FR3043300A1 - - Google Patents

Abstract

This invention provides a method for optimizing the allocation of radio frequencies used for transmission and / or reception by a radio base station, by sharing and combining: - the radio frequency occupancy information, collected by listening to the radio frequencies; radio frequencies (RF) in the vicinity of the transmitting and receiving sources, and, - the information on the allocation of radio frequencies provided to these sources by the entities responsible for the allocation of radio frequencies.

Description

Description of the state of the art

The unlicensed spectrum is widely used to communicate through radio interfaces. The common way to access without prior coordination to the same radio channel on unlicensed spectrum is to use collision avoidance protocols, such as "listen before talk" defined in the IEEE 802.11 standard. A similar procedure is used in other recently defined protocols, such as LAA, standardized within the 3GPP ("3rd Generation Partnership Project"), or LTE-U, standardized by the "LTE-U Forum".

To maximize spectrum usage, new access methods have been defined that allow primary users to share spectrum with secondary users. For example, the "Federal Communications Commission" has defined how to share the 3.5 GHz band between primary and secondary users (in "FCC 15-47"). A subset of this band is reserved primarily for use under license, while the remaining part is reserved exclusively for unlicensed use.

When a primary user is detected in a given geographical area, secondary users must stop using spectrum on frequencies used by primary users. One possible way to detect emissions from primary users is to deploy a network of sensors. 'When the spectrum is shared between multiple transmission sources, mechanisms such as listen before talk (or LBT) and the carrier sense multiple access with collision avoidance (CSMA / CA) approach are commonly used to minimize interference.

When a radio base station chooses a frequency only using such a mechanism, this radio base station can not know: - whether interference with nearby radio base stations will be created, for example because of the so-called hidden node problem, - what is the best estimated quality of service, among a multiplicity of frequencies available.

In addition, when the spectrum is shared with a primary user, a large number of radio base stations and devices belonging to the same network may be required to cease transmissions at the same time, if they use the same frequencies as the primary user, resulting in a complex reconfiguration of the network.

This invention, which may reside above the so-called LBT or CSMA / CA mechanisms, overcomes these limitations by sharing and combining the radio frequency occupancy information collected by measuring radio frequencies in the vicinity of the data sources. transmission or reception, with information on frequency allocations provided by the entities responsible for allocating frequencies to these sources.

Thus, the spectrum is used more optimally, improving the performance of the radio network, such as latency and throughput, and in addition the diversity of frequencies allocated on a set of radio base stations belonging to the same network improves the resilience radio network in case a primary user is detected.

DESCRIPTION OF THE FIGURES

Figure 1 shows an example of architecture on which this invention is applicable.

Figure 2 describes the steps for optimizing the allocation of radio frequencies or channels in accordance with the present invention.

Figure 3 shows an example of a First Level Report.

Figure 4 shows an example of a Second Level Report.

Figure 5 illustrates how a Second Level Report is created.

Figure 6 illustrates how a Second Level Report is used.

Figure 7 illustrates how a Second Level Report enriched with information on the occupancy of own traffic is used. - Figure 8 illustrates how a Second Level Report is used when information on overlapping coverage areas is available.

DESCRIPTION OF THE INVENTION

Architecture of the solution

Figure 1 illustrates an example of architecture on which the present invention is applicable.

This figure shows a deployment of radio base stations, labeled ST, belonging to the same or to different operators. Each radio base station is capable of communicating over a radio interface, for example with user-owned devices named DI to D4.

RFS sensors, capable of listening to radio frequencies and detecting radio signals, are deployed near ST radio base stations, or embedded on ST radio base stations, or integrated with ST radio base stations.

Each sensor is connected to a spectrum controller SM. The spectrum controller supplies the radio base stations ST with the allowed frequencies for transmission and reception. The spectrum controllers are connected to each other and able to exchange information, for example through an IP network. The information exchanged between spectrum controllers is used to determine the frequencies to be allocated to each ST radio base station, as further described in the following sections.

Figure 1 shows an example of an architecture in which spectrum controllers are distributed. In this case, each spectrum controller is responsible for allocating the frequencies of a single radio base station ST. The spectrum controller may be physically embedded or integrated with the ST radio base station. In an alternative architecture, not illustrated in Figure 1, all spectrum controllers can be centralized in a single server. Such a server could be located at a different location than the radio base stations.

Communication between spectrum controllers and sensors can be done via a physical link, or wirelessly (for example, using Wi-Fi or LTE). Some spectrum controllers can be connected to multiple sensors. Conversely, other spectrum controllers may not be connected to any sensor.

The spectrum controllers may communicate with the radio base stations via an entity controlling the ST radio base station network. In the case of a 3GPP network, such an entity may be the "Network Manager". This case is illustrated in Figure 1 by SMI which communicates with STI via interfaces [C2] and [C3]. In another alternative, the spectrum controllers can communicate directly with the radio base stations, for example via an IP network. This case is illustrated in Figure 1 by SM2 and SM3 which communicate with ST2 and ST3 via the interface [C1]. Other radio base stations not controlled by a spectrum controller, labeled FST in Figure 1, can be deployed within the same geographical area. Devices communicating with these radio base stations, labeled FD1 to FD4 are also shown in this figure. .Detail of the steps of the method to optimize the allocation of radio channel or radio frequency

Figure 2 illustrates the steps taken to optimize the radio channel allocation in accordance with the present invention.

The following 5 operations are performed at each radio site:

A. RF Detection B. First Level Report C. Second Level Report Creation and Dissemination D. Second Level Report Receipt E. Optimizing Radio Frequency or Radio Channel Allocation The following sections describe these operations in more detail. detail.

A. RF detection

Each RF S sensor listens for radio frequencies received around its location and detects the transmitted radio signals.

This processing can be carried out continuously, or triggered at regular intervals, at the expiration of a predefined "TSensing" counter. B. First Level Report Based on the RF measurements collected in step A, the RFS sensor creates a First Level Report containing information on the use of radio frequencies.

This step can be initiated at regular intervals, or at the end of a predefined "TFirstReport" counter.

The First Level Report includes, for each radio frequency or radio channel, its percentage of occupancy.

A frequency may be considered as unoccupied when, for example, the RF signal level detected by the RFS sensor for that radio frequency remains below a predefined threshold for a predefined minimum period of time.

An example of a First Level Report is shown in Figure 3. This example shows the occupancy for each radio channel. A similar table could be built for each frequency.

Additional parameters may be included in this report, to provide more precise information on the use of radio frequencies.

For example, the First Level Report can be enriched by: i. information on the use of radio channels, by technology (eg 60% use on LTE-U, 40% use over Wi-Fi), ii. information on the use of radio channels by type of license (eg, 80% (unlicensed), 20% (licensed)). In the case of the US 3.5GHz band, this information distinguishes GAA user traffic from PAL user traffic when the same frequency is shared, iii. information on the use of radio channels by type of medium access procedure (eg 40% LBT ("listen before talk") or similar, 60% non LBT), iv. information on the use of the radio channels by antenna sector, or by portion of the total coverage area of a radio base station located near the sensor. Such information can be collected, for example, using a sensor making directional measurements or rotating around an axis, using several sensors, or with a sensor equipped with several antennas. v. the location and altitude of the sensor (for example, GPS coordinates or preconfigured information), vi. the start and end time of each detected radio frequency transmission.

Once created, the First Level Report is transmitted to the spectrum controller connected to the sensor. The spectrum controller then saves this report locally. C. Creation and dissemination of the Second Level Report

The Second Level Report is created by the spectrum controller at regular intervals, when the TSecondReport counter expires.

The Second Level Report provides information on the use of radio frequencies or radio channels for a given radio station ST. This report combines the following information: i. information on the use of radio frequencies or radio channels provided by the First Level Reports associated with the ST radio base station. ii. information on the use of radio frequencies or radio channels provided by the spectrum controller controlling the radio base station ST. In particular, this information includes the frequencies or radio channels allocated to the radio base station ST.

Optionally, data provided by a third party could be used when creating the Second Level Report. For example, measurements obtained from the third party sensor network (eg ESC - "Environmental Sensing Capability" - in the case of the US 3.5GHz band) could be provided to the spectrum controller instead or in addition to the measurements of the RFS sensors shown in Figure 1.

Figure 4 shows an example of a Second Level Report associated with a given ST radio base station. This example shows, for each radio channel, the percentage of occupancy and an indication that the radio channel is allocated or not to the ST radio base station.

To determine the radio frequency or radio channel occupancy, the spectrum controller calculates, for each radio frequency or radio channel, the average of all the values received in the First Level Reports since the last created Second Level Report.

Figure 5 shows an example of creating a Second Level Report. The 58% value shown in the Second Level Report for Channel 1 is the average of all the values shown for Channel 1 in the First Level Reports received in the last '' TSecondLevel 'seconds elapsed. In addition the information "Not used by ST" in the third column of the table indicates that channel 1 is not currently used by the ST radio base station for transmission or reception.

The value of "TSecondReport" is typically significantly larger than the value of "TFirstReport". An example might be to set the value "30 seconds" to "TSecondReport" and the value "1 second" to "TFirstReport". The value "TSecondReport" is defined so that very short fluctuations in duration (for example at the data packet scale) are not reflected in the occupancy value associated with a radio frequency or a radio channel included in the Second Level Report.

In the case where multiple RFS sensors are deployed around an ST radio base station, the spectrum controller receives a First Level Report from each sensor. The spectrum controller can then calculate the average of the radio frequency or radio channel occupancy values provided in all these First Level Reports.

When more information is available in the First Level Report (eg occupation by technology, sector, etc.), the Second Level Report can be enriched accordingly.

In addition, information on the radio base station ST associated with the spectrum controller may be included in the Second Level Reports, such as: i. Information to determine the coverage area of the ST radio base station, such as: - the location and altitude of the ST radio base station (eg GPS coordinates or preconfigured information), - information indicating if the ST radio base station is located indoors or outdoors, the height of the antenna in relation to the ground level, - the maximum transmission power of the ST radio base station. ii. An indication, for each radio frequency or radio channel, of the percentage of traffic associated with the radio base station ST. This information could be determined, for example, by using the information provided by the radio base station ST via the interface [C1] on the amount of uplink and downlink traffic associated with the radio base station ST.

Once created, the Second Level Report is broadcast over the network that connects the spectrum controllers. In the case where the spectrum controllers are connected through an IP network, this operation can be performed, for example, by broadcasting UDP packets on the IP layer, including a predefined destination port. In the case where the spectrum controllers are centralized, this step is not necessary.

When spectrum controllers associated with radio base stations of multiple operators are connected to the same network of spectrum controllers, some of the information provided in the Second Level Reports may be encrypted (for example by using the public key of the spectrum controller). certificate of an operator) so that it is accessible (for example by using the private key of the certificate of an operator) than to the spectrum controllers associated with the radio base stations of the same operator. D. Receiving Second Level Reports

Each spectrum controller receives all Second Level Reports broadcast on the network that connects them to each other.

The spectrum controller may store only a subset of these Second Level Reports. For example, the spectrum controller can store only the Second Level Reports associated with the spectrum controllers of the neighboring STs.

The list of neighboring ST stations can be configured in each spectrum controller, for example by the operator. Alternatively, neighboring STs can be automatically detected using the STs information included in the Second Level Reports, such as GPS coordinates, altitude, and coverage area size. E. Optimization of Radio Frequency or Radio Channel Allocation

This step may be initiated at regular intervals, or upon receipt of a request to change spectrum usage, for example when greater bandwidth is required, or when less bandwidth is required. Such a request can be sent directly by the radio base station ST via the interface C1, or through a network controller via the interfaces C2 and C3.

During this step, the spectrum controller uses the information included in the Second Level Reports to identify the optimal radio frequencies or channels that can be allocated to the ST radio base station.

The criteria for selecting the best radio frequencies or radio channels may be, for example, a combination of the following: i. maximize the total throughput of all STs belonging to the same network, ii. guarantee a minimum bit rate, for each ST in the same network, iii. maximize the diversity of radio channels allocated on the ST network. This reduces the number of STs to be reconfigured simultaneously when a primary user is detected on a given radio channel. The exact algorithm used by the spectrum controller is outside the scope of the present invention. In order to maximize the total throughput, while ensuring fairness, the following rules can be used, in combination: i. Prioritize radio channels that are not widely used, ii. Choose as a priority the radio channels that are rarely used by neighboring ST stations, iii. Choose radio channels on which interference estimation with neighboring stations STs is low. o The level of interference with a neighboring ST radio base station can be estimated using the data provided in the Second Level Reports, for example using a Radio Environment Card (REM), as well as the data provided by the network operator of STs, such as: i. The estimation of overlapping coverage areas between TS, in 2 or 3 dimensions, ii. An indication that ST stations are installed inside or outside a building, iii. The results of calibration procedures. iv. Choose as a priority the radio channels on which the same type of access procedure to the medium or the same access technology used by ST is used. The action resulting from the optimization algorithm may be to use new radio channels in addition to or instead of the radio channels in use. When multiple radio channels are used, the spectrum controller may indicate a weight for each radio channel at the radio base station ST, so that more traffic is sent on the weakly used channels.

Figure 6 shows an example of using the Second Level Report.

In this example, ST2 has two neighbors: STI and ST3. At the expiration of the "TOptimize" counter, the ST2 spectrum controller analyzes the local Second Level Report, as well as the Second Level Reports received from the spectrum controllers of the two neighboring ST stations.

The ST2 spectrum controller determines that: - The channel in use by ST2 is heavily occupied (the SM2 Second Level Report indicates a value of 99% for channel 3). - Channel 1 is not used by any neighboring ST station but is heavily used. - Channel 2 is not used by any neighboring ST station and is moderately busy. Using this information, the ST2 spectrum controller decides to start using channel 2 instead of channel 3.

Figure 7 shows another example of using the Second Level Report.

In this example, the Second Level Report includes additional information indicating the percentage of traffic (downlink or downlink and amount or uplink) from the ST station associated with the spectrum controller. When the timer "TOptimize" expires, the ST2 spectrum controller analyzes the local Second Level Reports, as well as the Second Level Reports received from the spectrum controllers of the neighboring stations STs.

The ST2 spectrum controller determines that: - The channel in use is heavily occupied (the SM2 Second Level Report indicates a value of 100% for channel 2). - Channel 3 is less busy than Channel 2. - Channel 1 is less busy than Channel 2.

Although channel 1 and channel 3 have the same level of occupancy (95%), channel 3 is more busy with traffic associated with neighboring stations STs than channel 1. Indeed, SMI indicates that 90% of traffic on channel 3 corresponds to traffic sent or received by STI, while SM3 indicates that only 40% of traffic on channel 1 corresponds to traffic received or transmitted by ST3. From this information, the ST2 spectrum controller decides to use channel 1 instead of channel 2.

Figure 8 shows another example of using the Second Level Report.

In this example, the information on coverage areas superimposed between the STs is known by the spectrum controllers, for example from the estimation of the propagation obtained with the aid of a radio environment card ( REM) on board. Upon receipt of a request to allocate a new channel to ST2, the spectrum controller SM2 analyzes the Second Level Report as well as the Second Level Reports received from the spectrum controllers of the neighboring STs.

The spectrum controller of ST2 determines that: - Channel 1 is heavily occupied, - Channel 2, used by STI, and channel 3, used by ST3 are weakly occupied.

Although the TSI occupancy of channel 2 (80%) is less than the ST3 occupancy of channel 3 (92%), the common coverage area at ST2 and STI is much larger than the common coverage area at ST2 and ST3.

As a result, the spectrum controller of ST2 decides to allocate channel 3 to ST2.

Claims (10)

1) A method for optimizing the allocation, to a radio base station, of radio frequencies used for transmission and / or reception, consisting of the following operations: i. Detection of radio signals transmitted near said radio base station using at least one sensor installed near said radio base station, embedded on said radio base station, or integrated with said radio base station , and connected to a spectrum controller responsible for allocating radio channels to said base station for transmission and / or reception. ii. Generation of first level reports associated with the measurements made in step i by each of the one or more sensors. iii. Transmitting said first level reports to said spectrum controller controlling said radio base station. iv. Generation by said spectrum controller of a second level report on the use of the spectrum, from: a. The information provided by these first level reports, and, b. The information on the channels allocated to said radio base station for transmission and / or reception. v. Broadcasting of the second level report by said spectrum controller to the spectrum controllers controlling the other radio base stations. vi. Receiving, by said spectrum controller, second level reports from the spectrum controllers controlling the other radio base stations. vii. Identification by said spectrum controller of the best radio channels to be allocated to said radio base station for transmission and / or reception, using the received second-level reports. viii. Sending by said spectrum controller to said radio base station a request to indicate the authorized channels for transmission and / or reception. 2) The method according to claim 1, characterized in that the spectrum controllers controlling radio base stations belonging to the same network are centralized in a central server, or distributed among the radio base stations. 3) The method according to at least one of claims 1 to 2, characterized in that said radio base stations and said spectrum controller communicate via network management equipment "Network Manager" or via a direct interface. 4) The Time method according to at least one of claims 1 to 3, characterized in that said first level ratio is generated and transmitted smoothly to said spectrum controller at predefined intervals. 5) The method according to at least one of claims 1 to 4, characterized in that said first level report generated to said sensor comprises, for each radio channel, at least one of the following elements: i. an indication of the total occupancy of the radio channel, based on the time during which the RF signal level has not been detected below a predefined threshold, ii. an indication of radio channel occupancy for each detected technology, iii. an indication of radio channel occupancy for each type of use: licensed or unlicensed, iv. an indication of the occupancy of the radio channel for each type of media access procedure, v. an indication of the occupancy of the radio channel for each antenna sector of said radio base station, vi. information on the location of the sensor, in 2 or 3 dimensions. 6) The method according to at least one of claims 1 to 5, characterized in that said second level report generated by said spectrum controller comprises at least one of the following: i. an average, for each type of channel occupancy provided by said first level report, of all values received by said spectrum controller from the previous generated second level report, ii. an indication, for each radio channel, that said radio channel is currently allocated or not to the radio base station associated with said spectrum controller, iii. an indication, for each radio channel, of the uplink and downlink or downlink traffic associated with the radio base station associated with said spectrum controller, iv. information on the coverage area of the radio base station associated with said spectrum controller, v. information about the location of the radio base station, in 2 or 3 dimensions, the height of the antenna relative to the ground level, the transmission power, the fact that the radio base station associated with said spectrum controller is located inside or outside a building. 7) The method according to at least one of claims 1 to 6, characterized in that the second level report is broadcast at regular intervals. 8) The method according to ime at least claims 1 to 7, characterized in that the determination by said spectrum controller of the best radio channels to allocate to said radio base station is initiated at regular intervals, or at the request of said radio base station. 9) The method according to at least one of claims 1 to 8, characterized in that the set of criteria for identifying the best radio channels to allocate to a given base station comprises at least one of the following elements : i. prioritize weakly used channels, ii. select as a priority those channels on which use by other radio base stations belonging to the same network as said radio base station is low, iii. selecting in priority the channels for which the estimate of interference with other radio base stations belonging to the same network as said radio base station is low, iv. to select, in priority, the channels on which the type of access procedure to the medium is identical to that used by said radio base station, v. select as a priority the channels on which the detected access technology is identical to that used by said radio base station, vi. select channels to maximize the total throughput of all radio base stations in the same network, vii. select channels to ensure a minimum level of flow equity among radio base stations in the same network, viii. select the channels so as to maximize the diversity of radio channels allocated on a given area among a set of radio base stations belonging to the same network and deployed on that given area. 10) The method according to at least one of claims 1 to 9, characterized in that part of the information provided in the second level reports can be encrypted so that this information is accessible only to spectrum controllers associated with radio base stations of the same operator.