WO2016142756A1

WO2016142756A1 - Repeater with flexible zoning assignment based on packet switch

Info

Publication number: WO2016142756A1
Application number: PCT/IB2015/055175
Authority: WO
Inventors: Keld Knut LANGE
Original assignee: Andrew Wireless Systems Gmbh
Priority date: 2015-03-10
Filing date: 2015-07-08
Publication date: 2016-09-15

Abstract

A telecommunications system can transport information between base transceiver stations and remotely located units for wireless transmission. The system includes an Ethernet switch with circuitry configured for routing information for different zones between the base transceiver stations and the remotely located units.

Description

[0001 ] This claims priority to U.S, Provisional Application Serial Number 82/130,958, titled "Repeater with Flexible Zoning Assignment Based on Packet Switch^" and filed March 10, 2015, the entirety of which is incorporated by reference.

Background

[0002] Telecommunications systems, such as repeaters and distributed antenna systems or "DAS's") can be used to extend wireless coverage in an area. Signals can be transported in analog form between a source of signals, such as a base transceiver station, and remote units associated with antennas, to extend coverage. Some telecommunications systems can transport signals in digital form. These digital systems can require a large, flexible switching capability in transporting various sectors from base transceiver stations to coverage zones covered by the system.

[0003] A digital telecommunications system has limited switching capability, often relying solely on a field-programmable gate array (FPGA), which can be limited to thirty-two sectors switched to thirty-two zones. For example, an FPGA has a limited number of high data rate input/output ports and a limited amount of signal processing logic resources available. A telecommunications system with a high switching capability is desired.

Summary

[0004] In one example, a telecommunications system is provided for transporting information between base transceiver stations and remotely located units for wireless transmission. The telecommunications system includes an Ethernet switch with circuitry configured for routing information for different zones between the base transceiver stations and the remotely located units.

[0005] The telecommunications system may further include a zoning unit comprising a field-programmable gate array (FPGA) and a backplane that includes the Ethernet switch. The FPGA includes a transport interface for transceiving signals with the base transceiver stations; expander circuitry for generating copies of signals from the base transceiver stations based on a number of remotely located units to which the signals are to be transported; combiner circuitry for combining uplink signals, per zone; and packetiser circuitry for packetizing signals to be transported to the remotely located units and for receiving uplink signals from the remotely located units.

[0006] The Ethernet switch can be configured for determining ports of the remotely located units to which to transport the copies of the signals and for determining a port of the combiner circuitry to which to provide uplink signals.

[0007] The Ethernet switch can include a downlink Ethernet switch communicatively coupled to the expander circuitry and the packetiser circuitry; and an uplink Ethernet switch communicatively coupled to the combiner circuitry and the packetiser circuitry.

[0008] The FPGA can include an interface to the remotely located units.

[0009] The packetiser circuitry can include at least two packetisers.

[0010] The transport interface can be configured for transceiving signals with the base transceiver stations through at least one point of interface device,

[001 1 ] The telecommunications system can also include links between the

FPGA and the Ethernet switch that are configured to transport signals between the FPGA and the Ethernet switch at a data rate that is higher than a data rate provided by the transport interface.

[0012] In another example, a telecommunications system is provided that includes: a head unit that includes an Ethernet switch; a point of interface with donor devices configured for communicatively coupling with base transceiver stations to transceive signals and for communicatively coupling to the Ethernet switch; and a plurality of remote units positionable remotely to the head unit and configured for communicating with the head unit and for providing wireless coverage in an area. The Ethernet switch includes circuitry configured for routing information for different zones in the area, between the base transceiver stations and the plurality of remote units.

[0013] Each of the donor devices can include circuitry configured for extracting individual carriers from ports of the point of interface as RF signals, normalize the RF signals to a common power level, and digitize the RF signals into digitized signals.

[0014] The telecommunications system can be a distributed antenna system or a repeater and can include a second Ethernet switch communicatively coupled between the Ethernet switch and at least some of the plurality of remote units.

[0015] The head unit can include a zoning unit that includes a field- programmable gate array (FPGA) and a backplane. The FPGA can include a transport interface for transceiving signals with the point of interface; expander circuitry for generating copies of signals from the base transceiver stations based on a number of the plurality of remote units to which the signals are to be transported; combiner circuitry for combining uplink signals from at least some of the plurality of remote units, per zone; and packetiser circuitry for packetizing signals to be transported to the plurality of remote units and for receiving uplink signals from the plurality of remote units.

[0016] The Ethernet switch can be configured for determining ports of the plurality of remote units to which to transport the copies of the signals, determining a port of the combiner circuitry to which to provide uplink signals, and associating MAC addresses for the ports with the copies of the signals.

[0017] The Ethernet switch can include: a downlink Ethernet switch communicatively coupled to the expander circuitry and the packetiser circuitry; and an uplink Ethernet switch communicatively coupled to the combiner circuitry and the packetiser circuitry.

[0018] The packetiser circuitry can include at least two packetisers.

[0019] The telecommunications system can include links between the FPGA and the Ethernet switch that are configured to transport signals between the FPGA and the Ethernet switch at a data rate that is higher than a data rate provided by the transport interface.

[0020] In another example, a method is provided that includes:

digitizing RF signals received from base transceiver stations through a point of interface to form digitized RF signals;

expanding the digitized RF signals by generating copies of the digitized RF signals; and

routing the copies of the digitized RF signals to one or more zones served wirelessly by a telecommunications system using an Ethernet switch and information associated with the copies of the digitized RF signals and with ports of remote units. [0021 ] The information associated with the copies of the digitized RF signals can include MAC addresses. The method can further include determining the MAC addresses corresponding to the ports of the remote units.

[0022] The method can further include providing the copies of the digitized RF signals to the Ethernet switch from a field-programmable gate array (FPGA) at a data rate that is higher than a data rate at which the FPGA receives the digitized RF signals from the point of interface.

[0023] A number of the copies of the digitized RF signals can be based on a number of the ports of the remote units to which to the copies will be routed.

[0024] FIG. 1 is a block diagram of a repeater with a switch according to one example of the disclosure.

[0025] FIG. 2 is a block diagram of a repeater with cascaded switches according to one example of the disclosure.

[0026] FIG. 3 is a block diagram of a repeater with daisy-chained remote units and a switch according to one example of the disclosure.

[0027] F!G. 4 is a block diagram of a switch for a telecommunications system according to one example of the disclosure.

[0028] Certain aspects and features of the present disclosure relate to using packet switches, such as Ethernet switches, in a distributed antenna system or another telecommunications system to transport digital signals that represent narrow radio signals or broadband radio signals. Doing so may overcome flexibility limitations and switching capability limitations.

[0029] In large-scale repeater installations, the radio signals of numerous base transceiver stations can be repeated by a high number of remote units. The remote units can include multiple radio transceivers serving multiple radio bands. Per radio band, multiple carriers of mobile operators can be served. The number of repeater remote units can be selected to provide radio coverage in a defined area. The capacity (e.g., the number of users, network throughput) of the installation can be determined by the number of attached radio base transceiver stations. While the requirements on coverage (e.g., network qualify) in a given area can be stable, the capacity needs can increase over time. The radio signal of a base transceiver station can be distributed by one or more repeater remote units. One base transceiver station may feed ail repeater remote units if the capacity needs are low. In installations for maximum capacity, there can be a one-to-one relation between base transceiver stations and repeater remote units. Zoning can include assigning a base transceiver station to one or more repeater remote units. An individual zoning rule can be supported per radio carrier.

[0030] In some examples, a central zoning unit or switch is interconnected with point of interface (POI) devices of a repeater installation and with the repeater remote units or other type of telecommunications system, such as a distributed antenna system. The zoning unit can route downlink (e.g., from a base transceiver station toward a mobile device) digital signals, such as in-phase (!) and quadrature (Q) streams, digitized RF, or other types of digital streams to multiple repeater remote units (e.g., poinf-to-multipoinf (P2MP)). A stream may represent the radio signal of a single carrier. In an uplink direction (e.g., from a mobile unit and toward a base transceiver station), the individual receive signals of the repeater remote units can be aggregated, for example, by summing the l/Q samples. The zoning unit can include complex signal processing capabilities to implement various functionalities.

[0031 ] F!G. 1 depicts an example of a repeater system 100 coupled to base transceiver station (BTS) clusters 102 of different operators. The repeater system 100 can include donor devices 104A-N of a point of interface (POl) device or devices 106, a switch 108, and remote units 1 10A-N (each shown as "RU").

[0032] The BTS clusters 102 can include base transceiver stations for different radio technologies, such as GSM, CDMA, UMTS, LTE-FDD, TD-LTE, etc., serving different radio bands or the same radio band. The physical ports PA - PN of the BTS clusters 102 can be terminated at the respective donor device 104A-N. Multiple radio carriers at different frequencies may be applied per port. In some examples, the point of interface devices 106 and the switch 108 are in a head unit. In other examples, the point of interface devices 106 and the switch 108 are in separate units.

[0033] A donor device can be a unit or a component of a unit that performs certain signal processing. Examples of the signal processing include carrier separation, digitization, conversion to analog, and variable gain adjustments per carrier. A donor device 104A-N can extract individual carriers from the ports as RF signals, normalize the extracted RF signals to the same power, and digitize the normalized RF signals. The digitized carriers CA-CN of the signals from the BTS clusters 102 can be transported to a zoning unit or switch 108 by streaming (e.g., CPRI) or packetizing (e.g., Ethernet), In the switch 108, the carriers can be processed to implement a point-to-multipoint distribution in downlink or a multipoint- to-point aggregation in uplink. Although depicted separately, the switch 108 and the donor devices 104A-N may be in the same unit in other examples. An example of the switch 108 is an Ethernet switch.

[0034] Appropriate switching mechanisms, such as the switch 108, can implement the zoning rules individually per carrier. For example, the switch 108 can be a high-bandwidth Ethernet switch that can efficiently implement the large set of zoning rules. In other examples, the switch 108 can be a Serial RapidIO® switch or a PC!-E switch. Each carrier can be assigned to one or more carriers CR1 to CRM of different repeater remote units 1 10A-N. In some examples, the carriers for a remote unit can be bundled on a single connection by the zoning unit,

[0035] The remote units 1 0A-N may be coupled to antennas for wireiessly transmitting RF signals in one or more coverage areas or zones. In some examples, each of the remote units 1 10A-N can convert downlink signals into RF signals at selected frequencies, amplify the RF signals to a selected power level, and provide the amplified RF signals to the antennas. The remote units 1 10A-N can also receive uplink RF signals, detected by the antennas, from mobile units, or other type of RF transmitter, in the coverage zones, process the uplink RF signals into a desired format for transporting to the switch 108. The switch 108 can sum or aggregate signals, particularly signals in the same frequency band, from multiple remote units 1 10A-N.

[0036] FIGs. 2 and 3 depict additional examples of repeaters 200, 300 coupled to the BTS clusters 102. !n FIG. 2, an additional switch 202 can be used between the zoning unit that is switch 108 and some of the remote units 1 10A-1 10B so that the switching mechanism can be cascaded. In FIG. 3, the remote units 1 10A-N of FIG. 1 are replaced with daisy-chained remote units 310A-N. For example, remote unit 31 OA is daisy-chained with remote unit 310B. Remote unit 31 OB can communicate with the switch 108 through remote unit 31 OA. Remote unit 31 OA may pass signals from remote unit 31 OB through to the switch 108. In other examples, remote unit 31 OA can sum or aggregate signals from remote unit 31 OB with signals received by remote unit 31 OA.

[0037] FIG. 4 depicts an example of the switch 108 (e.g., zoning unit) according to one aspect. The switch 108 includes an input/output (I/O) board 402 and a backplane 404. An example of the I/O board 402 is a field-programmable gate array (FPGA). The I/O board 402 includes a transport interface 406 (e.g., transmit and receive ports), a mu It ί point-to-point (MP2P) combiner 408, a point-to-multipoint (P2MP) expander 410, packefisers 412, and another transport interface 414. An example of a packetiser is a packet multiplexer, such as a 10: 1 multiplexer. The I/O board 402 may also include an IQ TDM multiplexer. The backplane 404 includes Ethernet switches 416, 418. Each Ethernet switch may be a managed Ethernet L2 switch. Although certain numbers of these components are shown, any number of each component can be used. For example, the functionality provided by the Ethernet switches 416, 418 may be implemented using one Ethernet switch.

[0038] In a downlink direction, digital l/Q signals can be received from the POI by the transport interface 406. The I/O board 402 can determine the number of remote units that will transmit the signals, per carrier, according to a setting stored in the I/O board 402. In some examples, the setting may be received from a technician and stored. The P2MP expander 410 can generate copies of the digital signals according to the number of remote units that will transmit the signals. The average expansion factor (e.g., the ratio of remote unit ports to BTS ports) may be greater than two. The expander 410 may also add a MAC address associated with the signal. In other examples, the MAC address is added to the signals by the PO!. The MAC address may be an address of the destination for the signals. For example, a MAC address can identify the remote unit port or ports to which the signals will be sent.

[0039] The multiple copies can be provided through a link 420 to Ethernet switch 416 in the backplane 404. In some examples, the link 420 may be a 25 Gb/s link bundled in four to total 100 Gb/s. The link 420 can provide a higher data rate for signal switching than the data rate at which signals are received or processed by the I/O board 402. The Ethernet switch 416 can derive the destination port for each remote that is to receive the signals, based on the MAC address associated with the signals. In some examples, the Ethernet switch 416 determines that the signals are to be sent to ail available destinations if the MAC address is unknown.

[0040] The signals can be provided from the Ethernet switch 416 to the I/O board 402 to be packetized by the packetisers 412. Multiple packetisers 412 can be used to handle a large number of signals, although in other examples one packetiser can be used. The packetized signals can be provided to the proper remote units on links 422 through interfaces 414. Each of the links 422 may be a 10 Gb/s link.

[0041 ] In the uplink direction, signals can be received through the interface 414 by the packetisers 412, which can combine streams of signals and provide the streams to the uplink Ethernet switch 418. The packetisers 412 may associate an uplink MAC address with the signals or the remote units may associate an uplink MAC address with the signals. The uplink Ethernet switch 418 can determine from the MAC address which port in the MP2P combiner 408 to provide the signals and can route the signals to the determined port through links 424. The data rate provided by the links 424 can be higher than the data rate of the interfaces 406, 414 of the I/O board 402. For example, the data rate of the links 424 may be 100 Gb/s. An example of the interfaces 406, 414 is an l/Q time-division multiplexing crosspoint switch. The MP2P combiner 408 can strip packetization from the signals to form un- packetized signals, and combine the payioads from a selected carrier in a particular zone. The 1VIP2P combiner 408 can output a single inphase/quadrature (l/Q) stream per zone that is transported to a particular BTS port from the transport interface 406.

[0042] Each of the Ethernet switches 416, 418 may provide 32x full duplex 100 Gb/s ports. Each may have 3.2 Tb/s of bandwidth. The ports can be grouped into sixteen pairs. Each pair can be connected to the I/O board 402. Flow control (e.g., pause commands) can be applied to each of the 100 Gb/s ports individually. The downlink and uplink traffic signals can be handled by independent switches to avoid wasting switching capacity. In a single-switch design, the switch matrix can allow downlink traffic to be routed to uplink ports and vice versa, which may not be needed. Incoming carriers from the POI devices can be processed by the I/O board 402 that is an FPGA. The expansion factor applied by the P2MP expander 410 of an individual carrier may be high, but for the bundle of carriers a rather low expansion factor can be expected. This factor can correspond to the bandwidth ratio between POI and the remote unit ports. In one example, 80 Gb/s POI traffic is expanded to 200 Gb/s remote unit traffic. Vice versa, outgoing carriers to the POI devices can be processed by the IV1P2P combiner 408 in the FPGA. Depending on the zoning rules, the destination Ethernet address can be selected by the P2MP expander 410 for downlink and by the remote units for uplink. The zone rules for the IQ streams can be implemented by proper selection of destination MAC addresses. The P2IV1P expander 410 and MP2P combiner 408 may be a low complexity example for signal processing in the switch 108. Functionality with higher complexity can replace those components. [0043] The foregoing description of the examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the subject matter to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of this disclosure. The illustrative examples described above are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts.

Claims

Claims What is claimed is:

1 . A telecommunications system for transporting information between base transceiver stations and remotely located units for wireless transmission, the telecommunications system comprising:

an Ethernet switch with circuitry configured for routing information for different zones between the base transceiver stations and the remotely located units.

2. The telecommunications system of claim 1 , further comprising:

a zoning unit comprising a field-programmable gate array (FPGA) and a backplane, the backplane including the Ethernet switch, the FPGA including:

a transport interface for transceiving signals with the base transceiver stations;

expander circuitry for generating copies of signals from the base transceiver stations based on a number of remotely located units to which the signals are to be transported;

combiner circuitry for combining uplink signals, per zone; and

packetiser circuitry for packetizing signals to be transported to the remotely located units and for receiving uplink signals from the remotely located units.

3. The telecommunications system of claim 2, wherein the Ethernet switch is configured for determining ports of the remotely located units to which to transport the copies of the signals and for determining a port of the combiner circuitry to which to provide uplink signals.

4. The telecommunications system of claim 2, wherein the Ethernet switch includes:

a downlink Ethernet switch communicatively coupled to the expander circuitry and the packetiser circuitry; and

an uplink Ethernet switch communicatively coupled to the combiner circuitry and the packetiser circuitry,

5. The teiecommunications system of ciaim 2, wherein the FPGA includes an interface to the remotely located units.

8. The teiecommunications system of claim 2, wherein the packetiser circuitry includes at least two packetisers.

7. The telecommunications system of claim 2, wherein the transport interface is configured for transceiving signals with the base transceiver stations through at least one point of interface device.

8. The telecommunications system of claim 2, further comprising:

links between the FPGA and the Ethernet switch that are configured to transport signals between the FPGA and the Ethernet switch at a data rate that is higher than a data rate provided by the transport interface.

9. A telecommunications system, comprising:

a head unit that includes an Ethernet switch;

a point of interface with donor devices configured for communicatively coupling with base transceiver stations to transceive signals and for communicatively coupling to the Ethernet switch; and

a plurality of remote units positionable remotely to the head unit and configured for communicating with the head unit and for providing wireless coverage in an area,

wherein the Ethernet switch includes circuitry configured for routing information for different zones in the area, between the base transceiver stations and the plurality of remote units.

10. The telecommunications system of claim 9, wherein each of the donor devices includes circuitry configured for extracting individual carriers from ports of the point of interface as RF signals, normalize the RF signals to a common power level, and digitize the RF signals into digitized signals.

1 1. The telecommunications system of claim 9, wherein the telecommunications system is a distributed antenna system or a repeater and includes a second Ethernet switch communicatively coupled between the Ethernet switch and at least some of the plurality of remote units.

12. The telecommunications system of claim 9, wherein the head unit includes a zoning unit comprising a field-programmable gate array (FPGA) and a backplane, the FPGA including: a transport interface for transceiving signals with the point of interface; expander circuitry for generating copies of signals from the base transceiver stations based on a number of the plurality of remote units to which the signals are to be transported;

combiner circuitry for combining uplink signals from at least some of the plurality of remote units, per zone; and

packetiser circuitry for packetizing signals to be transported to the plurality of remote units and for receiving uplink signals from the plurality of remote units,

13. The telecommunications system of claim 12, wherein the Ethernet switch is configured for determining ports of the plurality of remote units to which to transport the copies of the signals, determining a port of the combiner circuitry to which to provide uplink signals, and associating MAC addresses for the ports with the copies of the signals.

14. The telecommunications system of claim 12, wherein the Ethernet switch includes:

an uplink Ethernet switch communicatively coupled to the combiner circuitry and the packetiser circuitry.

15. The telecommunications system of claim 12, wherein the packetiser circuitry includes at least two packetisers.

18. The telecommunications system of claim 12, further comprising: links between the FPGA and the Ethernet switch that are configured to transport signals between the FPGA and the Ethernet switch at a data rate that is higher than a data rate provided by the transport interface.

17. A method, comprising:

routing the copies of the digitized RF signals to one or more zones served wirelessly by a telecommunications system using an Ethernet switch and information associated with the copies of the digitized RF signals and with ports of remote units.

18. The method of claim 17, wherein the information associated with the copies of the digitized RF signals includes MAC addresses, the method further comprising: determining the MAC addresses corresponding to the ports of the remote units.

19. The method of claim 17, further comprising:

providing the copies of the digitized RF signals to the Ethernet switch from a field-programmable gate array (FPGA) at a data rate that is higher than a data rate at which the FPGA receives the digitized RF signals from the point of interface.

20. The method of claim 17, wherein a number of the copies of the digitized RF signals is based on a number of the ports of the remote units to which to the copies will be routed.