CN201797604U - A base station subsystem - Google Patents

Abstract

The utility model provides a base station subsystem, which comprises a baseband processing unit (BBU) and a pair of single-channel radio remote units (RRUs). The BBU is connected with the pair of single-channel RRUs via optical fibers, and the pair of single-channel RRUs is respectively connected to two ports of a pair of dual-polarizing antennas via radiofrequency feed cables. In the downlink direction, the BBU sends the same baseband signal to the pair of single-channel RRUs, and the pair of single-channel RRUs converts the baseband signal into radiofrequency signals to be outputted to the dual-polarizing antenna, so that downlink polarizing transmission is realized. When in the uplink direction, the pair of single-channel RRUs converts the two channels of radiofrequency signals from the dual-polarizing antenna into two channels of baseband signals to be sent to the BBU, and the two channels of baseband signals are then associated by the BBU, so that uplink polarizing diversity reception is realized. The base station subsystem is capable of improving performance of wireless uplink and downlink so as to increase system capacity.

Description

A base station subsystem

technical field

The utility model relates to the field of mobile communication, in particular to a base station subsystem.

Background technique

The time division multiplexing (TD) base station subsystem includes a baseband processing unit (BBU) and a remote radio unit (RRU). The BBU and the RRU are connected through optical fibers, and the RRU is further divided into a multi-channel RRU and a single-channel RRU. A multi-channel RRU means that a remote radio unit provides multiple (port) radio frequency outputs, and a single-channel RRU provides only one (port) radio frequency output. Multi-channel RRUs are mainly used in macro base station scenarios and used in conjunction with smart antennas; single-channel RRUs are mainly used in indoor coverage scenarios. The principle of the smart antenna is to direct the radio signal to a specific direction, generate a spatially directional beam, align the main beam of the antenna with the direction of arrival of the user signal, and align the side lobes or nulls with the direction of arrival of the interference signal, so as to fully and efficiently utilize the mobile user signal and for the purpose of deleting or suppressing interfering signals.

For some special scenarios such as high-speed rail, subway, tunnel, maglev and other high-speed scenarios, if multi-channel RRU+smart antenna technology is used, in order to meet the coverage requirements in the direction of the train, the base station is usually set within tens of meters away from the track , the main disadvantages of using multi-channel RRU+smart antennas are as follows:

First, at the near end of the base station, the high-speed switching of high-speed trains in the transverse direction between shaped beams places extremely high requirements on the smart antenna shaping algorithm, which is difficult to achieve in the industry, even if the cost is quite high.

Second, at the far end, trains, etc. travel in the same shaped beam of the smart antenna. Compared with the ordinary sectorized antenna, the smart antenna does not reflect the advantage of the lobe following of the smart antenna, and the smart antenna can use a narrower beam. Instead of the sectorized antenna, the multi-channel RRU loses the meaning of use.

In the construction of indoor coverage and community coverage, due to the restrictions on the use of smart antennas in many scenarios, single-channel RRUs and conventional vertically polarized small flat-panel antennas or ceiling antennas are often used in the TD network construction process (or when multi-channel RRUs are used, each independent channel to cover a different area). However, this method sacrifices the shaped beam capability of TD, the uplink and downlink both lose the shaped gain, and the uplink loses the advantage of reducing interference brought by the shaped beam. Overrides have a bigger impact. Smart antenna is one of TD's unique key technologies, and its shaped gain (6-7dB) is one of the key indicators affecting system link design. Using a single-channel RRU for indoor coverage, due to the loss of shape-forming gain, the uplink and downlink performance of the TD system will drop sharply, and the capacity of the TD system will be seriously lost. After simulation, the system capacity will be lost by about 2/3 (depending on different scenarios) different).

Utility model content

The technical problem to be solved by the utility model is to provide a base station subsystem to improve the performance of the uplink and downlink wireless links, and further increase the system capacity.

In order to solve the problems of the technologies described above, the utility model provides technical solutions as follows:

A base station subsystem, comprising:

A baseband processing unit BBU and a pair of single-channel remote radio unit RRU, the BBU and the pair of single-channel RRU are connected through optical fibers, and the pair of single-channel RRU are respectively connected to a dual-polarized antenna through a radio frequency feeder cable two ports;

In the downlink direction, the BBU sends the same baseband signal to the pair of single-channel RRUs, and the pair of single-channel RRUs respectively convert the baseband signal into a radio frequency signal and output it to the dual-polarized antenna to realize the downlink polarized emission;

In the uplink direction, the pair of single-channel RRUs convert the two-way radio frequency signals from the dual-polarized antenna into two-way baseband signals and send them to the BBU, and the BBU performs signal combination on the two-way baseband signals , realizing uplink polarization diversity reception.

The above-mentioned base station subsystem includes multiple stages of remote radio parts cascaded through optical fibers, and each stage of remote radio parts includes the pair of single-channel RRUs.

In the above-mentioned base station subsystem, the signal combination performed by the BBU on the two baseband signals is maximum ratio combination or selective combination.

In the above base station subsystem, the dual-polarized antenna is a ±45° dual-polarized antenna.

A base station subsystem, comprising:

A baseband processing unit BBU and a multi-channel remote radio unit RRU, the BBU is connected to the multi-channel RRU through an optical fiber, and the two channels in the multi-channel RRU are respectively connected to a dual-polarized antenna through a radio frequency feeder cable two ports;

In the downlink direction, the BBU sends the same baseband signal to the two channels in the multi-channel RRU, and the two channels respectively convert the baseband signal into a radio frequency signal and output it to the dual-polarized antenna , to achieve downlink polarized emission;

In the uplink direction, the two channels convert the two channels of radio frequency signals from the dual-polarized antenna into two channels of baseband signals and send them to the BBU, and the BBU performs signal combination on the two channels of baseband signals to realize Uplink polarization diversity reception.

The above-mentioned base station subsystem includes multiple stages of remote radio parts cascaded through optical fibers, and each stage of remote radio parts includes one multi-channel RRU.

In the above-mentioned base station subsystem, the signal combination performed by the BBU on the two baseband signals is maximum ratio combination or selective combination.

In the above base station subsystem, the dual-polarized antenna is a ±45° dual-polarized antenna.

Compared with the prior art, the beneficial effect of the utility model is: through the increase of the uplink and downlink polarization, the uplink and downlink wireless link performance of the TD system in the case of using non-smart antennas (loss of shaped gain) is improved, Especially for the performance of the TD uplink, it is more helpful; due to the improvement of the performance of the uplink and downlink wireless links, the system carrier-to-interference ratio is improved, and the system capacity of TD is also improved in the case of non-smart antennas (loss of shaped gain). uplifted.

Description of drawings

FIG. 1 is a schematic structural diagram of a base station subsystem in Embodiment 1 of the present invention;

FIG. 2 is a schematic structural diagram of a base station subsystem in Embodiment 2 of the present invention;

FIG. 3 is a schematic structural diagram of a base station subsystem in Embodiment 3 of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment one

Referring to Fig. 1, the base station subsystem of the embodiment of the present invention includes: a BBU101 and a pair of single-channel RRU102, 103, BBU101 and single-channel RRU102, 103 are connected by optical fiber, single-channel RRU102, 103 are respectively connected to a pair of Two ports of the polarized antenna 104 . In the figure, the solid line represents the optical fiber, and the dotted line represents the radio frequency feeder cable.

The processing process of the downlink signal by the base station subsystem is as follows:

The BBU101 sends the same baseband signal to the single-channel RRU102, 103, and the single-channel RRU102, 103 respectively converts the baseband signal into a radio frequency signal and outputs it to the dual-polarized antenna 104, and the dual-polarized antenna 104 uses different polarization modes ( For example, ±45° polarization) transmits the radio frequency signal, thus realizing downlink polarized transmission.

The processing process of the uplink signal by the base station subsystem is as follows:

The dual-polarized antenna 104 receives (for example, ±45° polarization) radio frequency signals in different polarization modes to obtain two radio frequency signals, and sends the two radio frequency signals to single-channel RRUs 102, 103, and single-channel RRUs 102, 103, respectively. 103 converts the two radio frequency signals from the dual-polarized antenna 104 into two baseband signals and sends them to the BBU101. The BBU101 combines the two baseband signals. In this way, uplink polarization diversity reception is realized.

Wherein, the signal combining performed by the BBU 101 on the two channels of baseband signals may be maximum ratio combining or selective combining.

Embodiment two

In this embodiment, a pair of single-channel RRUs in Embodiment 1 is replaced by a multi-channel RRU.

Referring to Fig. 2, the base station subsystem of the utility model embodiment includes: a BBU201 and a multi-channel RRU202, the BBU201 and the multi-channel RRU202 are connected by optical fibers, and the two channels in the multi-channel RRU202 are respectively connected to a dual-polarized The two ports of the antenna 203. In the figure, the solid line represents the optical fiber, and the dotted line represents the radio frequency feeder cable.

The processing process of the downlink signal by the base station subsystem is as follows:

The BBU201 sends the same baseband signal to the two channels in the multi-channel RRU202, and the two channels respectively convert the baseband signal into a radio frequency signal and output it to the dual-polarized antenna 203, and the dual-polarized antenna 203 uses different The radio frequency signal is sent out in a specific polarization mode (for example, ±45° polarization), so that downlink polarized transmission is realized.

The processing process of the uplink signal by the base station subsystem is as follows:

The dual-polarized antenna 203 receives (for example, ±45° polarization) radio frequency signals in different polarization modes to obtain two radio frequency signals, and sends the two radio frequency signals to the two channels respectively, and the two radio frequency signals are respectively sent to the two channels. The channel converts the two radio frequency signals from the dual-polarized antenna 203 into two baseband signals and sends them to the BBU201. The BBU201 combines the two baseband signals. In this way, uplink polarization diversity reception is realized.

Wherein, the signal combining performed by the BBU201 on the two channels of baseband signals may be maximum ratio combining or selective combining.

Embodiment three

This embodiment is a cascading application to RRUs.

In some special scenarios, such as high-speed mobile main line scenarios (maglev, high-speed rail, etc.), the system needs a longer handover transition area in order to make the handover work normally under high-speed conditions. On the premise of not reducing network performance, in order To reduce the number of handovers along the line and reduce the possibility of dropped calls, one solution is to combine multiple physical sectors composed of "RRU+antenna" into one logical sector, and combine the coverage of one logical cell To be extended, the original handover area is transformed into the same logic cell (handover does not occur at the original handover point).

The cascading of RRU devices under the same logical cell by the existing manufacturer’s equipment is limited by the total number of fan channels CA of the cascading link. Since multi-channel RRUs generally have 6 or 8 channels, let’s take 8 channels as an example. Assuming that the carrier sector configuration of the logical cell is 6 carrier sectors, after using a multi-channel RRU, the total number of carrier sector channels CA is: 6 carrier sectors × 8 channels = 48CA, which has reached the limit value of existing industry equipment, that is, for 8 channels Under the configuration of 6 carrier sectors, the RRU cannot be cascaded, that is, the extension of the coverage of the logical cell cannot be realized through multi-level cascading.

Assuming that two single-channel RRUs are used for dual-polarization connections, and each level of 2 RRUs provides 2 ports, then the number of cascaded RRUs = 48CA/6 carrier fans/2 channels = 4 levels of RRUs, that is, 4 levels of bipolar Optimized connection (that is, the coverage area of a logical cell is expanded to 4 times of the original).

Referring to Fig. 3, the base station subsystem of the embodiment of the present invention includes: a BBU301 and multi-level (3 levels in this embodiment) radio remote part cascaded through optical fibers, and each stage of radio remote part includes a pair of single-channel RRUs , are single-channel RRU302, 303, single-channel RRU304, 305, single-channel RRU306, 307, single-channel RRU302, 303 are respectively connected to two ports of a dual-polarized antenna 308 through RF feeder cables, and single-channel RRU304, 305 are respectively connected through The RF feeder cable is connected to two ports of a dual-polarized antenna 309 , and the single-channel RRUs 306 and 307 are respectively connected to two ports of a dual-polarized antenna 310 through the RF feeder cable. In the figure, the solid line represents the optical fiber, and the dotted line represents the radio frequency feeder cable.

In the downlink direction, the BBU101 sends the same baseband signal to the single-channel RRU302, 303, and the single-channel RRU302, 303 respectively converts the baseband signal into a radio frequency signal and outputs it to the dual-polarized antenna 308, and the dual-polarized antenna 308 uses different The radio frequency signal is sent out in a polarization mode (for example, ±45° polarization), so that downlink polarized transmission is realized.

In addition, the single-channel RRUs 302 and 303 also transmit the baseband signals to the single-channel RRUs 304 and 305, and the single-channel RRUs 304 and 305 respectively convert the baseband signals into radio frequency signals and output them to the dual-polarized antenna 309. The dual-polarized antenna 309 sends the radio frequency signal in a different polarization manner (for example, ±45° polarization), so that downlink polarized transmission is realized.

In addition, the single-channel RRUs 304 and 305 also transmit the baseband signals to the single-channel RRUs 306 and 307, and the single-channel RRUs 306 and 307 respectively convert the baseband signals into radio frequency signals and output them to the dual-polarized antenna 310. The dual-polarized antenna 310 sends the radio frequency signal in a different polarization manner (for example, ±45° polarization), so that downlink polarized transmission is realized.

In the uplink direction, the dual-polarized antenna 310 receives radio frequency signals in different polarization modes (for example, ±45° polarization), obtains two radio frequency signals, and sends the two radio frequency signals to single-channel RRUs 306 and 307, respectively, The single-channel RRU306, 307 converts the two-way radio frequency signals from the dual-polarized antenna 310 into two-way baseband signals and then sends them to the BBU301 through the single-channel RRU304, 305, single-channel RRU302, 303, and the BBU301 performs the processing on the two-way baseband signals Signals are combined, thus realizing uplink polarization diversity reception.

In addition, the dual-polarized antenna 309 receives radio frequency signals in different polarization modes (for example, ±45° polarization), obtains two radio frequency signals, and sends the two radio frequency signals to single-channel RRUs 304 and 305 respectively. RRU304, 305 converts two channels of radio frequency signals from dual-polarized antenna 309 into two channels of baseband signals, and then sends them to BBU301 through single-channel RRU302, 303, and BBU301 performs signal combination on the two channels of baseband signals, thus realizing uplink Polarization diversity reception.

In addition, the dual-polarized antenna 307 receives radio frequency signals in different polarization modes (for example, ±45° polarization), obtains two radio frequency signals, and sends the two radio frequency signals to single-channel RRUs 302 and 303 respectively. The RRUs 302 and 303 convert the two radio frequency signals from the dual-polarized antenna 104 into two baseband signals and send them to the BBU301. The BBU301 combines the two baseband signals. In this way, uplink polarization diversity reception is realized.

Wherein, the signal combining performed by the BBU301 on the two channels of baseband signals may be maximum ratio combining or selective combining. Among them, in the uplink signal processing of the multi-level RRU cascading mode, the BBU 301 can choose to perform "cell combination of multi-level RRU signals" and "polarization combination of each level of RRU" according to the specific implementation mode.

In Embodiment 3, each radio remote processing stage is a pair of single-channel RRUs. In other embodiments, each radio remote processing stage may also be a multi-channel RRU, and two of the multi-channel RRUs The channels are respectively connected to two ports of a dual-polarized antenna through radio frequency feeder cables. The uplink and downlink signal processing procedures in this implementation mode are similar to those in Embodiment 3, and will not be repeated here.

To sum up, in the base station subsystem of the embodiment of the utility model, in the downlink direction, two single-channel RRUs (or two independent channels of a multi-channel RRU) connected to the same BBU output the same downlink signal, realizing Polarized transmission: In the uplink direction, the two uplink signals received by the ±45° dual-polarized antenna are combined at the base station to form a polarization gain. Compared with the conventional single-channel RRU single-polarization connection mode, the uplink and downlink can obtain 3dB polarization gain through polarization application respectively. In the TD system that loses the shaping gain, the 3dB polarization gain can improve the uplink and downlink wireless For link performance, it is very important to improve the air interface capacity of the wireless network. Theoretically, the air interface capacity will be increased by 80% to 100%.

Compared with the multi-channel RRU cascading method, after using two single-channel RRUs (or two independent channels of a multi-channel RRU) for dual-polarization connection and cascading, the cell can reach a maximum of 4 levels of cascading. Configured as 6 carrier fans, the noise floor does not increase significantly, and the capacity of the air interface is protected. On the premise of not degrading the network performance, the carrier fan configuration capability of the logical cell is protected. At the same time, the coverage capability of the logical cell is effectively improved, and the high-speed scenario is improved. The probability of successful handover under .

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model without limitation. Those of ordinary skill in the art should understand that the technical solution of the utility model can be modified or equivalently replaced without departing from the utility model. The spirit scope of the new technical solution should be included in the scope of the claims of the present utility model.

Claims (8)

1. A base station subsystem, characterized in that, comprising: A baseband processing unit BBU and a pair of single-channel remote radio unit RRU, the BBU and the pair of single-channel RRU are connected through optical fibers, and the pair of single-channel RRU are respectively connected to a dual-polarized antenna through a radio frequency feeder cable two ports; In the downlink direction, the BBU sends the same baseband signal to the pair of single-channel RRUs, and the pair of single-channel RRUs respectively convert the baseband signal into a radio frequency signal and output it to the dual-polarized antenna to realize the downlink polarized emission; In the uplink direction, the pair of single-channel RRUs convert the two-way radio frequency signals from the dual-polarized antenna into two-way baseband signals and send them to the BBU, and the BBU performs signal combination on the two-way baseband signals , realizing uplink polarization diversity reception. 2 . The base station subsystem according to claim 1 , comprising multiple stages of remote radio parts cascaded through optical fibers, and each stage of remote radio parts includes the pair of single-channel RRUs. 3. The base station subsystem according to claim 1, characterized in that: The signal combination performed by the BBU on the two channels of baseband signals is maximum ratio combination or selective combination. 4. The base station subsystem according to claim 1, characterized in that: The dual-polarized antenna is a ±45° dual-polarized antenna. 5. A base station subsystem, characterized in that, comprising: A baseband processing unit BBU and a multi-channel remote radio unit RRU, the BBU is connected to the multi-channel RRU through an optical fiber, and the two channels in the multi-channel RRU are respectively connected to a dual-polarized antenna through a radio frequency feeder cable two ports; In the downlink direction, the BBU sends the same baseband signal to the two channels in the multi-channel RRU, and the two channels respectively convert the baseband signal into a radio frequency signal and output it to the dual-polarized antenna , to achieve downlink polarized emission; In the uplink direction, the two channels convert the two channels of radio frequency signals from the dual-polarized antenna into two channels of baseband signals and send them to the BBU, and the BBU performs signal combination on the two channels of baseband signals to realize Uplink polarization diversity reception. 6 . The base station subsystem according to claim 5 , comprising multiple stages of remote radio parts cascaded through optical fibers, and each stage of remote radio parts includes one multi-channel RRU. 7. The base station subsystem according to claim 5, characterized in that: The signal combination performed by the BBU on the two channels of baseband signals is maximum ratio combination or selective combination. 8. The base station subsystem according to claim 5, characterized in that: The dual-polarized antenna is a ±45° dual-polarized antenna.

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