Optimized telecommunications distribution system

Systems and methods for optimized telecommunications distribution are provided. For example, a distributed antenna system can include a master unit for transceiving signals with remote units operable for wirelessly transceiving signals with mobile devices in a coverage area. A self-optimized network analyzer can be in a unit of the distributed antenna system. A self-optimized network controller in the distributed antenna system can output commands for changing operation of a component in the distributed antenna system in response to analysis results from the self-optimized network analyzer. In some aspects, the master unit includes base transceiver station cards for receiving call information in network protocol data from a network and for generating digital signals including the call information from the network protocol data for distribution to the remote units.

TECHNICAL FIELD

The present invention relates generally to telecommunications and, more particularly (although not necessarily exclusively), to optimized systems for distributing telecommunications signals.

BACKGROUND

A distributed antenna system (“DAS”) can be used to extend the coverage of a cellular communication system to areas of traditionally low signal coverage, such as within buildings, tunnels, or in areas obstructed by terrain features. A DAS can extend coverage by receiving signals from a base station of a cellular communication system and re-transmitting the signals directly into low-coverage areas. A DAS can include a master unit distributing signals to, and receiving signals from, remote antenna units that are physically separate from the master unit, but in communication with the master unit over a link. A remote antenna unit can wirelessly communicate signals to wireless devices positioned in a coverage area.

Optimized DAS's and/or DAS's having base transceiver station capabilities are desirable.

SUMMARY

In one aspect, a distributed antenna system is provided that includes a master unit, a self-optimized network analyzer, and a self-optimized network controller. The master unit can transceive signals with remote units that can wirelessly transceive signals with mobile devices in a coverage area. The self-optimized network analyzer is in a unit of the distributed antenna system. The self-optimized network controller can output commands for changing operation of a component in the distributed antenna system in response to analysis results from the self-optimized network analyzer.

In another aspect, a distributed antenna system is provided that includes a master unit. The master unit can communicate digitized signals with remote units operable for providing wireless network coverage in an area. The master unit includes base transceiver station cards that can receive call information in network protocol data from a network and that can generate digital signals including the call information from the network protocol data for distribution to the remote units.

In another aspect, a distributed antenna system is provided that includes a master unit, a self-optimized network analyzer, and a self-optimized network controller. The master unit can communicate digitized signals with remote units operable for providing wireless network coverage in an area. The master unit includes base transceiver station cards that can receive call information in network protocol data from a network and that can generate digital signals including the call information from the network protocol data for distribution to the remote units. The self-optimized network analyzer is in a unit of the distributed antenna system. The self-optimized network controller is in the master unit and can output commands for changing operation of a component in the distributed antenna system in response to analysis results from the self-optimized network analyzer.

The details of one or more aspects and examples are set forth in the accompanying drawings and the description below. Other features and aspects will become apparent from the description, the drawings, and the claims.

DETAILED DESCRIPTION

Certain aspects and examples of the present invention are directed to a distributed antenna system (“DAS”) that is optimized. In some aspects, a DAS includes self-optimized network (“SON”) capabilities, also referred to as self-organizing network capabilities or self-organized network capabilities. SON capabilities can include, among others, detecting interference in a downlink band and modifying transmission of signals in the downlink band, identifying free frequencies by analyzing frequencies used in a macro-cell environment, and storing information about frequencies using in a macro-cell environment. SON capabilities can use less centralized network planning and employ algorithms that can, for example, identify the locally used frequencies and determine the frequencies for a new base station transceiver (“BTS”) from the results of the algorithms. Local or remote databases can be used to support the algorithms. The algorithms can minimize the amount of interference created and experienced by new BTS signals.

In some aspects, the DAS is a multi-base transceiver station DAS (“MB-DAS”). The MB-DAS may include the SON capabilities and/or additional SON capabilities, or no SON capabilities. The MB-DAS can include one or more BTS cards. The BTS cards can encode signals, decode signals, process signals into a proper wireless protocol, communicate signals to a BTS controller or mobile telephone switching office, and provide processed signals for digital distribution to distributed antennas in a coverage area. In some aspects, a MB-DAS can distribute signals without requiring installation or use of a conventional BTS. The BTS cards can be easily added, removed, or replaced to provide desired wireless communication protocol transmission and allow capacity to be easily configurable. An MB-DAS, according some aspects, may include additional SON capabilities, such as synchronization in frequency and in timing among BTS cards, macro-cell to DAS-cell hand-in configuration, DAS-cell to macro-cell hand-off configuration, maintenance of macro-cell and DAS-cell database information, and mapping of antenna units with macro-cell hand-off and hand-in support. Although “BTS” and “MB-DAS” are used herein, NodeB (e.g., for 3G-UMTS wireless networks) and/or eNodeB (e.g., for 4G LTE) can additionally or alternatively be used.

FIG. 1depicts an example of a DAS110in communication with one or more base stations112a-n, which may be base transceiver stations. The DAS110can include a master unit114, remote units116a-d, and an extension unit118. The DAS110may be positioned in an area of low signal coverage, such as the interior of a building, to extend wireless communication coverage. Extending wireless coverage can include communicating signals between base stations112a-nand wireless devices positioned in a coverage area of the DAS110.

The master unit114can receive downlink signals from one or more base stations112a-nvia a wired or wireless communication medium. The master unit114can also provide uplink signals to the base stations112a-n.

The master unit114can communicate uplink and downlink signals between the base stations112a-nand one or more remote units116a-ddistributed in the environment to provide coverage within a service area of the DAS110.

The master unit114can convert downlink signals received from the base stations112a-n, such as RF signals, into one or more digital data streams. A group of signals represented by digital data streams can form a band set. The master unit114can include circuitry, such as summers or multiplexers, configured to combine the digital data streams within a band set into a band stream. The band stream may be a single digital data stream that includes the digital data streams representing the signals in a band set. In some aspects, combining the digital data streams can include summing or adding signals within a band set. In other aspects, combining the digital data streams can include multiplexing the digital data streams into a serialized band stream.

The master unit114can provide downlink signals, such as digital data streams, to some of the remote units, such as remote units116a-bvia an extension unit118. A non-limiting example of an extension unit is a transport extension node. The extension unit118can extend the range of the master unit114. A master unit114may transmit optical downlink signals over an optical fiber link to extension unit118. The extension unit118can convert the optical downlink signals to electrical downlink signals and provide the electrical downlink signals to remote units116a-bover a copper cable, such as a coaxial cable, or other suitable communication medium.

The master unit114can also directly provide downlink signals to the remote units, such as remote units116c-d. Directly providing downlink signals can include, for example, communicating the downlink signals from the master unit114to the remote units116c-dwithout the downlink signals being received by a separate communication device, such as a transport extension node or other device, in the signal path between the master unit114and a remote unit.

The remote units116a-dcan convert digital data streams to RF signals. The remote units116a-dcan amplify the downlink signals and radiate the downlink signals using antennas to a number of different wireless devices, such as (but not limited to) cellular phones, operating in the environment of the DAS110. A non-limiting example of a remote unit is a universal access point.

In an uplink direction, the remote units116a-dcan receive uplink RF signals, convert them to digital data streams, and provide the uplink digital data streams to the master unit114or the extension unit118. The extension unit118can combine uplink digital data streams into combined digital data streams, such as band streams, and provide the combined digital data streams to the master unit114. In some aspects, the master unit114can convert uplink digital data streams received from the remote units116a-dand/or the extension unit118into uplink RF signals. The master unit114can provide the uplink RF signals to the base stations112a-n. In other aspects, the master unit114can convert uplink digital data streams received from the remote units116a-dinto digital signals formatted for transmission to the base stations112a-nthat communicate using digital signals, in a standardized digital format or otherwise.

The master unit114, extension unit118, and remote units116a-dcan communicate via communication transport links. A communication transport link can include one or a series of physical connections over which a remote unit can communicate with the master unit114directly or through the extension unit118. A communication transport link can include any type of communication medium capable of transporting signals between the master unit114, the extension unit118, and/or the remote units116a-d.

Although the DAS110is depicted as including one master unit114, one extension unit118, and four remote units116a-d, any number (including one) of each can be used. For example, a DAS110may include dozens of extension units and hundreds of remote antenna units.

The DAS110can also include SON components, such as SON controller120and one or more SON analyzers122a-c. The SON controller120is shown as being located in the master unit114, but the SON controller120can be located in other components of the DAS110, as a separate component of the DAS110, or in a device external to the DAS110. In some aspects, the DAS includes one SON analyzer located in a component of a DAS.

Each of the SON analyzers122a-cmay be capture and analysis sub-systems that can analyze signals or other information associated with the DAS110and provide analysis results to the SON controller120. The SON controller120can output commands for changing operation of a component in the DAS110in response to the analysis results and/or information stored locally or stored remotely, such as in a database device124in communication with the master unit114but remote from the DAS110.

DAS110may provide mobile telecommunication coverage for an area and be located close to macrocell coverage areas, such as areas serviced by macrocell base station126aby a first carrier, macrocell base station126bby a second carrier, and macrocell base station126cby a first carrier.

FIG. 2depicts an example of the SON controller120. Other configurations and examples may, of course, be utilized. The SON controller120may be any device that can process data and execute code that is a set of instructions to perform actions. The SON controller120includes a processor202, a memory204, a bus206, and an input/output (I/O) interface208. The memory204includes a controller engine210and a data store212.

The processor202can execute code stored on a computer-readable medium, such as the memory204, to cause the SON controller120determine a command and output the command to change operation of a component of a DAS. Non-limiting examples of a processor202include a microprocessor, an application-specific integrated circuit (“ASIC”), a field-programmable Gate Array (“FPGA”), or other suitable processor. The processor202may include one processor or any number of processors.

The processor202can access code stored in the memory204via a bus206. Memory204may be any non-transitory computer-readable medium capable of tangibly embodying code and can include electronic, magnetic, or optical devices. Non-limiting examples of a memory204include random access memory (RAM), read-only memory (ROM), magnetic disk, an ASIC, a configured processor, or other storage device. Bus206may be any device capable of transferring data between components of the SON controller120. Bus206can include one device or multiple devices. Instructions can be stored in the memory204as executable code. The instructions can include processor-specific instructions generated by a compiler and/or an interpreter from code written in any suitable computer-programming language.

The controller engine210can receive through an I/O interface208inputs such as analysis results from one or more of the SON analyzers122a-cand information from database device124inFIG. 1. The controller engine210can also cause data to be stored in data store212and access the data in data store212. For example, the controller engine210can store a history of measurements and use the stored history of measurements to perform DAS configuration changes at a later date.

FIG. 3depicts an example of a SON analyzer122. Other configurations and examples may, of course, be utilized. The SON analyzer122is similar to the SON controller120ofFIG. 2and may be any device that can process data and execute code that is a set of instructions to perform actions. The SON analyzer122includes a processor302, a memory304, a bus306, and an input/output (I/O) interface308. The memory304includes an analyzer engine310and a data store312.

The processor302can be similar to the processor202ofFIG. 2and can execute code stored on a computer-readable medium, such as the memory304, to cause the SON analyzer122to receive signals and information, analyze the signals and information, and output analysis results. The processor302can access code stored in the memory304via a bus306. Memory304can be similar to memory204ofFIG. 2, and may be any non-transitory computer-readable medium capable of tangibly embodying code and can include electronic, magnetic, or optical devices. Bus306may be any device capable of transferring data between components of the SON analyzer122.

The analyzer engine310can receive through an I/O interface308inputs such as signals and information from the DAS110, analyze the signals and information, and provide the analysis results through the I/O interface308for receipt by the SON controller120. In some aspects, the analyzer engine310can be triggered to analyze signals or other information based on a command from a SON controller or a device external to the DAS110.

Examples of SON Capabilities

A DAS according to some aspects, can be located close to (or in some cases in) an environment served by a macrocell. Signals from the macrocell may be strong enough to interfere with one or more signals transmitted by a remote unit of the DAS. For example, macrocell interface may be caused by signals in a downlink band in which the remote unit also transmits signals. There may also be sources of interference other than a macrocell. The SON controller120and SON analyzer122can detect and measure sources of interference in an uplink (e.g., a signal path from a mobile device to the master unit114) band and/or a downlink (e.g., a signal path from the master unit114to the mobile device) band and modify operation of the DAS110in response to that analysis.FIG. 4is a flow chart that depicts one example for detecting interference in a downlink band and modifying operation of the DAS110.

In block402, the SON controller120outputs a command for preventing the DAS110from transmitting signals in a selected downlink band by a remote unit, such as one of the remote units116a-d, a subset of the remote units116a-d, or all of the remote units116a-d. The downlink band can be selected in the order of downlink bands being transmitted by the DAS110, a list of potential macrocell bands, or otherwise.

In block404, the SON controller120sends a command to tune a receiver in the remote unit to receive signals in the downlink band. Receivers in remote units116a-dcan be tuned to selected uplink bands for the DAS to receive signals from mobile devices in a coverage area. The receiver can respond to the command from the SON controller120by changing operation to receive the downlink band rather than the uplink band.

Signals in the downlink band can be received by the remote unit. In block406, a SON analyzer122located in the remote unit, in the extension unit118, or in the master unit114, processes the signals received in the downlink band. In some aspects, the signals are digitized and processed by the SON analyzer122to detect RF power in the downlink band, detect the power of individual RF channels in the downlink band, determine the modulation type of the channel, and decode information on the detected channel. The SON analyzer122can send the analysis results to the SON controller120. In some aspects, the SON analyzer122analyzes the signal power level of the pilot signal instead of the composite signal level, which can depend on traffic level, in each channel, portion of a channel, or multiple portions of the downlink band.

In block408, the SON controller120determines, based on the analysis results, whether the received signals are above an interference threshold. The interference threshold may be a pre-set threshold that is defined by the user of the DAS110or pre-defined within the DAS110during manufacturing. The interference threshold may be stored locally or remotely and accessed by the SON controller120.

If the received signals are not above the interference threshold, the SON controller120sends a command to resume transmission of DAS signals in the downlink band and causes the receiver to be re-tuned to the uplink band instead of the downlink band, in block410. The command may be sent to one or more components of the master unit114and/or a remote unit. If the received signals are above the interference threshold, the SON controller120sends a command to modify transmission of signals in the downlink band, in block412. For example, the SON controller120can cause the gain applied to the signals in the downlink band to increase and cause the receiver to be re-tuned to the uplink band rather than the downlink band. If the received signals are significantly above the interference threshold, the SON controller120can cause downlink signals to be transmitted in a different downlink band or a different portion of the downlink band.

The measurement and enabling/disabling of signal transmission by the remote unit can be performed upon user command, automatically during initial commissioning, or automatically scheduled during times that are least likely to impact system interference (e.g., during nighttime hours). If performed automatically at certain intervals, hysteresis can be used to prevent frequent enabling/disabling of signals at a remote unit. In addition, a history of past measurements can be stored for the remote unit and the history can be used to evaluate whether to enable or disable the signal at the remote unit. In other aspects, a remote unit can include a dedicated receiver for downlink bands rather than tuning a receiver normally used for uplink signal reception. In addition or alternatively, this process can be used to measure transmit power by neighboring remote units as received by a particular remote unit and to adjust the power level of each remote unit in the case of multiple factors.

SON capabilities can include selecting channels for use in the DAS110.FIG. 5depicts an example of a process for doing so. In block502, signals from a macro-cell environment are received by a SON analyzer122. In some aspects, the SON analyzer122can perform received signal strength indication (RSSI) of the wireless bands to identify active channels within the wireless bands. The number of channels can be estimated from the centers of RSSI energy. Local or remote database information can be used to determine on which frequency to expect a wireless communication channel. A potential macro-cell channel candidate list that is sorted according to the RSSI strength and the channel bandwidth can be maintained for a predetermined depth. In addition, a second list of channels where no significant activity has been detected can be maintained as a list of potential DAS-cell channel candidates. This list can be sorted according to the RSSI level or the change from the noise level and its available bandwidth, ranking the entry the highest that has the lowest RSSI and the highest bandwidth.

In some aspects, the SON controller120can initiate the scan of the SON analyzer122of wireless communication bands to measure RSSI and decode identified signals present in the coverage area of the DAS. The scanning can be performed by tuning the receive section of one or more of the remote units116a-dto downlink frequencies or bands. Transmit portions of the remote unit used for scanning (and potentially one or more adjacent remote units) can be caused by the SON controller120to temporarily pause transmission during scanning. Scanning can be performed on all bands or just a subset of bands, and can be periodically repeated.

In block504, the SON analyzer122processes the signals from the macro-cell environment. For example, the SON analyzer122can periodically decode the signals from the potential macro-cell channel candidate list and determine parameters, such as the absolute frequency of the decoded channel with respect to the internal frequency reference, the timing offset to the internal timing reference, the absolute timing such as the frame number, and key network parameter such as Mobile Country Code, Mobile Network Code, Cell ID, Location Area Code, list of neighbor cells, etc. The SON controller120can maintain the results in a database.

In block506, the SON controller120receives database information stored locally or remotely in database device124or otherwise. The database information can include the parameters and/or other types of information related to the macrocell and DAS. For example, the database information can include scanning results for each remote unit individually or on a per operator basis, identification of a comment set of cells according to signal strengths and presence counted in each remote unit, and/or cell parameters (e.g., for GSM network, MCC, MNC, CellID, LAC, BSID, and Neighbor Cells). In some aspects, the database information includes a location of the DAS system. For example, the SON controller120can determine the location of the DAS system using user-configured location data, GPS receiver data, macro-cell trilateration functions, macro-cell system location information (CellID or the location coordinates when transmitted), and/or map data, such as data from GOOGLE MAPS™. The SON controller120can use the information to determine the position of a mobile device from the presence of the wireless carriers received by the device. The SON controller120may also determine and store the assigned frequencies for each operator that is planned to be assigned to the DAS110using the determined location and/or information from public databases, private databases, the FCC database or information published by the European Communications Office. Map information to determine the boundaries of the assigned frequencies can also be retrieved from local or remote databases.

The SON controller120can determine whether the operator has assigned a preferred channel or set of channels to be used for a SON-type network from database information. As an alternative, the channel or set of channels present in the neighbor list of the detected macro-cell signals that do not show any RSSI activity may be used.

In block508, the SON controller120selects channels for use in the DAS110based on the processed signals from the macro-cell environment and database information. For example, the SON controller120can analyze the list of potential DAS-cell channel candidates and select channels that are preferred, have the lowest RSSI, or have the highest distance in frequency to high RSSI channels. The SON controller120can output commands to components of the DAS110to configure the components to transmit and/or receive the selected channels. For frequency and timing synchronization, the SON controller120can use the strongest received channel from one operator. If the frequency and timing is different for signals in different RF bands for the same operator, the SON controller120can maintain synchronicity with signals from both bands. A similar process can be applied to signals from the same operator employing different standards.

Multi-Base Transceiver Station Distributed Antenna System

A DAS according to some aspects may be an MB-DAS with configurable distribution that may use active antenna units. The MB-DAS can include a centralized host or master unit housing BTS cards. In other aspects, one or more remote units of the MB-DAS includes BTS cards that can receive network protocol data, such as internet protocol data, from a host or master unit.

BTS cards may be capacity elements that are connected to a network backbone via IP-based interfaces. Wireless communication signals can be communicated to and from the BTS cards via a digital interface as complex digital baseband signals or complex digital or real digital intermediate frequency signals at a relatively low sampling rate. A BTS card may be associated with a single operator or a multiple operator. The BTS card can be dedicated to the generation and decoding of signals that are targeted for transmission and reception in a single wireless communication RF band or be dedicated to multiple wireless communication RF bands. Multiple bands can be communicated to and from the BTS card using individual busses for each band or using a multiplexed data interface.

FIG. 6depicts one example of an MB-DAS. The MB-DAS includes a master unit602that can transceive IP data with call information600over an IP network, and can transceive digital signals with a remote unit604that can wirelessly transceive RF signals for providing coverage in an environment. In some aspects, the remote unit604is an active antenna unit. Included in the master unit602are one or more BTS cards606.

The digital wireless downlink signals of each BTS card606may be re-sampled, converted to an individual digital IF signal (represented as complex or real samples), digitally conditioned, and digitally summed or otherwise combined with other digital downlink signals from BTS cards to a summed digital IF signal stream. Each digital IF signal stream can be designated to be transmitted in the same wireless communication RF band. To frequency position the signals of each BTS card606within the summed digital IF stream by the system controller, the target RF center frequency of the BTS card signal can be determined. The summed digital signal can be multiplexed and framed for transport via a digital communication link to a signal processor board on which it can be further digitally switched and summed with other summed signal streams into a digital zone signal stream. The zone signal stream can be multiplexed and framed onto a transport stream, which can be a parallel or serial link. In one aspect, the transport stream is a serial digital stream such as a 10 Gb/s Ethernet data link on an optical fiber or CAT6a cable. Alternatively, higher bit rates, such as 40 Gb/s or 100 Gb/s, as well as lower bit rate connections can be used for the transport. The transport stream can be provided to the remote unit604directly or through an extension unit.

An MB-DAS according to various aspects may or may not include SON capabilities.FIG. 7depicts the MB-DAS having SON capabilities. The MB-DAS includes a master unit602, remote units604a-d, and an extension unit714. The master unit602, through the BTS cards606a-n, can communicate with a switch708that allows for network communication to the base station controller712over an IP backbone710via Abis or other interface, such as Iu or S1. In other aspects, the MB-DAS includes the switch708. In some aspects, the master unit602communicates with other components, such as a mobile telephone switching office, directly instead of through the base station controller712. In other aspects, the base station controller712is replaced with a radio network controller (“RNC”), for example in a 3G-UMTS network. In still other aspects, such as in implementations in a 4G LTE network, no BSC, RNC or equivalent is used. Instead, the BTS cards606a-n, which would be eNodeB cards, include RNC functionality and can communicate directly with a core network. It should be noted that in 3G-UMTS and 4G LTE, base stations with neighboring cells can have a direct interconnection that is Iur (for 3G UMTS) or X2 (for 4G LTE).

The master unit602can communicate with the remote units604a-ddirectly or through the extension unit714. The extension unit714can receive the transport stream and fan (i.e., distribute) it out to multiple remote units. The fan out may be performed without any change to the stream. In systems having multiple master units, the extension unit714may multiplex or digitally sum multiple zone streams from different transport streams.

A remote unit can receive the transport stream and perform bit & clock recovery, conversion back to a parallel data stream, de-framing, and de-multiplexing of the zone streams. Each zone stream can be provided to an RF back-end that can convert it from a digital IF signal to an analog RF signal for transmission via an antenna to wireless devices.

In the uplink direction, each of the remote units604a-dcan receive the wireless signal from the mobile device and convert the RF signal into a digital sampled signal represented by either real or complex digital samples. The uplink digital signals can be in the same or similar format as the downlink zone streams, and can be further processed, filtered, digitally up- or down-converted, re-sampled, amplitude and phase conditioned, digitally summed, multiplexed with other digital signals, and framed and serialized for transport via a digital transport link. The link may connect to the extension unit714or to the master unit602. In the extension unit714or the master unit602, the serial data stream can be received, bit & clock recovered, converted back to a parallel data stream, de-framed, de-multiplexed, potentially processed, and potentially digitally summed with other digital signals from one or more different remote units604a-d. Digital signals that are digitally summed may be prevented from overlapping in the frequency spectrum for later separation. Signals can be prevented from overlapping by keeping them on different frequencies in their digital spectral distribution and positioning or through multiplexing them with other digital data streams.

The extension unit714or the master unit602can sum the uplink signals according to the zone distribution matrix and provide them for further processing, or can send provide them without adding. Before sending uplink digital signals back to the BTS cards606a-n, the zone stream may be digitally conditioned, filtered, converted to an individual digital (represented as complex or real samples) IF signal, and re-sampled. The sequence of the processes listed does not necessarily represent the sequence of their application to the digital signal.

Included in the master unit602is a SON controller720, which may be configured similar to SON controller120ofFIG. 2, and capable of outputting commands for changing operation of the MB-DAS. Remote unit604dincludes a SON analyzer722that may be configured similar to SON analyzer122ofFIG. 3, and capable of analyzing signals and other information about the MB-DAS and providing analysis results to the SON controller720. In other aspects, each of the other remote units604a-c, the master unit602, and/or the extension unit714includes a SON analyzer. The SON controller720and SON analyzer722can provide SON capabilities, such as those described previously and additional SON capabilities.

For example, a remote unit can provide the downlink received signals from the RF environment to support the SON capabilities. Receiving downlink signals can include tuning the uplink frontend to downlink frequencies while the downlink back-end is deactivated. The SON analyzer722can perform the capture, filtering, frequency conversion, demodulation, decoding, frequency & timing offset determination, and data extraction. In order to allow the analysis to be performed on one remote unit, other remote units that would typically be summed together with the signal of the remote unit can be paused for that time period. Alternatively, the capture can be taken at the remote unit or at the input of the extension unit714and transported via a dedicated data transport link to the unit that includes the SON analyzer722. The SON controller720can coordinate the capture and analysis function, retrieve the results from the SON analyzer722, store it locally or remotely and distribute it to the various elements in the systems.

The SON controller720can schedule the monitoring process that can analyze the downlink spectrum of the relevant wireless network bands. It can schedule the deactivation of the downlink path of one or more of the remote units604a-d, the tuning of a remote unit receiver to downlink bands, the capture of samples, the transport to the SON analyzer722, the processing of the captures, and the presentation of the results.

Another example is synchronization in frequency and in timing. An internal clock or alternatively a clock offset to the internal clock dedicated for each operator can be maintained by the SON controller720and provided to the BTS cards606a-n. Each BTS card can generate wireless signals according to the in-synch with the macro-cell network. An absolute timing such as the absolute frame count of the operator can also be provided. For CDMA signals, a GPS accurate clock may be used.

Another example is macrocell-to-DAS-cell hand-in configuration. To allow hand-in from the macrocell network into the MB-DAS-cell network the channels used by the MB-DAS-cell can be in the neighbor list of the macro-cell network. This can be from a mobile device user entering the areas of the MB-DAS system with an active data session or a voice call. Having a proper hand-in can transfer the mobile device directly to the MB-DAS-cell and remove the traffic from the macrocell.

A localized broadcast control channel (“BCCH”) generated within the master unit602in one of the BTS cards606a-cwith limited signaling can be used to facilitate hand-ins. The BCCH can be on the channel list of the adjacent macro-cells for a hand-in. The localized BCCH can be a fully functional BCCH that offers traffic support, or it can be a reduced-feature-set BCCH that is used to allow the hand-in from the macrocell and hands the call or data session directly off to a designated fully functional MB-DAS-cell.

Another example is DAS-cell-to-macrocell hand-off configuration. If a user with a mobile device is leaving the MB-DAS coverage area and into the macrocell network coverage area, a proper hand-off can be used to allow uninterrupted data and/or voice communication when the transition is occurring. The macrocell channels can be added to the neighbor cell list in the SON controller720. The BTS card associated with the hand-off can be connected with the base station controller712and mobile switch to support the hand-off.

Another example is mapping of remote units with macrocell hand-off and hand-in support. One feature of an MB-DAS cell network may be to capture the possible traffic in the confined area and not have the macrocell network be burdened with high-density traffic from the area that the MB-DAS network attempts to cover. Mobile devices operated at the border of the MB-DAS network can hand-over to the macrocell network if it is expected that the mobile device will leave the MB-DAS network coverage area. Therefore, a hand-over can be supported in select areas and omitted in others. For example, remote units close to entrances to the building or structure may be candidates to support hand-in or hand-off to the macrocell network. Entrances that are considered emergency exits may be supported as well. Hand-over support in areas with a high number of transitions between the MB-DAS and the macrocell network can be provided. Hand-over can be suppressed in other areas, such as windows, where the macrocell network signals may be strong. The suppression can be achieved by excluding the macrocell channels in the neighbor cell lists of the signals radiated in the remote units.

Each of the BTS cards606a-nmay be a plug-in card capable of being plugged into a donor card slot using a similar type of interface to a backplane as a donor card. Signals from the BTS cards606a-ncan be distributed to remote units digitally. BTS cards606a-ncan be a hardware implementation or a software implementation using a FPGA or a DSP.

BTS cards606a-ncan be various types and include various configurations. For example, a BTS card can be a femto, pico, nano, or micro BTS cards. Femto BTS cards can indicate a low capacity. A pico BTS card can indicate a low-to-medium capacity. A nano BTS card can indicate a medium-to-high capacity. A micro BTS cards can indicate a full capacity. A BTS card can be a plug-in BTS resource to plug into the donor card slot within master unit602or extension unit714. A BTS card can be an internal or an external card. A BTS card can combine several femto, pico, nano, and/or micro BTS signals into one stream to be sent to a specific number of remote antenna units. BTS cards can be combined with donor cards that have either an analog RF interface or a digital standardized interface (e.g., CPRI, OBSAI, and ORI) or both. A BTS card can have an IP backbone link that may use Ethernet LAN or WAN. A BTS card can use knowledge of the location of the MB-DAS. The location may be received from a location server, such as a server including a centralized GPS receiver, or the location can be determined by trilateration of the detected macrocell that is proximate to the MB-DAS. A BTS card can configure cells for the MB-DAS by subdivision or combining BTS cells on different frequencies to provide increased capacity, depending on available free frequencies in the macrocell environment.

In some aspects, BTS cards606a-ncan have an analog IF interface to an analog DAS that distributes signals in analog form instead of digital. Instead of processing the digital signals, the analog IF signals from the BTS cards606a-ncan be processed (e.g., frequency converted through mixing, filtered, amplified or attenuated, combined with other signals or provided through a splitter, transported via an analog link such as coax cable or analog optical RF signal via optical fiber, amplified and radiated via passive or active antenna units.

FIG. 8depicts an example of part of the master unit602in communication with the switch708. The master unit602includes a multiplexer/de-multiplexer850, a backplane852, a summer854, a reference clock distribution component856, and a system controller858. Also depicted are BTS cards606a-n,certain details according to some aspects are shown.

For example, each of the BTS cards606a-ncan include a BTS processor device such as BTS chipset860, resample devices862,864, frequency translation components866,868, and digital gain components870,872. In a downlink direction (i.e., toward a wireless device), each of the BTS chipsets860a-ncan receive data from the IP switch708as internet protocol data, or data in another network protocol. The BTS chipsets860a-ncan decode the data, convert the data to an appropriate wireless communication protocol, digitize the data, and modulate the digitized data. The modulated digital data can be resampled by resampler devices862a-nto, for example, increase the sample rate of the modulated digital data. In other aspects, resampler devices862a-nare not used, or the resampler devices862a-nresample at the same rate by which the digitized data was generated. The modulated digital data can be provided to frequency translation components866a-nthat, using a local oscillator874a-n(a numerically controlled oscillator (NCO), for example, as depicted inFIG. 8), can move the modulated digital data in frequency, up or down, such that the modulated digital data is centered around a certain frequency. Moving the modulated digital data to a different frequency can facilitate summing or otherwise combining the modulated digital data with modulated digital data from other BTS cards.

Gain may be applied to the modulated digital data by digital gain components870a-n. Digital gain may be used to level each of the data signals prior to summing. The digital interface may use all the bits available to represent the digital signal. For example, if the bit width of the signal is sixteen bits, the signal level can traverse the sixteen bits to represent the signal amplitude. The signals from a BTS card can be scaled such that when the signals are combined with signals from other BTS cards, the signals will not clip the output of the summer. For example, if two signals are combined, the BTS signals may be reduced by ½ prior to summing. If four BTS cards are summed, the signal can be reduced by ¼ prior to summing. The depth of the bit width of the output signal can be increased to avoid the loss of dynamic range. For example, the bit width may be increased by at least one bit for summing two signals.

Another use of the digital gain may be to control the level of the BTS BCCH (or pilot channel, beacon, or equivalent) in the downlink direction to control handover areas between two MB-DAS cells, each associated with one BTS card. The wireless device can measure BCCH (or equivalent) signal level to determine which BTS to which to lock. The signal level of the BCCH can be controlled to move the handover region away from high traffic areas when there is overlapping BTS coverage, such as in building entrances, lobbies, and elevators. The signal level of the BCCH can be controlled with the digital gain in the downlink direction to control which BTS card a wireless device locks to and to prevent handovers in high traffic areas.

The uplink and downlink gain can be adjusted to be equal so any gain adjustment performed to the downlink signal of a BTS card can be performed to the uplink path with the same amount of gain. In other embodiments, no gain is applied.

The modulated digital data from a BTS card can be provided directly to the multiplexer/de-multiplexer850, provided to a summer854for digitally summing the modulated digital data with modulated digital data from one or more other BTS cards prior to being provided to the multiplexer/de-multiplexer850, or both. The multiplexer/de-multiplexer850can multiplex the data into a serialized digital data stream that is provided to a backplane for digital transport to one or more remote units. The remote units, such as remote units604a-dofFIG. 7, can convert the modulated digitized data to analog RF, amplify the analog RF, and cause the analog RF to be radiated by one or more antenna elements for receipt by wireless devices in a coverage area.

In the uplink direction (i.e., from the wireless devices), a remote unit can receive analog RF from a wireless device, convert the analog RF to digitized upstream data, and cause the digitized upstream data to be transported to the master unit602by multiplexing the data with other data to a serial data stream. The backplane852of the master unit602can receive the digitized upstream data and provide it to the multiplexer/de-multiplexer850. The multiplexer/de-multiplexer850can de-multiplex the data and provide it to a proper BTS card. Digital gain components872a-ncan apply a gain to the digitized upstream data. Frequency translation components868a-n, using a local oscillator876a-n, can change the center frequency (up or down, but typically down) to a different frequency for further processing. The digitized upstream data may be resampled by resampler devices864a-nto reduce the sample rate, and can be provided to the BTS chipsets860a-n.The BTS chipsets860a-ncan demodulate the digitized upstream data, convert it to analog RF, and encode the analog RF into an Internet Protocol. The encoded data can be provided to the IP switch708for transport through an IP backbone to a base station controller.