is associated with the strongest SINR, the lowest interference power, or other information. The specific interfering base station is selected by the mobile station from all interfering base stations (not including the serving base station). In general, a particular interfering base station is selected by the mobile station. However, under certain circumstances, the serving base station instructs the mobile station to report a specific interfering base station.

  In other embodiments, the interference measurement result is indicated by an indicator that identifies preferred or otherwise undesired radio resource regions calculated based on measured interference statistics. Since the mobile station's different time-frequency domain interference statistics are quite different, the mobile station can collect different interference statistics by duplicating different time-frequency domain interference measurements. After collecting interference statistics in different time-frequency regions, the mobile station can select an index that identifies radio resource regions that are preferred or not. For example, the preferred radio resource area is identified by the highest SINR or the lowest interference power, and the undesirable radio resource area is identified by the lowest SINR or the highest interference power.

  The interference measurement result obtained from the actual interference measurement by the mobile station reflects the dynamic network state and is more accurate than the interference power estimated from the geographical position or measured from the preamble. This allows serving base stations or other network elements (eg, network operators, network controllers, or other similar elements) to make adaptive frequency reuse more effective based on accurate interference measurement results. Can be applied to achieve the higher system capacity required for the fourth generation 4G mobile communication system.

  In a second novel aspect, the mobile communication system optimizes link performance and improves system capacity using adaptive frequency reuse technology based on interference measurement results. Due to the flexibility with which time-frequency reuse is assigned to different cells, adaptive frequency reuse is particularly suitable for OFDMA cellular systems. Under adaptive frequency reuse technology, the mobile station arranges to be served by different radio resource regions and appropriate frequency reuse patterns. In addition, adaptive frequency reuse further uses system resources more actively in conjunction with radio resource allocation, scheduling, power allocation, antenna placement, and channelization format, and can be used together to improve system performance. Optimize. In OFDMA cellular systems, adaptive frequency reuse is achieved by centralized network control elements or base station internal BS coordination.

  FIG. 8 is a diagram illustrating a first embodiment of an OFDMA cellular system 50 according to a second novel aspect. The OFDMA cellular system 50 includes a centralized radio resource control element 51, a plurality of cells including cells 52-55, a plurality of serving base stations including BSs 56-59, and a plurality of mobile stations. In the example of FIG. 8, the radio resource control element 51 first receives the interference measurement result from the base stations BS56-59 (or directly from the mobile station). Thereafter, the radio resource control element 51 determines a frequency reuse pattern based on the received interference measurement result and other network setting parameters.

  FIG. 9 is a diagram illustrating a second embodiment of an OFDMA cellular system according to the second novel aspect. In the example of FIG. 9, the serving base stations BS56-59 first receive interference measurement results from the mobile stations. The serving base stations BS56-59 then communicate with each other based on the received interference measurements and other network configuration parameters to determine the frequency reuse pattern. In one example, the downlink frame of cell 54 is divided into three radio resource regions with frequency reuse factors (1 / K) of 1, 1, 2 and 1/4, respectively. Serve three mobile stations located in.

  FIG. 10 is a flowchart applying adaptive frequency reuse of an OFDMA cellular system according to the second novel aspect. When the OFDMA cellular system has a centralized radio resource control element, the radio resource control element receives an interference measurement result from the serving base station (step 61). On the other hand, if there is no centralized control element available, the serving base station receives the interference measurement result from the mobile station (step 62). In step 63, the radio resource control element or the serving base station determines a frequency reuse pattern based on the received interference measurement result. More specifically, it is determined by the following items: the number of radio resource areas allocated to each cell, the frequency reuse factor used for each radio resource area, and the time-frequency used for each radio resource area It is an area. In step 64, the radio resource control element or the serving base station sets a radio reuse allocation based on the determined frequency reuse pattern. More specifically, it is determined by the following items: transmission power of each radio resource region, antenna arrangement (eg, light pattern, precoding vector) of each radio resource region, and channelization format of each radio resource region ( For example, a replacement rule on a multi-cell).

  In order to facilitate the determination of the frequency reuse pattern, the mobile station measures their interference statistics on different radio resource regions associated with the corresponding frequency reuse factor. In one embodiment, each mobile station measures the received interference power or SINR on different radio resource areas, and then reports the measured interference power or SINR to its serving base station. The radio resource control element receives the measured interference power or SINR, and then, based on the number of mobile stations located in each cell, or the SINR of each mobile station in a different radio resource area, frequency re-transmission is performed. Determine usage patterns. In one example, the frequency reuse pattern is such that the average interference power is minimized or the interference power of each mobile station is compared to a predetermined threshold (eg, the interference power of each mobile station is less than a predetermined threshold value). To be determined. In another example, the frequency reuse pattern is such that the average SINR is maximized or the SINR of each mobile station is compared to a predetermined threshold value (eg, the SINR of each mobile station is greater than the predetermined threshold value). ) To be determined.

  FIG. 11 is a diagram illustrating an embodiment in which the antenna arrangement is determined based on the received interference measurement result in the OFDMA cellular system 50. In the example of FIG. 11, the base station BS56 originally serves the mobile station MS68 by precoding the matrix index (PMI) #k. Under the adaptive frequency reuse technique according to the second novel aspect, the mobile station MS69 performs measurement and reports the interference measurement result (eg, PMI index #k used for the interference station BS56) to its serving base station BS57. Thereafter, the base station BS57 transmits the interference measurement result to the radio resource control element 51. Since the mobile station MS69 approaches the MS68, the MS69 suffers strong interference due to the PMI # k used for the interference station BS56. As a result, in order to reduce such strong interference by the radio resource control element 51, the base station BS57 requests the BS 56 to change the light beam pattern.

  FIG. 12 is a diagram illustrating an embodiment for determining a channelization format based on received interference measurement results in the OFDMA cellular system 50. In the local channelization process, the physical subcarriers of each logical channel are distributed over a local region in the frequency domain. The channelization subcarrier arrangement in different cells is maintained in the same way. As a result, interference from specific interference sources is very noticeable. In the alternate channelization process, the physical subcarriers of each logical channel are interleaved in the frequency domain. The subcarrier arrangement of channelization in different cells varies depending on the pseudo-random method. As a result, interference from a specific interference source is randomized. Usually, the radio resource control element 51 can be coordinated with inter-cell interference using a local channelization method. However, if the interference is too dynamic to harmonize, the serving base station simply randomizes all signals transmitted over a particular radio resource region and uses an alternate channelization method to Achieve the effect. Interference measurement results help OFDMA cellular systems to mitigate inter-cell interference using different or mixed channelization methods.

  FIG. 13 is a diagram illustrating an OFDMA cellular system 80 according to a third novel aspect. The OFDMA cellular system 80 includes a cell 81, a serving base station BS82 serving the cell 81, and mobile stations MS83 and MS84 located in the cell 81. According to the third novel aspect, the serving base station BS82 receives the interference measurement result from the mobile station during the downlink FFR control, or measures the interference statistic value during the uplink FFR control. The serving base station BS82 then arranges for the mobile station to be served in the appropriate radio frequency region based on the interference measurement results.

  FIG. 14 is a flowchart for arranging for the mobile station to be served by an appropriate radio resource area based on the interference measurement result. In downlink FFR control, the serving base station instructs each mobile station to measure its interference statistic on the specified time-frequency domain under different radio resource domains (step 91). In step 92, the serving mobile station receives interference measurement results from each mobile station. In step 95, the serving mobile station arranges each mobile station to be served by the adaptive radio resource region under a corresponding frequency reuse factor, and the network performance is optimized. In the uplink FFR control, the serving base station measures its own interference statistic (step 93). In step 94, the serving base station transmits the interference measurement result to another base station or another centralized network control element. In step 95, an appropriate frequency reuse pattern is determined by the serving base station alone or by internal BS adjustment based on the interference measurement result.

  FIG. 15 is a diagram illustrating an example of scheduling a mobile station based on the interference measurement result in the OFDMA cellular system 80. The OFDMA cellular system 80 includes an interfering base station BS 85 that serves a neighboring cell 81. In the example of FIG. 15, the physical structure 86 is located between the mobile station MS84 and the interfering base station BS85. MS83 uses a high frequency reuse factor (1 / K = 1), MS84 uses a low frequency reuse factor (1 / K = 1/3), and then MS83 causes strong interference from interfering station BS85. The signal 87 is received and the MS 84 does not receive the interference signal. On the other hand, when MS 83 uses a low frequency reuse factor (1 / K = 1/3) and MS 84 uses a high frequency reuse factor (1 / K = 1), MS 83 receives an interference signal from interference station BS85. And the MS 84 receives a weak interference signal 88 that is blocked by the physical structure 86. Thereby, based on the interference measurement result reported to the serving base station BS82, the BS82 arranges for the mobile station MS83 to be served in the radio resource area of the frequency reuse factor 1 / K = 1/3, The MS 84 arranges to be served in the radio resource area with a frequency reuse factor 1 / K = 1. By dynamically determining the frequency reuse pattern based on the interference measurement results of each mobile station, radio resources are allocated and a good balance between high system capacity and good service quality is achieved.

  FIG. 16A is a diagram illustrating an example in which adaptive frequency reuse is applied together with uplink power control by internal BS adjustment based on the interference measurement result. If the target interference on the terminal level (IoT) of other cells in the radio resource area is small, the mobile stations assigned to the radio resource area are instructed to transmit at low power and do not disturb other cell users To. On the other hand, when the target IoT level of another cell in the radio resource area is high, the mobile station allocated to the radio resource area can transmit high power. In order to control system-wide interference, the serving base station adjusts the radio resource distribution and the corresponding target IoT level in harmony with other base stations. Similarly, FIG. 16B is an example of SINR-based uplink power control, where different target SINRs specify different radio resource regions.

  In the present invention, preferred embodiments have been disclosed as described above. However, the present invention is not limited to the present invention, and any person who is familiar with the technology can use various methods within the spirit and scope of the present invention. Variations and moist colors can be added, so the protection scope of the present invention is based on what is specified in the claims.

Claims (48)

A method for providing interference measurement results, which supports OFDMA cellular systems by at least one mobile station and enables frequency reuse,
(A) In the time-frequency domain, measure interference statistics by at least one mobile station (which is located in a cell served by a serving base station), thereby causing interference in an OFDMA cellular system Obtaining measurement results;
(B) reporting the interference measurement result to the serving base station;
Consists of
The method for providing an interference measurement result, wherein the mobile station is located in a cell served by a serving base station.   The interference measurement result is generated from the interference statistics, and the interference measurement result includes at least one interference power, a signal-to-interference ratio SIR, a signal-to-interference plus noise ratio SINR, a first index index of an interference station, and The method of claim 1, comprising a second index indicator of a radio resource area.   The measurement in (a) includes the step of measuring signal power received from one or more interfering stations on the time-frequency domain, wherein the serving base station is on the time-frequency domain. The method for providing an interference measurement result according to claim 1, wherein no signal is transmitted.   The measurement in (a) includes a step of measuring reference signal power from one or more interfering stations, and the serving base station transmits a signal in the time-frequency domain. A method for providing an interference measurement result according to claim 1.   The measurement in (a) includes the step of the mobile station identifying a signal transmitted from the serving base station and a signal from one or more interfering stations, the serving base station The method of claim 1, wherein a signal is transmitted over the time-frequency domain.   The interference according to claim 2, wherein the first index includes one or more index values and is an indicator of one or more precoding vectors of the interfering station. A method of providing measurement results.   The second index includes at least one of an index value of a preferable radio resource area and an index value of an unfavorable radio resource area, and the preferable radio resource area is defined by having the highest SINR or the lowest interference power. The method of claim 2, wherein the undesirable radio resource region is defined by a minimum SINR or a maximum interference power.   The method of claim 1, wherein the time-frequency domain is obtained based on radio resource allocation information transmitted from the serving base station. Furthermore,
The method of claim 1, further comprising: (c) receiving an interference measurement instruction from the serving base station, wherein the interference measurement instruction indicates the designated time-frequency region. how to. Furthermore,
(D) transmitting an interference measurement request to the serving base station;
The method for providing interference measurement results according to claim 9, comprising:   The method of claim 2, wherein the cell is divided into different radio resource areas, and the mobile station is served by a corresponding radio resource area having a corresponding frequency reuse pattern. .   The method of claim 11, wherein the interference statistics are measured by the mobile station on different radio resource areas.   The interference measurement result according to claim 11, wherein the interference statistic is used for adaptive frequency reuse, and the frequency reuse pattern is determined by comparing the interference power with a threshold value. How to provide.   The interference measurement result according to claim 11, wherein the interference statistic is used for adaptive frequency reuse, and the frequency reuse pattern is determined by comparing the SINR and the threshold ratio. How to provide. A mobile station that provides interference measurement results, supporting OFDMA cellular systems, enabling frequency reuse,
An interference measurement result is obtained by measuring an interference statistic value and obtaining the interference measurement result in the OFDMA cellular system, and the mobile station reports the interference measurement result to a network element. Mobile station.   The interference measurement result is obtained from the interference statistics, and the interference measurement result includes at least one interference power, a signal-to-interference ratio (SIR), a signal-to-interference plus noise ratio (SINR), and a first index of an interference station. The mobile station providing the interference measurement result according to claim 15, wherein the mobile station includes an index and a second index index of a radio resource area.   The mobile station providing an interference measurement result according to claim 15, wherein the network element is a serving base station that serves the mobile station.   The measurement module measures the interference statistic on a specified time-frequency domain, and the serving base station does not transmit a signal on the specified time-frequency domain. Item 18. A mobile station that provides the interference measurement result according to Item 17.   The measurement module measures the interference statistic on a specified time-frequency domain, and when the serving base station transmits a signal on the time-frequency domain, the measurement module further specifies The mobile station providing the interference measurement result according to claim 17, wherein at least one interference signal from a plurality of interference stations is identified.   The mobile station of claim 15, wherein the measurement module includes a programmable software module. A mobile station,
A transceiver,
In the OFDMA cellular system, measurement means for measuring interference statistics and obtaining interference measurement results;
And the means reports the interference measurement result to a network element of the OFDMA cellular system.   The mobile station according to claim 21, wherein the network element is a serving base station that serves the mobile station. A method for configuring radio resource allocation, comprising:
(A) obtaining an interference measurement result of a mobile station located in a cell of the OFDMA cellular system;
(B) determining a frequency result and setting a corresponding radio resource assignment based on a part of the interference measurement result;
A method for configuring radio resource allocation, comprising:   The radio resource according to claim 23, wherein a frame of each cell is divided into several radio resource areas, and each mobile station is served by a corresponding radio resource area having a corresponding frequency reuse pattern. How to set the quota.   The method for setting radio resource allocation according to claim 23, wherein the determination of the frequency reuse pattern in (b) is determined by comparing the interference power received by the mobile station with a predetermined threshold value. .   The method for setting radio resource allocation according to claim 23, wherein the determination of the frequency reuse pattern in (b) is determined by comparing the SINR received by the mobile station with a predetermined threshold ratio. The step of determining the frequency reuse pattern in (b) is as follows:
The method for setting radio resource allocation according to claim 24, comprising determining the quantity and size of the radio resource area of each cell and the frequency reuse factor of each radio resource area. The step of determining the frequency reuse pattern in (b) is as follows:
The method of setting radio resource allocation according to claim 24, comprising the step of defining and synchronizing the time-frequency domain used for each radio resource region between neighboring cells. The step of setting the radio resource allocation in (b)
The method of setting radio resource allocation according to claim 24, comprising the step of determining the transmission power of each radio resource region. The step of setting the radio resource allocation in (b)
The method of setting radio resource allocation according to claim 24, comprising determining an antenna arrangement of each radio resource region. The step of setting the radio resource allocation in (b)
The method of setting radio resource allocation according to claim 24, comprising determining a channelization format for each radio resource region.   The method of setting radio resource allocation according to claim 23, wherein the determining and setting step in (b) is performed by a centralized radio resource control element of the OFDMA cellular system.   The method for setting radio resource allocation according to claim 23, wherein the determining and setting step in (b) is performed by harmony between neighboring base stations of the OFDMA cellular system. An OFDMA cellular system,
Multiple mobile stations that measure interference statistics and obtain interference measurement results,
A network element that receives the interference measurement result, determines a frequency reuse pattern, and sets a corresponding radio resource allocation based on a portion of the received interference measurement result;
An OFDMA cellular system characterized by comprising:   The OFDMA cellular system of claim 34, wherein the network element is a centralized radio resource control element of the OFDMA system.   35. The network device according to claim 34, wherein the plurality of mobile stations are served by a serving base station, and the serving base station includes the network element that receives the interference measurement result and determines a frequency reuse pattern. OFDMA cellular system.   The plurality of mobile stations are served by a plurality of serving base stations, and each of the plurality of serving base stations receives the interference measurement result and determines a frequency reuse pattern by harmony between adjacent base stations. 35. The OFDMA cellular system of claim 34. A method for scheduling mobile stations, comprising:
(A) obtaining interference measurement results by a base station in an OFDMA cellular system;
(B) scheduling the mobile station to be served by a radio resource region based on a portion of the obtained interference measurement result;
A method for scheduling a mobile station, comprising:   The mobile station according to claim 38, wherein the mobile station is located in a cell divided into several radio resource areas, and each radio resource area is applied with a corresponding frequency reuse pattern. How to schedule. The step of obtaining the interference measurement result in (a) is as follows:
The method of scheduling a mobile station according to claim 38, comprising receiving the interference measurement result from the mobile station. The step of obtaining the interference measurement result in (a) is as follows:
The method of scheduling a mobile station according to claim 38, further comprising: measuring interference statistics by the base station and obtaining the interference measurement result. Scheduling the mobile station in (b),
The scheduling of a mobile station according to claim 38, comprising arranging for the mobile station to be served by the radio resource region, wherein the received interference power of the mobile station is lower than a predetermined threshold value. how to. Scheduling the mobile station in (b),
The method of scheduling a mobile station according to claim 38, comprising arranging for the mobile station to be served by the radio resource region, wherein the SINR of the mobile station is higher than a predetermined threshold ratio. Furthermore,
(C) instructing the mobile station to measure interference statistics on a specified time-frequency domain, wherein the serving base station does not transmit a signal on the specified time-frequency domain 40. The method of scheduling a mobile station according to claim 38. Furthermore,
39. The method of scheduling a mobile station according to claim 38, further comprising: (c) transmitting the interference measurement result to a neighboring base station of the OFDMA cellular system. An OFDMA cellular system,
A mobile station,
A serving base station that obtains interference measurement results and arranges the mobile station to be served by a radio resource region based on a portion of the obtained interference measurement results;
An OFDMA cellular system characterized by comprising:   The mobile station according to claim 46, wherein the mobile station measures an interference statistical value, thereby obtaining the interference statistical result, and the serving base station receives the interference measurement result from the mobile station. OFDMA cellular system.   The OFDMA cellular system according to claim 46, wherein the serving base station measures interference statistics and obtains the interference measurement result.

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