ITVE20120018A1 - METHOD AND EQUIPMENT FOR IMPROVING THE EFFICIENCY OF OPPORTUNIST ACCESS TO THE ELECTROMAGNETIC SPECTRUM - Google Patents

Description

METHOD AND EQUIPMENT TO IMPROVE THE EFFICIENCY OF OPPORTUNISTIC ACCESS TO THE ELECTROMAGNETIC SPECTRUM

DESCRIPTION

The main field of application of the present invention relates to the use of the television spectrum in an opportunistic way for medium and short range applications.

In general, the concept of opportunistic use of electromagnetic spectrum resources provides that said resources are assigned primarily to certain purposes and users, which are defined as primary. However, when primary users do not use these resources, other users can be expected to have the opportunity to use said resources of the electromagnetic spectrum. The latter users, who access these electromagnetic spectrum resources only if they have the opportunity, as the primary users are not using them, are defined as secondary.

Opportunistic access to the radio spectrum presupposes that a secondary user uses certain frequencies only â € œwhenâ € and â € œwhereâ € ™ the primary user is not using them. In fact, the primary user is the holder of the right to use these frequencies whenever he needs them, and only when these are not used by the primary user can one think of making them available for other purposes for the benefit of other users. , which are for this reason called secondary users.

The fundamental problem with this form of access to the radio spectrum consists in ascertaining that the primary user is not using certain frequencies.

We are looking at this access mode with great interest, both because the transmission capacities that could become available are considerable (especially in some contexts), and because it is a method that is not yet exploited at the moment and therefore It is full of potential.

In general, there are many theoretical studies that refer to the exploitation of the opportunistic use of frequencies for radio communications in all radio bands; however, today, attention is essentially focused on the possibility of using the band allocated to terrestrial television broadcasters in an opportunistic way, where, on a worldwide level, it is estimated that significant unused transmission capacities are available. The expression â € œWhite Spacesâ € generally indicates these radio frequency bands allocated to television broadcasting services but not used throughout the territory and therefore available for opportunistic access. The various bodies that deal with these topics generally refer to the following definition of â € œWhite Spaceâ €: â € œportion of spectrum that becomes available for radiocommunication applications in a given time and in a given geographical area that does not disturb the services primary and other services with higher priorityâ €. The opportunistic access is therefore carried out on said â € œWhite Spacesâ €, defined as just reported.

The activity aimed at studying for the efficient exploitation of â € œWhite Spacesâ € (hereinafter also WS) is not only of a scientific and technological nature, but the regulatory and standardization frameworks necessary for a quick and practical exploitation of the method. The CEPT (European Conference of Post and Telecommunication Administrations), for example, has set up a â € œworking groupâ €, the WG SE43 with the aim of:

â € ¢ Develop the correct approach to WS by combining geolocation databases and spectrum sensing

â € ¢ Study the impact that white space devices (WSD) will have on services in the frequencies adjacent to those of the 470-790 MHz band

â € ¢ Define the requirements for operating with cognitive radio systems in the white spaces of the 470-790 MHz band

â € ¢ To ensure the protection of the services holding certain frequencies

â € ¢ Quantify the potential spectrum increase available with WS

The end of the works is scheduled for the month of September 2012.

Opportunistic access to the television band is a possibility that, if exploited, can make a considerable amount of band available for new services. This is why many countries are looking at this opportunity with great interest.

The industry is also very active in this sector and there are various DSA (Dynamic Spectrum Access) devices that are able to activate radio communications dynamically, using the television spectrum in an opportunistic way.

The issue is also heavily covered at the level of patents and patent applications.

It is therefore natural that there is a lot of known art on the subject. This large amount of known art has all in common the fact that it considers a certain band of radio frequencies not used by the primary user (the one to whom it is reserved primarily) in a certain â € œspaceâ € and in a certain â € œtimeâ When said primary user is not transmitting in that band in that specific â € œspaceâ € and determined â € œtimeâ €.

The methods used to identify the bands that can be used opportunistically belong essentially to two families:

â € ¢ methods based on â € œcarrier sensingâ €,

â € ¢ and methods based on geo-location and â € œdata baseâ €.

The methods based on â € œcarrier sensingâ € consist of measurements carried out by the secondary systems which, before carrying out the transmissions, are put in reception on the band they intend to use to verify that it is not already occupied with other transmissions. Furthermore, the â € œcarrier sensingâ € methods are in any case implemented in DSA devices, as well as for the identification of WS, also to manage the disturbances suffered and to try not to produce disturbances to other secondary users.

The methods based on â € œcarrier sensingâ € essentially have the problem of reliability, as the listening of the spectrum necessarily takes place in a point, that is, in the point where the sensor is present, while the disturbance generated by a transmission affects a more or less vast space, which is why, when used, these methods apply very precautionary margins which end up considerably reducing the advantages of resorting to opportunistic access itself.

Given the difficulty of using the methods based on â € œcarrier sensingâ €, these are generally confined to very particular applications and generally, when applied, use extremely sensitive (and expensive) receivers in order to allow very prudent evaluations, noting the presence of even very weak signals.

Methods based on â € œdata baseâ € require the primary user to declare in advance where and when he intends to transmit in the band assigned to him, and to make this information available in a database. In this way, secondary users can consult this database and use the radio band when and where this is not needed by the primary user.

Methods based on â € œdata baseâ € are certainly more reliable, conceptually simpler, and more easily applicable in wider contexts.

The main problem associated with such "data base" methods is that the information is generally not very detailed and is based on necessarily approximate propagation models. They lend themselves well to some cases, such as the case in which a television broadcaster who has a license in a large territory, decides not to broadcast in a particular part of that territory in which he does not think he has a significant â € œshareâ €. This broadcaster can therefore declare this choice and allow others to use "his" frequency in that territory. We are therefore talking about very large areas in which a broadcaster renounces his rights, and therefore we do not consider small areas where, accidentally, a signal is not present with the necessary power to be received and decoded.

The application of the methods based on the â € œbase dataâ € however requires that there is a structure capable of managing this information and the communications between secondary users and the â € œbase dataâ €.

Both methods, even when hypothetically applied with success and absolute precision, in any case underestimate the band that can be used opportunistically. In fact, a frequency can be said to be truly used only when on this frequency, in addition to the presence of someone who transmits, there is also someone who receives.

If someone transmits and nobody receives, in theory, this frequency cannot be said to be used in a radio communication.

The main purpose of the present invention is to propose a method and the related apparatuses that allow an opportunistic use of frequencies to a greater extent than is implemented with the methods and apparatuses according to the known art.

This purpose is achieved through the use of secondary transmitting apparatuses or systems suitable for transmitting radio signals through the occupation, carried out in an opportunistic way, of electromagnetic spectrum resources characterized by the fact that said secondary systems have means that allow to perform a verification procedure that no primary receiver system, active in the area surrounding said secondary transmitter systems, is receiving on a channel that uses the electromagnetic spectrum resources opportunistically occupied by said secondary transmission systems.

It is observed that in this description the term apparatus or device, now the term system, has been used indifferently to refer to the primary or secondary transmitters or receivers. This is due to the fact that both transmitters and receivers are always systems composed of at least a part of signal processing and a part of radio transceiving and that, in the case of systems inserted in contexts of opportunistic use of radio resources, they are additional information processing elements are also required. In many cases all these parts can be integrated into a single apparatus or device, in others they can be distinguished. A typical example of a system that is generally not integrated into a single device is given by the primary television receivers: in fact the television reception antenna is generally located far from the televisions or decoders necessary to complete the reception of television channels. .

This invention also has further advantages which will be made more evident by the following description, by the attached claims which form an integral part of the description itself and by the illustration of some examples of practical embodiment described, by way of non-limitative, in the following and in the attached drawings in which:

figure 1 shows a case of opportunistic use of radio band according to the known art; figure 2 shows a case of opportunistic use of the band according to the invention in a simple case;

figure 3 shows a case of opportunistic use of the band according to the invention in a more general case;

figure 4 shows a case of opportunistic use of the band according to the invention in a case characterized by a possible variant;

Figure 1 highlights the essential elements involved in an opportunistic access application to the radio band. The number 100 indicates a transmitting station of a primary user of the frequencies. The number 130 indicates a primary receiver that receives from the primary station 100, and must not be disturbed by interference on the transmission frequency. The number 200 indicates a secondary station that can transmit on the frequencies of a primary user when he does not use them.

Figure 2 highlights further elements involved in the application of the present invention. Since the invention is mainly applicable in indoor environments, a house has been highlighted with the number 301, inside which the secondary station 200 is located. frequencies used for television broadcast transmissions, the primary receiver considered is a system consisting of an antenna for television reception 110 and a television 120 which tunes to a channel transmitted by the primary station 100. In figure 2 it is also highlighted a network for local communications 310 which allows the exchange of information between the television 120 and the secondary station 200.

Figure 3 shows a more general scenario in which there is more than one house, and therefore in addition to house 301, there is also house 302. Furthermore, a WTL 220 network is shown in the figure. (Watch Television Lan), and a WTL server 210. The WTL 220 network is used to communicate with each other the devices connected to the residential networks 310 of the various homes and possibly with a WTL server 210. The WTL server 210 is a server where it can a database can be stored which can contain information relating to the reception and transmission status of the various primary and secondary transmitters and receivers. In particular, it is important that this WTL server 210 contains updated information regarding the state of tuning of the primary receivers: it is in fact essential that it is known what the primary receivers are receiving, moment by moment, as it is precisely this reception that it must be preserved from any disturbance potentially caused by secondary transmitters 200.

It is important to note how, in the scenario represented in Figure 3, it is important that the secondary transmitter systems 200 are equipped with means for communicating with a remote server and means for executing consultation programs of a computer database, and that the receiving systems primaries are equipped with means for communicating with a remote server and for updating some of the data stored in said server.

Figure 4 shows the case in which the house 301 is not connected to the WTL 220 network and the television 120 is not a â € œconnected TVâ €. In this case the television 120 can communicate the channel to which it is tuned by means of a radio transmission system which allows to carry out a transmission 230 which can be received by the secondary transmitters 200 present in the coverage area reachable by the transmission 230. In this case à It is important to note that the secondary transmitter systems 200 must be able to be set up to receive the transmission 230 carried out by the primary receiver systems.

In general: the secondary transmitter systems according to the invention must be able to acquire configuration parameters that exclude the occupation of certain resources of the electromagnetic spectrum. In particular, the resources that are used for the transmission of signals on which there is some primary receiver tuned in the surrounding area must be excluded. The ways in which this configuration can be acquired by the secondary transmitters can be the most varied: the possibility of manual or automatic configurations can be envisaged. In the case of automatic configurations, these can be calculated on the basis of information found on suitable databases or information received by other means.

At the base of the invention there is first of all a more careful rereading of the aforementioned definition of â € œWhite Spaceâ €: â € œportion of spectrum that becomes available for radiocommunication applications in a given time and in a given geographical area that do not disturb primary services and other higher priority servicesâ €.

In practice, we want to highlight that, what must be guaranteed, is that the highest priority services are not disturbed, and a radio transmission is disturbed if the receiver is disturbed: consequently if no one is receiving in a particular area, obviously no one can be disturbed.

It is also observed that the television signal has certain values in the outdoor environment and in free space (ie above the roofs where the television receiving antennas are normally placed) and significantly more attenuated values in indoor environments. It is common experience, in fact, that portable televisions with built-in antenna receive poorly, and not all channels, when used indoors.

If the television spectrum were used indoors and for short range applications (e.g. few rooms), the transmission could take place, by a secondary transmitter at relatively low powers, it would be enough to remain 20-30 dB above the attenuated television signal. (which, as mentioned, is generally not very intense) present in the indoor environment in which the communication is to be carried out.

The problem caused by this way of proceeding is given by the fact that this transmission is superimposed on the television signal, at worst, obscuring it. This overlap is in any case limited in space: there will therefore be a space in which this secondary transmission, whose intensity is given by the needs of the specific transmission and is to be determined case by case, makes the television signal inadmissible or excessively disturbed throughout. a surrounding area.

Consequently, all the television reception antennas placed in that space are disturbed by the secondary transmission.

However, these antennas, while receiving all the television channels, are generally used to receive only one channel at a time (or a few channels at a time).

To avoid misunderstandings, it is specified that the term â € œchannelâ € (referring to a television broadcast) means the radio resource necessary for the transmission of a television service: it is clear that generally on a carrier they are multiplexed by time division plus services, therefore each television channel uses a radio resource defined in frequency and time, and it is this resource, understood in this way, that must be considered for a possible opportunistic use.

Figure 2 helps to exemplify, in a simple case, the basic idea.

The primary transmitting station 100 (in this case a TV tower) broadcasts many channels, all received by the 120 antenna of the house 301, but the TV receiver 120 of the house 301 is tuned to only one channel (or on few channels in the more general case). If the secondary station 200 broadcasts on physical channels on which the 120 receivers of the house 301 are not tuned, these can continue to receive the channels they are tuned to without evidently being affected by noise.

The idea consists in carrying out the secondary transmission only in the physical channels that no one, in the area that is disturbed, is receiving (ie on the channels that no one is seeing or recording): in fact, no damage is caused in the interfere with a channel in a space where no one is tuned into that channel.

The example represented in figure 2 is very simple, and in any case it immediately emerges what the first problem may be to apply such a method: it is necessary to inform the secondary transmitter 200, about which channels are disturbable if transmitted on the frequencies they associated.

The simplest and most direct way is to connect both the television receivers 120 and the secondary transmitters 200 to a local communications network 310. In this way each secondary transmitter 200 can be aware of the channel or channels on which the televisions 120 are tuned. that could be disturbed.

A first important observation consists in the fact that television frequencies are made to be received by televisions, and that televisions, being objects of a certain complexity, can easily be predisposed to collaborate in an opportunistic use of television frequencies, making available the information relating to their tuning. In fact, the modification to be made to televisions is relatively simple so that they make the information relating to the channel on which they are tuned available in an appropriate form.

In general, it can be said that it is possible to provide that primary receivers are equipped with means to export information relating to physical radio resources that must not be interfered with at a given time, and such information must be made available on a database or, in general, on any device suitable for storing information in electronic format.

A particular embodiment of the present invention provides that the primary receiving systems, and in particular the televisions 120, are equipped with means of communication for transmitting data to a remote server which allow to trace the radio resources on which no disturbances must be present so that they can receive correctly.

However, the example illustrated so far does not highlight a further problem which is instead clarified in figure 3 which presents a more general case, in which a secondary transmitter 200 can disturb the television reception of the neighborhood, and not only of the receivers present in the same house in which the secondary transmitter 200 that is transmitting is located.

The first question that arises when analyzing the general case concerns the measures to be adopted to reduce the number of antennas for television reception inside the disturbed space.

It is undoubtedly important to reduce as much as possible the number of antennas that can be disturbed by each secondary transmitter 200. In this regard, however, it must be said that the television antennas 110 placed on the roofs receive television signals from above. or from the horizon and their receiving lobes are certainly not oriented downwards; while the secondary transmitters 200 are usually found lower than the television antennas 110 as they are generally placed inside the premises.

By further shielding the television antennas 110 at their base (or in the opposite directions to those of origin of the useful television signal), it is possible to attenuate the noise signals generated by the secondary transmitting devices 200, limiting potential disturbances to those caused by the secondary transmitting devices 200 placed in the space included within a certain angle with respect to the direction of reception of the television antennas.

As already said, in general, given an indoor environment (typically a private house), the nearest 110 television reception antenna is the one that serves the 120 television receivers of these environments: these receivers can therefore communicate the channels on which they are tuned to the secondary transmitter 200, and therefore the nearest television antenna 110, even if within the disturbed space, can be free from serious disturbances as the channels on which the 120 receivers are tuned to this they can be left undamaged. The most serious problem arises for the antennas 110 placed inside the space disturbed by the transmission carried out by secondary transmitters 200, but which cannot communicate through a local residential network 310 with the secondary transmitter 200, and therefore it is not immediate to communicate to this secondary transmitter 200 on which channels the receivers 120 connected to these neighboring antennas 110 are tuned. The problem is quite easily manageable in a widespread â € œConnected TVâ € context in which the 120 TV receivers are connected to networks accessible from the outside. For example, such television receivers 120 could be managed by a â € œResidential Serverâ € and the latter could publish, or make known in some way, the channels to be left undisturbed.

According to many analysts, from a commercial point of view, this scenario of widespread presence of â € œConnected TVâ € will take place relatively quickly.

Figure 3 represents this scenario, in which it is possible to define and implement a sort of common management of information relating to the channel on which the various televisions are tuned. Figure 3 assumes the construction of a WTL (Watch Television LAN) 220 and a WTL server 210.

The possibility of connecting to the WTL server 210 through a special network 220 (which can also be a virtual network) allows: the television receivers 120 to communicate the channels on which they must not be disturbed, and the secondary transmitters 200 to check whether the they are using is received by some 120 TV set nearby.

In this hypothesis, WTL 220 could be a protected and closed network, accessible only by certain devices that would only allow a few M2M (Machine to Machine) communications to pass through in which data security would be easily manageable with known methods.

In the absence of a local residential network 310 or television receivers 120 set up to communicate on said local residential network 310, it is possible to resort to other methods so that the secondary transmitters 200 are known about the channels on which the potentially disturbable 120 television receivers are tuned. and which therefore must not be interfered with by the secondary transmitter apparatuses 200 active in the zone.

It is clear that in order to be able to carry out this communication it is in any case necessary to make a change to the television: a change that can generally be kept as simple as possible.

Such alternative methods of communication can be aimed at communicating the tuned channel:

â € ¢ to the â € œWTL serverâ € 210,

â € ¢ or directly to the secondary 200 transmitter devices involved.

In the case of communication to the â € œWTL serverâ € 210, a certainly interesting opportunity is that of transmitting the information with “conveyed wave” techniques (Power Line Communication). Various communication scenarios are then possible downstream of a first transmission section via “conveyed waves” by the 120 TV receivers.

For example, in the case of widespread presence of `` smart meters '' for electrical distribution, the data on the tuned channel can be communicated with a `` conveyed wave '' technique to the `` smart meter '' which manages the loads of the home. in which the television receivers 120 are present. At that point the â € œsmart meterâ € is, by definition, electronically connected to some service center which could therefore easily take charge of updating the â € œWTL serverâ € 210; this idea is full of variants and details that can certainly be explored and that have in common the fact of exploiting a first communication segment with `` conveyed wave '' techniques (also called `` power line '' techniques), i.e. using the power grid to transmit a small amount of data.

In the case of communication of the information directly to the secondary transmitters 200 concerned, it is possible to exploit the fact that the television reception antennas could also be used to transmit, and that the transmission could be carried out by such antennas at such a power as to be receivable. only from the secondary transmitters 200 close enough to be the very ones that could potentially disturb those antennas.

Figure 4 exemplifies this option. In this case the house 301 is not equipped with a local network 310 therefore the case is described according to which the television receiver 120 which is inside the house 301 communicates the channel on which it is tuned through a radio communication carried out with the antenna 110 (as in the case in the figure) or with another antenna that could be installed near the television reception antenna 110. This radio communication is represented by the dashed arrow, and by the number 230. This communication 230 will be received by the secondary transmitters 200 active in the vicinity. Figure 4 shows a secondary transmitter 200 which is located inside the house 302: in this way the secondary transmitter 200 which is inside the house 302 is able to transmit in opportunistic on channels that do not disturb the television reception of the receiver 120 which is located inside the house 301.

This method provides a solution that can be adopted by those who do not have a â € œConnected TVâ €, and represents an alternative way to have guarantee of no disturbance on televisions tuned to channels potentially usable by 200 active secondary transmitters nearby.

The method just described presents the burden of having to set up a communication transmission system 230, but it also has some advantages: it allows the viewing of television programs even in a non-connected TV contest, and directly affects only the secondary transmitters 200 which are in the vicinity of the television receiver 120 which must not be disturbed.

This solution, while potentially feasible with relative simplicity, has some critical issues that could hinder its diffusion.

Sensitive information is transmitted in the air (a certain degree of confidentiality must be guaranteed); therefore, a channel characterized by suitable devices and mechanisms that make it â € œdifficult to decipherâ € should be used. It is clear that this information should in any case be decipherable by the secondary transmitting devices and therefore potentially readable by the owners of the devices themselves, however, since it is an M2M communication, this could be limited to devices approved for the purpose, in which the information is not exportable, but this would require the introduction of a specific regulatory and control system.

This problem could be partially obviated by providing that the channels usable by the secondary transmitting devices 200 are only some channels defined as â € œdeclarableâ € and for which viewing confidentiality would not be guaranteed. In this way, televisions tuned to â € œnot declarableâ € channels would be exempted from having to make it public and would guarantee the confidentiality of viewing. However, this option also provides for the introduction of a standard.

In any case, communication 230 should be standardized, and TVs wishing to make use of this communication should be made compatible with this operation (possible single object to replace the decoder or integrated service in new TVs), as it should be modified or integrated. the antenna system.

A further method for preserving certain channels from potential disturbances in a given area trivially consists in the possibility of directly configuring the secondary transmitters 200 so that they do not use one or more channels at certain times.

Also this option, which can be seen as a feature of the secondary transmitters 200, as will be clarified further on, can be of some use in certain scenarios.

The main advantage of the invention described is that a considerable amount of band at very valuable frequencies is made available in an opportunistic way for radio communications.

In fact, if we consider a frequency occupied because a TV station is transmitting, in practice the whole spectrum could be occupied (in many places, and in Italy in particular), while if we consider the band of a radio channel to be occupied only when a TV receiver It is tuned to this channel, in practice, only a few channels may be occupied at each point (those on which the TV receivers present in the `` surroundings '' are tuned) compared to many channels used for television broadcasting: in practice, one a significant percentage of the television spectrum would be reusable for short-range networks.

The widespread reuse of the television band is essentially the main advantage of the invention. Some considerations are now cited below which highlight facilitating aspects for the diffusion of the present invention and which, resulting overall positive, can be considered as further advantages brought by the invention.

The establishment of a WTL 220 that serves the purpose is definitely a simple operation and compatible with a near future scenario characterized by:

- presence (in many countries) of infrastructures for access to databases for the use of â € œWhite Spacesâ €

- strong diffusion of â € œConnected TVâ €

- widespread diffusion of â € œsmart metersâ € associated with electrical distribution.

An added benefit of the method is that it can be introduced gradually. In fact it can be foreseen that initially only a limited number of channels can be used in an opportunistic way by the secondary transmitters 200 according to the teachings of the present invention. Such channels would therefore have a guarantee of not being disturbed only for users who are equipped to communicate that they are watching them.

In this way, a significant number of protected channels could be preserved, visible in the old ways, that is, without requiring the viewer anything new so that he or she still has the guarantee of undisturbed viewing. However, it is evident that for those who live in isolated environments, and at a certain distance from other homes, the risks of being disturbed (or disturbed) are drastically reduced until they are practically nil. Keep in mind, in any case, that any user who wants to continue to use an old TV that is not designed to communicate his own tuning, would still have the possibility of â € œdefend himselfâ € with alternative methods, eg. shielding the antenna from the side of the neighboring jammers, or communicating in another way the channels to be kept protected (for example, it could be envisaged that by paying an extra fee, a user can protect himself free from disturbances up to a maximum of N channels) in its area. In that case the secondary transmitting devices 200 which could disturb a given user, consulting the â € œWTL serverâ € 210 would find the information of further channels not to be used in an opportunistic way in that given zone.

A further mechanism that could be envisaged is that of manually inserting one or more channels not to be used into one's secondary transmitter device 200. This feature could be useful for example for a user who had an old portable TV that he keeps in the garage on which he sees some channels while dedicating himself to his hobbies (we are obviously assuming an example), well in this way he could preserve those channels at least from disturbances from their own secondary transmission devices 200.

Ultimately, however, the concept is that the application of the present invention can take place without the old televisions, which will continue to exist for a long time, become totally unusable in a short time, but can continue to be used, perhaps with a guarantee. viewing only for a smaller number of channels, or with precautions by the user himself.

The studies and proposals currently in place for the exploitation of â € œWhite Spacesâ € are geared towards initiatives that can already be implemented quickly today. It is also important to mention them in the context of the present invention as they can provide indications on how the secondary transmitter apparatuses will be made which could soon spread to many countries of the world. It seems that these devices, in addition to being quite similar to the current RFP WI-FI, will be characterized by the integration of two peculiar features:

1. the ability to consult a centralized database to verify the availability of a frequency

2. the ability to perform a â € œspectrum sensingâ € with good sensitivity.

The performance of â € œSpectrum Sensingâ € (also called â € œCarrier Sensingâ €) is already present also in the current devices that operate in unlicensed band (the RFP WI-FI) with the aim of managing the mutual interferences that can be generated when there are a plurality of private WI-FI coverage in the same area. Well, in future secondary transmitting devices this performance can also be used to avoid interference with the primary user and, as we said, will make use of much more sensitive receivers.

In general, therefore, it is observed that many of the technical problems that must be solved during the practical realization of devices operating according to the teachings of the present invention, are the same problems that are currently being faced in the field of known art, and for create devices capable of opportunistically exploiting the radio band, according to the commonly adopted meaning of the â € œWhite Spaceâ € concept. The coordination between potential users of the same band in an opportunistic way, can therefore take place through methods similar to those known or evolutions of these, also given the availability of hardware dedicated to â € œSpectrum Sensingâ € with state-of-the-art performance.

In general, most of the problems for creating and managing the equipment necessary for the practical implementation of the present invention are the same as those encountered for the construction and management of the equipment for the opportunistic exploitation of the radio spectrum according to the known art, and therefore the feasibility and applicability of the invention does not present difficulties substantially higher than those that would be encountered in the application of the known art.

In fact, it can be assumed that the application of the known art provides that each secondary transmitter device is not only equipped with hardware suitable for â € œSpectrum Sensingâ €, but also that it is an apparatus designed to consult a â € œbase dataâ € remote. Therefore each secondary transmitter device (both according to the known art and according to the invention) has the advantage of having context information, as it must necessarily "communicate" with a server that authorizes it to use certain frequencies. This server, in addition to containing and providing information on televisions, can therefore also keep track of other active secondary transmitter devices, and also provide this information for purposes of coordination of the various active secondary transmitters (many algorithms can also be proposed in this last scope).

A possible application of the inventive idea foresees that the secondary transmitter devices can in the first instance behave like the devices according to the prior art and consult a remote â € œdata baseâ € to access information on the transmission by the primary users on each frequency.

On the basis of this first information, the device can detect the presence in its area of a â € œWhite Spaceâ € (according to the current meaning) and therefore can transmit according to the known methods that are already being agreed in many countries. However, in other countries such â € œWhite Spacesâ € would be too rare or practically non-existent in many large areas, nevertheless the information on the transmission of the primary user is also very useful for the application of the present invention. In fact, the secondary transmitter device which, as mentioned, will also have electric field sensors, will be able to compare the expected power of the primary user signal (according to an hypothesis of propagation in the open field) with the power of the signal actually present. By doing so, the secondary transmitter device can estimate the attenuation it can rely on due to being in an indoor environment. It is clear how this information is very useful for deciding on what channel and at what power to transmit, also in the context of the present invention.

The secondary transmitter device will have to search for the channel that allows it to transmit at the lowest possible power (because this will be the smaller circle within which it will have to make sure there are no tuned televisions).

This information will also be useful to ensure that the secondary transmitter device has different behaviors if installed in attics or terraces or in very internal indoor environments, and this will ensure that even the owners of these devices are encouraged to observe certain guidelines in the ™ install their devices. In fact, those who install the device near a window, outdoors or in other particularly disturbing positions, would not have as high performance as those who installed it in the innermost room of their apartment.

In this regard, it is recalled that, unlike the target services designed for the so-called `` super WI-FI '' (the opportunistic bandwidth service that will soon be allowed in the United States), the services referred to in conceiving the present invention they are designed for short-range indoor coverage.

It is clear that in a communication according to the invention, not only the bases transmit and receive, but also the terminals. The latter are mobile and can, occasionally, be in less shielded positions, and consequently disturb and be disturbed more. However, it is clear that, for the establishment of a radio connection on a certain channel, an appropriate protocol will have to be implemented: this protocol cannot disregard BER and SNR measurements or estimates (as commonly occurs for establishment of radio connections between mobile devices); through these measurements, and from their comparison with the performance expected from the radio channel, both the secondary transmitter of the base and that of the terminal can obtain sufficient information to establish whether a channel can be used for the connection, and at what power. Finally, even the terminals can, theoretically, make use of information derived through â € œSpectrum Sensingâ €, and these too can be useful to establish how much the terminal is shielded with respect to free space.

As you can see, the establishment of a connection on opportunistic bands is, on the one hand, rightly more articulated, on the other it can still count on a lot of information that allows you to search for the frequencies on which transmissions can take place at the minimum possible power. . It is clear that the establishment of these connections will also have to make use of slightly more complex control protocols than the current ones as some additional assessments must be made for the choice of the radio resource to be used.

For this purpose, it is observed that, in reality, the question is evolving very quickly. Only in September 2010 the FCC decided that a good part of the television frequencies, if not used, will be available to provide wireless access services and to refer to these services has a new name certainly evocative was coined: â € œSuper WI-FIâ € .

Very soon, a similar measure will also be taken by OFCOM. Regulations for the opportunistic use of these frequencies are expected within a few months, and in all likelihood, methods based on data-base and geo-localization will be used initially. In other words, a system (a server) accessible to DSA devices will be launched, in which information relating to the frequencies that can be used at a given point will be found. It is clear that this system is already set up to become the WTL just described: as long as, in addition to DSA devices, it is also accessible to televisions.

It is clear that in some countries, or rather, in some places in some countries, the available bandwidth will be significant because few broadcasters transmit it, but in other places there will not be sufficient band availability, due to the presence of broadcasters in all frequencies. Thus the opportunistic use criterion introduced in this invention could drastically change the reusability ratios of the frequencies.

Finally, it is worthwhile to frame what has just been explained on the inventive idea in the broader context of the â € œCognitive Radioâ €: in their most general sense, the â € œCognitive Radioâ € techniques aim to allow two devices to communicate via radio by searching for and using a radio band in an opportunistic way and, in general, by adopting the transmission parameters that best suit the application on a case-by-case basis. All aiming for maximum flexibility. The topic is not explored here, and is cited only for the purpose of pointing out a very advanced topic that is currently being brought to the attention of many universities and research centers and that presents some significant connections with the proposal. inventiveness and its developments.

It is clear how absolutely ambitious such an objective is if thought of in its general meaning, consequently the studies currently in the field focus on proposals that limit the objective.

Among these proposals, some can be attributed to a trend that deserves particular mention: these are proposals that make use of the definition of a so-called CPC (Cognitive Pilot Channel). According to some of these CPC-based proposals, the creation of a network dedicated to the distribution of information functional to the establishment of â € œCognitive Radioâ € communications is hypothesized.

It is clear that the possible existence of a CPC distribution network could be usefully exploited also to package implementations of the present invention.

However, not only the â € œCognitive Radioâ € context can be favorable to the development and evolution of the present invention, but also the basic idea of the invention can be incorporated into the topic of â € œCognitive Radioâ €. In fact, to date, studies on the subject propose algorithms and processing (also known as: Cognitive Engine Brain) based on information relating to the transmitters, while it could also be useful to process information relating to the active receivers in the area.

Claims (9)

CLAIMS 1. Secondary transmitter apparatus or system (200) suitable for transmitting radio signals through the occupation, carried out in an opportunistic way, of electromagnetic spectrum resources, and characterized by the fact that said secondary transmitter apparatus or system (200) has means which allow you to perform a verification procedure that no primary receiver system active in an area surrounding said secondary transmitter apparatus (200) is receiving on a channel that uses the electromagnetic spectrum resources appropriately occupied by said secondary transmitter apparatus (200 ). 2. Secondary transmitter apparatus or system (200) according to claim 1 characterized in that at least one of said means suitable for carrying out said verification procedure, performed before opportunistically occupying electromagnetic spectrum resources, is a processor electronic programmed to execute a database consultation program. 3. Secondary transmitter apparatus or system (200) according to claim 1 characterized by the fact that at least one of said means suitable for carrying out said verification procedure, performed before opportunistically occupying electromagnetic spectrum resources, is a system of electronic communication suitable for establishing a telematic link with an electronic device (210). 4. Secondary transmitter apparatus or system (200) according to claim 1 arranged to dynamically acquire, in an automatic or manual way, a configuration which excludes the use of the electromagnetic spectrum resources which must not be used for opportunistic transmissions. 5. Primary receiver system or apparatus characterized by being set up to export information that allows to trace the channels that must not be used by secondary transmitters active in the area surrounding said primary receiver system or apparatus. 6. Primary receiving apparatus or system according to the preceding claim characterized by the fact that it has means which allow said primary receiving apparatus or system to access a database or a device for electronic storage of information through a telematic network to update information therein. related to the current state of your tuning. Primary receiver system according to the preceding claim which comprises a television (120) on which reception takes place. 8. Primary receiver system according to claim 5 comprising a primary receiver and a radio transmission system suitable for transmitting the information which allows to trace the channels that must not be used by the secondary transmitters in an area sufficient to reach all secondary transmitters that could potentially generate disturbances for said primary receiver. 9. Method of opportunistic use of the electromagnetic spectrum which includes at least the following phases: to. identification of radio spectrum resources to be accessed in an opportunistic way; b. check that there are no primary receivers tuned to transmissions carried out on said radio resources and within the area in which any opportunistic use of said radio resources by a secondary transmitter could generate disturbances on reception by said primary receivers; c. in the event that the verification referred to in the previous point is successful, establishment of a radio communication that uses the radio spectrum resources identified in point a ..