METHOD FOR JAMMING COMMUNICATIONS IN A CLOSED-LOOP
CONTROL NETWORK
The invention relates to a method for selectively, dynamically and
5 adaptively jamming the third-party radio communications that are external to a radio communication network to be protected, which optimizes the effectiveness of the jamming and which uses closed=loop control to limit fratricidal effects on the telecommunication transmitters/receivers to be preserved. The invention relates to an MIMO-oriented method for
10 dynamically jamming the third-parly communications which uses only the radio interface and performs closed-loop control of fratricidal effects on a network to be protected. The communication network to be protected and the jammer or the network and the jammers are treated as a macronetwork of closed-loop multiple-input-multiple-output or MIMO type and are managed
15 jointly by using return channels from the receivers to be protected in order to adapt the jamming instructions and the transmission instructions.
The method according to the invention is used, by way of example, to jam certain chosen communication links between entities that are external to the network to be preserved, which are present in a certain
20 geographical area, while maintaining the available communication links and services, in a quality that is sufficient and controlled in the communication network to be preserved.
The joint use of transmission networks and jammers (or of
25 networks of jammers) by the same force in a theatre of operation in the broad
sense, and particularly in terrestrial convoys, in aircraft squadrons and in
naval squadrons, is often severely penalized by the absence of precise
control over the effects caused by the jammer or jammers on the
transmission station or stations of the force's network or networks.
30 The technical problem to be solved for the jointly used
transmission networks and jammers is that of limiting the fratricidal effects of the jammers on the transmission stations, while guaranteeing minimum

effectiveness of the jamming on targets or on the areas of interest in the
theatre.
Definitions:
Jammer; transmission system capable of transmitting a signal that is 5 intended to prevent the operation of all or some of the equipment using the
electromagnetic spectrum (transmission stations, radar or navigation systems
that are present in the theatre of operation).
Network of jammers: coordinated set of transmission systems that are
capable of transmitting signals intended to prevent the operation of all or 10 some of the equipment using the electromagnetic spectrum and present in
the theatre of operation.
"Friendly" transmission station or "friendly station": transmission station
defined as being part of the communication system to be preserved and
needing to be protected from the effects of the jamming. 15 "Friendly" transmission netifflrkoLJMCTdiyjjeMQlk!: interconnectable set of
"friendly" transmission stations.
Friendly transmission: transmission coming from a friendly station or from a
friendly jammer.
"Target" equipment: equipment defined as needing to be affected by the 20 jamming.
Communicating jammer: jammer equipped with a "friendly" transmission
station.
Network of communicating jammers: network of jammers equipped with
"friendly" transmission stations, constituting a subnetwork of friendly 25 transmissions.
Jamming of a piece of target equipment: transmission of a signal or of a
plurality of signals, from a jammer or from a network of jammers, so that the
target equipment is prevented from getting to work or from continuing to
serve. 30 Jamming of a geographical area: transmission of a signal or of a plurality of
signals, frorti a jammer or from a network of jammers, so that any piece of
target equipment that is present in the geographical area is prevented from

getting to work or continuing to serve.
Detection of a signal: ability to decide on the presence of a friendly
transmission or of a transmission coming from an external entity and to
intercept the signal. This detection is performed in the band and the duration 5 of analysis of one or more interceptors which may be accommodated by the
friendly transmission stations, for example.
Detection of a transmitter: ability to decide on the presence of a transmitter in
the theatre by detecting the signal or signals which it transmits.
Localization of a transmitter: ability to decide on the location of a transmitter 10 in the theatre by detecting the signal or signals that it transmits.
SISO: single input single output: refers to a transmission system having one
transmitting channel Tx and one receiving channel F^x.
SI MO: single input multiple output: refers to a transmission system having
one Tx channel and N Rx channels. 15 MJSO: multiple input signal output: refers to a transmission system having M
Tx channel and one Rx channel.
MLMO: multiple input multiple output: refers to a transmission system having
M Tx channels and N Rx channels.
Effectiveness of an area: signifies the level of prevention of the setup and/or 20 maintenance of third-party communications that corresponds to the stations
and infrastructures that are present in this area, i.e. prevention of all
communications other than protected communications in the area.
Fratricidal effects: level of prevention of the setup and/or maintenance of
communications which need to be protected, owing to residual jamming and 25 interference outside the effective jamming area.
The estimation of the propagation channels corresponds to
estimation of the impulse response of the propagation channel, or the
numbers, amplitudes and phases of the various multiple propagation paths,
between jamrner(s) and protected receiver(s), which allows adaptation of 30 power and the spatio-temporal modulation/coding scheme in the network of
the jammer or in the network of jammers in order to minimize or quash the
impact on the demodulator/decoder of the protected receiver(s). At the same

time and in parallel, the impulse response measured on the transmitters
allows ~ as in an MIMO network = optimization of the protected transmission
links by means of adaptation of the modulation/coding schemes of the
protected transmitters and receivers.
5 The field of jamming has been the subject of numerous works and
inventions. However, fratricidal effects are still dealt with fairly poorly in developments known to date. In general, the constraints associated with implementing the methods and systems known to the applicant have the notable effect of drastically limiting the scopes and the number of 10 simultaneous friendly radio communications, or even of preventing the use of friendly r^adio communications.
The subject matter of the present invention relates, notably, to a
method which will allow the effective limitation of fratricidal effects with
15 sufficient flexibility and scope to simultaneously allow jamming of the targets
or areas to be jammed and the operation of communications between friendly
stations in an operational context.
The method and the system implemented by the present invention are based
notably on the use of the following elements:
20 © jammers that are programmable and dynamically configurable in terms
of waveform (envelope, modulation, amplitude, phase, etc.), frequency
map (choice of bands among bands and carriers for the jamming
signal), temporal transmission pattern (recurrence of transmissions on
the basis of time, frequency, waveform, etc), and that are managed
25 by a centralized or dispersed control component,
a sequences of digital signals transmitted by the jammers, specifically
intended to allow precise transmission channel measurements, and
jamming power measurements in the friendly stations,
© sequences of digital signals transmitted by the friendly transmitters,
30 specifically intended to allow precise transmission channel
measurements, and jamming power measurements in the friendly stations,

«> communications between networks of jammers or a component for
managing the network of jammers, and a friendly network or a control
component in the friendly network, (return channels, instructions to the
jammers, etc.),
5 • a control component allowing the preparation of transmission
instructions for the jammers with a control loop based on the measurements taken in the interceptors on the signal sequences and on the estimation of the propagation channels.
The invention can be implemented on any friendly stations 10 provided that:
- the transmitters implement signal sequences as specified above,
- the receivers are able to take the measurements on the jamming signals and to deliver all of the measurements (on transmitter signals and jammer signals), or else the antenna elements of the receiver are able to be coupled
15 to interceptors taking these measurements.
The description below of the methods and systems implementing the present invention is based notably on :
•> a formal description of the interactions between friendly transmittinq
stations (denoted by Tx for short), friendly receiving stations (denoted
2,0 by Rx for short), jammers (denoted by Br for short) and external
entities to be jammed (denoted by Ci for short), by means of graphs
and macrographs which will be clarified below,
<» on a general propagation model for the transmission channel,
generalized in consideration of the effective interactions between
25 friendly transmitting and receiving stations (Tx, Rx) (generally
integrated together within a friendly transmission station), jammers
(Br) and external entities (Ci), through a generalized channel matrix
notion that is clarified below,
© on a formation then resolution of a problem of optimization undei
30 constraints, clarified below.

The subject matter of the invention relates to a method for optimizing the jamming of P predefined areas or positions in a network of communication transmitters, jammers and receivers comprising a plurality N_pl of platforms, a number M < N_pl of said platforms being equipped with 5 antennas and systems for transmitting useful transmission signals, a nurtiber N < N_pl of said platforms being equipped with antennas and systems for receiving useful transmission signals, a number J < N_pl of said platforms that are managed by a master station being equipped with jamming systems and antennas suitable for preventing the transmissions between entities that 10 are external to said network, said platforms constituting an interplatform netuvork, characterized in that it comprises at least the following steps:
• measuring the useful communication signals received by all of the N
reception platforms, taking these measurements as a basis for
estimating the y*W useful propagation channels, and transmitting
15 these measurements to the master' station managing the platforms
equipped with the jamming antennas,
f measuring all of the jamming signals received by the N reception
platforms, taking these measurements as a basis for estimating the
J*N fratricidal propagation channels, and transmitting these
20 measurements to said master station,
® taking the measurements of the useful communication signals and
propagation ctiannels and of the jamming propagation signals and
channels as a basis for calculating, in the master station, jamming
instruction values, such as the jamming signals, the recurrence of the
25 transmissions, the carrier frequencies for the transmissions, the
leads/delays upon transmission in relation to a synchronization
reference, the radiated equivalent powers, the amplitude and phase
weightings on the transmitting antenna networks, guaranteeing an
effectiveness for the P areas to be jammed corresponding to the
30 entities that are external to the network, while minimizing the fratricidal
effects on the N receiving platforms,

e transmitting these instructions to the J platforms equipped with a
jamming antenna,
© taking the first calculated and applied instructions, while continuously
making use of the measurements from the fratricidal propagation
5 channels coming from the receiving platforms, as a basis for
optimizing by means of iteration the jamming of the areas to be jammed while maintaining fratricidal jamming which is acceptable for the quality of the useful transmissions.
By way of example, the method uses the measurement from the
10 propagation channels coming from the N reception platforms in order to
jointly optimize the jamming and quality of the useful transmissions on the
transmitting platforms by adapting the transmission power levels, and/or the
spatio-temporal coding schemes and/or the transmission protocols in the
time/frequency domain of the jammers and the transmitters.
15 According to one implementation variant, the master station used
is one of the transmission network nodes which is associated with a component for calculating the instructions intended for the jammers.
By way of example, it uses programmable jammers that are suitable for dynamically taking into account transmission instructions, on the 20 power and/or on temporal parameters, the waveform, spatio-temporal coding, the amplitude-phase weighting.
By way of example, the method is used in transmission netm/orks
using the MIMO, MISO, SIMO or SISO protocol with a return channel from
the receivers to the transmitters.
25 According to another implementation variant, the method is used
in a radio network in which the receivers are suitable for measuring channel values on the useful transmitters and on the jammers.
By way of example, the method is used in a radio network in which the reception stations have antenna elements that are coupled to an 30 interceptor taking the channel measurements on the useful transmitters and on the jammers.

other features and advantages of the present invention will become more apparent on reading the appended description of the figures, which is provided by way of illustration and is by no means limiting, in which: • Figure 1 shows an example of architecture for the system according to the 5 invention,
e Figure 2 shows a specific example of a propagation channel model generalized for the MIMO case, with definitions and denotations for the pertinent geometrical and physical quantities, 9 Figures 3A and 3B show an illustration of the notions of network graph and
10 macrograph which are used to describe the links between friendly stations (Tx, Rx), the interactions between jammers (Br) and external entities to be jammed,
©Figure 4 shows a logical product between network graph and channel matrix, defining a generalized channel matrix which takes account both of the
15 links or interactions between the players, transceivers, jammers, areas or points to be jammed, and propagation channels between these players.
The example below is provided by way of illustration and in by no means limiting fashion for a system having N_pl transmission platforms
20 which have MIMO, MISO, SIMO or SISO (a single listening antenna) communication stations.
Figure 1 schematically shows an example of architecture for a transmission network in which the method according to the invention can be implemented. A master station 1 is linked by radio communication channel to
25 N_pl = 1 friendly transmitter/receiver platforms or stations, for example, that is to say stations equipped with a transmitting part Tx and with a receiving part Rx. Among these N_pl platforms, J "jammer" platforms, Bri,...Brj, have a jamming antenna, of omnidirectional type, of directional type or of network type. The friendly platforms ("jammers" or without a jammer) thus have an
30 interplatform communication network which appears as a macronetwork when all of the antenna elements are considered. Figure 1 also shows an area to be jammed 3, which may contain radio equipment external to the

network of friendly stations. The master station 1 receives the common signal
measurements and the jamming signal measurements from the N stations
Rxi---RxN- The master station transmits the jamming instructions to the J
jammers Bri,... Brj.
5 The transmission network may be made up of a plurality of nodes,
and it is possible for the master station used to be one of the nodes or platforms of the transmission network that is associated with a component for calculating the instructions intended for the jammers. The communication links are shown in the following manner:
10 I: conventional common link including all of the measurements taken on the communication or "reporting" links (measurements taken by the interceptors on the sequences of signals transmitted by the friendly transmitters Tx, for example in the friendly Rx stations) that are retransmitted by return channel to the friendly Tx stations and/or to the master station of the jammers,
15 II: link comprising the "reporting" of the measurements on a jammer signal, i.e. all of the measurements taken on the jammer signals (measurements taken by the interceptors on the sequences of signals transmitted by the jammers Br, for example in the friendly Rx stations) that are r'etransmitted by return channel to the master station of the jammers and/or to the friendly Tx
20 stations,
III: command link used to support the broadcasting and application of the instructions from the master station by the jammers, and IV: transmission of the jamming signals to the targeted area 3 and/or to the entities CI that are external to the friendly network.
25 The method implemented by the invention is based notably on:
e the recordings/measurements of the communication signals received by
the interceptors, which are the friendly stations, for example, • the recordings/measurements of the jamming signals interfering with the friendly stations.
30 In the rest of the description, the channels are determined as
being made up of all of the radio propagations between each of the transmitters (jammer or friendly comt^nunication transmitter) and each of the

10
friendly communication receivers or each of the targets or areas to be jammed Ci (the areas to be jammed being discretized in the form of lists of points to be jammed).
The channel matrix is the matrix of the combinations of radio 5 propagation channels between the transmitters and the receivers (Tx Rx channel matrix), between the jammers and the receivers (Br Rx channel matrix) or between the jammers and each of the points to be jammed (Br, Ci channel matrix). These matrices are considered in a first global approach between the platforms (and not between the antenna elements), and the
10 value ai,j of an element of the channel matrix thus physically and globally describes the radio channel between the platform I and the platform j. When a friendly receiver comes into play, the matrix Is informed on the basis of the measurements taken on the useful and jamming signals. When an area or a point to be jammed comes into play, the matrix is informed on the basis of a
15 propagation model betvi/een a jammer f3r and a target Ci. =A!I of these matrices are then considered in a second approach between each transmission antenna element (each platform may be equipped with a plurality of transmission antennas, for example a jamming antenna and a transmission antenna, which are themselves made up of networks of
20 elements) and each reception antenna element (each platform may be equipped with a plurality of reception antennas, which are themselves made up of networks of elements). For each of the approaches, the first level of description of this matrix is binary ai,j =1 if the platform, or the antenna, j receives a signal from the platform (or the antenna) i, and a finer level in the
25 second approach, in particular, corresponds to considering a!,j as the impulse response of the channel i,j, which totally characterizes a multiple input multiple output or MIMO, multiple input single output or MISO, single input multiple output or SIMO, or single input single output or SISO linear channel. This impulse response can be estimated according to the measurements
30 taken by the friendly Rx receivers on the signal sequences, or according to the propagation models considered between jammers and the target or area to be jammed.

11
Knowledge of the positions of the stations is useful for optimizing the operation of the communication network and is necessary for optimizing the jamming. Synchronism or precise dating of the measurements is also useful for better global optimization. Similarly, precise knowledge of the 5 signal sequences contained in the jamming or communication signals is necessary for the measurement of the propagation channels by the friendly Rx receivers and contributes to global optimization.
The graphical representations provide the advantage of offering a synthetic representation of all of the interactions between the players. By way 10 of example, it is possible to show the platforms or the antennas by placing an arc between two platforms or antennas if the signal transmitted by one is received by the other, and therefore if the channel has been able to be measured.
Example provided for the implementation of the methcjci according to 15 the invention
"Useful" MIMO, MiSO, SIMO, SISO communication stations are available on platforms numbering N_PI, of which J platforms have jammers.
Thus, N_pl communication platforms are available. Each of these
20 platforms is MIMO, MISO, SIMO or SISO. Mi, M2...,MNJI, denotes the
number of transmitting antenna elements of each of these platforms. N-i,
N2---,NNJI denotes the number of receiving antenna elements of esach of
these N platforms.
The network made up of the TMJ\ = '^m=^...HJ,\ ^m transmitting 25 antenna elements Tx or Br and of the ENJI = Sn=i...Nji Nn antenna elements Rx appear as a macronetwork, a priori largely incomplete. All of the communication platforms make up a network that is represented by the network graph of size N_pl as defined above and denoted by GO. When all of the antenna elements are considered, it is preferred to represent them by 30 means of the macrograph of size ZMJH-N_PI as defined above and denoted by GO'.

12
The channel matrix of this macronetwork made up of N_pl platforms and EMJRN^PI antenna elements can be written formally, as will be clarified below or as can be seen in Figures 3A, SB and 4, in the generalized form HO'(Tx,Rx) = GO' oc [HO^'^'(Tx,Rx), HO^'^^(Rx,Tx)]. It is determined by the 5 topology of the network (which determines GO and GO') and the channel matrices HO^^^ and HO*"^' that are proper to each TXn —> Rxn link. The Tx^ —> master station communication links comprise the return lines for low-speed messaging systems intended to transmit the data about the channel measurements and about the quality measurements for the transmission to
]o the master station in order to adapt and optimize the transmission instructions.
In the method implemented, called a "closed-loop" method, the transmitters, receivers and communication nodes in the friendly network manage, at each instant t (sampling t^, k = 1, 2,...), the communication links
15 and the pertinent parameterizations (protocols, bit rates, tioding and modulation schemes, if need be, the weighting of the transmitting/receiving antenna networks, use of relays, etc.), while adapting themselves to the radio environment and to the possible jamming residues, but without being explicitly guided by the control component. It is the jamming itself that is
20 controlled by means of the estimation and minimization of the residual fratricidal effects.
All of the antenna networks of the transmitters Txi,..., Txy (M < N_pl) and of the receivers Rxi,..., RXN (N < N_pl) are therefore formalized as a macronetwork GO' (defined by a matrix of size (EMJI'^-ZNJI)^), the links of
25 which are fully described as in Figure 4 by a generalized channel matrix
J Rxn link. The formal construction of these matrices is shown in Figure 4, examples in 30 Figures 3A and 3B and in Figure 2 show the consideration of the propagation channel for constructing the channel matrices that are proper to each Txm -> I'^Xn link. For the Tx„, -> F^Xn crossing, the forma! expression of the useful

13
signals coming from the transmitting platforms and received by the receiving platforms is thus as follows at each instant t:

X,(t)

HOi

HO

IM

s,

X(t) = (HO' *s\t) i.e.

(t)

X^(t)
v^My
HO Ni HO
5 where
9 N is the exact number of receiving platforms having a reception antenna (N < N jl),
e M is the exact number of transmitting platforms having a transmission antenna intended for useful transmissions (M < N _pl), 10 e HO' is the generalized "transmitters to receivers" channel matrix,
• Xn(t) n = 1,..., N is the vector of the useful signals received on the network of the antenna elements of the receiving platform indexed n,
• Sm(t) n = 1,...,IVI is the vector of the signals transmitted on the network of the antenna elements of the transmittitig platform indexed m, in band B.
15 Figure 2 also shows the geometry of the propagation on an axis
X(east), Y(north).
The' link between the element indexed m in the network of transmitting
platforms and the element indexed n in the network of receiving platforms is
characterized by: 20 Sm(t) as mentioned above,
Xnm(t), the contribution vector of the signal Sm received on the element n in
the receiving antenna network,
Xn(t) as mentioned above,
Lmn the number of paths in the propagation channel, 25 I the index of the l-th rnultipath,
^(m, n)| |[^g attenuation of the path I relative to average losses,
^(m, n)j^ ii^g average direction of arrival of the path I,
x^*^"'"'!, the average delay in the path L, the delays being contained in a range
[O, T'""'"'] depending on the urban, mountainous, etc. channel,

14
l^(m,n) jg |j,^g number of subpaths associated with the path I that are supposed to be indiscernible to the band=B signal and are therefore distributed within a range of duration T*'"'"'«1/B, ni is the index of the subpath I, 5 (p''"' "'ni,i is the phase of the subpath indexed I and ni,
a^'"' "^ ni,i is the relative level of the subpath indexed I and ni,
9 *"'"'"' ni,i is the direction of arrival of the subpath indexed I and ni,
Us(6 *""'"' ni,i) is the directional vector corresponding to the subpath indexed I
and ni for the signal source s.
10 "iamrrjers"
Moreover, J platforms among the N_pl are equipped with "jammers" suitable for jamming the communications of the elements that are external to ttie friendly network, which are denoted by Br-i,..., Brj. All of the jammers Br-i,..., Brj and receivers and Rxi,..., Rx^ make up a "jamming"
15 network represented by an interference graph denoted by GJ and subject to a generalized propagation channel HJ'= GJ' & Hj(Br,Rx) defined'according to the process described in Figure 4, while considering the number of transmitting platforms J, the number of receiving platforms N and the associated J x N elemental channel matrices.
20 All of the useful transmitters Tx■(,..., Txy, jammers Br-],..., Brj and
useful receivers Rxi,..., RXN make up a network of "interference/jamming" that is represented by an interference graph denoted by Gl, and subject to a generalized propagation channel Hr= Gl' & H|(Br,Rx) defined according to the same process as in Figure 4, while considering the number of
25 transmitting platforms M+J, the number of receiving platforms N and the associated (M+J) x N elemental channel matrices.
Each of the jammers Brj, indexed j, has an equivalent power level radiated during transmission (PIRE) that is defined by a range [0, F'IREMAXj] with which the following are associated for implementation of the invention:
30 = a power level instruction C_ PIREj, ~ a jamming signal Bj,

IS
= one or more jamming durations Tbj with recurrences Rbj and a lead or delay xj in transmission of the signal Bj in relation to an instruction coming from the master station,
= one or more jamming frequency ranges denoted by Fbj that correspond to 5 the jamming ranges,
- amplitude Aj and phase cpj weightings,
- if need be, an antenna orientation Tj which will be classed below as spatial weighting caused by the antenna directivity.
The master station indicates to the jammers the power levels
10 PIRE, the jamming signals,, the durations of the jamming signals, the recurrences with which these signals appear, the delays, the frequencies and the weightings A\(pi\\ii to be applied, using a specific communication link. The friendly communication network allows the master station to be informed in real time (that is to say at each instant t or at each temporal sariiple tk) and
15 allows the jammers to be managed on the propagation channels Br - Rx (received useful levels, received interference, multipaths, etc.) and on the fratricidal effects caused by the signals Bj j = 1... J. "Jammer interference":
According to the above, all of the antenna networks of the
20 jammers Bri,..., Brj and the reception antenna networks of the receiving platforms Rxi,..., RXN are formalized by two interference rnacronetworks that are defined by:
= a "fratricidal network jamming" macrograph, denoted by GJ', that integrates the transmissions by the single jammers and the associated generalized
25 channel matrix HJ' (Figures 2, 3A and 3B),
= a "fratricidal jamming + network interference" macrograph, denoted by Gl', that integrates the useful transmitters and the jammers, and the associated generalized channel matrix HI' (Figures 2, 3A and 38).
The formal expression J(t) of the interfering/jamming signals
30 received on a receiving network is thus as follows at any instant t; limiting oneself to the signals coming from the single jammers Br:

16

Ji(t)

HJ,

HJ,

^B ^

J(t) = (HJ'f^)*B^t) i.e.

(t)

JNCO

HJ

Njy

vB.y

where
© N is the exact number of receiving platforms having a reception antennci
(N < Njp\),
5 e J is the exact number of platforms having a jamming antenna (J< N_pl),
» HJ'* is the generalized "jammers to receivers" channel matrix, e Jn(t) n = 1,...,N is the vector of the jamming signals received on the
network of the antenna elements of the receiving platform indexed n,
• Bj(t) j = 1,...,J is the vector of the jamming signals transmitted on the
10 network of the antenna elements of the platform indexed j.
"Targets and ia_mmers": Network of jammers:
All of the antenna networks of the jammers Bri,..., Brj and at the target points Cii,.,., Cip are formalized in the manner of the above by a 15 jamming macronetwork that is defined by:
» a "jammernetwork macrograph", denoted by GB", and the generalized
channel matrix HB', which are determined by the topology of the
jammers and of the target areas (whicti determines GB'),
i> the models of channel matrices that are proper to each "jamming" uf Brj
20 in the direction of Cp, which determine HB' (of. Figures 2, 3A, 38 and
4). The formal expression of the jammer signals for the target points is thus as follows at each instant t:

Z,(t)'

HBii

HB,

^B ^

Z(t) = (HB' *B)(t) i.e.

(t)

Zp(t)

yHB^,

H

NJ J

V^jy

25 Network of the useful transmitters + jammers:

17

10

All of the contributions by antenna networks of the useful transmitters Tx-i,..., 1% to the jamming of the target points Cii,..,, Cip, denoted by bii,...,bip below, can also be considered and formalized by a macronetwork of caused jamming that is defined by a macrograph for the "useful transmitters", denoted by Gbi', and the generalized channel matrix Hbi', which are determined by the topology of the transmitters and of the target areas (which determines Gbi') and the models of channel matrices that are proper to each "radio link" from Tx^ to Cip, which determine Hbi'. The formal expression of the jamming signals thus becomes the following at each instant t:

bi(t) + z(t)= [{HB') (nb')]*

s^l

(0 i.e.

Z,(t)

Hbi',

Hbi,,

HB;,

HB,

\^M/

(t)

Zp(t)^

vKbif,,

Hbi„

VHBN,

"Jammer signal optimization instructign":
15 Moreover, each of the jammers applies at each instant t an
instruction denoted by Cons_j(t) that corresponds to a set of parameters
defined in a field of values that is formerly denoted Oorn _Cj.
Dom_Cj is a set defined by the possible parameterizations of the jarTiming
transmissions:
20 • a value PIREj to be chosen in the range [PlREiVllNj, PIREMAXj] (a
constraint PIREMINj > 0 is necessary in order to prevent the solution
to the optimization problem from systematically converging 0 to the
initialization and/or in the transitory phase),
s a jamming signal bj in a discrete and a finite preprogrammed set of
25 signals,
• one or more jamming durations Tbj with the recurrences Rb| and a lead or a delay in transmission TJ, all of these values being limited by predefined limit values IVlax_ Tbj, IVlax_ Rbj, Max Jxj|,

Bj

18
• one or more frequency ranges, denoted by Fbj, that are limited by limit
values [Fb_min, Fb_max|,
e relative amplitude Aj, phase cpj and relative directivity Dj weightings that
are limited by limit value ranges, respectively [V(PIREMINj),
5 V(P!REMAXj)]; [0.27i] and [0.1].
In practice, if, bj(t) denotes the jamming waveform transmitted by the jammer Brj, the jamming signal vector is formally defined by bj(t) and Cons j(t): all of the instructions applied to the jamming waveform bj(t).
The output provides a jamming signal vector Bj(t) of dimension 10 denoted by MBJ which takes the following form, similar to the general formulation of a signal transmitted at the antenna output: In baseband:
4,,(/).e^-(')

4>/., (0-«

fj.Nu,. (')

Dj\i//jj).bj(/-tj).Sjj {t)

On carrier fo:
15

B.(t) = Re

e'^"-'"'.Dj(i^jj)bjit-^-j)

= Re^^^"^"' .DJ ((//,, t]bj (t ^ t. )rs„^ (/)}

where:
e MBrj: is the number of antenna elements of the network used to transmit
20 the jamming signal from the platform j, each antenna element having
the directivity Dj(v|yj,t), that is supposed to be identical in order to
simplify writing (but without restricting the scope of the invention),
e bj(t=Tj) is the baseband waveform of the jamming signal transmitted by
the platform j, delayed by TJ, and supposed to be identical over all the
25 elements of the transmission network in order to simplify writing
(without restricting the scope of the invention),

19
•• A.m(t), (pj,m(t) are the amplitude and phase weightings of the jamming signal on the element m of the antenna network of the jamming platform j,
e SBJ is the guiding vector of the jamming signal transmitted by the
5 platform j, formed by the amplitude and phase weightings Aj,m(t) and
9j,rn(t),
e fo is the carrier frequency of the jamming signal following transposition. All of the parameters other than the application of a delay, the choice of transmission frequencies or subbands and a choice of the 10 waveform apply linearly to the jamming signal and correspond to a convex admissible domain. "Target area or target receiver"
The J platforms Bri...Brj are intended to jam one or more targets or areas characterized by a list of positions Cii ... Cip to be jammed. These 15 positions are firstly geographical but may, by extension, be defined "in the broad sense" in the time/frequency/space domains:
e in the time domain: the area Ci may correspond to time slots to be
jammed which are indexed on a pseudoperiodic frame that is known
and/or controlled by the master station of the jammers,
20 © in the frequency domain: the area Ci may correspond to jamming
subbands to be jammed either in a known manner or in a periodic
manner (with indexing on a pseudoperiodic frame) that is known
and/or controlled by the master station of the jammers,
» in the space domain: the area Ci may correspond to the position of an
25 identified target, to a geographical area around this position, to a focus
towards this position. This allows consideration of a channel matrix
HBC for the jammers towards the target areas (which is reduced in the
case of a single jamming area to a line vector 1xJ), for which the
default values can be determined as a function of a geometrical model
30 or an empirical model of isotropic average attenuation depending on
the distance or any other parametric or empirical model (the target
area does not a priori inform the jammers of the eiTectiveness of the

20
jamming... the jammer network can thus initiate its jamming strategy
only on. the basis of a model, and only then can it control the
effectiveness of the jamming if need be ■= for example using a
technique known by the acronym look-through).
5 The measurement results from the interceptors, for example
implemented in the friendly receivers, are used to calculate instructions in a
master platform which manages the jammers (centralized control/command):
» the useful signals and the measurement and equalization procedures
for these signals in the interceptors, notably on synchronization
10 sequences or pilot sequences, allow the MxN useful communication
channels to be estimated,
» the jamming signals, which also integrate known sequences,
measurement and equalization procedures for these signals, apply in
the same way to these signals in the interceptors.
15 The results of tlie measurements are communicated to the control
component of the master station.
In order to estimate the JxN jamming channels on the targets Ci, the master station extrapolates the determination of the propagation channel (obtained from friendly Rx) to the Brj => Cp propagation channel (based on behavioural 20 models for channels, for example).
The master station optimizes the reception of the useful communications by means of amplitude and phase instructions sent to the jammers which allow minimization of the fratricidal levels received by the reception antennas (instruction = minimization of fratricidal jamming under the constraint of Tx 25 average power or under another constraint) while maintaining the objective of performance on the targets Ci.
IVIinimizing the fratricidal effects on the N reception platforms involves, schematically, guaranteeing tolerable fratricidal effects at the same time as jamming. 30 Guaranteeing tolerable fratricidal effects comes down to minimizing or guaranteeing a level lower than a certain limit for the impact of the signals coming from the jammers, on the signakto-noise ratio + residual interference

21
+ jamming at the output of the demodulators/decoders to be protected, the level limits in question are dependent precisely on the waveform and on the demodulation/coding scheme and on the structure of the network to be protected. By way of example, a common order of magnitude for such a
5 threshold is a binary error rate or BEF^ that is caused by the residual interference and jamming of 10'^ at the demodulation output, which translates into a threshold on the S/J level at reception depending on the modulation (in the order of 7 dB for conventional single-carrier BPSK modulation received with a strong signai-to-noise ratio S/N).
10 tSuaranteeing effective jamming comes down to maximizing the level of jamming or to obtaining a level of jamming that is higher than a given threshold at the points in the area to be jammed: there again, the minimum effectiveness thresholds are dependent on the robustness of the target stations that are intended to be jammed, but except for very specific cases
15 (PN waveform) generating a J/S (jamming over signal) ratio higher than 0 dB in the band of the target receiver is sufficient to guarantee the effectiveness of the jamming.
The station optimizes spatio-temporal coding in the network of 20 jammers under the previous constraints. Implementation variants
1/ Nature of the instnjctions and jamming modes: - sectorial
= min/max/average power
25 - spatio-temporal pattern
2/ In one variant of the method, instructions can likewise be prepared and broadcast to the friendly transmitters.
3/ Nature of the spatio-temporal schemes implemented in the friendly
transmitting stations:
30 e single spatial redundancy between Tx channels and temporal
redundancy

IJIJ
e ST scheme that is robust in the Rx with respect to external interference
(i.e. non=multipath)
• use of one of the Tx antennas for the jamming signal on each MIMO Tx
and of the other Tx antennas for the communication
5 • formation of jamming "spatial channels" with a transmitting subnetwork
(incomplete) of "hybrid" communication/jammer iVllSO Tx. 4/ Nature of the spatio-temporal filters implemented in the friendly receiver stations
Various spatio-temporal filter solutions can be implemented. A nonexhaustive 10 and nonlimiting list is given below:
- Jammer cancellation
- SI MO by means of channel formation (CF) or by means of adaptive spatial filtering (ASF)
- Optimum filter in the presence of external interference
15 - Rejection filter making use of the known jammer F.O. apriority
Optimization in the control component of the master station
Given the topology of the networks and the useful transmission signals SI,...,SM, an instruction vector Cons=(Consi,...,Consj) is sought at
20 each instant t = ..., tk-i , tk, .... in the "admissible" definition domain Dom^C-i x ...x Dom_C J inducing the jamming signal vector B = (Bi,...,Bj)^ and verifying a plurality of constraints such as those clarified below. (i) At least one "BC constraint" linked to the_exjiected^etfectiveness of the jamming, which can be written in several forms on the basis of the above,
25 revealing one of the following convex functionals:
- a BC14ype constraint relating to the maximum level of average jamming or of average "jamming + useful residual" on the target points Cip

(ConSi5...5ConS/) G (Dom^Cj x.„xDom_C/)

j=i
implementfag Max ||Z||J ^ Max
Cons,,...,Consj Cons,,...,CoiiSj
e(Dom_Q x....xDom_C,) G(Doni_Ci x....xDom_Cj

1 V

;(HB;^*B.)(O

or

implemerithg Max
ConSj,,..,ConSj
.xDom C,)

|Z + Z)|f = Max
e (Doni Q x... .xDomCj.)

j=i
P

p=

/,=!

and/or
- a BC2-type constraint relating to a minimum threshold for the average level 5 on the target points Cip for the jamming or "jamming + useful residual" signal
(Cons,,...,Cons,) e (Dom_C, x...xDom_C,)

'/,=!
-'° 7> \ \ /L.^ 'P

P

p=
r(i-iB;^*B^)(0
j=i

> Av eff BC threshold

or

'■'^ -FW''-'-

" =1 "
p II p=l

5](HB'pj*Bj)(0 +XZl™'pm*^m)(0 >- Av^^eftBCjhreshold
j=l
p=l

and/or
= a BC34ype constraint relating to a minimum threshold for the jamming 10 signal level or the "jamming + useful residual" signal at each target point Cip:

(ConSj,...,ConS/) e (Dorn^Ci x...xDom_C^) Zj|=Mm J>;(HB;j*Bi^O
> Min eff BC threshold
Min p=i,..,p'
p J
tq. Min p=i,...,p
j=i
or

t.q. Min p=i,->p

Zp+6 J

= Min p=i,...,p

ZKj*Bjfc+EK.*s„,^o
j=i
Dl=l

> Min eff BC threshold

15 etc.

24
(ii) At least one "constraint J linked to the reduction in the_interference on the receivers, which can be written in several forms on the basis of the above, such as the following forms, revealing convex functionate: = a J1-type constraint relating to the minimization of the average fratricidal or 5 average fratricidal + interfering signal level of the receivers F^Xn:
(ConSi,...,Coiis,) e (Dom_C, x...xDom_C^)

1 hv J , I
— y y IHT' *R tfi
implemeiitiig Min |j|| I = Min
(Coiis,,.„,ConSj) "I '!■' (Coos, ConSj) TV Iprf I ■_,
e (DoniC, x...xDom_Cj) e (DomC, x...xDom_Cj)| V " ' '
Mi
'" '.i,...,ConSj) (CoaS|.....ConSj)
jmC] x...xDom_Cj) e (DOI
N M , , ' N 1 , ,
or implementiig Mm
(OofiSj,...,Coo;!;)
e (Dom C'l x ..! x DomCj )
Mill |l||l =
TV
(OofiSi,....Coos,) ^' " (Cons, Cons^,
'" " " " ^ 5 (Dome, x...xDom_Cj)

and/or
- a J24ype constraint relating to maximum thresholding for the average 10 fratricidal or fratricidal + interfering signal level on each receiver F^Xn:
(Cons,,...,Cons,) e (Dom_C, x...xDom_Cj)

< Av J Rx threshold

or

. ^ VlT P
t.q. —J > I

iJi

E\™>..n*S,„)(0 +}^ZlHJni*Bj)(0 ^ AvXRxJhresliold
m=l I H=l j=l

and/or 15 - a J3-type constraint relating to maximum thresholding for the interfering signal level on each receiver RXn:
(Cons,,...,ConSj) e (Dom__C, x...xDom_C,) tq. Max IJ jl = Max I -^, IfV (HJ • * B, Vr)
< Max J Rx (tu'eshold

1 ^
n=l„..,N" "I-" n=l„.„N ]\f
or
tq. Max|jl„|l= Max
,1-1 M^' "I-* ..-1 M

N 1 ■j=l
M , . " « J , ,
E(HO;„,*S,,)(O +EEK*B.)(/)

< Max .T Rx threshold

e4p
(iii) If need be a MinJ instruction linked to the minimization of the transmitted jamming power, which can be written in several forms on the basis of the above, such as the following forms, revealing convex functionals: = A MinJ14ype instruction: minimizing the average jamming power over the course of time t and on the jammers j

10

and/or = a MinJ24ype instruction: minimizing the maximum power averaged over time, transmitted by each jammer]

15


and/or - a MinJ34ype instruction: minimizing the instantaneous power transmitted by each jammer j (Cons,,...,Cons^) e (Dom^C, x...xDom C,)
MinMax^
Bj(Of)}

20
25

pip
Example 1: cooperative barrage iamming
This particular implementation example for the invention applies to the optimization of tactical barrage jamming in the presence of friendly frequency-hopping communication stations, a method which was the subject of the patent from the applicant under the number EP 1303069.
The text below shows how the general method of the invention described previously can be used for this particular application.
The master station manages a barrage jammer or a network of barrage jammers that are capable of interrupting, upon instruction, their

26
transmissions on a time slot and on a frequency channel indicated by an instruction.
P tactical stations that are present in the theatre need to be
jammed, denoted by Cip, p = 1,..., P. These stations are positions which are
5 known or otherwise. The sen/ices that they use and the corresponding points
of operation are supposed to be known, as are their features (jamming
thresholds/denial of various services, operating margins, etc.).
N friendly frequency-hopping tactical receivers need to be preserved, denoted by Rn n = 1,..., N. 10 These receivers are positions that are known approximately. Their waveform and their modes of operation are known features of the master station of the jammers:
•> The frequency-hopping law, and, if need be, the transmission powers
and waveforms used, are known a priori, or even guided by a tactical
15 communication node.
t . If these waveforms are decorreiated, each jammer thus has a transmitted total average power Cj=<|Bj(t)p>twhich is written as j = 1,...,J; Cj = Es=i...,s Cj,s.
P GNSS receivers need to be jammed, which are denoted by Cp p 5 - 1,..., P. These receivers are in known positions. The GNSS services that they use are supposed to be known, as are their features (jamming thresholds/denial of various services, operating margins, etc.).
N GNSS receivers to be preserved, which are denoted by R,, n =
1,..., N. These receivers are in known positions and have known features. In
10 this sense, the master station of the jammers has a priori information about
the interference caused on the receivers to be preserved as if there were a
return channel.
A linear interference model for the service s of each receiver n that is well known to a person skilled in the art (and, in oriier to simplify 15 denotations, subsequently supposed to be homogeneous for each receiver, which does not cause any loss of generality for the invention):

N,„I'\-\C.^^.GE.^,,L.^„l\,SSCj^,
with:
20 Cs: the power of the useful signal in fr^ont of ttie antenna for the service
supported by the signal s (dBm)
GRs: the gain obtained by the processing and by the reception antenna or the
reception antenna networ'k on the useful signal (dBi)
TIR: the yield internal to the reception chain (antenna yield, cable losses, 25 etc.)
pR.Nth: the thermal noise of the receiver taking account of the noise factor FR
of the reception chain
GEj,n: the antenna gain of the jammer j in the dii^ection of the receiver n (dBi),
the corresponding equivalent radiated isotropic power can be written as
30 PIREj = CsGEj,n

31

10
15

Dj,n: the directivity of the reception antenna n in the direction of the jarnmer j
(dBi)
SSCj,s: the coefficient of spectral correlation between the jammer signal Bj(t)
and the useful signal s(t) (with a value between 0 and 1)
Cj,s: the average power of the signal transmitted by the jarnmer j for the
denial of service supported by the signal s signal (dBm) (i.e. level of power
allocated by the jammer j to the FOB dedicated to the service s) Cj,s =
<|Bj,s(t)p>t
Cj: the average total power of the signal transmitted by the jarnmer j (dBm):
Cj = <|Bj(t)f >t:
Lj,n: the propagation loss between the jammer j and the receiver n (dB).
With the previous formalism, the problem is thus modelled in the form of instructions on the jammers Bj needing to comply with the constraints of eflBctiveness of the jamming on the targets C,, p=1,...,P, and the constraints of absence of fratricidal denial on receivers Rp n = 1,..,N; while minimizing the average total power of jamming:

^ConS|,...,Cons r j e (Dom__C| x...xDom__C r j tq.

(constrairitof lype(BC3))
Min |z„| = Mill
Max Pnl = Ma 11=1,...Jsf" ^^^ 11=1,.

_E(HB'. *Bj^/)| > Min_eff_BCjlireshold
:'|V jjj
< Max_J_Rx_threshold (constraintof type(J3))

mm
K,4

(J s ^
/LI 1^ ^ i V

(instructidi of type(MinJl))

20

The impulse responses HB' and HJ' are not known precisely but the associated channels can be modelled by an attenuation A that is estimated on the basis of the propagation models.

32
The use of the multisource interference model and of the antenna diagrams, by contrast, allows more precise clarification of the constraints of effectiveness and of absence of fratricidal denial: For each receiver p=1,...,P to be jammed,
5 for each service Sp = 1,... ,S used by the receiver p:
y.JlGE..C..L,..D..SSC^^ >A;, \/p = l,...,P and \fs=\,...,S
where A'Sp is the guaranteed non=operation threshold of the receivers for the service Sp
10 For each receiver n=P+1,...,P+N to be preserved,
for each service Sn = 1,...,S used by the r^eceiver n:
J S
y yG£',„.C. ./),„.Z. ,.,5'5'C , 0
Denotations:

33
C is defined by;

C:

[0]

[-1] vector of components -1 of dimension JxS [0] null vector of dimension N1+M1+J

X is defined by x =

CJ
E

vector of dimension J.S + (N1+M1+J)

with the following arrangement: l=j,s: j=1, ..J and for each j: s= 1,...,S

1,1
C,

C,

C

l,s

with CJ =

: vector of dimension JxS,

C,

c,

c

J,s

10

with E

vector of dimension N1 "i-MI+J

where en is a free variable representing the operating margin on the 15 receiver n
(difference between the operating threshold of the receiver and the global interference level).

34

-A r 0 0
A 0 -'MI 0
Q 0 0 I

of dimension (N1+M1+J) x

(J.S+N1+MH-J)
!NI identity matrix of size N1
5 I Ml identity matrix of size M1
!j identity matrix of size J

A =

... a

P.I

ocpj.GEj_^^.Dj^^.SSC^^^^.Lj^^^p (p = l,..,P.S ; / = (j,s) = l,...,JxS)

10

... p„j ...

P„j.OEj„.Dj„.SSC,„,.Lj_„ (n = P.S + 1,...,(P + N).S; / = (j,s) =1...JxS)

e=

^H,k

qn,k = 1 for k=(rv1).S+1, ...,n.S; qn,k = 0

otherwise b is defined by

15 b =

Dp CJ max

vector of dimension NI+l^l-s-K

with:

£>„

vector of dimension N1, p= 1 .. N1

D.

vector of dimension Ml, n= N1+1 ..(N1+M1)

35

CJ

CJ,

vector of dimension J

10

The optimization problem posed above that corresponds to the implementation of the invention in this particular example Is linear. The solution is thus obtained by implementing the simplex algorithm, which is well known to a person skilled in the art, for solving linear programming problems: given a set of linear inequalities over n real variables, the algorithm allows the optimum solution to be found for an objective function which is also linear.
In geometric terms, all of the linear inequalities define a polytope in n-dirnensional space.
The simplex solution makes it possible to determine whether the problem has solutions and, if this is the case (for example for a convex polytope), to determine an extremum, that is to say a minimum-power jamming solution.

CLAIMS
1- Method for selectively and dynamically optimizing, with reduced fratricidal
effects, the jamming of P predefined areas or positions in a network of communication transmitters, jammers and receivers comprising a plurality N_pl of platforms, a number M < lsl jal of said platforms being equipped with antennas and systems for transmitting useful transmission signals, a number
10 N < N_pl of said platforms being equipped with antennas and systems for receiving useful transmission signals, a number J < N_pl of said platforms that are managed by a master station (1) being equipped with jamming systems and antennas suitable for preventing the transmissions between entities that are external to said network, comprising at least the following
IS steps:
• measuring the useful communication signals received by all of the N reception platforms, taking these measurements as a basis for estimating the M*N useful propagation channels, and transmitting these measurements to the master station managing the platforms equipped with the jamming
20 antennas,
e measuring all of the jamming signals received by the N reception platforms, taking these measurements as a basis for estimating the J*N fratricidal propagation channels, and transmitting these measurements to said master station,
25 » taking the measurements of the useful communication signals and propagation channels and of the jamming propagation signals and channels as a basis for calculating, in the master station, jamming instruction values, the jamming signals, the recurrence of the transmissions, the carrier frequencies for the transmissions, the leads/delays upon transmission in
30 relation to a synchronization reference, the radiated equivalent powers, the amplitude and phase weightings on the transmitting antenna networks and on the jamming antennas, guaranteeing an effectiveness for the P areas to

37
be jammed corresponding to the entities that are external to the network,
while minimizing the fratricidal effects on the N reception platforms,
9 transmitting these instructions to the J platforms equipped with a jamming
antenna,
a taking the first calculated and applied instructions, while continuously
making use of the measurements from the fratricidal propagation channels
coming from the receiving platforms, as a basis for optimizing by means of
iteration the jamming of the areas to be jammed while maintaining fratricidal
jamming which is acceptable for the quality of the useful transmissions.
10
2 - Method according to Claim 1, characterized in that it uses the measurement from the propagation channels coming from the N reception platforms in order to jointly optimize the jamming and quality of the useful transmissions on the transmitting platforrTis by adapting the transmission 15 power levels, and/or the spatio-temporal coding schemes and/or the transmission protocols in the time/frequency domain of the jammers and the transmitters.
3- Method according to Claim 1 or 2, characterized in that the master station 20 used is one of the transmission network platforms which is associated with a component for calculating the instructions intended for the jammers.
4 - Method according to Claim 1 or 2, characterized in that it uses
programmable jammers that are suitable for dynamically taking into account
25 transmission instructions, on the power and/or on temporal parameters, the waveform, spatio-temporal coding, the amplitude-phase weighting.
5 - Use of the method according to one of Claims 1 to 4 in transmission
networks using the MIMO, MISO, SIMO or SISO protocol with a return
30 channel from the receivers to the transmitters.

39
Abstract METHOD FOR JAMMING COMMUNICATIONS IN A CLOSED-LOOP
CONTROL NETWORK
5 Method for selectively, dynamically and adaptively jamming the third=par1:y radio communications that are external to a radio communication netvjvork to be protected, which optimizes the effectiveness of the jamming of P predefined areas or positions in a network of transmitters, and which uses closed-loop control to limit fratricidal effects on certain platforms having 10 telecommunication transmitters/receivers to be preserved, said method using the following elements :
• jammers that are programmable and dynamically configurable in terms
of waveform, frequency map, amplitude and phase, temporal
transmission pattern, and that are managed by a centralized or
15 dispersed control component,
<» sequences of digital signals transmitted by the jammers suitable for
allowing precise transmission channel measurements, and jamming
power measurements in the friendly reception stations,
e sequences of digital signals transmitted by the friendly transmitters
20 suitable for allowing precise transmission channel measurements, and
useful signal power and jamming signal power measurements in the
friendly stations,
® communications between networks of jammers, component for
managing the network of jammers, friendly network, and control
25 component and communication nodes in the friendly network,
e a master station allowing the preparation of transmission instructions for
the jammers with a closed control loop, based on the measurements
taken in the friendly receivers (or in interceptors associated therewith),
which are themselves measured on the basis of useful and jammiiny
30 signal sequences and on the estimation of the propagation channels
on the basis of these sequences.

38
6 ~ Use of the method according to one of Claims 1 to 4 in a radio ne'twork in which the receivers are suitable for measuring channel values on the useful transmitters and on the jammers.
5 7 - Use of the method according to one of Claims 1 to 4 in a radio network in which the reception stations have antenna elements that are coupled to an interceptor taking the channel measurements on the useful transmitters and on the jammers.
10 Dated this 113/11/2012
(RANJNA MEHTA-DUTT)
OF REMFRY & SAOAR
ATTORNEY FOR THE APPLICANT[S]