Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/08—Access point devices
  • H04W88/085—Access point devices with remote components

Definitions

• the invention relates to a transmitting and receiving station comprising a distributed radio head and applies in particular to the field of wireless telecommunications.
• Some systems like WiFi do not manage the mobility of user terminals.
• the transmitting and receiving stations used allow access to services in an area corresponding to the coverage area of the station or stations deployed.
• a second-generation system is the GSM system, an acronym derived from the English expression "Global System for Mobile Communications”.
• An example of a third generation system is the UMTS system, an acronym derived from the English expression "Universal Mobile Telecommunications System”.
• An example of a fourth-generation system is the LTE system, an acronym derived from the Anglo-Saxon term "Long Term Evolution”.
• the transmitting and receiving stations of the GSM system are called base stations and are designated by the acronym BTS from the English expression "Base Transceiver Station”.
• the transmitting and receiving stations of the UMTS system are called NodeB and those of the LTE system are called eNodeB.
• the term "station” designates a transmitting and receiving station.
• radio access networks are evolving towards architectures comprising stations gathering a larger number of functions.
• a station includes for example radiofrequency treatments such as filtering and baseband switching but also digital processing such as channel coding and encryption. This is particularly the case for the BTS, nodeB and eNodeB stations used respectively in GSM, UMTS and LTE technologies.
• the NodeB plays the role of gateway with a second equipment of the radio access network called RNC, acronym from the English expression "Radio Network Controller”.
• the LTE standard defines an access network architecture composed of a single type of element called eNodeB. Most of the functions traditionally implemented by the RNC are distributed between the eNodeB and the core network of the system. The LTE access network is therefore composed only of eNodeB. These changes are intended to simplify the architecture of the radio access network and facilitate the deployment of the radio access network.
• Stations are very expensive, but operators have an interest in reducing their number in order to generate enough revenue.
• the area covered by a station must be as wide as possible. In the rest of the description, this zone is called the coverage zone.
• Minimize the number of stations involves relatively high transmit and receive power levels. These levels are necessary so that all user terminals present in this area can access the system. Power densities are therefore high in the areas covered by these systems and the population is concerned about the impact of these power densities on the health of living beings.
• these stations are usually large. Their visibility causes problems during their installation because these stations are less and less accepted by the population, especially because of their size and therefore their visibility.
• the energy consumption is important. It is therefore difficult to use solar energy using a panel located at the station. Indeed, the current power output of the stations is generally constrained by the power amplifier (s) used as well as by the calculation processors.
• WiFi terminals or set-top boxes set up at subscribers and use them as a radio access point.
• the energy bill of the operator is in this case effectively reduced but to the detriment of that of the subscriber.
• the latter is subjected to significant electromagnetic radiation and permanent in its housing due to the shared use of its equipment.
• a radio coverage outside the buildings in which the set-top boxes are located is made difficult because of the loss of penetration due to the walls.
• An object of the invention is in particular to overcome the aforementioned drawbacks.
• the invention has for object a wireless transmitting and receiving station comprising a distributed radio head allowing user terminals present in a geographical area covered by said station to access the services offered by a radio transmission system.
• wireless telecommunications Said radio head is composed of a distribution equipment, a plurality of distributed access points distributed in the coverage area and communication means between the distribution equipment and the distributed access points.
• the dispatcher includes means for transmitting samples of a baseband signal to be transmitted in the coverage area to all the distributed access points.
• the distributed access points comprise radiofrequency processing means making it possible to transpose on a carrier frequency said signal before transmitting it in the form of radio waves to the user terminals present in the coverage area.
• the distributed access points comprise means for transmitting radio signals received from the user terminals in the baseband before transmitting them to the dispatching equipment.
• the dispatching equipment comprises, for example, means for combining the signals coming from the radio access points.
• the dispatching equipment combines the signals from the distributed access points with a weighted sum.
• the result of the weighted sum is for example used to make the digital formation of antenna beams.
• the means of communication between the dispatching equipment and the distributed access points correspond to optical links of the CPRI type.
• the dispatching equipment is for example connected to each access point distributed by optical fibers of identical lengths so as not to cause delay spread of the signals transmitted and received by said distribution equipment.
• the means of communication between the distribution equipment and the distributed access points correspond for example to wired links or dedicated radio links.
• a distributed access point is turned off when no user terminal is detected nearby.
• an unlit distributed access point wakes up periodically to check whether a user terminal is nearby, the presence of a user terminal being verified when the received power level is greater than a predefined threshold value.
• the position of a user terminal is for example estimated by triangulation performed on the basis of several signals received by different distributed access points, said estimate being implemented at the splitter.
• the system is for example suitable for one or more of the following technologies: GSM, UMTS, LTE.
• the invention also relates to a distributed radio head enabling user terminals to access the services offered by a wireless telecommunications system, said radio head being composed of a distribution equipment, a plurality of access points distributed throughout a coverage area and means of communication between the dispatching equipment and the distributed access points, the dispatching equipment including means for transmitting a signal to be transmitted in the coverage area to all the points of distribution distributed access, said distributed access points comprising radiofrequency processing means for transposing on a carrier frequency said signal before transmitting it in the form of radio waves to the user terminals present in the coverage area.
• the distributed access points comprise means for transmitting radio signals received from the user terminals in the baseband before transmitting them to the dispatching equipment.
• Figure 2 shows an example of a wireless telecommunications system using a distributed radio head station
• FIG. 3 gives an example of an architecture in which distributed radio heads can be implemented
• FIG. 4 presents a simplified example of an architecture that can be used for a distribution equipment
• Figure 5 shows an example of a distributed access point architecture.
• FIGS 1a and 1b give two examples of transmitting and receiving station architecture.
• Transmitting and receiving station manufacturers seek to establish architectural standards, for example in consortia such as OBSAI, an acronym for the Open Base Station Architecture Initiative.
• OBSAI an acronym for the Open Base Station Architecture Initiative.
• the purpose of these standards is to reduce the infrastructure costs borne by telecom operators.
• the base station is composed of several standardized modules and therefore compatible. An operator can therefore compose his own stations from modules from different manufacturers.
• the CPRI interface an acronym derived from the English expression "Common Public Radio Interface”
• the recent stations are composed of one or more radio heads 101, 102, 104, 105, 106 and a control equipment 100, 103.
• the interface CPRI is an example of a standardized interface for simply connecting the elements dialing the station between them.
• the radio heads are designated by the acronym RE coming from the English expression "Radio Equipment”
• the control equipment is designated by the acronym REC, acronym from the expression "Radio Equipment Control””.
• Figure 1a gives a first example of a base station composed of several modules connected to each other using a standardized interface.
• a control equipment 100 is connected to a first radio head 101 using a standardized link 107.
• Said radio head 101 is then also connected to a second radio head 102 by means of a second standardized link 108.
• Standardized links are for example CPRI links.
• the CPRI type links make it possible to build a distributed architecture of stations where radio control equipment is remotely connected to one or more radio heads via optical fiber links, for example.
• the use of standardized links has the effect of reducing costs for service providers. Indeed, the radio heads must often be positioned in places difficult to access while the control equipment, including digital processors, can be positioned in remote areas more easily accessible.
• Figure 1 has an architecture where the radio heads are connected in series.
• the CPRI links are exemplary without this being limiting, other types of standardized links that can be implemented in the context of the invention.
• Figure 1b gives a second example of a base station composed of several modules connected to each other using a standardized interface.
• a control device 103 is connected to a first radio head 104 using a standardized link 109.
• This radio head 104 is also connected to two other radio heads 105, 106 using two standardized links 1 10, 1 1 1 .
• These standardized links 109, 109, 1 10, 1 1 1 are, for example, CPRI links. It appears that the radio heads can be connected to each other in a serial, parallel or hybrid network.
• Figure 2 shows an example of a wireless telecommunications system using a distributed radio head station.
• a mobile radio system is considered, but the invention can be applied to a wireless telecommunications system that does not manage the mobility of the user terminals.
• Five cells 200, 201, 202, 203, 204 cover a defined area during the deployment phase of the system, the radio resources of the system being distributed between said cells.
• these resources may be frequency resources, time resources and / or multiple access codes.
• radio heads For a given cell, one or more radio heads of the same type as those described with reference to FIGS. 1a and 1b can be used, a subset of radio resources being allocated for each of these radio heads. These radio heads are called conventional radio heads.
• a first cell 200 four conventional radio heads 210, 21 1, 212, 213 are used.
• a second cell 201 four conventional radio heads 213, 214, 215, 216, a conventional radio head 213 being used for both the first cell 200 and the second cell 201.
• a conventional radio head 217 is used in a third cell 202 a conventional radio head 217 is used.
• a conventional radio head 218 is used in a fourth cell 203.
• the fifth cell 204 of the system is covered by a distributed radio head.
• a distributed radio head differs from a conventional radio head.
• Dispatcher 209 communicates with the distributed access points using digitized baseband signals. This saves bandwidth and preserves the signal of disturbances.
• the stations are connected either directly or indirectly to a control equipment 218.
• FIG. 3 gives an example of an architecture in which distributed radio heads can be implemented.
• the system comprises at least one control equipment 300.
• This equipment 300 may be connected to one or more radio heads 301, 302.
• a control equipment 300 may also be connected to one or more distributed radio heads 303.
• a distributed radio head is composed of a device called splitter 304 and one or more distributed access points PAD 308, 309, 310, 31 1, 312.
• Control equipment 300 can be connected to dispatching equipment belonging to a distributed radio head and / or conventional radio heads 301, 302 using for example a standardized interface.
• This standardized interface can be a CPRI type optical link, a wired link or a dedicated radio link.
• Conventional radio heads 301, 302 and distributed radio heads 303 receive and transmit data to user terminals 305, 306, 307 based on radio resources allocated thereto. Depending on the radio technology implemented, these radio resources may correspond to a set of carrier frequencies, a set of CDMA codes and / or a set of time slots.
• a conventional radio head 301, 302 when a conventional radio head 301, 302 is used to cover a given geographical area, the radio resources it is used by the user terminals 305, 306, 307 present in this area through an access point located at said radio head.
• a conventional radio head includes an antenna or multiple co-located antennas to form an antenna array when multi-antenna technologies are used.
• the distributed access points PAD 308, 309, 310, 31 1, 312 are geographically distributed in this zone so that a user terminal always has a PAD nearby.
• the geographical distribution of the PADs has the particular advantage that the power emitted by these devices is reduced because of the proximity of the user terminals.
• the manner in which access points are distributed is part of the general knowledge of a radio engineer establishing link budgets. Due to the proximity of the user terminals and the distributed access points PAD, the size of the antennas used can be minimized.
• the small size of these distributed access points PAD allows a discreet installation and harmoniously integrated into the environment, which facilitates relations with the population during their installation. As the power of the transmitter is low, the power output of the power amplifiers is improved.
• no cooling device is required and a supply of distributed access points PAD using a solar panel is possible.
• Another advantage is that the signals will be less deformed because the temporal spread phenomenon of the signals well known to those skilled in the art is limited. Indeed, since the distributed access points RP 308, 309, 310, 31 1, 312 are distributed over the entire coverage area, the probability for a user terminal to be in line of sight with the An antenna of a distributed access point is improved over systems based only on conventional radio heads comprising a single radio access point.
• the decrease in the speed offered to users in Cell border is a well-known phenomenon because of the decrease in power density. This reduction will be reduced here because the power density is almost uniform throughout the cell thanks to the distributed nature of the PADs.
• relays In fourth-generation systems such as LTE, the use of relays is intended to combat the effects of shadows and improve the available bit rate at the edge of the cell.
• a relay receives the signals from the different channels of a cell, amplifies them and emits them again. These emissions may experience problems of glare and noise factor degradation.
• the shadow zone In a system implementing distributed radio heads, the shadow zone will be covered by a PAD connected to the splitter by a dedicated link, for example fiber-type.
• the same radio resources are used over the entire area covered by a distributed radio head using N distributed access points PAD. It is therefore not necessary to implement these "handover" techniques when user terminal moves within the area covered by a distributed radio head.
• a distributed access point PAD is turned off when no user terminal is detected nearby. For example, an unlit distributed access point may wake up periodically to check if a user terminal is nearby. For this, it can check the received power level in the frequency band of the system and compare it to a threshold value.
• a distributed access point PAD wakes up for example every P seconds for a period of 20 ms.
• the PAD distributed access points have a known position. Because of their proximity, a terminal is often in radio visibility with several radio access points. This radio visibility results in the existence of direct routes. Thus, the position of a terminal can be estimated by triangulation performed on the basis of several signals received by different distributed access points. Alternatively, the position of a terminal can be estimated by using identifiers ID allocated to each of the distributed access points PAD, the knowledge of the identifier or IDs of the PAD or with which a terminal communicates to this estimate.
• FIG. 4 shows a simplified example of an architecture that can be used for a dispatcher.
• the dispatching equipment includes means for connecting to one or more distributed access points PAD. These means correspond, for example, to input ports 400, 401, 402, 403 to which a data management module 404 is connected. function to format and synchronize the data received on the ports 400, 401, 402, 403 and the data to be transmitted on these same ports.
• Each port 400, 401, 402, 403 is for example connected to a distributed access point PAD by optical fibers of identical lengths so as not to cause delay spreading of the signals transmitted and received by the distribution equipment. This link makes it possible to transmit the digital samples of a baseband signal.
• the equipment also comprises a digital signal processing module 405. Its main function is to combine the digitized signals received from the different input / output ports 400, 401, 402, 403 using a simple weighted sum given by the following expression:
• Xi [k represents the k-th sample of the signal received on the ith port
• a £ represents the weighting coefficient applied to the signal received by the ith port
• y [k] represents the result signal of the weighted sum.
• M represents the total number of input / output ports used and therefore signals from the distributed access points PAD.
• the signal processing module also includes, for example, channel coding and decoding, source coding and decoding, filtering and anti-interference processing.
• the choice of functions to implement depends on the transmission technology used.
• the system according to the invention can be implemented for example for UMTS or LTE.
• the dispatching equipment further comprises means for connecting to one or more control equipment. These means correspond to means for managing an interface, for example of optical type CPRI.
• the equipment comprises an optical input and output port 407 followed by a first data management module 406.
• This module aims to format the received packets and to send on the optical interface. It groups functions corresponding to layers 1 and 2 of the OSI reference model, an acronym derived from the English expression "Open Systems Interconnection".
• FIG. 5 shows an example of a distributed access point architecture.
• a distributed access point RP comprises an input and output port 500 and a data management module 501 for managing the sending and receiving of digital data from the distributed access point PAD to the distribution equipment via an interface 505 for example optical.
• the purpose of the module 501 is to format the received packets as well as the packets to be sent on the optical interface. For example, it groups functions corresponding to layers 1 and 2 of the OSI reference model.
• a digital signal processing module 502 may be used to implement one or more digital filters.
• a conversion module 503 is used and includes a CAN-to-digital converter and a digital-to-analog converter CNA so as to perform the required conversions of the received signals and the signals to be transmitted from the access point RP to the user terminals.
• a radio frequency module 504 is then used in particular for the baseband conversion of the analog signals from the user terminals and the carrier frequency transposition of the signals to be transmitted to said terminals.
• the distributed access points do not include a conversion module, the signals being exchanged in analog between these two devices.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=47501144

Family Applications (1)

Country Status (7)

Families Citing this family (1)

Family Cites Families (5)

• 2011
  • 2011-12-16 FR FR1161859A patent/FR2984677B1/fr active Active
• 2012
  • 2012-12-13 CN CN201280069916.1A patent/CN104488350A/zh active Pending
  • 2012-12-13 SG SG11201404093TA patent/SG11201404093TA/en unknown
  • 2012-12-13 WO PCT/EP2012/075337 patent/WO2013087748A1/fr active Application Filing
  • 2012-12-13 EP EP12809692.2A patent/EP2792210A1/de not_active Withdrawn
  • 2012-12-13 KR KR1020147019702A patent/KR20140104489A/ko not_active Application Discontinuation
  • 2012-12-13 JP JP2014546501A patent/JP2015510290A/ja active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events