[0058] In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings.
[0059] figure 2 It is a flowchart of an LTE channel measurement and feedback method in the present invention, such as figure 2 As shown,
[0060] Step 201: Step 1: The base station configures channel state information measurement pilot CSI-RS resources for each signal transmission point in a CoMP, and sends the configuration information of the CSI-RS resources to the terminal;
[0061] Step 202: According to the configuration information of the CSI-RS resource, the terminal performs a channel measurement operation on each signal transmission point in CoMP, and sorts according to the obtained signal-to-noise ratio; and transmits signals whose signal-to-noise ratio meets preset conditions Point feedback to the base station;
[0062] Step 203: The base station selects a signal transmission point according to the feedback information of the terminal and the known working information of the base station, and sets one or more measurement hypotheses and corresponding CSI-RS resources for the terminal according to the selected signal transmission point; The measurement hypothesis and corresponding CSI-RS resource configuration information are sent to the terminal;
[0063] Step 204: The terminal performs further channel measurement according to the measurement hypothesis and the corresponding CSI-RS resources, and feeds back the measurement information of the selected signal transmission point to the base station; the base station performs resource pre-scheduling according to the feedback information of the terminal, if the terminal feeds back If the measurement information of the terminal cannot determine the resource scheduling mode, the base station repeats step 203, and if the measurement information fed back by the terminal can determine the resource scheduling mode, step 205 is executed;
[0064] Step 205: The base station performs resource scheduling according to the determined resource scheduling mode.
[0065] image 3 It is a detailed flowchart of an LTE channel measurement and feedback method in the present invention; such as image 3 As shown,
[0066] Step 301: The base station configures CSI-RS resources for channel measurement of long-term characteristics for each signal transmission point in a CoMP cooperation area, and sends configuration information of the CSI-RS resources to each terminal.
[0067] In step 301, the base station side configures CSI-RS resources for measuring the long-term characteristics of the channel for each signal transmission point in a CoMP cooperation area, and the corresponding relationship between the signal transmission point and the CSI-RS resource is stored on the base station side. That is, the base station side can locally acquire the ID of the signal transmission point corresponding to the CSI-RS resource through the ID of the CSI-RS resource in the CSI-RS resource configuration information fed back by the terminal.
[0068] Step 302: The terminal does not carry any measurement assumptions, and performs channel measurement on all signal transmission points according to the CSI-RS resources; screens out signal transmission points that have an impact on the terminal, and feeds back the signal transmission points to the base station.
[0069] In step 302, the terminal performs a channel measurement operation on each signal transmission point according to the CSI-RS resource configured by the base station, collects the signal-to-noise ratio of each signal transmission point, and sorts the signal-to-noise ratios in descending order according to the acquired signal-to-noise ratio. , Screening out signal transmission points that have an impact on the terminal through certain rules.
[0070] Wherein, the influential signal transmission point means that the signal sent by the signal transmission point has an impact on the terminal, and the signal transmission point may be a macro base station or a micro base station that provides services for the terminal, that is, the signal source ; It may also be a signal transmission point that interferes with the data transmission of the terminal, that is, the interference source.
[0071] In an embodiment of the present invention, the received signal emission points are sorted in descending order of signal-to-noise ratio, and all signal emission points within a certain attenuation range are selected based on the maximum signal-to-noise ratio. . Wherein, the certain attenuation range can be set according to the configuration of the base station or the actual network deployment; for example, the attenuation range can be 3db.
[0072] Or, sort the received signal emission points in descending order of signal-to-noise ratio, and select all signal emission points beyond a certain power range based on the interference of signal emission points outside the corresponding CoMP area; among them, signal emission The point measurement set includes all signal emission points to be considered. The signal emission points outside the corresponding CoMP area correspond to the interference generated by the signals of the emission points outside the RRM measurement set, because the terminal does not have a separate reference symbol resource to measure all CoMP areas Signal emission points outside can only measure the overall effect. For example, where the power beyond a certain range is 3dB
[0073] In another embodiment of the present invention, the received signal emission points are sorted in descending order of the signal-to-noise ratio, and based on the maximum signal-to-noise ratio, the signals other than the maximum signal-to-noise ratio are The transmitting point is used as the interference source; the interference sources are classified into the signal source according to the signal-to-noise ratio from strong to weak, and the combined signal-to-noise ratio is operated until the combined signal-to-noise ratio reaches a specified value, for example, 3dB. Among them, the combined signal-to-noise ratio is through the formula Calculate; where P merge Is the combined signal-to-noise ratio, P signal source For the sum of the detected received power of all valid signals from multiple signal sources to be combined, P Interference source To measure the sum of the detected received power of multiple interference sources outside the set of transmitting points, P noise Is the noise power.
[0074] In other embodiments of the present invention, the received signal emission points are sorted in descending order of the signal-to-noise ratio, and based on the maximum signal-to-noise ratio, the signal emission points other than the maximum signal-to-noise ratio are selected. As an interference source; the interference sources are classified into signal sources one by one from strong to weak SNR, and the combined SNR operation is performed until the change in the two adjacent combined SNR operations is less than a specified value, such as 1dB.
[0075] Among them, all signal emission points assigned to the signal source are selected signal emission points.
[0076] In other screening embodiments of the present invention, the received signal emission points are sorted in descending order of signal-to-noise ratio, the signal emission point corresponding to the received maximum signal-to-noise ratio is used as the signal source, and the remaining signal Transmitting points are all used as interference sources, and the interference sources are eliminated one by one. Among them, assuming that the base station is turned off and there is no interference power, the combined SNR is calculated. When the combined SNR is greater than the set value, or two adjacent ones The calculated variation is less than the specified value; then all the signal sources in the combined signal-to-noise ratio and the power transmission point are turned off as the selected signal transmission point. Wherein, the obtained combined signal-to-noise ratio is greater than the set value, which can be specifically: such as meeting the SNR level of a certain bit error rate of a specific transmission mode, for example, when 64QAM modulation mode, no coding, and bit error rate of 0.1, Assume that the transmission under Gaussian channel corresponds to -2dB.
[0077] In a preferred embodiment of the present invention, the base station configures a specific signal transmission point as a reference reference point through high-level signaling, and sorts the signal-to-noise ratios of the received signal transmission points from largest to smallest, and sorts all The signal transmission point whose signal-to-noise ratio is greater than the signal-to-noise ratio of the reference reference point is used as the selected signal transmission point. In the actual measurement process, the base station can select different screening methods according to specific conditions and compare them with other screening methods. Mode coordination, selecting a qualified signal emission point below the reference reference point.
[0078] The terminal selects signal transmission points that affect itself according to a specific screening method, where the selected signal transmission point may be a signal source or an interference source. The signal transmission point is fed back to the base station. Specifically, the terminal feeds back the ID of the selected signal transmission point and the number of signal transmission points to the base station. In the specific embodiment of the present invention, the terminal can feed back the ID of the signal transmission point and the number of signal transmission points at the same time or sequentially; for example, the number of signal transmission points is fed back first, and then the base station arranges resources to feed back the corresponding The ID of the signal emission point. According to different feedback modes, it is divided into feedback to high-level signaling and feedback to physical layer scheduling information.
[0079] Step 303: The base station selects a suitable measurement hypothesis for the terminal according to the working information stored on the base station side and the measurement information initially fed back by the terminal.
[0080] In step 303, the base station sets one or more measurement hypotheses for the terminal based on the known operating information on the base station side, combined with the ID of the signal transmission point fed back by the terminal, and the number of signal transmission points that meet the preset conditions. Wherein, the working information includes scheduling information stored on the base station side for resource scheduling and scheduling parameters pre-configured on the base station side; the measurement hypothesis includes: information on selected signal transmission points and information on signal transmission points in determined states , And the priority CoMP working mode.
[0081] In the case that the resource scheduling mode of some signal transmission points has been determined, the influence of this part of the signal transmission points on this terminal can be determined; for example, it has been occupied to serve another terminal and cannot accommodate a new terminal, then It is definitely interference for the measuring terminal, and the interference vector has been determined, and can be sent to the terminal as an interference parameter. The scheduling parameters pre-configured on the base station side include the location information of the signal transmission point, the coverage area, the transmission coverage under a specific vector, and the logical connection of the macro cell/micro cell stored on the base station side.
[0082] In the CoMP working mode, each measurement hypothesis is suitable for different working scenarios. In an embodiment of the present invention, different measurement hypotheses are set by judging different signal emission points that may be correlated:
[0083] When the number of signal transmission points fed back by the terminal is 1, the base station sets the terminal to perform channel measurement in a single cell mode;
[0084] When multiple signal transmission points are selected by the base station, they are discussed in specific situations.
[0085] When the selected signal transmission point belongs to three sectors of a cell, and the relative time offset or frequency offset is less than the specified value, then in the measurement assumption set by the base station for the terminal, the set priority CoMP working mode is: Channel according to JT Measurement; Among them, in an embodiment of the present invention, the relative frequency deviation is less than 5%, can specify the JT mode.
[0086] When the selected signal transmission points belong to different sites, and the relative time offset or frequency offset is greater than a specified value, the preferred CoMP operating mode set by the base station for the terminal is: channel measurement according to the CS/CB mode. Wherein, in an embodiment of the present invention, the relative frequency deviation is greater than 5%, and the CS/CB mode can be specified.
[0087] In other embodiments of the present invention, when the number of signal transmission points fed back by the base station is greater than 4, the base station is set for the terminal, and the channel measurement is performed in a macrodiversity manner. Because when the number of terminal feedback is greater than 4, the amount of feedback information may be so large that CoMP can no longer work, you can directly use the measurement assumption of macrodiversity transmission, or you can not schedule the terminal on the relevant PRB resources, and give up temporarily Configure new measurement assumptions for the terminal.
[0088] When the multiple transmission points fed back by multiple terminals all use the macro base station as the strongest signal transmission point, the priority CoMP working mode set by the base station for the terminal is: the cell splitting gain is the priority principle, and the signal transmission point of the macro base station is turned off. Because when multiple terminals include the signal transmission point of the macro base station, and the signal transmission point of the macro base station is the main interference source, if these terminals are distributed in different directions, it can be assumed that the transmission power of the macro base station is turned off. In order to obtain cell splitting capacity gain, if these terminals are distributed in roughly the same direction, the beamforming direction can be assumed to be offset from this direction first, and while avoiding interference to these terminals, it also provides services to other terminals.
[0089] The base station can set one or more measurement hypotheses for the terminal according to the actual situation, and is not limited by the foregoing embodiment.
[0090] Step 304: The base station configures CSI-RS resources for channel measurement real-time characteristics for the selected signal transmission point, and sends the configured measurement hypothesis and corresponding CSI-RS resource configuration information to the terminal.
[0091] In step 304, the base station selects a signal transmission point with uncertain resource scheduling mode among the signal transmission points fed back by the terminal according to the information of the signal transmission point fed back by the terminal and combined with known work information on the base station side. All or part of the channel parameters of the signal transmission point in the uncertain resource scheduling manner cannot be determined unless further measurement is required to obtain additional measurement information. Among them, the base station uses information that can determine the signal transmission point of the resource scheduling mode as an interference parameter that affects other terminals. Set the interference parameters in the measurement hypothesis and inform the terminal.
[0092] After setting one or more measurement hypotheses for each terminal, the base station sends the one or more measurement hypotheses and the corresponding CSI-RS resource configuration information to the terminal. Among them, the measurement hypothesis and CSI-RS resource configuration information sent to the terminal include: CoMP working mode information, measurement information of known signal transmission points on the base station side, status information of signal transmission points on the corresponding PRB, and signal The transmission precoding vector information of the transmission point, the change parameter of the transmission vector of the signal transmission point, the adjustment parameter of the transmission power, and other parameters that can be used to measure the channel in detail, such as the detailed channel information of some terminals, the change information of the signal transmission point Wait.
[0093] Step 305: The terminal re-measures the channel state on the corresponding CSI-RS resource according to the newly configured measurement hypothesis, and feeds back the obtained measurement information to the base station.
[0094] In step 305, the terminal performs further signal measurement operations on the configured CSI-RS resource for the selected signal transmission point according to one or more measurement hypotheses configured by the base station to obtain the channel state information of the signal transmission point with the best capacity . In an embodiment of the present invention, the terminal obtains the rank indicator (RI, Rank Indicator)/precoding matrix indicator (PMI, Precoding Matrix Indicator)/channel quality indicator (CQI) during the re-channel measurement operation. , Channel Quality Indicator) and other parameters are fed back to the base station.
[0095] The base station performs resource pre-scheduling according to the feedback information of the terminal. If the measurement information fed back by the terminal cannot determine the resource scheduling mode, the base station repeats steps 303 to step 305. If the measurement information fed back by the terminal can determine the resource scheduling mode, perform step 306; Steps 303 to 305 are repeated. After multiple repeated measurements, the scope of the measurement hypothesis is gradually narrowed until the measurement information fed back by the terminal can determine the resource scheduling mode; that is, the signal transmission point that provides service to the terminal is selected, and the signal transmission point The measurement information is fed back to the base station.
[0096] In other embodiments of the present invention, the measurement parameters of some terminals may be determined first, and these determined measurement parameters may be used as interference parameters affecting other terminals, which are transmitted by the base station to relevant terminals, so as to gradually narrow the hypothesis range.
[0097] Step 306: The base station makes a final scheduling decision based on the meticulously measured channel information, and arranges the physical downlink shared channel PDSCH transmission.
[0098] In step 306, the base station obtains a signal transmission point that provides services for the terminal according to the detailed measurement information fed back by the terminal, and configures resources for PDSCH transmission on the signal transmission point.
[0099] Figure 4 It is a working schematic diagram of multi-cell in CoMP mode in the present invention, such as Figure 4 As shown,
[0100] There are 5 transmission points in the figure, macro cell A, macro cell B, and three micro cell m, micro cell n, and micro cell k in macro cell A; the macro cells are all configured with 4 antenna ports, and the micro cells are all It is configured with 2 antenna ports, and the terminal has dual antennas. The base station adopts the R10 CSI-RS resource configuration arrangement, macro cell A adopts 4 antenna port position configuration 1, macro cell B adopts 4 antenna port configuration 2, three micro cells m, micro cell n, and micro cell k respectively adopt 2 antenna port positions Configure 0, 5, 10, and the period is 50ms.
[0101] The first step: the base station side configures CSI-RS resources for each signal transmission point in the CoMP area, performs channel measurement, and sends the configuration information of the CSI-RS resources to the terminals 1 to 7.
[0102] Step 2: Terminals 1 to 7 perform channel measurement operations on each signal transmission point according to the CSI-RS resource configuration information sent by the base station, obtain the signal-to-noise ratio of each signal transmission, and sort according to the obtained signal-to-noise ratio , Select the signal transmission point that meets the preset conditions and feed it back to the base station; among them, the terminal detects the signal-to-noise ratio of all 5 corresponding transmission points, respectively, as follows:
[0103] Terminal 1 feedback 4 antenna configuration ports 1 and 2 antenna port configuration 0 belongs to the set of signal transmission points that will affect itself, and the base station side checks the corresponding relationship according to the ID of the CSI-RS resource in the configured CSI-RS resource configuration information Are the macro cell A and the micro cell m;
[0104] Similarly, it is obtained that terminal 2 is significantly affected by macro cell A and micro cell n, terminal 3 is affected by macro cells A, B and micro cell k, while terminal 4 is only affected by macro cell A, and terminal 5 is only affected by macro cells. The influence of cell B; terminal 6 and terminal 7 are both affected by macro cell A and macro cell B. Each terminal feeds back the measurement information obtained through preliminary measurement to the base station.
[0105] The third step: the base station selects the signal transmission point according to the feedback information of the terminal and the known working information of the base station side, and sends the measurement hypothesis and the corresponding configuration information of the CSI-RS resource to the terminal.
[0106] Since the physical location information of micro cell m, micro cell n, and micro cell k can be recorded on the base station side in advance, the base station knows that the approximate coverage of micro cell m, micro cell n, and micro cell k is in the same direction of the base station, and can be turned off Transmit or beamforming to avoid interference to the area; due to cost issues, the frequency characteristics of the micro cell k are not good, and the distance between the macro cell and the macro cell is relatively large, it is not suitable to do JT operation with the macro cell B, and the current situation is cell A The user density is relatively high, and the method that can obtain cell capacity splitting gain is preferred.
[0107] The base station sets one or more measurement hypotheses for the terminal according to the selected signal transmission point. among them,
[0108] The terminal 4 and the terminal 5 feedback only one signal transmission point, and the configured measurement assumes that the single-cell measurement is performed at the signal transmission point fed back.
[0109] The terminal 6 and the terminal 7 both feed back the macro cell A and the macro cell B, and the configured measurement assumes that the single cell measurement of the two cells is performed separately to find their respective best precoding vectors.
[0110] When the optimal precoding vector of the terminal 6 and the terminal 7 is determined, the information of the signal transmission point of the corresponding macro base station on the terminal 6 and the terminal 7 is used as the interference of the signal affecting the micro cell m, micro cell n, and micro cell k Parameter, in the newly configured measurement hypothesis, the transmission of the best precoding vector of terminal 4 and terminal 5 to terminal 1, terminal 2, and terminal 3 corresponds to the null direction. And it is decided not to schedule the scheduling of terminal 6, terminal 7 and the scheduling of terminal 1, terminal 2, and terminal 3 at the same time.
[0111] The best pre-coding vectors of terminal 4 and terminal 5 are sent to other terminals as part of the measurement assumptions. Among them, the measurement assumptions configured for terminal 1, terminal 2, and terminal 3 are respectively in micro cell m, micro cell n, The micro cell k performs single cell measurement to find the respective best precoding vector of the terminal and obtain the corresponding channel quality information.
[0112] In addition, terminal 6 and terminal 7 are configured with other measurement assumptions for multi-user JT pairing parameter measurement, and the capacity is compared with their respective measurement assumptions using the best transmission vector, and the JT or CB mode is selected for operation according to the principle of capacity optimization. .
[0113] Until the best channel transmission mode of each signal transmission point is determined, the best resource allocation mode is determined.
[0114] In summary, the present invention first arranges the CSI-RS for each signal transmission point by the base station to perform long-term channel measurement, and first screens out some signal transmission points that have an impact on the terminal. By determining which transmission points may have an impact and feeding back to the base station, it helps the base station to effectively eliminate inappropriate working assumptions based on actual conditions. It can reduce the requirements for the configuration period, accommodate more transmission points, and help the implementation of the CoMP solution. Step by step determination of the working hypothesis through the base station, and then the actual channel measurement corresponding to the data transmission, can effectively reduce the calculation workload of the terminal, and reduce the number of invalid calculations by eliminating the low-probability working hypothesis, and also reduce the uplink wireless transmission. Burden.
[0115] The foregoing descriptions are only preferred embodiments of the present invention, and are not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.
