CN103731914A - Method and device for calibrating channel reciprocity between RRHs in wireless network base station - Google Patents

Abstract

The invention relates to a method for calibrating the channel reciprocity between RRHs in a wireless network base station. The RRHs are jointly connected to a between-RRH calibrating module, and each RRH comprises an RRH internal calibrating module. The method includes the steps of selecting the between-RRH calibrating module, opening the between-RRH calibrating module under a joint transmission application scene, executing transmitting and receiving calibration with the between-RRH calibrating module, calculating a calibration weight with a base band, and applying the calibration weight to calibration of a transmitting antenna array composed of the RRHs, wherein the calibration weight comprises at least one of a between-RRH calibrating module calibrating weight, a RRH internal calibrating weight and a comprehensive weight. By means of the method, the between-RRH calibrating module calibrating weight can be easily calculated under the condition that hardware is not changed or slightly changed, the between-RRH calibrating module calibrating weight can be applied to calibration of the transmitting antenna array composed of the RRHs, and therefore the aim of calibrating the channel reciprocity between the RRHs in the wireless network base station can be achieved.

Description

Method and device for calibrating channel reciprocity between RRHs in wireless network base station

Technical Field

The present invention relates to a wireless communication network, and more particularly, to a method and apparatus for calibrating channel reciprocity between RRHs in a wireless network base station.

Background

In a system using Coordinated Multi-Point (CoMP), the system needs to accurately obtain downlink channel information to perform precoding operation. Under Time Division Duplex (TDD), since the uplink and downlink use different Time slots of the same frequency band, if the Time slot interval is smaller than the relevant Time delay of the channel, the uplink and downlink channel states have symmetry, i.e. reciprocity. The CoMP system can directly obtain downlink information from uplink information by using channel reciprocity without feedback of a user. This is one of the important advantages of TDD systems over Frequency Division Duplex (FDD) systems. However, in an actual system, channel reciprocity is not ideal due to the influence of factors such as mismatch of radio frequency links of a transmitting end and a receiving end, doppler shift caused by mobility, different interference environments of a user end and a base station end, and the like. How to eliminate the channel reciprocity error is a concern. In order to ensure channel reciprocity, corresponding compensation measures must be taken to regain channel reciprocity.

Nowadays, a base station is generally divided into two parts, namely a Radio base band control (Radio Server) and a Remote Radio Head (RRH). The wireless equipment part can be independently and remotely set, so that the capital expenditure and the operation cost of an operator are reduced while the network is flexibly constructed.

Fig. 1 and 2 illustrate a self-calibration solution within and between RRHs of a conventional Remote Radio Head (RRH).

In fig. 1, in order to realize self-calibration inside the RRH, a calibration transceiver (Cal TRX) is connected to a general transceiver through a calibration cable network composed of a plurality of couplers and a combiner. Radio frequency signals are exchanged between the ordinary transceiver and the calibration transceiver to calibrate the reciprocity of the ordinary transceiver.

The existing inter-RRH calibration solution is to simply extend the intra-RRH calibration solution to the application scenario of multiple RRHs located at the same place. In the solution shown in fig. 2, all RRHs share one calibration transceiver. A calibration algorithm similar to the RRH internal calibration can also be used, assuming all transceivers have a common timer and common controller. However, this solution also has many problems, such as:

1) this scheme imposes timing and control constraints on all connected RRHs, even if these RRHs individually make a single RRH transmission, which reduces the flexibility of the system; further, in the above-described case,

2) RRHs made by different manufacturers also suffer from compatibility issues, making the solution less than well implemented.

Various Air interface (OTA) calibration solutions for RRH/inter-eNB calibration are proposed in 3GPP RAN1Tdoc for LTE and LTE-A, R1-094622, R1-093026, R1-080494, R1-090563, R1-093378, R1-094623, 2009. The performance simulations of these OTA calibration solutions can all achieve a high degree of accuracy, but the problem is that the implementation of these solutions also depends on the support of further standards.

Therefore, there are a series of problems in the prior art, for example, by using simple RRH internal self-calibration, it is not possible to calibrate the reciprocity of channels in the scenario of multiple RRH joint transmission application; however, the conventional inter-RRH calibration scheme also has the above two problems, so that an effective technical scheme for calibrating the channel reciprocity between RRHs in the wireless network base station under the premise of minimal change is still lacking.

Disclosure of Invention

In light of the foregoing background and the problems that exist, it would be advantageous to provide a method and apparatus that provides for calibrating channel reciprocity between RRHs in a wireless network base station with little or no modification to existing hardware.

According to a first aspect of the present invention, a method for calibrating channel reciprocity between RRHs in a wireless network base station is provided, wherein the RRHs are commonly connected to an inter-RRH calibration module and each of the RRHs includes an intra-RRH calibration module, the method comprising: a. selecting the calibration module between RRHs and opening the calibration module between RRHs under a combined transmission application scene; b. performing transmit and receive calibration using the inter-RRH calibration module and calculating calibration weights from a baseband; applying the calibration weight to a calibration of a transmit antenna array comprised of the RRHs, wherein the calibration weight comprises an inter-RRH calibration module calibration weight and at least one of an intra-RRH calibration weight and an integrated weight. By using the method, the related calibration weights such as the calibration weights of the calibration module between RRHs can be calculated very easily under the condition that the hardware is not changed or is slightly changed, and the calibration weights of the calibration module between RRHs can be applied to the calibration of the transmitting antenna array consisting of RRHs, thereby realizing the aim of calibrating the channel reciprocity between RRHs in the wireless network base station.

In one embodiment, the step b further comprises: setting the inter-RRH calibration module to a transmit mode, transmitting a first calibration signal by a transmitter of a transceiver of the inter-RRH calibration module to a receiver of a calibration transceiver inside the RRH connected thereto; setting the inter-RRH calibration module to a receive mode, transmitting a third calibration signal by a transmitter of a calibration transceiver inside the RRH to a receiver of a transceiver of the inter-RRH calibration module; and q, the baseband calculates the calibration weight of the RRH calibration module according to the channel response in the steps o and p. In this embodiment, it is possible to overcome the disadvantages of the conventional inter-RRH calibration method by slight changes in the calculation algorithm.

In one embodiment, the step o further comprises: simultaneously transmitting a second calibration signal by a transmitter of a normal transceiver internal to the RRH to a receiver of a calibration transceiver internal to the RRH, wherein the second calibration signal and the first calibration signal are orthogonal to each other; and said step p further comprises: simultaneously transmitting, by a transmitter of a calibration transceiver internal to the RRHs connected to the inter-RRH calibration module, a fourth calibration signal to a receiver of the inter-RRH calibration module, wherein the fourth calibration signal and the third calibration signal are orthogonal to each other; and further comprising in said step q: and the baseband calculates RRH internal calibration weight, RRH inter-calibration module calibration weight and comprehensive weight according to the channel responses in the steps o and p. In the implementation form, the traditional fusion of RRH internal calibration and RRH inter-calibration is realized, the calibration weight of the RRH inter-calibration module, the RRH internal calibration weight and the comprehensive weight can be obtained, and the redundancy of related parameters can be provided, so that the possibility of dynamic switching of joint and non-joint transmission among a plurality of RRHs is provided.

In one embodiment, the inter-RRH calibration module includes a combiner having a number of ports corresponding to the number of RRHs connected. The combiner enables the formation of multiple calibration channels with other interested parties.

In addition, the second aspect of the present invention also provides an apparatus for calibrating channel reciprocity between RRHs in a wireless network base station, the apparatus comprising: at least two RRH modules, wherein each of the at least two RRH modules comprises a RRH internal calibration module; and an inter-RRH calibration module connected with the at least two RRH modules, the inter-RRH calibration module being one of a separate calibration module independent of the RRHs or an intra-RRH calibration module in the RRHs, wherein the inter-RRH calibration module is turned on in a joint transmission application scenario, performs transmission and reception calibration, and calculates a calibration weight from a baseband and applies the calibration weight to calibration of a transmission signal, the calibration weight including at least one of an inter-RRH calibration module calibration weight and an intra-RRH calibration weight and an integrated weight.

In one embodiment, the inter-RRH calibration module includes a combiner having a number of ports corresponding to the number of RRHs connected.

In one embodiment, the following steps are performed in the inter-RRH calibration module:

setting the inter-RRH calibration module to a transmit mode, transmitting a first calibration signal by a transmitter of a transceiver of the inter-RRH calibration module to a receiver of a calibration transceiver inside the RRH connected thereto;

setting the inter-RRH calibration module to a receive mode, transmitting a third calibration signal by a transmitter of a calibration transceiver inside the RRH to a receiver of a transceiver of the inter-RRH calibration module;

and q, the baseband calculates the calibration weight of the RRH calibration module according to the channel response in the steps o and p.

In one embodiment, the following steps are further performed in the inter-RRH calibration module:

simultaneously transmitting a second calibration signal by a transmitter of a normal transceiver internal to the RRH to a receiver of a calibration transceiver internal to the RRH, wherein the second calibration signal and the first calibration signal are orthogonal to each other;

simultaneously transmitting, by a transmitter of a calibration transceiver internal to the RRHs connected to the inter-RRH calibration module, a fourth calibration signal to a receiver of the inter-RRH calibration module, wherein the fourth calibration signal and the third calibration signal are orthogonal to each other;

q ', the baseband calculates RRH internal calibration weight, RRH inter-calibration module calibration weight and comprehensive weight according to the channel response in the steps o ' and p '.

By the method and the device, the defects of the traditional single RRH internal calibration and the RRH inter-calibration can be overcome by improving the algorithm on the premise of slightly changing or even not changing the hardware, the related calibration weight such as the calibration weight of an RRH inter-calibration module can be very easily calculated, and the calibration weight of the RRH inter-calibration module can be applied to the calibration of the transmitting antenna array consisting of RRHs, thereby realizing the aim of calibrating the channel reciprocity between RRHs in the wireless network base station.

Drawings

Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which proceeds with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram illustrating a device for calibrating channel reciprocity inside an RRH in a wireless network base station in the prior art;

fig. 2 is a schematic structural diagram illustrating an apparatus for calibrating channel reciprocity between RRHs in a wireless network base station in the prior art;

fig. 3 illustrates a flowchart of a method of calibrating channel reciprocity between RRHs in a wireless network base station in accordance with the present invention;

fig. 4 is a schematic structural diagram illustrating an apparatus for calibrating channel reciprocity between RRHs in a wireless network base station according to an embodiment of the present invention; and

fig. 5 is a schematic structural diagram illustrating an apparatus for calibrating channel reciprocity between RRHs in a wireless network base station according to still another embodiment of the present invention.

In the drawings, like or similar reference numbers indicate like or similar devices (modules) or steps throughout the different views.

Detailed Description

Fig. 1 and fig. 2 respectively show a hardware structure diagram of a conventional RRH internal calibration and RRH inter-calibration, which has been described in the background art and is not described herein again.

Fig. 3 is a flowchart illustrating a method for calibrating channel reciprocity between RRHs in a wireless network base station according to the present invention, and as shown, the method 300 includes the following three steps: first, in step 310, that is, in step a, an inter-RRH calibration module is selected and opened in a joint transmission application scenario; next, in step 320, i.e., step b, performing transmission and reception calibration using the opened inter-RRH calibration module and calculating calibration weights from the baseband; finally, in step 330, step c, the calculated calibration weights are applied to the calibration of the transmit antenna array consisting of RRHs, wherein the RRHs are commonly connected to the inter-RRH calibration module and each of the RRHs comprises an intra-RRH calibration module, and the calibration weights comprise the inter-RRH calibration module calibration weights and at least one of the intra-RRH calibration weights and the synthetic weights. By using the method, the calibration weight of the calibration module among RRHs can be calculated very easily under the condition that hardware is not changed or slightly changed, and the calibration weight of the calibration module among RRHs can be applied to the calibration of the transmitting antenna array consisting of RRHs, so that the aim of calibrating the channel reciprocity among RRHs in the wireless network base station can be fulfilled.

In one embodiment, the step b further comprises: setting the inter-RRH calibration module to a transmit mode, transmitting a first calibration signal by a transmitter of a transceiver of the inter-RRH calibration module to a receiver of a calibration transceiver inside the RRH connected thereto; setting the inter-RRH calibration module to a receive mode, transmitting a third calibration signal by a transmitter of a calibration transceiver inside the RRH to a receiver of a transceiver of the inter-RRH calibration module; and q, the baseband calculates the calibration weight of the RRH calibration module according to the channel response in the steps o and p. In this embodiment, it is possible to overcome the disadvantages of the conventional inter-RRH calibration method by slight changes in the calculation algorithm.

In one embodiment, the step o further comprises: simultaneously transmitting a second calibration signal by a transmitter of a normal transceiver internal to the RRH to a receiver of a calibration transceiver internal to the RRH, wherein the second calibration signal and the first calibration signal are orthogonal to each other; and said step p further comprises: simultaneously transmitting, by a transmitter of a calibration transceiver internal to the RRHs connected to the inter-RRH calibration module, a fourth calibration signal to a receiver of the inter-RRH calibration module, wherein the fourth calibration signal and the third calibration signal are orthogonal to each other; and further comprising in said step q: and the baseband calculates RRH internal calibration weight, RRH inter-calibration module calibration weight and comprehensive weight according to the channel responses in the steps o and p. In the implementation form, the traditional fusion of RRH internal calibration and RRH inter-calibration is realized, the calibration weight of the RRH inter-calibration module, the RRH internal calibration weight and the comprehensive weight can be obtained, and the redundancy of related parameters can be provided, so that the possibility of dynamic switching of joint and non-joint transmission among a plurality of RRHs is provided.

In order to be able to implement the above method, and thus implement the related functions, support of related hardware design is necessarily required. Fig. 4 is a schematic diagram 400 illustrating an apparatus for calibrating channel reciprocity between RRHs in a wireless network base station according to an embodiment of the present invention, where the apparatus 400 does not change the internal structure 410 of a single RRH, but adds an inter-RRH calibration module consisting of a combiner 430 and an inter-RRH calibration transceiver 440 between multiple RRHs. The inter-RRH calibration module includes a combiner 430 having a number of ports corresponding to the number of RRHs connected. The merger 430 enables the formation of multiple calibration channels with other interested parties.

The inter-RRH calibration module selected in this embodiment is a separate calibration module independent of the calibration module 418 inside the RRH, so in particular when performing the above method, it is obtained in steps o and p, respectively: h is_{c_rxcal，j}＝h_ccth_cr，jN and h, j ═ 1, 2,. N and h_{c_txcal，j}＝h_ct，jh_ccrN1, 2.. N, in step q according to the formula:calculating the calibration weight of the calibration module between RRHs, wherein h_{c_rxcal，j}Denotes the receiver calibration channel, h, between the jth RRH_cctTransmitter channel, h, representing an inter-RRH calibration transceiver_cr，jDenotes the jth calibration receiver channel, h_{c_txcal，j}Denotes the jth inter-RRH transmitter calibration channel, h_ct，jDenotes the jth calibration transmitter channel, h_ccrReceiver channel, w, representing an inter-RRH calibration transceiver_c，jRepresenting the true values of the inter-RRH calibration weights of the jth RRH internal calibration module,

substitution of inter-RRH calibration weights for jth RRH internal calibration moduleGeneration value, w_ccRepresenting weights of the inter-RRH calibration transceivers; the inter-RRH calibration weights are calculated in the most simplified steps only in the case, but are sufficient to calibrate the transmit antenna array consisting of RRHs in the context of joint transmission applications. Furthermore, the RRH internal calibration can also be performed simultaneously, and in this case, the following steps are obtained from the steps o and p: h is_txcal，m＝h_bt，mh_cr，m＝1，2，...M、h_{c_rxcal，j}＝h_ccth_cr，jN and h, j ═ 1, 2,. N and h_rxcal，m＝h_cth_br，m，i＝1，2，...M、h_{c_txcal，j}＝h_ct，jh_ccrN is 1, 2.. N, and the RRH internal calibration weights, the inter-RRH calibration module calibration weights and the integrated weights are calculated by the baseband 450 in step q according to the following formulas, respectively: <math> <mrow> <msub> <mi>w</mi> <mi>m</mi> </msub> <mo>&equiv;</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>bt</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>br</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mo>=</mo> <mo>=</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>txcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>rxcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mfrac> <msub> <mi>h</mi> <mi>ct</mi> </msub> <msub> <mi>h</mi> <mi>cr</mi> </msub> </mfrac> <mo>=</mo> <msub> <mover> <mi>w</mi> <mo>~</mo> </mover> <mi>m</mi> </msub> <msub> <mi>w</mi> <mi>c</mi> </msub> <mo>,</mo> </mrow> </math> <math> <mrow> <msub> <mi>w</mi> <mrow> <mi>c</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <mo>&equiv;</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>ct</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>cr</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>c</mi> <mo>_</mo> <mi>txcal</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>c</mi> <mo>_</mo> <mi>rxcal</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> </mfrac> <mfrac> <msub> <mi>h</mi> <mi>cct</mi> </msub> <msub> <mi>h</mi> <mi>ccr</mi> </msub> </mfrac> <mo>=</mo> <msub> <mover> <mi>w</mi> <mo>~</mo> </mover> <mrow> <mi>c</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>w</mi> <mi>cc</mi> </msub> </mrow> </math> and

m1, 2., M; 1, 2, N, wherein h_txcal，mDenotes the mth transmitter calibration channel, h_bt，mRepresents the mth common transmitter channel, h_crIndicating the calibration receiver channel, h_{c_rxcal，j}Denotes the receiver calibration channel, h, between the jth RRH_cctTransmitter channel, h, representing an inter-RRH calibration transceiver_cr，jDenotes the jth calibration receiver channel, h_rxcal，mDenotes the mth receiver calibration channel, h_ctIndicating the calibration transmitter channel, h_br，mDenotes the mth common receiver channel, h_{c_txcal，j}Denotes the jth inter-RRH transmitter calibration channel, h_cr，jDenotes the jthCalibrating the transmitter channel, h_ccrReceiver channel, w, representing an inter-RRH calibration transceiver_mRepresents the mth RRH internal calibration weight,represents the m-th RRH internal calibration weight, w_c，jRepresenting the true values of the inter-RRH calibration weights of the jth RRH internal calibration module,

alternative value of inter-RRH calibration weight, w, of jth RRH internal calibration module_ccRepresenting the weights of the inter-RRH calibration transceiver. In the embodiment, the traditional fusion of RRH internal calibration and RRH inter-calibration is realized, the calibration weight of the RRH inter-calibration module, the RRH internal calibration weight and the comprehensive weight can be obtained, and the redundancy of related parameters can be provided, so that the possibility of dynamic switching of joint and non-joint transmission among a plurality of RRHs is provided.

Of course, multiplexing of the inter-RRH calibration modules shown in fig. 4 can also be realized by the intra-RRH calibration module through control of time slots and the like, as shown in fig. 5, in this embodiment, the selected inter-RRH calibration module is one of the intra-RRH calibration modules 518 in the RRH, and at the same time, each RRH is not changed, i.e. 510 and 520 in the figure are not changed substantially, but only the combiner of the intra-RRH calibration module 518 at this time is multi-ported instead of the previous two-ported combiner, which is obtained in the steps o and p: h is_cal，ji＝h_cr，jh_ct，i(ii) a N, i ≠ j, 1, 2.. N, i ≠ j, which is determined in step q by the baseband 550 according to the formula:

calculating the calibration weight of the calibration module between RRHs, wherein h_cal，jiDenotes the calibration channel, h, from the jth transmitter to the ith receiver_cr，jDenotes the jth calibration receiver channel, h_ct，iIndicating the ith calibration transmitter channel and,

alternative value of inter-RRH calibration weight, w, of the i-th RRH internal calibration module_c，iTrue value, w, of inter-RRH calibration weight of ith RRH internal calibration module_c，1Represents its own calibration weight, h_cr，iDenotes the ith calibration receiver channel, h_cr，1Indicating the selected calibration receiver channel of the inter-RRH calibration module, h_cl，1Indicating the selected calibration transmitter channel of the inter-RRH calibration module, h_cal，1iIndicating the selected calibration channel, h, from the inter-RRH calibration module to the ith receiver_cal，i1Represents the calibration channel from the ith transmitter to the selected inter-RRH calibration module. Additionally, RRH internal calibration can also be implemented synchronously in this embodiment. At this time, the following steps are obtained from the steps o and p, respectively: h is_txcal，m＝h_bt，mh_crWherein m is 1, 2.. M, h_rxcal，m＝h_cth_br，mWherein M is 1, 2_cal，ji＝h_cr，jh_ct，i(ii) a i, j ≠ j-1, 2.. N, i ≠ j, and in step q the RRH internal calibration weights, the inter-RRH calibration module calibration weights, and the synthetic weights are calculated, respectively, according to the following formulas: <math> <mrow> <msub> <mi>w</mi> <mi>m</mi> </msub> <mo>&equiv;</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>bt</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>br</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>txcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>rxcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mfrac> <msub> <mi>h</mi> <mi>ct</mi> </msub> <msub> <mi>h</mi> <mi>cr</mi> </msub> </mfrac> <mo>=</mo> <msub> <mover> <mi>w</mi> <mo>~</mo> </mover> <mi>m</mi> </msub> <msub> <mi>w</mi> <mi>c</mi> </msub> <mo>,</mo> </mrow> </math> wherein, $w_c=\frac{h_{\mathrm{ct}}}{h_{\mathrm{cr}}},{\tilde{w}}_m=\frac{h_{\mathrm{txccal},m}}{h_{\mathrm{cxcal},m}},$ ${\tilde{w}}_{c,t}=\frac{w_{c,i}}{w_{c,1}}=\frac{h_{\mathrm{ct},i}}{h_{\mathrm{cr},i}}\frac{h_{\mathrm{cr},1}}{h_{\mathrm{ct},1}}=\frac{h_{\mathrm{cal},1i}}{h_{\mathrm{cal},i1}}$ and $w_{m,i}={\tilde{w}}_{m,i}{w}_{c,i}={\tilde{w}}_{m,i}{\tilde{w}}_{c,i}{w}_{c,1},$ wherein h is_txcal，mDenotes the mth transmitter calibration channel, h_bt，mRepresents the mth common transmitter channel, h_crIndicating the calibration receiver channel, h_rxcal，mDenotes the mth receiver calibration channel, h_ctIndicating the calibration transmitter channel, h_br，mDenotes the mth common receiver channel, h_cal，jiDenotes the calibration channel, h, from the jth transmitter to the ith receiver_cr，jDenotes the jth calibration receiver channel, h_ct，iRepresenting the ith calibration transmitter channel, w_mRepresents the mth RRH internal calibration weight,

represents the mth RRH internal calibration weight,alternative value of inter-RRH calibration weight, w, of the i-th RRH internal calibration module_c，iTrue value, w, of inter-RRH calibration weight of ith RRH internal calibration module_c，1Represents its own calibration weight, h_cr，iDenotes the ith calibration receiver channel, h_cr，1Indicating the selected calibration receiver channel of the inter-RRH calibration module, h_ct，1Indicating the selected calibration transmitter channel of the inter-RRH calibration module, h_cal，1iIndicating the selected calibration channel, h, from the inter-RRH calibration module to the ith receiver_cal，i1Represents the calibration channel from the ith transmitter to the selected inter-RRH calibration module.

Although the method described in fig. 5 does not require a separate inter-RRH calibration module, since a plurality of RRHs are no longer symmetrical to each other as before due to the fact that a plurality of separate inter-RRH calibration modules are omitted, it causes certain troubles in terms of compatibility, maintenance, and the like.

In summary, since the calibration of the inter-RRH calibration module depends on a wired network, such a network can be substantially free from the interference of external noise, which inevitably makes the precision of the calibration weight of the inter-RRH calibration module obtained according to the method of the present invention very high.

By the method and the device, the defects of the traditional single RRH internal calibration and the RRH inter-calibration can be overcome by improving the algorithm on the premise of slightly changing or even not changing the hardware, the related calibration weight such as the calibration weight of an RRH inter-calibration module can be very easily calculated, and the calibration weight of the RRH inter-calibration module can be applied to the calibration of the transmitting antenna array consisting of RRHs, thereby realizing the aim of calibrating the channel reciprocity between RRHs in the wireless network base station.

Those skilled in the art should understand that each device referred to in the present invention can be implemented by a hardware module, a functional module in software, or a hardware module integrating a software functional module.

It will be appreciated by persons skilled in the art that the above embodiments are illustrative and not restrictive. Different features which are present in different embodiments may be combined to advantage. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art upon studying the drawings, the specification, and the claims. In the claims, the term "comprising" does not exclude other means or steps; the indefinite article "a" does not exclude a plurality; the terms "first" and "second" are used to denote a name and not to denote any particular order. Any reference signs in the claims shall not be construed as limiting the scope. The functions of the various parts appearing in the claims may be implemented by a single hardware or software module. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (10)

1. A method of calibrating channel reciprocity between RRHs in a wireless network base station, wherein the RRHs are commonly connected to an inter-RRH calibration module and each of the RRHs contains an inter-RRH calibration module, the method comprising:

a. selecting the calibration module between RRHs and opening the calibration module between RRHs under a combined transmission application scene;

b. performing transmit and receive calibration using the inter-RRH calibration module and calculating calibration weights from a baseband; and

c. applying the calibration weight to calibration of a transmit antenna array consisting of the RRHs,

wherein the calibration weights include inter-RRH calibration module calibration weights and at least one of intra-RRH calibration weights and synthetic weights.

2. The method of claim 1, wherein step b further comprises:

setting the inter-RRH calibration module to a transmit mode, transmitting a first calibration signal by a transmitter of a transceiver of the inter-RRH calibration module to a receiver of a calibration transceiver inside the RRH connected thereto;

setting the inter-RRH calibration module to a receive mode, transmitting a third calibration signal by a transmitter of a calibration transceiver inside the RRH to a receiver of a transceiver of the inter-RRH calibration module;

and q, the baseband calculates the calibration weight of the RRH calibration module according to the channel response in the steps o and p.

3. The method of claim 2, wherein if the inter-RRH calibration module selected in the step a is a separate calibration module independent of the RRHs, then in the steps o and p, respectively, we obtain: h is_{c_rxcal，j}＝h_ccth_cr，jN and h, j ═ 1, 2,. N and h_{c_txcal，j}＝h_ct，jh_ccrN1, 2.. N, in step q according to the formula:

calculating the calibration weight of the calibration module between RRHs, wherein h_{c_rxcal，j}Denotes the receiver calibration channel, h, between the jth RRH_cciTransmitter channel, h, representing an inter-RRH calibration transceiver_cr，jDenotes the jth calibration receiver channel, h_{c_txcal，j}Denotes the jth inter-RRH transmitter calibration channel, h_ct，jDenotes the jth calibration transmitter channel, h_ccrReceiver channel, w, representing an inter-RRH calibration transceiver_c，jDenotes the jth RRThe true values of the inter-RRH calibration weights of the H internal calibration module,

alternative value of inter-RRH calibration weight, w, of jth RRH internal calibration module_ccRepresenting weights of the inter-RRH calibration transceivers;

if the inter-RRH calibration module selected in the step a is one of the RRH internal calibration modules in the RRH, then in the steps o and p: h is_cal，ji＝h_cr，jh_ct，i(ii) a i, j ≠ 1, 2,. N, i ≠ j, in step q according to the formula:

calculating the calibration weight of the calibration module between RRHs, wherein h_cal，jiDenotes the calibration channel, h, from the jth transmitter to the ith receiver_cr，jDenotes the jth calibration receiver channel, h_ct，iIndicating the ith calibration transmitter channel and,

alternative value of inter-RRH calibration weight, w, of the i-th RRH internal calibration module_c，iTrue value, w, of inter-RRH calibration weight of ith RRH internal calibration module_c，1Represents its own calibration weight, h_cr，jDenotes the ith calibration receiver channel, h_cr，1Indicating the selected calibration receiver channel of the inter-RRH calibration module, h_ct，1Indicating the selected calibration transmitter channel of the inter-RRH calibration module, h_cal，1iIndicating the selected calibration channel, h, from the inter-RRH calibration module to the ith receiver_cal，i1Represents the calibration channel from the ith transmitter to the selected inter-RRH calibration module.

4. The method of claim 2, wherein the step o further comprises:

simultaneously transmitting a second calibration signal by a transmitter of a normal transceiver internal to the RRH to a receiver of a calibration transceiver internal to the RRH, wherein the second calibration signal and the first calibration signal are orthogonal to each other;

and said step p further comprises:

simultaneously transmitting, by a transmitter of a calibration transceiver internal to the RRHs connected to the inter-RRH calibration module, a fourth calibration signal to a receiver of the inter-RRH calibration module, wherein the fourth calibration signal and the third calibration signal are orthogonal to each other;

and further comprising in said step q:

and the baseband calculates RRH internal calibration weight, RRH inter-calibration module calibration weight and comprehensive weight according to the channel responses in the steps o and p.

5. The method of claim 4, wherein if the inter-RRH calibration module selected in step a is a separate calibration module independent of the RRHs, then steps o and p yield, respectively: h is_txcal，m＝h_bt，mh_cr，m＝1，2，...M、h_{c_rxcal，j}＝h_ccrh_cr，jN and h, j ═ 1, 2,. N and h_rxcal，m＝h_crh_br，m，i＝1，2，...M、h_{c_rxcal，j}＝h_ct，jh_ccrN ═ 1, 2.. N, and the RRH internal calibration weights, the inter-RRH calibration module calibration weights, and the composite weights are calculated in step q according to the following formulas, respectively: <math> <mrow> <msub> <mi>w</mi> <mi>m</mi> </msub> <mo>&equiv;</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>bt</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>br</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mo>=</mo> <mo>=</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>txcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>rxcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mfrac> <msub> <mi>h</mi> <mi>ct</mi> </msub> <msub> <mi>h</mi> <mi>cr</mi> </msub> </mfrac> <mo>=</mo> <msub> <mover> <mi>w</mi> <mo>~</mo> </mover> <mi>m</mi> </msub> <msub> <mi>w</mi> <mi>c</mi> </msub> <mo>,</mo> </mrow> </math> <math> <mrow> <msub> <mi>w</mi> <mrow> <mi>c</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <mo>&equiv;</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>ct</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>cr</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>c</mi> <mo>_</mo> <mi>txcal</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>c</mi> <mo>_</mo> <mi>rxcal</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> </mfrac> <mfrac> <msub> <mi>h</mi> <mi>cct</mi> </msub> <msub> <mi>h</mi> <mi>ccr</mi> </msub> </mfrac> <mo>=</mo> <msub> <mover> <mi>w</mi> <mo>~</mo> </mover> <mrow> <mi>c</mi> <mo>,</mo> <mi>j</mi> </mrow> </msub> <msub> <mi>w</mi> <mi>cc</mi> </msub> </mrow> </math> and

m ═ 1, 2,. said, M; 1, 2, N, wherein h_txcal，mDenotes the mth transmitter calibration channel, h_bt，mRepresents the mth common transmitter channel, h_crIndicating the calibration receiver channel, h_{c_rxcal，j}Denotes the receiver calibration channel, h, between the jth RRH_cciTransmitter channel, h, representing an inter-RRH calibration transceiver_cr，jDenotes the jth calibration receiver channel, h_rxcal，mDenotes the mth receiver calibration channel, h_ctIndicating the calibration transmitter channel, h_br，mDenotes the mth common receiver channel, h_{c_txcal，j}Denotes the jth inter-RRH transmitter calibration channel, h_ct，jDenotes the jth calibration transmitter channel, h_ccrReceiver channel, w, representing an inter-RRH calibration transceiver_mRepresents the mth RRH internal calibration weight,represents the m-th RRH internal calibration weight, w_c，jRepresenting the true values of the inter-RRH calibration weights of the jth RRH internal calibration module,alternative value of inter-RRH calibration weight, w, of jth RRH internal calibration module_ccRepresenting weights of the inter-RRH calibration transceivers;

if the inter-RRH calibration module selected in the step a is one of the RRH internal calibration modules in the RRH, then the following steps are obtained from the steps o and p: h is_txcal，m＝h_bt，mh_crWherein m is 1, 2.. M, h_rxcal，m＝h_cth_br，mWherein M is 1, 2_cal，ji＝h_cr，jh_ct，i(ii) a i, j ≠ j-1, 2.. N, i ≠ j, and in step q the RRH internal calibration weights, the inter-RRH calibration module calibration weights, and the synthetic weights are calculated, respectively, according to the following formulas: <math> <mrow> <msub> <mi>w</mi> <mi>m</mi> </msub> <mo>&equiv;</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>bt</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>br</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mo>=</mo> <mfrac> <msub> <mi>h</mi> <mrow> <mi>txcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> <msub> <mi>h</mi> <mrow> <mi>rxcal</mi> <mo>,</mo> <mi>m</mi> </mrow> </msub> </mfrac> <mfrac> <msub> <mi>h</mi> <mi>ct</mi> </msub> <msub> <mi>h</mi> <mi>cr</mi> </msub> </mfrac> <mo>=</mo> <msub> <mover> <mi>w</mi> <mo>~</mo> </mover> <mi>m</mi> </msub> <msub> <mi>w</mi> <mi>c</mi> </msub> <mo>,</mo> </mrow> </math> wherein, $w_c=\frac{h_{\mathrm{ct}}}{h_{\mathrm{cr}}},{\tilde{w}}_m=\frac{h_{\mathrm{txccal},m}}{h_{\mathrm{cxcal},m}},$ ${\tilde{w}}_{c,i}=\frac{w_{c,i}}{w_{c,1}}=\frac{h_{\mathrm{ct},i}}{h_{\mathrm{cr},i}}\frac{h_{\mathrm{cr},1}}{h_{\mathrm{ct},1}}=\frac{h_{\mathrm{cal},1i}}{h_{\mathrm{cal},i1}}$ and $w_{m,i}={\tilde{w}}_{m,i}{w}_{c,i}={\tilde{w}}_{m,i}{\tilde{w}}_{c,i}{w}_{c,1},$ wherein h is_txcal，mDenotes the mth transmitter calibration channel, h_bt，mRepresents the mth common transmitter channel, h_crIndicating the calibration receiver channel, h_rxcal，mDenotes the mth receiver calibration channel, h_ctIndicating the calibration transmitter channel, h_br，mDenotes the mth common receiver channel, h_{cal, ji table}Showing the calibration channel, h, from the jth transmitter to the ith receiver_cr，jDenotes the jth calibration receiver channel, h_ct，iRepresenting the ith calibration transmitter channel, w_mRepresents the mth RRH internal calibration weight,represents the mth RRH internal calibration weight,

alternative value of inter-RRH calibration weight, w, of the i-th RRH internal calibration module_c，iTrue value, w, of inter-RRH calibration weight of ith RRH internal calibration module_c，1Represents its own calibration weight, h_cr，iDenotes the ith calibration receiver channel, h_cr，1Indicating the selected calibration receiver channel of the inter-RRH calibration module, h_ct，1Indicating the selected calibration transmitter channel of the inter-RRH calibration module, h_cal，1iIndicating the selected calibration channel, h, from the inter-RRH calibration module to the ith receiver_cal，i1Represents the calibration channel from the ith transmitter to the selected inter-RRH calibration module.

6. The method of any of claims 1-5, wherein the inter-RRH calibration module comprises a combiner having a number of ports corresponding to the number of connected RRHs.

7. An apparatus for calibrating channel reciprocity between RRHs in a wireless network base station, the apparatus comprising:

at least two RRH modules, wherein each of the at least two RRH modules comprises a RRH internal calibration module; and

an inter-RRH calibration module connected with the at least two RRH modules, the inter-RRH calibration module being one of a separate calibration module independent of the RRHs or an intra-RRH calibration module in the RRHs, wherein the inter-RRH calibration module is turned on in a joint transmission application scenario, transmission and reception calibrations are performed, and calibration weights are calculated from a baseband and applied to a calibration of a transmission signal, the calibration weights including at least one of an inter-RRH calibration module calibration weight and an intra-RRH calibration weight and an integrated weight.

8. The apparatus of claim 7, wherein the inter-RRH calibration module comprises a combiner having a number of ports corresponding to the number of RRHs connected.

9. The apparatus of claim 7, wherein the following steps are performed in the inter-RRH calibration module:

setting the inter-RRH calibration module to a transmit mode, transmitting a first calibration signal by a transmitter of a transceiver of the inter-RRH calibration module to a receiver of a calibration transceiver inside the RRH connected thereto;

setting the inter-RRH calibration module to a receive mode, transmitting a third calibration signal by a transmitter of a calibration transceiver inside the RRH to a receiver of a transceiver of the inter-RRH calibration module;

and q, the baseband calculates the calibration weight of the RRH calibration module according to the channel response in the steps o and p.

10. The apparatus of claim 9, wherein the following steps are further performed in the inter-RRH calibration module:

simultaneously transmitting a second calibration signal by a transmitter of a normal transceiver internal to the RRH to a receiver of a calibration transceiver internal to the RRH, wherein the second calibration signal and the first calibration signal are orthogonal to each other;

simultaneously transmitting, by a transmitter of a calibration transceiver internal to the RRHs connected to the inter-RRH calibration module, a fourth calibration signal to a receiver of the inter-RRH calibration module, wherein the fourth calibration signal and the third calibration signal are orthogonal to each other;

q ', the baseband calculates RRH internal calibration weight, RRH inter-calibration module calibration weight and comprehensive weight according to the channel response in the steps o ' and p '.

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