HK1226878A1 - Digital transport of data over distributed antenna network - Google Patents

Description

Digital transmission of data via a distributed antenna network

Cross Reference to Related Applications

This application claims priority from U.S. provisional patent application No. 61/918,386 entitled "digitalransportofdataoverhtributedantennanetworks" filed on 19.12.2013, and the disclosure of this application is hereby incorporated by reference in its entirety for all purposes.

Background

Wireless and mobile network operators face the ongoing challenge of establishing networks that efficiently manage high data traffic growth rates. The mobility and increasing level of end-users' multimedia content requires end-to-end network adaptation to support both new services and the increasing demand for broadband and flat-rate internet access. One of the most difficult challenges facing network operators is caused by the physical movement of subscribers from one location to another, and particularly when wireless subscribers are heavily populated in one location. An obvious example is an enterprise facility during lunch hours when a large number of wireless subscribers are traveling to a canteen location in a building. At that time, a large number of subscribers are away from their offices and flat workplaces. During lunch hours, there may be many places where few subscribers are present in the entire facility. If the resources of an indoor wireless network are sized appropriately during the design process for the subscriber load during normal operating hours when the subscriber is in its normal operating zone, then the lunch time scenario will most likely present some unexpected challenges in terms of available wireless capacity and data throughput.

To address these issues, Distributed Antenna Systems (DAS) were developed and deployed. Despite the advances made in DAS, there remains a need in the art for improved methods and systems related to DAS.

Disclosure of Invention

The present invention relates generally to communication systems using complex modulation techniques. More particularly, the present invention relates to distributed antenna systems that include a microprocessor or other digital component, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC). Timing synchronization in distributed antenna systems is sensitive to the content of data transmitted over the network. Cellular data is prone to weak signals for long periods of time, which may result in nulls for long periods. A scrambler/descrambler is an effective technique to prevent clock drift in high data rate links. Embodiments of the present invention provide an efficient and effective method of ensuring clock timing synchronization in a remote unit to which data has been transmitted over a digital link from a host unit to the remote unit.

Embodiments of the present invention provide systems and techniques based on performing scrambling of transmitted downstream data at a host unit and then descrambling of received data at a remote unit. Likewise, scrambling and descrambling are used for transmitted upstream data transmitted between the remote unit and the host unit.

According to an embodiment of the present invention, a system for transmitting data in a Distributed Antenna System (DAS) is provided. The system includes at least one Digital Access Unit (DAU) and a plurality of Digital Remote Units (DRUs) coupled to the at least one DAU. The plurality of DRUs are operable to transmit signals between the plurality of DRUs and at least one DAU. The at least one DAU includes a data transport encoder and a data transport decoder, wherein the data transport decoder includes a framer, an encoder, a scrambler, and a serializer, and the data transport decoder includes a deserializer, a decoder, a descrambler, a frame synchronizer, and a deframer.

According to a particular embodiment of the present invention, a system for transmitting data in a distributed antenna system. The system includes a plurality of Digital Access Units (DAUs). The plurality of DAUs are coupled and operable to route signals between the plurality of DAUs. The system also includes a plurality of Digital Remote Units (DRUs) coupled to the plurality of DAUs and operable to transmit signals between the plurality of DRUs and the plurality of DAUs. Each of the plurality of DRUs includes: the system comprises a data transmission encoder and a data transmission decoder, and a scheduler/distributor, wherein the data transmission encoder comprises a framer, an encoder, a scrambler and a serializer, and the data transmission decoder comprises a deserializer, a decoder, a descrambler, a frame synchronizer and a deframer.

According to a specific embodiment of the present invention, a method of providing serialized data is provided. The method includes receiving payload I and Q data and receiving IP data. The method also includes framing the payload I with Q data and IP data and encoding the frame. The method also includes scrambling the encoded frame to provide scrambled data, and serializing the scrambled data.

According to another embodiment of the present invention, a method of communicating RF data and IP data is provided. The method comprises the following steps: receiving RF data at an RF port of a Digital Access Unit (DAU); receiving the IP data at an Ethernet port of the DAU; processing the RF data to provide digital payload I and Q data; and framing the digital payload I and Q data and the IP data to provide framed data. The method also includes: encoding the framed data; scrambling the encoded data; serializing the scrambled data; and transmitting the serialized data over optical fiber to a Digital Remote Unit (DRU). The method further comprises the following steps: deserializing the serialized data; descrambling the deserialized data; extracting frame synchronization of the descrambled data; and decoding the descrambled data. The method additionally includes: converting the decoded data to provide a representation of the RF data and the IP data; amplifying the representations of the RF data and the IP data; and transmitting the amplified RF data and IP data from an antenna associated with the DRU.

According to a particular embodiment of the present invention, a system for transmitting data in a distributed antenna system is provided. The system includes a plurality of Digital Access Units (DAUs). A plurality of DAUs are coupled and operable to route signals between the plurality of DAUs. The system also includes: a plurality of Digital Remote Units (DRUs) coupled to the plurality of DAUs and operable to transmit signals between the DRUs and DAUs; a data transmission encoder including a framer, an encoder, a scrambler, and a serializer; and a data transport decoder including a deserializer, a decoder, a descrambler, a frame synchronizer, and a deframer.

According to another particular embodiment of the present invention, a system for transmitting data in a distributed antenna system is provided. The system includes a plurality of Digital Access Units (DAUs). The plurality of DAUs are coupled and operable to route signals between the plurality of DAUs. The system also includes: a plurality of Digital Remote Units (DRUs) coupled to the plurality of DAUs and operable to transmit signals between the DRUs and DAUs; a data transmission encoder including a framer, an encoder, a scrambler, and a serializer. The system also includes a data transport decoder including a deserializer, a decoder, a descrambler, a frame synchronizer, and a deframer. The system also includes a scheduler and an allocator.

In accordance with yet another particular embodiment of the present invention, a system for transmitting data in a distributed antenna system includes a plurality of Digital Access Units (DAUs), wherein the plurality of DAUs are coupled and operable to route signals between the plurality of DAUs. The system also includes: a plurality of Digital Remote Units (DRUs) coupled to the plurality of DAUs and operable to transmit signals between the DRUs and DAUs; and a plurality of Base Transceiver Stations (BTSs). The system also includes a data transport encoder including a framer, an encoder, a scrambler, and a serializer, and a data transport decoder including a deserializer, a decoder, a descrambler, a frame synchronizer, and a deframer.

Many benefits are achieved by the present invention as compared to conventional techniques. For example, embodiments of the present invention provide improved clock timing synchronization for use in transmitting cellular data. The present invention is applicable to any communication system that transmits cellular data over a medium. In some embodiments, a communication link is established between the local host unit and the remote unit. A Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC) incorporating a processor, such as a PowerPC or Microblaze, may be used to control the flow of data to and from the remote unit. These and other embodiments of the present invention, as well as many of the advantages and features of the present invention, are described in more detail below with reference to the accompanying drawings.

Drawings

Fig. 1 is a block diagram illustrating a Distributed Antenna System (DAS) including one or more Digital Access Units (DAUs) and one or more Digital Remote Units (DRUs).

Fig. 2 is a block diagram of a Digital Access Unit (DAU).

Fig. 3 is a block diagram of a Digital Remote Unit (DRU).

Fig. 4 illustrates a mapping of a data frame structure for transmission between a DAU and a DRU.

Fig. 5 is a block diagram of the coding structure at the Digital Access Unit (DAU) downstream path and the Digital Remote Unit (DRU) upstream path.

Fig. 6 is a block diagram of the coding structure at the Digital Access Unit (DAU) upstream path and the Digital Remote Unit (DRU) downstream path.

FIG. 7A is a block diagram of a scrambler for framed data in accordance with an embodiment of the present invention.

Figure 7B is a block diagram of a descrambler for framed data according to an embodiment of the invention.

FIG. 8 is a simplified flow diagram illustrating a method of providing serialized data in accordance with an embodiment of the present invention.

Fig. 9 is a simplified flowchart illustrating a method of transmitting RF data and IP data according to an embodiment of the present invention.

Detailed Description

Distributed Antenna Systems (DAS) provide an efficient way to utilize base station resources. The base stations associated with the DAS may be located at a central location and/or facility commonly referred to as a base station hotel. The DAS network includes one or more Digital Access Units (DAUs) that serve as an interface between base stations and Digital Remote Units (DRUs). The DAU may be collocated with the base station. DRUs can be daisy-chained together and/or placed in a star configuration and provide coverage for a given geographic area. DRUs are typically connected to DAUs by employing high-speed fiber links. This approach facilitates transmission of RF signals from the base station to a remote location or area served by the DRU.

The embodiment shown in fig. 1 illustrates a basic DAS network architecture according to an embodiment of the present invention and provides an example of a data transmission scheme between a base transceiver station 108, also referred to as a base station, and a plurality of DRUs 101, 104 and 106. In this embodiment, DRUs are connected to DAUs 103 in a star configuration to achieve coverage of a particular geographic area.

Fig. 1 is a block diagram of one embodiment of a distributed antenna system including one or more digital access units 103 and one or more digital remote units 101/104/106. The DAU interfaces to one or more Base Transceiver Stations (BTSs) 108. Up to N DRUs may be used in conjunction with the DAU. The BTS108 is coupled to the DAU by an RF cable 109 adapted to carry RF signals. In the embodiment shown in fig. 1, the DAU is connected to one or more DRUs using optical fibers 102/105/107. In other embodiments including more than one DAU, the DAUs may be coupled via ethernet cables, optical fibers, microwave line-of-sight links, wireless links, satellite links, etc. Although an optical fiber 102/105/107 is shown in fig. 1, in other embodiments, one or more DAUs are coupled to multiple DRUs via an ethernet cable, microwave line-of-sight link, wireless link, satellite link, or the like. Additional description relating to DAS architecture is provided in U.S. patent application No. 13/211,243, filed on 16/8/2011, now U.S. patent No. 8,682,338, the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

Fig. 2 is a block diagram illustrating a DAU system for a base station application according to one embodiment of the present invention. The DAU system 202 for base station applications has an RF input output 203 that receives and transmits RF input/output signals and an optical input output port shown by optical fibers 201A through 201F.

The DAU system 202 includes four key components, namely an FPGA-based digital component 205, a down-converter and up-converter component 204, an analog-to-digital converter and digital-to-analog converter component 208, and an optical laser and detector component 209. The FPGA-based digital component 205 includes a Field Programmable Gate Array (FPGA), a Digital Signal Processing (DSP) unit, a framer/deframer, and a serializer/deserializer. Additional description relating to the DAU is provided in U.S. patent application No. 12/767,669 (attorney docket No. 91172-821440(DW-1016US)) filed on year 2010 at month 4 and month 26, U.S. patent application No. 13/211,236 (attorney docket No. 91172-821470(DW-1022US)) filed on day 8 and month 16 on year 2011, U.S. patent application No. 13/211,247 (attorney docket No. 91172-821479(DW-1024US)) filed on day 2011 year 8 and month 4, and U.S. patent application No. 13/602,818 (attorney docket No. 91172-850985 (DW-1025)) filed on month 2012 and month 4, and all of these applications are hereby incorporated by reference in their entirety for all purposes.

As shown in fig. 2, the DAU202 is a quad-band digital access unit (i.e., operating at multiple frequency bands) that may include transmit/receive input/output at the 700MHz203A band, the 900MHz203B band, the 1900MHz203C band, and the AWS203D band, however, other frequency bands are also within the scope of the present invention. The DAU may have an RF base station interface (typically four parts). Although the DAU202 shown in fig. 2 includes the four Tx/RxRF ports described above, a fewer or greater number of Tx/RxRF ports may be utilized. On the optical interface side (i.e. the right side of fig. 2), the DAU is connected to a plurality of Remote Radio Units (RRUs), also referred to as digital remote units (RRUs), in a star configuration, a daisy chain configuration or a combination thereof, depending on the specific network design. As shown in fig. 2, six fiber optic interfaces 201A through 201F are used in the illustrated embodiment.

Referring to fig. 2, the downlink path RF signal entering the DAU at the duplex RF input/output port 203A is separated from the uplink signal by an RF duplexer 230 and frequency converted by a down/up converter 204, digitized by an analog-to-digital converter 231 and converted to baseband by a digital processing function 232, wherein the digital processing function 232 is part of the FPGA 205. Similar components are used for the other duplex RF input/output ports as shown in fig. 2. The data stream is then I/Q mapped and framed by the monitor and control signals in framer/deframer 206. The particular parallel data stream is then independently converted to a serial data stream in the serializer deserializer 207 and converted to an optical signal by the pluggable SFP optical transceiver module 209 and transmitted to the optical fibers 201A-201F. Six optical fibers carry the serial optical data stream to multiple RRUs. The other three sets of downlink RF paths operate in a similar manner.

Referring to fig. 2, following the above description, the uplink path optical signals received from the RRUs are received using optical fibers 201A through 201F, deserialized by serializer/deserializer 207, deframed by framer/deframer 206, and digitally upconverted by digital processing function 232. The data stream is then converted to an analog IF by a digital-to-analog converter 233 and upconverted by an upconverter UPC1, then amplified by an RF amplifier 234 and filtered by a duplexer 230. The uplink RF signal enters the base station at uplink RF port 203A. The CPU240 feeding the ethernet router 242 provides separate ethernet ports (remote and AUX) for different applications.

Fig. 3 is a block diagram illustrating a Digital Remote Unit (DRU) system according to an embodiment of the present invention. The DRU system 300 has bidirectional optical signals carried on one or more of optical fibers 1 and/or 2 to communicate with the DAU shown in fig. 2 and a bidirectional RF port 320, the bidirectional RF port 320 being operable to transmit and receive RF signals transmitted and received by an RF antenna (Tx/RxANT). The DRU system includes four key components described more fully below: FPGA-based digital components 312, down-and up-converters 313, 314, analog-to-digital converters (308) and digital-to-analog converters (309) (the group being labeled 321), optical laser and detector components including small form-factor pluggable (SFP) modules SFP1 and SFP2, and power amplifier components 318.

Fig. 3 shows a single-band remote radio head unit, also referred to as a digital remote unit, with one combined downlink/uplink antenna port 320. In other embodiments, a multi-band DRU is utilized, for example, with uplink/downlink antenna ports operating at 850MHz, 1900MHz, etc. Referring to fig. 3, fiber 1 connected to SFP1301 is a high speed fiber optic cable that transports data between the host unit location (and the base station) and the remote radio head units. The optical fibers 2 may be used to link other remote radio head units, which are thereby interconnected to a base station or DAU, in a daisy-chain manner. The software defined digital platform 312 typically performs baseband signal processing in an FPGA or equivalent, which software defined digital platform 312 may be referred to as an FPGA. The FPGA includes a serializer/deserializer 303. The deserializer section extracts the serial input bit stream from the fiber optic transceiver 301 and converts it to a parallel bit stream. The serializer portion performs the inverse operation for transmitting data from the remote radio head unit to the base station. In one embodiment, two different bit streams communicate with the base station over one optical fiber using different optical wavelengths, however in an alternative arrangement, multiple optical fibers may be used. The DSP unit 304 includes a framer/deframer that interprets the structure of the incoming bit stream and sends the deframed data to a crest factor reduction algorithm module that is a component of the DSP unit 304. The crest factor reduction algorithm module reduces the peak-to-average ratio of the incoming signal to improve the DC-to-RF conversion efficiency of the power amplifier. The waveform is then presented to a digital predistorter block in DSP 304. The digital predistorter compensates for the non-linearity of the power amplifier 318 with an adaptive feedback loop. The downlink RF signal from the power amplifier is fed to the duplexer 317 and then routed to the antenna port 320.

The digital up-converter 314 filters the unframed signal and digitally converts it to an IF frequency. The digital-to-analog converter 309 performs DA conversion and feeds the IF signal into the up-converter 314. The framer of the DSP unit 304 takes the data from the digital down-converter 305 and packages it into frames for transmission to the BTS via the fiber optic transceiver 301. The analog-to-digital converter 308 is used to convert the analog RF upstream signal to a digital signal. The receiver also includes a downconverter 313.

The ethernet cable may be connected to a gigabit ethernet switch 310, which gigabit ethernet switch 310 is coupled to a CPU311 and used for local communication with DRUs.

Fig. 4 illustrates an embodiment of a frame structure of data transmitted between a DAU and a DRU. The data frame structure includes five parts or elements: a synchronization part 401, a vendor specific information part 402, a control and management (C & M) part 403, a payload data part 404 and an IP data part 405. The synchronization portion 401 is used at the receiver to synchronize the clock of the transmitted data. Vendor specific information portion 402 is assigned to identify various vendor information, which may include an IP address associated with the information as well as other information that may be specific to a particular vendor (e.g., wireless carrier). Control and management section 403 is used to monitor and control remote units and perform software upgrades. Network control information and performance monitoring and control signals may be communicated in the C & M section 403. The payload I/Q data section 404 includes cellular baseband data from the BTS108 or from the RF antenna port 320. The IP data 405 is framed along with the payload I/Q data for transport between the DAU and DRU. The IP data may include IP traffic passing through ethernet router 242 or through ethernet switch 310. Finally, the framed data is scrambled/descrambled as illustrated in fig. 5. The IP data is framed along with the cellular data so that both types of data can be transmitted through the system in either the upstream path or the downstream path.

Fig. 5 shows a block diagram of an encoding structure of transmitted data including payload I/Q data from a plurality of inputs. Fig. 5 illustrates how the various portions of the data frame structure shown in fig. 4 are generated and how data may be encoded for the DAU downstream path and the DRU upstream path. Thus, the processing shown in fig. 5 occurs at the DAU of the downstream path and at the DRU of the upstream path.

The scheduler and switch 508, error coding 509, synchronization 514, C & M515, and vendor specific information 516 are set as inputs to the framer 510. Payload data (i.e., raw I and Q data) (payload I and Q data 501, 502, 503, 504, 505, and 506) and IP network traffic (network IP traffic 507) from multiple input ports are buffered and communicated to scheduler and switch 508. The scheduler and switch 508 checks the buffered payload data from the various ports and the IP network traffic for the framer 510. The scheduler utilizes an algorithm to ensure fairness among the ports and to allocate the allocated resources. The scheduler also decides to which port the resources are allocated. As an example, a lower priority may be assigned to the IP network data 507 than the payload data 501 to 506 from the respective ports.

The error encoder 509 performs cyclic redundancy check encoding of the transmitted data to ensure that no errors occur during the transmission of data from the DAU to the DRU. The framed data is scrambled using the scrambler 512 before being sent to the serializer 513. One of the functions provided by the scrambler 512 is to remove zeros and ones, for example, of long segments in the cellular data to ensure good frame timing synchronization. This functionality ameliorates the problem presented by payload I and Q data comprising downstream cellular data from multiple ports that fluctuates with use and may be susceptible to long segments of zeros or ones. Thus, embodiments of the present invention integrate scrambling as part of the framing process to improve system performance, particularly frame synchronization. As shown in fig. 4, the framing of the data provides for the separation of the payload I and Q data 404 and the IP data 405 as separate elements of the frame to provide for the separation of two different types of data and the consequent security provided by such separation into separate elements. After framing and encoding, scrambling of the frames shown in fig. 4 is performed to improve frame synchronization.

Referring to fig. 2, the correspondence between the functional blocks shown in fig. 5 and the modules of the FPGA205 is as follows. The payload I and Q data 501 to 506 are set as outputs of the DSPs 232, 252, 254 and 256. Network IP traffic 507 is provided as an output of ethernet router 242. This data and traffic is processed by various modules of FPGA205, including framer/deframer 206, which includes the functions provided by scheduler and switch 508, scrambler 512, and functional units therebetween, including error encoder 509, framer 510, and encoder 511. The serializer/deserializer module (serializer/deserializer) 207 in fig. 2 corresponds to the serializer 513 in fig. 5. For clarity, the data flow from the DSPs 232, 252, 254, 256 to the framer/deframer 206 and serializer/deserializer 207 is not shown in fig. 2, but will be apparent to one of ordinary skill in the art.

Fig. 6 shows a block diagram of a decoding structure of transmitted data. In fig. 6, the decoding of data of DAUs in the upstream path and data of DRUs in the downstream path is shown. The DAU receives upstream data from the remote unit. The serialized data then undergoes the following processing steps in the following modules: deserializer 614, descrambler 612, frame sync 611, decoder 613, deframer 610, in turn distribute 608 the data to the various output ports. The deframed data is decomposed into C & M615 data, vendor information data 616, error check decoding 609, and payload I and Q data. The allocation 608 routes the scheduled payload data to the various ports. The descrambler performs the inverse operation of the scrambler 511.

Referring to fig. 3, the elements having the functionality shown in fig. 6 correspond to the functionality provided by FPGA 312. The functions performed by the DSP304 positioned between the serializer/deserializer 303/307 and the DDC305/DUC306, including the functions of the decoder 613, descrambler 612, frame synchronizer 611, deframer 610, error check 609, and assignment 608, depending on whether the upstream or downstream path is used.

With respect to both fig. 2 and 5 and fig. 3 and 6, the functions performed by the various processing modules may be transferred to other modules as appropriate. For example, some or all of the functions of the framer/deframer 206 shown in fig. 2 may be implemented by the DSPs 232, 252, 254 and 256. Any person of ordinary skill in the art will recognize many variations, modifications, and alternatives.

FIG. 7A shows a scrambling function 1+ X representing³⁹+X⁵⁸A block diagram of the scrambler 701. The S # block 702/705 in fig. 7A and 7B is a shift register. Fig. 7B shows the corresponding descrambler 704 for this scrambling function. The scrambling/descrambling operation sums the signal received at adder 703 with the signal from 39 previous clock cycles and the signal from 58 previous clock cycles (i.e., binary addition). According to the embodiment of the inventionOther specific numbers of clock cycles than 39 and 58 may be used.

The cellular traffic load varies depending on the time of day, the number of active users, and many other factors. Periods of inactivity may result in weak signal strengths for various data payloads. These weak signals may result in zeros of long segments of payload data. This poses a problem for high data rate transmission of cellular signals. In particular, in the case of a long segment of zeros, it is very difficult to maintain frame synchronization at the receiver. The scrambler/descrambler is an effective technique for mitigating these effects because it injects ones and zeros in the data stream and then removes them by the descrambler at the receiving side. Referring to fig. 4 and 5, the payload I and Q data and the IP data are scrambled before being transmitted to the serializer.

It should be understood that the specific processing steps shown in fig. 5 and 6 provide specific embodiments of the present invention. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the steps listed above in a different order. Further, additional steps may be added or removed depending on the particular application. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

FIG. 8 is a simplified flow diagram illustrating a method of providing serialized data in accordance with an embodiment of the present invention. The method includes receiving payload I and Q data (810) and receiving IP data (812). Payload I and Q data may be calculated based on RF cellular traffic received at the DAU or DRU. The method also includes framing (814) the payload I with Q data and IP data and encoding (816) the frames. Framing payload I and Q data and IP data that may be independent of each other may utilize independent elements of the frame to keep different kinds of data in different regions of the frame to provide security and other benefits. The method also includes scrambling the encoded frame to provide scrambled data (818), and serializing the scrambled data (820).

In particular embodiments, the method also includes receiving the serialized data, e.g., at a DRU, deserializing the serialized data, descrambling the deserialized data, determining frame synchronization information, and decoding the descrambled data. The method also includes deframing the synchronized and decoded data. Thus, the method further comprises providing payload I and Q data and IP data, which may be distributed as shown in fig. 6.

It should be appreciated that the specific steps illustrated in FIG. 8 provide a particular method of providing serialized data in accordance with embodiments of the present invention. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the steps listed above in a different order. Moreover, the individual steps illustrated in FIG. 8 may include multiple sub-steps that may be performed in various sequences in accordance with the individual step. In addition, additional steps may be added or removed depending on the particular application. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

Fig. 9 is a simplified flowchart illustrating a method of transmitting RF data and IP data according to an embodiment of the present invention. The method comprises the following steps: receiving RF data (910) at an RF port of a Digital Access Unit (DAU); receiving the IP data at an Ethernet port of the DAU (912); and processing the RF data to provide digital payload I and Q data (914). The RF data may include analog RF data, cellular data, and the like. The IP data may be independent of the RF data. The method also includes: framing the digital payload I with Q data and IP data to provide framed data (916); encoding (918) the framed data; scrambling (920) the encoded data; serializing (922) the scrambled data; and transmitting the serialized data over optical fiber to a Digital Remote Unit (DRU) (924). As shown in fig. 4, in some embodiments, the payload I and Q data and the IP data are framed as separate elements of framed data.

At the DRU, the method includes: deserializing (926) the serialized data; descrambling (928) the deserialized data; and decoding (930) the descrambled data. As shown in fig. 6, in some embodiments, the frame synchronization information is extracted (932) prior to decoding (930) the descrambled data. In other embodiments, the method further comprises: extracting a frame sync (932) of the decoded data; converting the decoded data to provide representations of RF data and IP data (934), amplifying the representations of RF data and IP data (936); and transmitting the amplified RF data and IP data from an antenna associated with the DRU. Referring to fig. 3, the conversion of the decoded data may include digital-to-analog conversion processing by DAC309 and up-conversion by up-converter 314 as shown.

It should be understood that the specific steps shown in fig. 9 provide a particular method of communicating RF data and IP data in accordance with an embodiment of the present invention. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the steps listed above in a different order. Moreover, the individual steps illustrated in FIG. 9 may include multiple sub-steps that may be performed in various sequences in accordance with the individual step. In addition, additional steps may be added or removed depending on the particular application. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

It is also to be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.

Appendix I is a glossary of terms used herein, including acronyms.

Appendix I

Glossary of terms

ACLR adjacent channel leakage ratio

ACPR adjacent channel power ratio

ADC analog-to-digital converter

AQDM analog quadrature demodulator

AQM analog quadrature modulator

AQDMC analog quadrature demodulator corrector

AQMC analog quadrature modulator corrector

BPF band-pass filter

CDMA code division multiple access

CFR crest factor reduction

DAC digital-to-analog converter

DET detector

DHMPA digital mixed mode power amplifier

DDC digital down converter

DNC down converter

DPA Doherty power amplifier

DQDM digital quadrature demodulator

DQM digital quadrature modulator

DSP digital signal processing

DUC digital up-converter

EER envelope elimination and restoration

EF envelope following

ET envelope tracking

EVM error vector magnitude

FFLPA feed-forward linear power amplifier

FIR finite impulse response

FPGA field programmable gate array

GSM global mobile communication system

I-Q in-phase/Quadrature

IF intermediate frequency

LINC uses linear amplification of non-linear components

LO local oscillator

LPF low pass filter

MCPA multi-carrier power amplifier

MDS multidirectional search

OFDM orthogonal frequency division multiplexing

PA power amplifier

PAPR peak-to-average power ratio

PD digital baseband predistortion

PLL phase-locked loop

QAM quadrature amplitude modulation

QPSK quadrature phase shift keying

RF radio frequency

RRH remote radio head

RRU remote radio head unit

SAW surface acoustic wave filter

UMTS universal mobile telecommunications system

UPC up converter

WCDMA wideband code division multiple access

WLAN wireless local area network

Claims (18)

1. A system for transmitting data in a distributed antenna system, the system comprising:

at least one Digital Access Unit (DAU);

a plurality of Digital Remote Units (DRUs) coupled to the at least one DAU, wherein the plurality of DRUs are operable to transmit signals between the plurality of DRUs and the at least one DAU;

wherein the at least one DAU comprises:

a data transmission encoder including a framer, an encoder, a scrambler, and a serializer; and

a data transport decoder comprising a deserializer, a decoder, a descrambler, a frame synchronizer, and a deframer.

2. The system of claim 1, wherein the at least one DAU is coupled to the plurality of DRUs via at least one of an ethernet cable, an optical fiber, a microwave line-of-sight link, a wireless link, or a satellite link.

3. The system of claim 1, wherein the plurality of DRUs are connected in a daisy chain configuration.

4. The system of claim 1, wherein the plurality of DRUs are connected to the at least one DAU in a star configuration.

5. The system of claim 1, wherein a port of the at least one DAU is operable to connect to a base transceiver station.

6. A system for transmitting data in a distributed antenna system, the system comprising:

a plurality of Digital Access Units (DAUs), wherein the plurality of DAUs are coupled and operable to route signals between the plurality of DAUs;

a plurality of Digital Remote Units (DRUs) coupled to the plurality of DAUs, the plurality of Digital Remote Units (DRUs) operable to transmit signals between the plurality of DRUs and the plurality of DAUs;

wherein each of the plurality of DRUs comprises:

a data transmission encoder including a framer, an encoder, a scrambler, and a serializer;

a data transmission decoder comprising a deserializer, a decoder, a descrambler, a frame synchronizer, and a deframer; and

a scheduler/allocator.

7. The system of claim 6, further comprising a plurality of Base Transceiver Stations (BTSs).

8. The system of claim 6, wherein one or more elements of the data transport encoder and the data transport decoder are implemented in an FPGA.

9. The system of claim 6, wherein both payload I and Q data and IP data are processed by the data transport encoder and the data transport decoder.

10. A method of providing serialized data, the method comprising:

receiving payload I and Q data;

receiving IP data;

framing the payload I and Q data and the IP data;

encoding the frame;

scrambling the encoded frame to provide scrambled data; and

serializing the scrambled data.

11. The method of claim 10, further comprising:

receiving the serialized data;

deserializing the serialized data;

descrambling the deserialized data;

synchronizing the descrambled data;

decoding the descrambled data;

deframing the decoded data; and

providing the payload I and Q data and the IP data.

12. The method of claim 10, wherein the payload I and Q data is associated with RF cellular traffic.

13. The method of claim 10, wherein the IP data is independent of the payload I and Q data.

14. A method of communicating RF data and IP data, the method comprising:

receiving RF data at an RF port of a Data Access Unit (DAU);

receiving IP data at an Ethernet port of the DAU;

processing the RF data to provide digital payload I and Q data;

framing the digital payload I and Q data and the IP data to provide framed data;

encoding the framed data;

scrambling the encoded data;

serializing the scrambled data;

transmitting the serialized data over optical fiber to a Digital Remote Unit (DRU);

deserializing the serialized data;

descrambling the deserialized data;

extracting frame synchronization of the descrambled data;

decoding the descrambled data;

converting the decoded data to provide a representation of the RF data and the IP data;

amplifying representations of the RF data and the IP data; and

transmitting the amplified RF data and IP data from an antenna associated with the DRU.

15. The method of claim 14, wherein the RF data comprises analog RF data.

16. The method of claim 14, wherein the RF data comprises cellular data.

17. The method of claim 14, wherein the payload I and Q data and the IP data are framed as separate elements of the framed data.

18. The method of claim 14, wherein converting the decoded data comprises a digital-to-analog conversion process.