Patent Description:
Some modem cellular base station equipment separates the radio equipment and the baseband equipment into different functional and physical entities. Additionally, packet-based fronthaul interfaces are being used between a radio equipment and a baseband equipment. Therefore, it may be beneficial to provide functionality for multiple radio units in a single radio unit to take advantage of packet-based fronthaul interfaces in base stations using a distributed architecture. Relevant examples of prior art can found in <CIT>, <CIT>, XP8138433 and <CIT>.

The invention is defined by a communication system and a corresponding method as defined by the independent claims. Further advantageous embodiments are defined in the dependent claims.

Understanding that the drawings depict only exemplary configurations and are not therefore to be considered limiting in scope, the exemplary configurations will be described with additional specificity and detail through the use of the accompanying drawings, in which:.

In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the exemplary configurations.

Separating radio equipment and baseband equipment into different functional and physical entities may maximize the radio performance of a base station (by mounting the radio equipment near the antenna(s)) while minimizing the equipment that is mounted outside on a tower. Furthermore, in a separated architecture, baseband processing resources may (but are not required to be) flexibly be pooled together in a central location.

Traditionally, the fronthaul interface between radio equipment and baseband equipment may use a point-to-point semi-standard protocol such as the Common Public Radio Interface (CPRI) or the Open Base Station Architecture Initiative (OBSAI). There is currently a movement in the wireless industry to make the fronthaul interface between the radio equipment and the baseband equipment more open-standard to facilitate more equipment interoperability (e.g., between equipment made by different equipment vendors) as well as incorporate methods to reduce the required link bandwidth and increase link reliability.

One such example of this type of fronthaul interface is that proposed by extensible Radio Access Network (XRAN) from their Next Generation Fronthaul Interface working group. In this example, Ethernet is proposed for the transport layer between the radio equipment (also referred to as the Radio Unit, RU) and the baseband equipment. Ethernet has advantages because it is a widely used and understood protocol, and it easily supports physically-remote and/or centrally-located baseband equipment communicating with remote RU equipment over a standard network.

Another trend in the wireless/cellular industry is the densification of base stations. More base stations are being added to wireless networks to increase capacity. There are often challenges installing this equipment including locating suitable space, achieving zoning approvals, and erecting support structures. This challenge is exacerbated when multiple wireless carriers are all trying to cover the same region and all require independent equipment. Shared space or shared networks may be to co-locate equipment. The neutral host concept is often used for Distributed Antenna System (DAS) equipment where a third party installs an RF distribution network that multiple wireless carriers connect to for shared access to a coverage area.

In order to take advantage of packet-based fronthaul interface protocols and accommodate the densification trend, the present systems and methods herein describe a system that consolidates multiple virtual radio units in a radio unit that is remote from baseband equipment. Programmable circuitry (e.g., a field programmable gate array (FPGA), application specific integrated circuit (ASIC), microprocessor, digital signal processor (DSP), etc.) in a single housing may include multiple processing cores, each of which implement a virtual radio unit (VRU). Each of the multiple VRUs may be packet-addressable, and therefore be able to share a single physical link (e.g., Ethernet) to communicate with various baseband equipment. The multiple VRUs may share a common antenna system and/or radio frequency front end circuitry.

As will be discussed in greater detail below, the systems and methods disclosed herein may have several advantages compared to conventional base stations, even compared to other distributed base stations with separated radio equipment and baseband equipment. For example, the systems and methods disclosed herein may enable more small cells to be deployed while minimizing the challenges associated with such deployment. The systems and methods disclosed herein may also enable remote modification of radio equipment, as well as increase interoperability between equipment owned by different carriers.

<FIG> is a block diagram illustrating an example communication system <NUM> with multiple virtual radio units (VRUs) 104A-M in a radio unit <NUM> that is remote from at least one baseband controller 106A-N. One or more of the VRUs <NUM> and one or more of the baseband controllers <NUM> may collectively implement the functionality of one or more base stations deployed in a wireless communication system, e.g., in a centralized radio access network (C-RAN) architecture. The radio unit <NUM> may be a physical housing (e.g., a chassis attached to an antenna tower) deployed at a site to provide wireless coverage and capacity for one or more wireless network operators. The physical location of the radio unit <NUM> may be strategically chosen by one or more network operators (i.e., carrier) based on network demand, signal propagation characteristics, location of other radio units <NUM>, etc..

In one configuration, the system <NUM> may be part of a Long Term Evolution (LTE) radio access network providing wireless service using an LTE air interface. LTE is a standard developed by the Third Generation Partnership Project (3GPP) standards organization. In an LTE configuration, a VRU <NUM> and a baseband controller <NUM> together may be used to implement an LTE Evolved Node B (also referred to here as an "eNodeB" or "eNB") that is used to provide wireless devices <NUM> with access to the wireless network operator's core network <NUM> to enable the wireless devices <NUM> to wirelessly communicate data and voice (using, for example, Voice over LTE (VoLTE) technology).

In an LTE configuration, each core network <NUM> may be implemented as an Evolved Packet Core (EPC) <NUM> comprising LTE EPC network elements such as, for example, a mobility management entity (MME) <NUM> and a Serving Gateway (SGW) <NUM> and, optionally, a Home eNodeB gateway (HeNB GW) (not shown in <FIG>) and a Security Gateway (SeGW) (not shown in <FIG>).

Furthermore, systems and methods of this disclosure can be utilized with any release of the LTE standard, including Frequency-Division Duplex (FDD) and Time-Division Duplex (TDD) variants, or with a variety of other future or existing air interface technologies, such as <NUM> New Radio (NR), the IEEE <NUM>, which is more popularly known as Wi-Fi, or IEEE <NUM>, which is also known as Wi-Max, or even <NUM> air interfaces such as Universal Mobile Telecommunications System (UMTS).

The system <NUM> may include multiple virtual radio units (VRUs) <NUM> in a single radio unit <NUM> that is physically remote from one or more baseband controllers <NUM>. The baseband controllers <NUM> may be co-located (e.g., in a central baseband unit (not shown)) or physically remote from each other (e.g., if multiple wireless operators share single radio unit <NUM>). Alternatively, some of the baseband controllers <NUM> (e.g., baseband controllers B-N) may be located in the same location and/or housing while others (e.g., baseband controller A) are physically remote. Each baseband controller <NUM> may perform baseband processing for a particular air interface that is being used to wirelessly communicate over the RF channel, i.e., from an antenna system <NUM> to the wireless device(s) <NUM>. The baseband controllers <NUM> may process signals in the baseband frequency range, the lowest range of frequency spectrum. The baseband controllers <NUM> may provide the signaling, timing, framing, messaging, and control system interface between the core network <NUM> and the radio unit <NUM>. The baseband controllers <NUM> may operate on incoming and outgoing digital signals, and provide functions such as resource element mapping/de-mapping, precoding, equalization, layer mapping, scrambling/de-scrambling, coding/de-coding, modulation and/or rate-matching. In some instances, one or more of these functions could additionally, or alternatively, be implemented in the VRU <NUM>.

In contrast to proprietary (or semi-proprietary) fronthaul interface standards (e.g., the Common Public Radio Interface (CPRI) and/or Open Base Station Architecture Initiative (OBSAI) family of specifications), newer fronthaul interfaces <NUM> may utilize an Ethernet network <NUM> (e.g., an enterprise-grade Ethernet network) to transport in-phase and quadrature (IQ) data between the baseband equipment and radio equipment.

In order to save bandwidth across the Ethernet network <NUM>, some of these Ethernet-based fronthaul interfaces <NUM> may communicate IQ data representing frequency-domain symbols for the air interface (rather than time-domain IQ data) between the baseband controllers <NUM> and the VRUs <NUM>. This frequency-domain IQ data may represent the symbols in the frequency domain. Each VRU <NUM> may then perform an inverse fast Fourier transform (IFFT) to produce the time-domain IQ data. Some other Ethernet-based fronthaul interfaces <NUM> may communicate IQ data at a reduced data rate either as a result of downsampling the data to a baseband frequency or filtering the data to a reduced bandwidth. It should also be noted, that any suitable compression and processing techniques may be used to enable the use of an Ethernet-based fronthaul interface <NUM>.

Each baseband controller <NUM> may be implemented in software and/or firmware executing on one or more suitable programmable processors. Each baseband controller <NUM> (or portions thereof) can be implemented in other ways (for example, in a field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc.). Each baseband controller <NUM> may include one or more baseband modems (not shown). In one configuration, one or more virtual radio units (VRUs) <NUM> together with a baseband modem (in a baseband controller <NUM>) form a physical cell, e.g., each baseband modem may have the data transmission capacity of a single LTE cell/sector. Alternatively, multiple baseband modems (in the same or different baseband controller <NUM>) may serve a single cell. Alternatively, or additionally, a particular baseband modem may serve multiple cells.

The radio unit <NUM> may include multiple independent VRUs <NUM> that each perform processing to convert a baseband signal from one or more baseband controllers <NUM> into an RF signal that can be radiated from the antenna system <NUM> (that is connected to an RF front end unit <NUM>), i.e., each VRU <NUM> may perform processing for the air interface that is not performed in the baseband controller <NUM>. The VRU <NUM> processing may include modulating the baseband signal, e.g., using QPSK, 16QAM, 64QAM, etc. The VRU(s) <NUM> further may include data compression and decompression functions as well as digital beamforming, cyclic prefix addition/removal, and/or FFT/iFFT functions. In one configuration, multiple VRUs <NUM> may cooperatively operate in a Coordinated Multi Point (CoMP) or Carrier Aggregation (CA) methodology, e.g., in a similar way that independent radio units (i.e., if not implemented using VRUs <NUM>) would work together in a CoMP or CA methodology.

One or more VRUs <NUM> may belong to a particular cell. If multiple VRUs <NUM> belong to a particular cell, each of the VRUs <NUM> may broadcast the same cell identifier, e.g., an LTE Cell-ID in LTE Primary and Secondary Synchronization Signals (PSS/SSS). Each of the VRUs <NUM> in a particular cell may communicate with the at least one baseband controller <NUM> (e.g., one or more baseband modems in at least one baseband controller <NUM>) that is serving the particular cell.

The RF front end unit <NUM> may include a receive chain and a transmit chain, and may connect to a common shared antenna system <NUM>. The receive chain may include circuitry configured to filter, mix, amplify, and/or digitize analog signals received from wireless devices <NUM> (via the shared antenna system <NUM>) and pass them to the appropriate VRU <NUM>. The transmit chain may include circuitry configured to convert digital signals received from the VRUs <NUM> into analog signals, then mix and amplify the analog signals before they are transmitted to one or more wireless devices <NUM> (via the one or more antennas <NUM>). The antenna system <NUM> may include one or more antennas used to transmit downlink signals to and receive uplink signals from the wireless devices <NUM>.

In one configuration, each VRU <NUM> may have a different internet protocol (IP) address and appear to the baseband controller <NUM> (that the VRU <NUM> is communicating with) as an independent radio unit <NUM>, i.e., multiple VRUs <NUM> may coexist in the same physical housing (i.e., the radio unit <NUM>), but may be individually addressable using their respective IP addresses.

In another configuration, each VRU <NUM> may have a common internet protocol (IP) address, but a different internet protocol (IP) address port number, and appear to the baseband controller <NUM> (that the VRU <NUM> is communicating with) as an independent radio unit <NUM>, i.e., multiple VRUs <NUM> may coexist in the same physical housing (i.e., the radio unit <NUM>), but may be individually addressable using their respective IP addresses port number. In such a configuration, The VRUs <NUM> may all recognize the same IP address, but each VRU <NUM> may be configured to only recognize a particular port number assigned to that respective VRU <NUM>.

Each of the multiple VRUs <NUM> may be implemented as an independent digital instance (e.g., a processing core) on one or more programmable processors, e.g., where each programmable processor is an FPGA, ASIC, microprocessor or DSP device. The multiple VRUs <NUM> may share analog components in a single RF front end unit <NUM>, e.g., one or more antenna, band pass filter, low noise amplifier, power amplifier, duplexer, etc. that implement the receive chain and the transmit chain. Alternatively, the radio unit <NUM> may include more than one RF front end unit <NUM>, e.g., an RF front end unit <NUM> for each of the VRUs <NUM> in the radio unit <NUM>. Since the processor implementing the VRUs <NUM> may be programmable, VRUs <NUM> may be added, deleted, and/or reconfigured by changing the software and/or firmware in the process remotely, i.e., without having a technician at the site of the radio unit <NUM>. Each processing core in the programmable processor may use a unique set of instructions (software and/or firmware) to implement a particular VRU <NUM>. Alternatively, different multiple VRUs <NUM> may share some or all of the instructions implementing the VRUs <NUM>.

In addition to remotely adding, deleting, and reconfiguring VRUs <NUM>, the system <NUM> described herein may have several other advantages. First, in contrast to many other systems, the system <NUM> described herein may enable many different VRUs <NUM> to share the same radio unit <NUM>, thus minimizing the aesthetic and physical impact associated with deploying radio equipment in new locations and enabling denser placement of radio equipment per physical area.

Second, the system <NUM> described herein may enable easier compatibility between radio equipment (and/or between radio equipment and baseband equipment). In one configuration, two VRUs <NUM> may be used to implement different frequency bands or channels for a common wireless carrier. In another configuration, two VRUs <NUM> may be used to implement different frequency bands or channels for different wireless carriers. For example, a first VRU <NUM> may implement (i.e., communicate on) the <NUM> LTE frequency band, while a second VRU <NUM> may implement the <NUM> LTE frequency band (for the same or different wireless carrier as the first VRU <NUM>). Multiple VRUs <NUM> may implement any specific combination of the following frequency bands: <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, <NUM> LTE, etc. Despite these differences, the multiple VRUs <NUM> may be included in the same physical housing (i.e., the same radio unit <NUM>), may use the same fronthaul interface <NUM>, and/or may use the same RF front end unit <NUM> and antenna system <NUM>.

Furthermore, two VRUs <NUM> in the same radio unit <NUM> may use different air standards, but may be included in the same physical housing (i.e., the same radio unit <NUM>), may use the same fronthaul interface <NUM>, and/or may use the same RF front end unit <NUM> and antenna system <NUM>. For example, a first VRU <NUM> may communicate to wireless devices <NUM> using LTE, while a second VRU <NUM> may use a non-LTE standard, e.g., WiMAX, UMTS, Wi-Fi, etc. Additionally, or alternatively, a first VRU <NUM> may communicate to wireless devices <NUM> using Time Division Duplex (TDD), while a second VRU <NUM> may use Frequency Division Duplex (FDD).

Furthermore, two VRUs <NUM> in the same radio unit <NUM> may use different modulation schemes, but may be included in the same physical housing (i.e., the same radio unit <NUM>), may use the same fronthaul interface <NUM>, and/or may use the same RF front end unit <NUM> and antenna system <NUM>. For example, a first VRU <NUM> may communicate to wireless devices <NUM> using a first modulation scheme, while a second VRU <NUM> may use a second modulation scheme. Multiple VRUs <NUM> may use any specific combination of the following modulation schemes: quadrature phase-shift keying (QPSK), <NUM>-phase quadrature amplitude modulation (16QAM), <NUM>-state quadrature amplitude modulation (64QAM), other phase-shift keying (PSK), other quadrature amplitude modulation (QAM), frequency-shift keying (FSK), amplitude-shift keying (ASK) modulation, etc. Additionally, or alternatively, two baseband controllers <NUM> may be operated by different wireless carriers, but still be able to communicate with their respective corresponding VRU <NUM> via the same fronthaul interface <NUM>.

Third, the system <NUM> may allow the baseband equipment to be located further away from the radio equipment. Having less equipment at the radio unit <NUM> site (e.g., a tower) means less maintenance, power, and/or cooling, which may reduce costs for carriers.

<FIG> is block diagram illustrating logical connections between multiple baseband controllers 106A-N and multiple VRUs 104A-M in a radio unit <NUM>. As described above, multiple VRUs <NUM> may be housed within a physical radio unit <NUM>, and multiple baseband controllers <NUM> may be remotely located from the radio unit <NUM>, e.g., in the same or different housing. In some configurations, some of the baseband controllers (e.g., baseband controllers 106B-N) may be in the same physical housing, but not other baseband controller(s) (e.g., baseband controller 106A).

Although not illustrated in <FIG>, an Ethernet network <NUM> (and fronthaul interface <NUM>) may be used to connect each VRU <NUM> to its corresponding baseband controller <NUM>. VRUs <NUM> may be added, deleted, and/or modified via software and/or firmware to adjust the radio unit <NUM> to service different users from a common hardware platform.

Additionally, the system <NUM> may involve any number of baseband controllers <NUM> and VRUs <NUM> greater than <NUM>, e.g., N = <NUM>, <NUM>,. Furthermore, the number of baseband controllers <NUM> need not be the same as the number of VRUs <NUM> in the system <NUM>, i.e., in some configurations M≠N. Furthermore, more than one baseband controller <NUM> may be used to serve a particular VRU <NUM> or a single baseband controller <NUM> may be used to serve more than one VRU <NUM>. However, the system <NUM> in <FIG> is illustrated (and described) as having a <NUM>:<NUM> baseband controller <NUM> to VRU <NUM> ratio.

In the system <NUM>, each baseband controller <NUM> may communicate with a corresponding VRU <NUM> and preferably has no direct interaction with other VRUs <NUM> that are also present in the radio unit <NUM>. For example, a first baseband controller 106A may communicate with a first VRU 104A. However, the first baseband controller <NUM> preferably does not interact or communicate with (and is preferably not even aware of) the other VRUs 104B-M in the same radio unit <NUM> as the first VRU 104A. Similarly, a second baseband controller 106B may communicate with a second VRU 104B, but preferably not the other VRUs 104A, 104C-M in the same radio unit <NUM> as the second VRU 104B. The VRUs <NUM> may share common radio unit <NUM> infrastructure function(s), such as power, clock signals, and/or cooling fans, etc..

The physical connection (into the radio unit <NUM>) may involve only one physical link (e.g., Ethernet link), and the VRU <NUM> connections may be segmented by their IP address. Thus, a single Ethernet port could act as the sole physical data connection into the radio unit <NUM>, and packets may be routed to the appropriate VRU <NUM> using the packet IP address, e.g., the IP address located in a received packet header. In other words, the fronthaul interface <NUM> may communicate with one or more baseband controllers <NUM> (on behalf of multiple VRUs <NUM>) via a single Ethernet port.

The baseband controllers <NUM> and/or the VRUs <NUM> may access the Ethernet network <NUM> (e.g., the Internet cloud) on an encrypted link, e.g., using Secure Sockets Layer (SSL), Transport Security Layer (TSL), or any other suitable encryption mechanism. Each baseband controller <NUM> may know the IP address of the VRU <NUM> it communicates with, and each VRU <NUM> may know the IP address of the baseband controller <NUM> that it communicates with. Furthermore, each baseband controller <NUM> would not need to know that there may be other VRUs <NUM> operating (e.g., in the same or different bands and/or by other wireless carriers) within the same radio unit <NUM>.

Older distributed base station architectures (e.g., using the CPRI or OBSAI family of specifications) generally locate more of the high data rate processing in the radio equipment and use compression technology between the radio unit <NUM> and baseband controllers <NUM>. In contrast, newer interface technology protocols (e.g., standards developed by XRAN or Institute of Electrical and Electronics Engineers (IEEE)) reduce bandwidth requirements between the radio unit <NUM> and the baseband controllers <NUM>. Because of the reduced bandwidth demand of modern fronthaul interfaces <NUM> (and because today's Internet interfaces are supporting higher fundamental bandwidths), multiple VRUs <NUM> may be supported over a single (e.g., Ethernet) network connection. In other words, multiple VRUs <NUM> may share a common fronthaul interface <NUM>.

The VRUs <NUM> may be implemented on at least one programmable processor in the radio unit <NUM>, e.g., where each programmable processor is an FPGA, ASIC, microprocessor or DSP device. In some configurations the VRUs <NUM> are implemented across multiple programmable processors of different types, e.g., a first VRU <NUM> is implemented on a first type of programmable processor (e.g., FPGA), a second VRU <NUM> is implemented on a second type of programmable processor (e.g., ASIC), etc. Each VRU <NUM> is implemented in a separate processing core within the at least one programmable processor. Although not illustrated in <FIG>, the fronthaul interface <NUM> may also be implemented in the programmable processor. Alternatively, the fronthaul interface <NUM> may be implemented in the radio unit <NUM>, but not on the programmable processor.

The VRUs <NUM> may share a common RF front end unit <NUM>. As will be discussed below, the RF front end unit <NUM> may include various analog components, e.g., one or more band pass filters, low noise amplifiers, power amplifiers, and/or duplexers to implement a receive chain and a transmit chain. The RF front end unit <NUM> may access two antennas 132A-B to transmit downlink signals to and receive uplink signals from one or more wireless devices <NUM>. Alternatively, the radio unit <NUM> may include more than one RF front end unit <NUM>, e.g., an RF front end unit <NUM> for each VRU <NUM>. Furthermore, each front end unit <NUM> may access more or less than two antennas <NUM>.

<FIG> is a block diagram illustrating an RF front end unit <NUM> and at least one programmable processor <NUM> in a radio unit <NUM>. The radio unit <NUM> may be used to implement RF functionality in a communication system <NUM>. The radio unit <NUM> may communicate with one or more baseband controllers <NUM> (e.g., via an Ethernet network <NUM> and fronthaul interface <NUM>) and one or more wireless devices <NUM> (e.g., via an air interface).

The programmable processor <NUM> may include multiple VRUs <NUM> (M = <NUM>, <NUM>,. In one configuration, each of the VRUs <NUM> may be included in a single programmable processor <NUM>. Alternatively, the VRUs <NUM> may be implemented across multiple programmable processors <NUM>. Each VRU <NUM> may perform processing along with the RF front end to convert a baseband signal (from one or more baseband controllers <NUM>) into an RF signal that is radiated from one or more antennas <NUM> that are connected to the RF front end unit <NUM>. In other words, each VRU <NUM> may perform processing for an air interface that is not performed in the baseband controller <NUM>. Each of the multiple VRUs <NUM> is implemented in a respective processing core of the at least one programmable processor <NUM>. Each of the at least one programmable processor <NUM> may be an FPGA, ASIC, microprocessor or DSP. Although it is not illustrated in <FIG>, each of the at least one programmable processor <NUM> may also include a fronthaul interface <NUM>. Alternatively, the radio unit <NUM> may include a fronthaul interface <NUM> that is not implemented in the at least one programmable processor <NUM>.

Preferably, the multiple VRUs <NUM> may share a single RF front end unit <NUM>. However, the radio unit <NUM> may include multiple RF front end units <NUM>, e.g., an RF front end unit <NUM> for each VRU <NUM>. The RF front end unit <NUM> may include a receive chain <NUM> and a transmit chain <NUM>. It is understood that the receive chain <NUM> and transmit chain <NUM> configurations illustrated in <FIG> are merely examples, and other configurations for an RF front end units <NUM> may be used.

The receive chain <NUM> may include circuitry configured to filter, mix amplify, and digitize analog signals received from wireless devices <NUM> (via one or more antennas <NUM>) and pass them to the appropriate VRU(s) <NUM>. Specifically, an RF analog signal may be received wirelessly at the one or more antennas <NUM> connected to the RF front end unit <NUM> and fed to a duplexer <NUM>. The duplexer <NUM> may be configured to selectively enable a signal from the antenna <NUM> to pass through the receive chain <NUM> or a signal from the transmit chain <NUM> to pass through to the antenna <NUM>, but not both at the same time. In this way, the duplexer <NUM> may minimize interference between signals in the receive chain <NUM> and the transmit chain <NUM>, and enable the receive chain <NUM> and the transmit chain <NUM> to share the same one or more antennas <NUM>. The duplexer <NUM> may be implemented using one or more switches, filters or other circuitry configured to select between different signal paths. A band-pass filter (BPF) <NUM> in the receive chain <NUM> may be configured to filter the received analog signal to prevent out-of-band signals from propagating through the receive chain <NUM>, i.e., frequency components above and below a particular frequency band may be attenuated or eliminated by the BPF <NUM> while the components in a desired frequency band remain unattenuated (or minimally attenuated). The output of the BPF <NUM> may be fed into a low-noise amplifier <NUM> that may be configured to amplify the output of the BPF <NUM>. A first mixer 144A may then be configured to mix the output of the LNA <NUM> with a sinusoidal signal from a local oscillator <NUM>, e.g., to downconvert the output of the LNA <NUM> from the RF band of the received signal to an intermediate frequency (IF) band. An analog-to-digital converter (ADC) <NUM> may be configured to digitize the mixed signal before sending to a VRU <NUM>.

The transmit chain <NUM> may include circuitry configured to convert digital signals received from the VRUs <NUM>, then mix and amplify the analog signals before they are transmitted to one or more wireless devices <NUM> (via the one or more antennas <NUM>). A digital-to-analog converter (DAC) <NUM> may be configured to convert a digital signal from a VRU <NUM> to an analog signal, which is then fed into a second mixer 144B. The second mixer 144B may then be configured to mix the output of the DAC <NUM> with a sinusoidal signal from the local oscillator <NUM>, e.g., to upconvert the output of the DAC from an intermediate frequency (IF) band to an RF band. The analog RF signal may then be input into a power amplifier (PA) <NUM> that may be configured to increase the power of the signal before transmitting to one or more wireless devices <NUM> via the one or more antennas <NUM>.

<FIG> is a flow diagram illustrating a method <NUM> for using a radio unit <NUM> with multiple VRUs <NUM> to transmit a wireless signal to one or more wireless devices <NUM>. The method <NUM> may be performed by a radio unit <NUM> in a communication system <NUM>. The multiple VRUs <NUM> in the radio unit <NUM> may each be implemented in a separate processing core in at least one programmable processor <NUM>, e.g., where each programmable processor <NUM> is an FPGA, ASIC, microprocessor or DSP device. Different VRUs <NUM> may implement the same or different frequency bands, air standards, and/or modulation schemes for the same or different wireless carriers.

In addition to the radio unit <NUM>, the system <NUM> may one or more baseband controllers <NUM> that are physically remote from the radio unit <NUM>. Alternatively, the multiple baseband controllers <NUM> may be located in multiple physical locations, all of which are remote from the radio unit <NUM>. The one or more baseband controllers may perform baseband processing to generate a baseband signal.

The radio unit <NUM> may be configured to receive <NUM> a baseband signal from at least one baseband controller <NUM> that is physically remote from the radio unit <NUM>. Each VRU <NUM> may be configured to communicate with only one baseband controller <NUM> or more than one baseband controller <NUM>. The radio unit <NUM> may include a fronthaul interface <NUM> that is configured to access an Ethernet network <NUM> to communicate with the one or more baseband controllers <NUM>. The VRUs <NUM> may access the Ethernet network <NUM> (e.g., the Internet) using an encrypted connection. The fronthaul interface <NUM> may be implemented in the same programmable processor <NUM> as the VRUs <NUM>. Alternatively, the fronthaul interface <NUM> may be located in the radio unit <NUM>, but not implemented in the same programmable processor <NUM> as the VRUs <NUM>. Since the VRUs <NUM> are individually addressable (i.e., they each have their own IP address), a single Ethernet port may act as the only physical data connection into the radio unit <NUM>, and packets may be routed to the appropriate VRU <NUM> using a respective IP address for the VRU <NUM>.

The radio unit <NUM> may be configured to perform <NUM> processing to convert the baseband signal (e.g., frequency-domain IQ data) from the at least one baseband controller <NUM> into an RF signal for radiating from an antenna system <NUM> that is connected to an RF front end unit <NUM>, i.e., each VRU <NUM> may perform processing for the air interface that is not performed in the baseband controller <NUM>. In some configurations, the processing may include performing an inverse fast Fourier transform (IFFT), on frequency-domain IQ data from a baseband controller <NUM>, to produce the time-domain IQ data. The baseband signal from the baseband controller <NUM> may be transmitted as frequency-domain IQ data because it is smaller in size, and requires less bandwidth to transmit, than the corresponding time-domain IQ data. The processing may also include one or more of the VRUs <NUM> modulating the time-domain IQ data, e.g., using QPSK, 16QAM, 64QAM, etc. The processing may also include an RF front end unit <NUM> converting the modulated digital signal received from the VRUs <NUM> into analog signals, then mixing and amplifying the analog signals.

The radio unit <NUM> may be configured to transmit <NUM> the RF signal to one or more wireless devices <NUM> via the one or more antennas <NUM>. Each of the VRUs <NUM> may share the same RF front end <NUM> and/or one or more antennas <NUM>. Alternatively, the radio unit <NUM> may include more than one RF front end units <NUM>, e.g., an RF front end unit <NUM> for each VRU <NUM>.

<FIG> is a flow diagram illustrating a method <NUM> for using a radio unit <NUM> with multiple VRUs <NUM> to receive a wireless signal from a wireless device <NUM>. The method <NUM> may be performed by a radio unit <NUM> in a communication system <NUM>. The multiple VRUs <NUM> in the radio unit <NUM> may each be implemented in a separate processing core in at least one programmable processor <NUM>, e.g., where each programmable processor <NUM> is an FPGA, ASIC, microprocessor or DSP device. Different VRUs <NUM> may implement the same or different frequency bands, air standards, and/or modulation schemes for the same or different wireless carriers.

In addition to the radio unit <NUM>, the system <NUM> may one or more baseband controllers <NUM> that are physically remote from the radio unit <NUM>. Alternatively, the multiple baseband controllers <NUM> may be located in multiple physical locations, all of which are remote from the radio unit <NUM>.

The radio unit <NUM> may be configured to receive <NUM> an analog RF signal from a wireless device <NUM> via the one or more antennas <NUM>. Each of the VRUs <NUM> may share the same RF front end <NUM> and/or one or more antennas <NUM>. Alternatively, the radio unit <NUM> may include more than one RF front end unit <NUM>, e.g., an RF front end unit <NUM> for each VRU <NUM>.

The radio unit <NUM> may be configured to perform <NUM> processing to convert the received analog RF signal into a baseband signal. In some configurations, the processing may include filtering, mixing, amplifying, and/or digitizing the received analog RF signal and passing it to the appropriate VRU <NUM>, e.g., by an RF front end unit <NUM>. The processing may also include the VRU <NUM> demodulating the time-domain IQ data from the RF front end unit <NUM>, e.g., using QPSK, 16QAM, 64QAM, etc. The processing may also include the VRU <NUM> performing a fast Fourier transform (FFT), on the demodulated time-domain IQ data, to produce frequency-domain IQ data. The frequency-domain IQ data may be smaller in size and require less bandwidth to transmit to a baseband controller <NUM>, than the corresponding time-domain IQ data.

The radio unit <NUM> may be configured to transmit <NUM> the baseband signal (e.g., frequency-domain IQ data) from the VRU <NUM> to at least one baseband controller <NUM> that is physically remote from the radio unit <NUM>. Each VRU <NUM> may be configured to communicate with only one baseband controller <NUM> or more than one baseband controller <NUM>. The radio unit <NUM> may include a fronthaul interface <NUM> that is configured to access an Ethernet network <NUM> to communicate with the one or more baseband controllers <NUM>. The VRUs <NUM> may access the Ethernet network <NUM> (e.g., the Internet) using an encrypted connection. The fronthaul interface <NUM> may be implemented in the same programmable processor <NUM> as the VRUs <NUM>. Alternatively, the fronthaul interface <NUM> may be located in the radio unit <NUM>, but not implemented in the same programmable processor <NUM> as the VRUs <NUM>. A single Ethernet port may act as the only physical data connection that is used by multiple VRUs <NUM> to communicate with the baseband controllers <NUM> (via the fronthaul interface <NUM> and Ethernet network <NUM>). Optionally, a baseband controller <NUM> may receive the baseband signal and perform baseband processing on it.

The method <NUM> illustrated in <FIG> and the method <NUM> in <FIG> may be performed sequentially (method <NUM> followed by method <NUM> or method <NUM> followed by method <NUM>). Alternatively, the methods <NUM>, <NUM> may be performed in parallel. Alternatively, the steps of the methods <NUM>, <NUM> may be mixed in between the steps of the other.

The methods and techniques described here may be implemented in digital electronic circuitry, or with a programmable processor (for example, a special-purpose processor or a general-purpose processor such as a computer) firmware, software, or in combinations of them. Apparatus embodying these techniques may include appropriate input and output devices, a programmable processor, and a storage medium tangibly embodying program instructions for execution by the programmable processor. A process embodying these techniques may be performed by a programmable processor executing a program of instructions to perform desired functions by operating on input data and generating appropriate output. The techniques may advantageously be implemented in one or more programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and DVD disks. Any of the foregoing may be supplemented by, or incorporated in, specially-designed application-specific integrated circuits (ASICs).

Brief definitions of terms, abbreviations, and phrases used throughout this application are given below.

The term "determining" and its variants may include calculating, extracting, generating, computing, processing, deriving, modeling, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, "determining" may also include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like.

In other words, the phrase "based on" describes both "based only on" and "based at least on". Additionally, the term "and/or" means "and" or "or". For example, "A and/or B" can mean "A", "B", or "A and B". Additionally, "A, B, and/or C" can mean "A alone," "B alone," "C alone," "A and B," "A and C," "B and C" or "A, B, and C.

The terms "connected", "coupled", and "communicatively coupled" and related terms may refer to direct or indirect connections. If the specification states a component or feature "may," "can," "could," or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

The terms "responsive" or "in response to" may indicate that an action is performed completely or partially in response to another action. The term "module" refers to a functional component implemented in software, hardware, or firmware (or any combination thereof) component.

Unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

Claim 1:
A communication system (<NUM>), comprising:
at least one baseband controller (106A, 106B, ... 106N) configured to process signals in a baseband frequency band; and
at least one radio unit (<NUM>) that is physically remote from the at least one baseband controller (106A, 106B, ... 106N), wherein each radio unit (<NUM>) comprises:
a plurality of virtual radio units (VRUs) (104A, 104B, ... <NUM>) in a physical housing of the respective radio unit (<NUM>), wherein each of the plurality of VRUs (104A, 104B, ... <NUM>) is implemented in a different processing core of a programmable processor (<NUM>);
a fronthaul interface configured to communicate with the at least one baseband controller (106A, 106B, ... 106N) using a packet-based protocol on behalf of each VRU (104A, 104B, ... <NUM>);
wherein each VRU (104A, 104B, ... <NUM>) implemented in the programmable processor (<NUM>) has a unique internet protocol (IP) address, wherein each VRU is individually addressable using the respective IP address; and
at least one radio frequency front end unit (<NUM>) configured to transmit from and receive on behalf of each of the VRUs (104A, 104B, ... <NUM>).