Patent Description:
The disclosure relates generally to telecommunications and, more particularly (although not necessarily exclusively), to management and optimization of a radio access network and a distributed antenna system using a self-optimizing network entity.

A distributed antenna system (DAS) can include one or more head-end units and multiple remote units coupled to each head-end unit. A DAS can be used to extend wireless coverage in an area. Head-end units can communicate with one or more radio base stations of a radio access network (RAN). Each radio base station can be part of a separate node of the RAN. A head-end unit can receive downlink signals from the radio base station and distribute downlink signals in analog or digital format to one or more remote units. The remote units can transmit the downlink signals to user equipment devices within coverage areas serviced by the remote units. In the uplink direction, signals from user equipment devices may be received by the remote units. The remote units can transmit the uplink signals received from user equipment devices to a head-end unit. The head-end unit can transmit uplink signals to the serving radio base stations. The DAS may provide coverage extension for communication signals from the radio base stations.

Optimizing both the DAS and the radio base station can be difficult in part because these are separate units. <CIT>, relates to a configuration sub-system for telecommunication systems. The configuration sub-system can include a test signal generator, a power measurement device, at least one additional power measurement device, and a controller. The test signal generator can be integrated into components of a telecommunication system. The test signal generator can provide a test signal to a signal path of the telecommunication system. The power measurement device and the additional power measurement device can respectively be integrated into different components of the telecommunication system. The power measurement device and the additional power measurement device can respectively measure the power of the test signal at different measurement points in the signal path. The controller can normalize signals transmitted via the telecommunication system by adjusting a path gain for the signal path based on measurements from the power measurement device and the additional power measurement device.

The invention is defined by the accompanying claims. In one aspect, a method according to claim <NUM> is provided.

In another aspect, a program product according to claim <NUM> is provided.

In another aspect, a system according to claim <NUM> is provided.

Certain aspects and features relate to optimizing the radio frequency characteristics of signals transmitted between a radio base station (RBS) and a distributed antenna system (DAS). For example, a self-optimizing network (SON) entity can be communicatively coupled to the DAS head-end unit and the RBS. The head-end unit of the DAS can measure certain radio frequency parameters specific to the performance of the DAS and provide the measured radio frequency parameters to the SON entity. For example, the measured radio frequency parameters can be parameters of the radio frequency communications between the head-end unit and remote units of the DAS. The SON entity determines adjustments to operations and management parameters of the RBS using the radio frequency parameters.

Adjustments to the operations and management parameters include adjustments to the uplink RBS gain. Increasing the radio frequency gain of received uplink signals at the RBS can compensate for noise generated by the DAS. Adjustments to the operations and management parameters can also include adjustments to the radio frequency branch delay of received uplink signals at the RBS. Adjusting the radio frequency branch delay at the RBS can compensate for signal latency from the DAS (e.g., the transmit time delay resulting from radio frequency signals traveling from the base station to remote units and back). Adjustments to operations and management parameters can also provide an open loop power control mechanism, where the SON entity can specify the nominal receive power level of the RBS. If the SON entity specifies a higher nominal received power level, the SON entity can instruct the head-end unit to increase uplink gain for providing signals to the RBS. While non-limiting examples to adjustments of RBS operations and management parameters are mentioned above, other adjustments are also possible.

Adjusting operations and management parameters of an RBS using measured radio frequency parameters from the DAS can offset any impairment in the radio frequency path from the RBS to DAS remote units. Optimizing the operations and management characteristics of the RBS through a SON entity can facilitate communication between the RBS, DAS head-end units, and DAS remote units and reduce network delays caused by independently optimizing the RBS and DAS. In some aspects, the SON entity can periodically and automatically reoptimize the radio frequency characteristics of the RBS and DAS so that the signals between the RBS and DAS are continually tuned for optimal performance.

While the above examples describe a SON entity that uses radio frequency characteristics measured from a DAS to send commands regarding operations and management characteristics to an RBS, other aspects include a SON entity that uses radio frequency characteristics measured at an RBS to send commands regarding operations and management parameters to the DAS head-end unit. For example, the RBS can provide its transmit power level to the SON entity. Using the transmit power level of the RBS, the SON entity can instruct the DAS head-end unit to set its input radio frequency attenuation to a certain level in order to obtain the optimal input power to drive the DAS.

These illustrative aspects and examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional features and examples with reference to the drawings in which like numerals indicate like elements, and directional descriptions may be used to describe the illustrative aspects but, like the illustrative aspects, should not be used to limit the present disclosure.

<FIG> is a block diagram depicting an example of a DAS <NUM> for being in communication with an RBS <NUM> and a SON entity <NUM>. The DAS <NUM> can include a head-end unit <NUM> communicatively coupled to one or more remote units 122a-b. The head-end unit <NUM> can receive downlink signals from RBS <NUM> and transmit uplink signals to the RBS <NUM>. Any suitable communication link can be used for communication between the RBS <NUM> and the head-end unit <NUM>, such as (but not limited to) a wired link. A wired link can include, for example, a link via a copper, optical fiber, or other suitable communication medium. When communicating via a wired link, the radio frequency front-end can include a PHY interface for connecting radio frequency coaxial cables. The head-end unit <NUM> can also include equipment associated with a point-of-interface to receive radio frequency communications from the radio frequency front-end <NUM>. The head-end unit <NUM> can implement radio frequency signal conditioning on received downlink signals from the RBS <NUM>. Signal conditioning may include attenuation, coupling, splitting, or radio frequency routing functions.

In some aspects, the head-end unit <NUM> can combine downlink signals received multiple radio base stations. Multiple radio base stations allow the DAS <NUM> to receive wireless communication from multiple cells, different carrier frequencies, and different wireless service providers. In some aspects, the RBS <NUM> can include duplexed radio frequency output ports at the radio frequency front-end <NUM>, allowing the downlink and uplink radio frequency chains to be treated independently within the DAS <NUM>.

The head-end unit <NUM> can transmit the combined downlink signals to the remote units 122a-b. While two remote units 122a-b are shown for illustrative purposes, any number of remote units <NUM> can be communicatively coupled to the head-end unit <NUM>. The remote units 122a-b can provide signal coverage to user devices positioned within the coverage zones by transmitting downlink signals to the user devices and receiving uplink communication signals from the user devices. The head-end unit <NUM> can combine uplink signals received from remote units 122a-b for transmission to the RBS <NUM>.

The head-end unit <NUM> can include a measurement and configuration module <NUM> that can measure and configure DAS radio frequency parameters. Additionally, the measurement and configuration module <NUM> can configure radio frequency parameters in the DAS <NUM> by adjusting, for example, the uplink gain and downlink gain of signals transmitted by the head-end unit <NUM> and remote units 122a-b.

Radio frequency parameters of the DAS <NUM> measured by the measurement and configuration module <NUM> can be provided to the SON entity <NUM> via a DAS operations and management application programming interface (API) <NUM> included in head-end unit <NUM>. In some aspects, the DAS head-end unit <NUM> can include a master controller that implements the operations and management functions of the DAS <NUM>. The interface between the DAS master controller / DAS head-end unit <NUM> and the SON entity <NUM> can be based on a Simple Network Management (SNMP) protocol or other network management protocol.

While <FIG> depicts the SON entity <NUM> separate from the RBS <NUM> and the DAS <NUM>, in some aspects, the SON entity <NUM> can be embedded within the head-end unit <NUM>. In further aspects, the SON entity <NUM> can be embedded within the RBS <NUM>.

The SON entity <NUM> can include a corresponding operations and management API <NUM> to communicate with the head-end unit <NUM>. The SON entity <NUM> can also include a radio frequency branch operations and management API <NUM> for communicating with the RBS <NUM>. Similar to the interface between the SON entity <NUM> and the RBS <NUM> can be based on the SNMP protocol or any other network management protocol. The RBS <NUM> can include a corresponding radio frequency branch operations and management API <NUM> for receiving instructions from the SON entity <NUM>.

The operations and management APIs <NUM>, <NUM>, <NUM>, and <NUM> can include any software or hardware interface for providing information. For example, the RBS <NUM>, head-end unit <NUM>, and SON entity <NUM> can each include a respective processing device executing program code defining operations of the respective RBS <NUM>, head-end unit <NUM>, and SON entity <NUM>. The radio frequency branch operations and management APIs <NUM> and <NUM> can include software interfaces allowing the SON entity <NUM> to communicate with the appropriate software modules executing in the RBS <NUM>. For example, the radio frequency branch operations and management API <NUM> can be a network management interface based on the SNMP protocol, SOAP protocol, or other suitable network management protocol. If the SON entity is located near the RBS <NUM> and the DAS head-end unit <NUM>, the communication can also be implemented through any serial interface (e.g., RS232, RS485), or an Ethernet cable. The SON entity <NUM> can, via the radio frequency branch operations and management API <NUM>, transmit commands to the RBS <NUM> instructing the appropriate software module executing in the RBS <NUM> to adjust relevant operations and management parameters. Operations and management APIs <NUM>, <NUM> can include similar software interfaces for communicating between relevant software modules executing in the head-end unit <NUM> and SON entity <NUM>, respectively. The radio frequency operations and management API <NUM> can also be used to control the operation of the radio frequency front-end <NUM>, providing the SON entity <NUM> the control of the power amplifiers, attenuators, filters, and other radio frequency components of the RBS <NUM>.

Using the radio frequency parameters measured by the measurement and configuration module <NUM>, the SON entity <NUM> can adjust radio frequency operations and management parameters of the RBS <NUM>. The SON entity <NUM> can support self-optimizing procedures at the radio frequency level for the radio base stations that are coupled to the DAS <NUM>. For example, the radio frequency branch operations and management API <NUM> can provide to the SON entity <NUM> a variety of programmable parameters. Non-limiting examples of programmable parameters included in the radio frequency branch operations and management API <NUM> include the number of radio frequency parameters transmitted by the RBS <NUM>, the downlink and uplink radio frequency branch gains, a radio frequency branch delay adjustment, a nominal receive power level, and radio frequency output power.

In some aspects, the radio frequency branch operations and management API <NUM> can also provide measured radio frequency characteristics specific to the RBS <NUM> to the SON entity <NUM>. For example, the radio frequency branch operations and management API <NUM> can provide information indicating the downlink and uplink differential delay between radio frequency branches of the RBS <NUM>, downlink and uplink radio frequency branch attenuation of the RBS <NUM>, the uplink received signal strength level, and the uplink received total wideband power. Using the measured radio frequency parameters from the RBS <NUM>, the SON entity <NUM> can further optimize radio frequency characteristics of the signals provided to the DAS <NUM>. For example, the SON entity <NUM> can manage or optimize delay adjustments between any MIMO radio frequency branches (e.g., adjust for signal delays caused by multiple radio base stations transmitting in a MIMO configuration).

In some aspects, the head-end unit <NUM> can measure the relative delay between MIMO branches of the RBS <NUM> (the relative delay caused for example to the different cable lengths of the MIMO branches coupling the RBS <NUM> to the DAS <NUM>). The head-end unit <NUM> can report the relative delay back to the SON entity <NUM>. The SON entity <NUM> can compute the proper time delta required to realign the MIMO branches in order to minimize the relative delay and provide the adjusted time delta values to the head-end unit <NUM>. The DAS head-end unit <NUM> can receive the adjusted time delta values via the DAS operations and management API <NUM>. The measurement and configuration module <NUM> can adjust for the relative delay of MIMO signals from the RBS <NUM> by applying the received delta adjustment values from the SON entity <NUM>. For example, in a digital DAS head-end unit <NUM>, analogto-digital conversion (ADC) units can digitize the RBS <NUM> radio frequency downlink signals associated to each antenna port of the RBS <NUM> coupled to the DAS head-end unit <NUM>. The delay between the MIMO signals can be equalized by properly setting the digital buffering stages following the ADC units for each MIMO signal. The measurement and configuration module <NUM> can set digital shift registers containing the digital samples of each MIMO signal. A time shift equal to the measured time delta between the MIMO signals can be applied to the shift register containing the samples of a given MIMO signal in order to compensate for the reported time delta.

In other aspects, the SON entity <NUM> can monitor all parameters related to radio frequency downlink/uplink paths of the DAS <NUM> and RBS <NUM> and adjust the DAS <NUM> based on the measured radio frequency parameters. For example, the RBS <NUM> can continuously or periodically report the measured received total wideband power of the RBS <NUM> and DAS <NUM> to the SON entity <NUM>. Based on the total wideband power and the target uplink noise power known by the SON entity <NUM>, the SON entity <NUM> can instruct the measurement and configuration module <NUM> to adjust the DAS uplink gain (e.g., the gain of uplink signals transmitted by head-end unit <NUM>). As another example the SON entity <NUM> can use RBS <NUM> transmit power levels to optimize the input power of the DAS <NUM>. The DAS <NUM> can, in some aspects operate most efficiently at certain input power levels. Using the transmit power level of the RBS <NUM>, the SON entity <NUM> can optimize the radio frequency operations and management parameters of the DAS <NUM> by sending instructions to the head-end unit <NUM> to attenuate or amplify incoming downlink signals from the RBS <NUM>.

The SON entity <NUM> can be implemented as a combination of hardware, software, or firmware to be stored or executed by a computing device, such as a server platform. In some aspects, the SON entity <NUM> can be remotely positioned with respect to the head-end unit <NUM>. In other aspects, the SON entity <NUM> can be included as a software module in the head-end unit <NUM> and can be executed by a microprocessor hosted in the head-end unit <NUM>. In other aspects, the SON entity <NUM> can be embedded as a software module in the RBS <NUM> and can be executed by a microprocessor hosted in the RBS <NUM>.

<FIG> is a block diagram depicting an example of a SON entity <NUM> positioned remotely from the head-end unit <NUM> according to one aspect. The SON entity <NUM> includes a system bus <NUM> that communicatively couples a processing device <NUM> with a memory device <NUM>, DAS operations and management API <NUM>, and radio frequency branch operations and management API <NUM>.

The processing device <NUM> can include any device suitable for executing program instructions to control operation of the SON entity <NUM>. Examples of processing device <NUM> include a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other suitable processor. The processing device <NUM> may include one processor or any number of processors. The memory device <NUM> can include any non-transitory media for storing program code defining the operations of the SON entity <NUM>. Non-limiting examples of memory device <NUM> can include read-only memory (ROM), random-access memory (RAM), optical storage, magnetic storage, flash memory, or any other medium from which the processing device <NUM> can read program code. The memory device <NUM> can include program code for defining instructions that, when executed by the processing device <NUM>, determine appropriate adjustments to the radio frequency operations and management parameters for the RBS <NUM> based on radio frequency parameters provided by the head-end unit <NUM>.

<FIG> is a flowchart depicting a process <NUM> for optimizing an RBS <NUM> using radio frequency parameters collected from the DAS <NUM>. In block <NUM>, the measurement and configuration module <NUM> can measure radio frequency parameters pertaining to the radio frequency communications between a head-end unit <NUM> and remote unit <NUM> of the distributed antenna system <NUM>. For example, the measurement and configuration module <NUM> can collect information indicating the radio frequency performance of the DAS <NUM>. Non-limiting examples of radio frequency parameters that the measurement and configuration module <NUM> can measure are the uplink gain of the DAS <NUM> (e.g., uplink gain from the remote unit <NUM> to the head-end unit <NUM>), downlink gain of the DAS <NUM> (e.g., downlink gain from the head-end unit <NUM> and the remote unit <NUM>), and signal interference and noise generated by the DAS <NUM>. Additional examples of radio frequency parameters that the measurement and configuration module <NUM> can measure are signal impairments between the head-end unit <NUM> and the remote units 122a-b, the number of radio frequency signals being transmitted through the DAS <NUM>, the downlink delay period in transmitting downlink signals from the head-end unit <NUM> to remote units 122a-b, the uplink delay period in uplink signals provided by the remote units 122a-b to the head-end unit <NUM>, differential delay between multiple-input multiple-output (MIMO) radio frequency branches in the DAS <NUM>, and uplink noise generated by the DAS <NUM> at the head-end unit <NUM> output port.

The head-end unit <NUM> can provide the radio frequency parameters measured by the measurement and configuration module <NUM> to the SON entity <NUM>, as shown in block <NUM>. For example, the head-end unit can provide the measured parameters via the DAS operations and management API <NUM>. The DAS <NUM> can be configured to periodically measure radio frequency parameters and provide the measured radio frequency parameters to the SON entity <NUM>. In other aspects, the SON entity <NUM> can instruct the head-end unit <NUM> to measure specific radio frequency parameters and send the measured radio frequency parameters to the SON entity <NUM>.

In block <NUM>, the SON entity <NUM> determines adjustments to the radio frequency operations and management parameters of the RBS <NUM> based on the measured radio frequency parameters. Adjusting the radio frequency operations and management parameters of the RBS <NUM> based on radio frequency performance characteristics of the DAS <NUM> can optimize overall performance of the telecommunications system by, for example, compensating for noise and latency present in the DAS <NUM>. In some aspects, the carrier (e.g., wireless service provider for the RBS <NUM>) may specify key performance indicators that indicate minimum levels of performance for the RBS <NUM> and DAS <NUM>. Examples of key performance indicators include a maximum noise floor at the RBS <NUM> and minimum signal latency for signals transmitted from the RBS <NUM> through the DAS <NUM> to connected user devices.

For example, the adjustments to the radio frequency operations and management parameters determined by the SON entity <NUM> can include compensation for the radio frequency branch delay caused by the DAS <NUM>. In this aspect, the radio frequency parameters measured by the measurement and configuration module <NUM> can include the delay in providing a downlink signal received from the RBS <NUM> to a user device via the remote unit <NUM> (e.g., the delay caused by the extended distance downlink signals travel between the head-end unit <NUM> and the remote unit <NUM>). The delay to be compensated is the delay between the head-end unit <NUM> and the remote unit <NUM> in both the uplink and downlink directions. The radio frequency parameters can also include the delay in providing an uplink signal received at a remote unit <NUM> to the RBS <NUM> via the head-end unit <NUM>. Using the measured uplink or downlink signal delay, the SON entity <NUM> can determine a compensation value for the delay as an adjustment to the radio frequency operations and management parameters. For example, the compensation value due to the delay can include frame synchronization counters.

A more detailed example of adjusting the radio frequency branch delay of the DAS <NUM> follows. The downlink and uplink delay introduced by the DAS <NUM> is measured by the measurement and configuration module <NUM> of the DAS head-end unit <NUM>. The SON entity <NUM> can adjust the uplink and downlink radio frequency branch delay parameters available at the RBS <NUM> (e.g., uplink / downlink parameters set through frame synchronization counters) by sending a command to adjust the parameters to the RBS <NUM> through the radio frequency branch operations and management API <NUM>. The delay introduced by the DAS <NUM> can be compensated by setting the above mentioned downlink / uplink parameters to the same values of the uplink / downlink delay measured by the DAS <NUM>.

In another aspect, the RBS <NUM> can adjust the Ncs Cyclic Shift, which is part of the Random Access Channel (RACH) Preamble generation, in order to compensate for the Round Trip (downlink + uplink) Delay (RTD). The Ncs Cyclic Shift, maximum RTD, and channel delay spread due to the over the air propagation are all related to the cell radius. In the case of 3GPP LTE, the relationship between the Ncs Cyclic Shift, maximum RTD, channel delay spread, and cell radius is provided with the following formula: <MAT>.

The Preamble Duration in 3GPP LTE is <NUM> microseconds and the Preamble Length is <NUM>. The RTD can be calculated as (<NUM> x the cell radius) / speed of light. The relationship between Ncs Cyclic Shift, maximum RTD, channel delay spread, and cell radius in LTE is thus: <MAT>.

The cell radius of the RBS <NUM> is accordingly: <MAT>.

For example, assuming a Delay Spread of <NUM> microseconds and an Ncs Cyclic Shift value of <NUM>, the cell radius for the RBS <NUM> is <NUM> kilometers. By adjusting the Cyclic Shift value, the RBS <NUM> can thereby adjust the maximum cell radius of the RBS <NUM>, thus compensating for increased delay spread from the DAS <NUM>. To adjust the radio frequency branch delay of the DAS <NUM>, the SON entity <NUM> can send instructions to the RBS <NUM> via the radio frequency branch operations and management API <NUM> to adjust radio frequency parameters pertaining to the Ncs Cyclic Shift value. Additionally, the SON entity <NUM> can adjust the Ncs Cyclic Shift value based on a desired cell radius. For example, measured radio frequency parameters sent to the SON entity <NUM> from the measurement and configuration module <NUM> can include the delay spread and desired maximum cell radius. The SON entity <NUM> can calculate the appropriate Ncs Cyclic Shift value and provide the adjusted value for the Ncs cyclic shift to the RBS <NUM>.

In another aspect, the adjustments to the radio frequency operations and management parameters can include adjustments to the RBS <NUM> nominal receive power level for open loop power control. In an open loop power control procedure, the RBS <NUM> can set the minimum power level at which a user device should transmit to communicate with the carrier network. The nominal receive power level of the RBS <NUM> corresponds to the minimum power level of uplink signals that should be received by the RBS <NUM>. By increasing the radio frequency operations and management parameters that correspond to the nominal receive power level, the RBS <NUM> can instruct connected mobile devices to increase transmit power such that incoming uplink signals can be received at the nominal receive power level. For example, the nominal receive power level may be set three decibels higher than a default value to account for a lack of receive diversity in a single receive antenna DAS configuration.

In block <NUM>, the SON entity <NUM> sends commands to the RBS <NUM> to change the operations and management parameters using the adjustments determined by the SON entity <NUM>. For example, the SON entity <NUM> can send commands to the RBS <NUM> via the radio frequency branch operations and management API <NUM>, as discussed above with respect to <FIG>. The RBS <NUM> can change the appropriate operations and management parameters by applying the adjustments determined by the SON entity <NUM>. Changing the operations and management parameters of the RBS <NUM> can, for example, adjust the downlink and uplink radio frequency branch gains of the RBS <NUM>, compensate for signal delay, adjust the nominal receive power level, or adjust the radio frequency output power of the RBS <NUM>.

Operating the DAS <NUM> can, in some aspects, result in an increased uplink noise floor at the radio frequency front-end <NUM> of the RBS <NUM>. Adjustments to the radio frequency operations and management parameters of the RBS <NUM> can compensate for any uplink noise floor rise at the RBS <NUM> caused by the DAS <NUM>. For example, the radio frequency parameters provided to the SON entity <NUM> can include the uplink DAS gain, downlink DAS gain, and uplink DAS noise power level. Based on these measurements, the SON entity <NUM> can determine adjustments to the radio frequency operations and management parameters of the RBS <NUM> by determining an updated value for changing the uplink radio frequency branch gain.

<FIG> depicts a flowchart for an example process to determine adjustments to the radio frequency operations and management parameters of the RBS <NUM> for adjusting for increased noise floor rise at the RBS <NUM>. In block <NUM>, the SON entity <NUM> can receive the uplink DAS gain, downlink DAS gain, and an uplink DAS noise power level. For example, the SON entity <NUM> can receive this information from the radio frequency parameters measured and provided by the head-end unit <NUM>.

In block <NUM>, the SON entity <NUM> calculates the uplink noise floor rise due to the DAS <NUM>. For example, the uplink noise floor rise can correspond to the difference between the uplink noise power level measured by the RBS <NUM> and reported to the SON entity <NUM> with the DAS <NUM> connected to the RBS <NUM> and the uplink noise power level measured by the RBS <NUM> and reported to the SON entity <NUM> without the DAS <NUM> connected to the RBS <NUM>. To obtain the uplink noise power level at the RBS <NUM> without the DAS <NUM> connected to the RBS <NUM>, the SON entity <NUM> can disable the radio frequency uplink output of the DAS head-end unit <NUM>. For example, one non-limiting way to disable the radio frequency uplink by the DAS head-end unit <NUM> is by terminating the output port of the DAS <NUM> with a <NUM> ohm load.

Using the uplink noise floor rise, the SON entity <NUM> can determine the optimal value for the uplink radio frequency branch gain to apply to the RBS <NUM>, as shown in block <NUM>. The optimal value for the uplink radio frequency branch gain can include the amount of gain the RBS <NUM> should apply to incoming uplink signals from the DAS <NUM> in order to compensate for the increased noise from the DAS <NUM>. The optimal value for the uplink radio frequency branch gain can be calculated as follows: uplink radio frequency branch gain = uplink DAS gain - downlink DAS gain + uplink DAS noise rise. The SON entity <NUM> can provide the calculated optimal value for the uplink radio frequency branch gain as adjustments to the radio frequency operations and management parameters for the RBS <NUM>.

Claim 1:
A method, comprising:
receiving, at a self-optimizing network entity, SON, measurements of radio frequency parameters of a distributed antenna system (<NUM>), DAS;
determining, with the SON, adjustments to operations and management parameters of a radio base station (<NUM>), RBS, using the measurements of the radio frequency parameters of the DAS (<NUM>); and
sending, from the SON, commands to the RBS for changing the operations and management parameters of the RBS using the determined adjustments (<NUM>);
wherein the radio frequency parameters of the DAS include an uplink DAS gain, a downlink DAS gain, and an uplink DAS noise power;
wherein adjustments to the operations and management parameters include an updated value for an uplink RBS gain; and
wherein the updated value for the uplink RBS gain is determined by calculating an uplink DAS noise rise, and summing the uplink DAS noise rise with a difference of the uplink DAS gain and the downlink DAS gain.