Millimeter wave communication system

Abstract

The invention relates to a communication system (1) operable in the millimeter-wave spectrum, comprising:-a transmitter (10) arranged to transmit a transmit millimeter-wave signal,-a polymeric millimeter-wave fiber (30) arranged to propagate the transmit millimeter-wave signal,-a receiver (20) arranged to receive the transmit millimeter-wave signal from the polymeric millimeter-wave fiber (30), the transmitter (10) is arranged to receive an input signal and comprises:-an in-phase path (5) and a quadrature path (7) for the input signal,-modulation means (16) for performing modulation by means of a millimeter wave carrier signal,-amplifier means (17),-combiner means (18), and is characterized in that the in-phase path (5) and the quadrature path (7) are coupled to the in-phase path (5) and the quadrature path (7), and in that the in-phase path (5) and the quadrature path (7) are coupled to the in-phase path (7). The in-phase path and the quadrature path each comprise a pre-equalization filter (12, 14) to filter an input signal before the input signal is applied to the modulator device, the amplifier device and the combiner device.

Description

Technical Field

[0001] The present invention generally relates to the field of high frequency signal communication systems. More specifically, the present invention relates to a millimeter wave communication system for data transmission between two points via a millimeter wave dielectric waveguide. Background Art

[0002] For many years, fiber-based communication links have been gaining increasing attention as an alternative to wire links for high-speed data communications, e.g. at transmission signal wavelengths in the range of 200nm to 2000nm. While the demand for sufficient bandwidth and data rates is increasing, the link length of wires is limited by transmission losses, while optical links are feasible and widely used for long link lengths. On the other hand, the costs associated with conventional optical link solutions increase rapidly when laser sources in specialized III-V technologies and Bragg gratings with microlenses in precision components are required. Furthermore, components like modulator drivers or transimpedance amplifiers set limits on the bandwidth used. As a result, optical links become less interesting as the link length decreases.

[0003] Since about ten years ago, communication systems have been introduced in which dielectric waveguide / optical fiber is also used to transmit millimeter wave (mm-wave) signals with low loss beside a pair of transceivers. This optical fiber is also referred to as polymer millimeter wave fiber or PMF in the literature. The PMF solution uses a millimeter wave carrier signal with a frequency range of 30 to 300GHz. Different millimeter wave bands have been proposed for high-capacity communication systems. Contrary to optical fiber and optical-to-electric conversion equipment or precise alignment equipment, plastic waveguide interconnections do not require expensive electrical-to-optical conversion equipment and optical-to-electric conversion equipment, or precise alignment. In addition, due to good field confinement and low path loss, they provide long transmission distances. Multiple plastic waveguides can be used in parallel, and modulated data of different frequencies can be multiplexed to increase data rates.

[0004] PMF uses a switching modulator fully integrated in IC technology. The transceiver can be implemented completely electrically in standard chip technology. The relatively large wavelength (compared to optical) allows the use of an antenna on the package or on a printed circuit board (PCB) as a coupler to launch the signal into the optical fiber without the use of microlenses. Due to the three orders of magnitude difference between optical and millimeter wave wavelengths, the entire assembly is much more tolerant to misalignment and vibration.

[0005] However, PMF solutions face very different channel conditions than systems using optical fiber. In the latter case, only a very small part of the fiber bandwidth is used for the communication channel, for example only 0.01%. The losses are practically constant over frequency in a single channel and are very low. The available signal bandwidth is limited by chromatic dispersion and polarization mode dispersion.

[0006] In contrast, a communication system with a PMF waveguide shows very different channel characteristics. A communication channel in a PMF occupies relatively more of the available bandwidth. For example, the fractional bandwidth of the channel may amount to 18% or more of the dielectric waveguide bandwidth. In addition, the losses may vary significantly from the lowest frequency to the highest frequency of the communication channel. If the center frequency of the communication channel is considered, it can be said that the upper and lower sidebands relative to the center frequency have very different characteristics.

[0007] Millimeter wave transmitters and receivers (transceivers) are known in the art. Such millimeter wave transmitters typically include a modulator that receives a carrier signal from an oscillator and modulates it with a data signal. Examples can be found in US2017 / 237457.

[0008] Therefore, further improvements in communication systems using PMF waveguides are needed to take into account the specific characteristics of the channels in such systems. Summary of the invention

[0009] It is an object of embodiments of the present invention to provide a communication system via millimeter wave dielectric waveguides that overcomes at least some of the limitations and disadvantages imposed by such transmission media.

[0010] The above mentioned objects are achieved by the solution according to the invention.

[0011] In a first aspect, the present invention relates to a communication system capable of operating in the millimeter wave spectrum, comprising:

[0012] - a transmitter arranged to transmit a millimeter wave signal,

[0013] - a polymer millimeter wave optical fiber arranged to propagate the transmission millimeter wave signal,

[0014] - a receiver arranged to receive the propagated transmitted millimetre wave signal,

[0015] Wherein, the optical transmitter is arranged to receive an input information signal and comprises:

[0016] - In-phase path and quadrature path for input signal,

[0017] - modulation means for performing modulation by means of a millimeter wave carrier signal,

[0018] - an amplifier device,

[0019] - Combiner device.

[0020] The communication system is characterized in that the in-phase path and the quadrature path each include a pre-equalization filter to filter the input signal, and then obtain a transmission millimeter wave signal by applying the filtered input signal to a modulator device, an amplifier device, and a combiner device.

[0021] The proposed solution does allow for higher throughput communications in polymer millimeter wave fiber waveguides. Channel non-idealities are pre-compensated in a pre-equalization filter on the transmitter side, where the in-phase path and the quadrature path are readily available. The advantage of the proposed system is that the amount of inter-symbol interference on the receiver side is reduced or even completely eliminated. The advantage of the proposed system is that no carrier recovery mechanism is required.

[0022] In a preferred embodiment, the transmitter comprises a millimeter wave coupler for coupling the transmission millimeter wave signal to the polymer millimeter wave optical fiber. The use of this millimeter wave coupler is useful in order to avoid electromagnetic power losses.

[0023] Preferably, the communication system further comprises a clock and data recovery module to derive a clock signal of the input signal. The recovered clock signal can be advantageously used in a pre-equalization filter.

[0024] In some embodiments, the modulator means comprises a generator means for generating a millimeter wave carrier signal and a mixing means for mixing the millimeter wave carrier signal with a filtered input signal in an in-phase path and a quadrature path, respectively. The combiner means is then preferably adapted to combine the mixed signals in the in-phase path and the quadrature path to obtain a transmit millimeter wave signal. The amplifier means may then be adapted to amplify the combined mixed signal before obtaining the transmit millimeter wave signal. In an advantageous embodiment, a voltage controlled oscillator or a frequency multiplication chain and a hybrid coupler are provided.

[0025] In a preferred embodiment, the amplifier means and the mixing means are part of an RF digital-to-analogue converter structure.An advantage of using an RF-DAC structure is that the amplitude linearity requirements on the signals in the I-path and the Q-path can be relaxed.

[0026] Advantageously, the filtered input signals in the in-phase path and the quadrature path, respectively, are combined and then modulated with a millimeter wave carrier signal. The communication system may then comprise a conversion module, wherein the amplitude and phase of the signal are combined with said filtered input signal.

[0027] In one embodiment, the phase is applied to a phase shifter and the amplitude is applied to an amplifier device.A phase shifter provides the advantage that it exhibits a highly linear characteristic.

[0028] In some embodiments, the pre-equalization filter is a digital filter.

[0029] In some embodiments, the pre-equalization filter is a mixed signal filter.

[0030] For the purpose of summarizing the present invention and the advantages achieved relative to the prior art, certain objects and advantages of the present invention have been described above in this document. Of course, it should be understood that not all such objects or advantages may be achieved according to any particular embodiment of the present invention. Thus, for example, those skilled in the art will recognize that the present invention can be embodied or performed in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0031] The above and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout the various figures.

[0033] Figure 1 A general scheme of a millimeter wave communication system according to the present invention is shown.

[0034] Figure 2 A preferred embodiment of the communication system of the present invention is shown.

[0035] Figure 3 A preferred embodiment of the communication system of the present invention is shown.

[0036] Figure 4 An alternative embodiment of the communication system of the present invention is shown.

[0037] Figure 5 shows the Figure 2 Some simulation results obtained from the setup in . DETAILED DESCRIPTION

[0038] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0039] Furthermore, the terms first, second, etc. in the specification and in the claims are used to distinguish between similar elements and not necessarily to describe a sequence, temporally, spatially, in ranking, or in any other manner. It should be understood that the terms so used are interchangeable where appropriate, and that the embodiments of the invention described herein are capable of operation in a sequence different from that described or illustrated herein.

[0040] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Thus, the term should be interpreted as specifying the presence of the stated features, integers, steps or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of component A and component B. This means that for the present invention, the only relevant components of the device are A and B.

[0041] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in various embodiments" in various places throughout this specification do not necessarily all refer to the same embodiment, but may refer to different embodiments. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0042] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the inventive aspects lie in fewer features than all of the features of a single preceding disclosed embodiment. Thus, the claims appended to the Detailed Description are hereby expressly incorporated into the Detailed Description, with each claim itself representing a separate embodiment of the invention.

[0043] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in these other embodiments, the combination of features of different embodiments is intended to fall within the scope of the present invention and form different embodiments, as will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0044] It should be noted that the use of a particular term in describing certain features or aspects of the present invention should not be taken as implying that the term is redefined herein to be limited to include any specific characteristics of the feature or aspect of the present invention associated with the term.

[0045] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques are not shown in detail to avoid obscuring the understanding of this specification.

[0046] The present invention discloses a communication system operable in the millimeter wave (mm-wave) spectrum. The millimeter wave spectrum refers to a frequency range of 30 GHz to 300 GHz and preferably to 500 GHz. A frequency of 30 GHz corresponds to a wavelength of 10 mm, 300 GHz corresponds to a wavelength of 1 mm, and 500 GHz corresponds to a wavelength of 0.6 mm, hence the name millimeter wave spectrum.

[0047] Figure 1 A general block diagram of a communication system for communicating through a millimeter wave dielectric waveguide according to the present invention is depicted. The system comprises a transmitter (10) and a receiver (20) connected via a millimeter wave dielectric waveguide (30).

[0048] The baseband signal m(t) is applied at the input of the transmitter portion (10) of the system. In a preferred embodiment, the baseband signal is a pulse amplitude modulated (PAM) signal. As is well known to those skilled in the art, the information bits to be transmitted are thereby encoded in the amplitude of a series of signal pulses. PAM signals are generally considered to be used for high-speed data connection links. In other embodiments, the baseband signal may be a pulse width modulated (PWM) or pulse code modulated (PCM) data signal, but is not limited thereto.

[0049] For high-speed baseband signals carried by millimeter wave signals, an important challenge is to deal with frequency-dependent power fading and frequency-dependent phase shift caused by dispersion in dielectric waveguides, which is caused by the propagation speed varying with wavelength. In the communication system of the present invention, this problem is solved by performing pre-equalization in the transmitter. Pre-equalization filters (12, 14) are provided in the in-phase path (8) and the orthogonal path (9), respectively. Each pre-equalization filter has its own filter coefficients and therefore its own impulse response.

[0050] Each pre-equalization filter receives a baseband signal m(t), such as a PAM signal, at its input. The filtered baseband signal is then fed to the rest of the transmitter scheme, which includes a modulator, an amplification device and a combiner. The modulator modulates the signal received at its input by a millimeter wave carrier signal. The carrier signal may be derived from a voltage-controlled oscillator operable in a frequency range of, for example, 30 GHz to 300 GHz (preferably in a range of 30 GHz to 500 GHz). Alternatively, the carrier signal may be obtained from a frequency multiplication chain, i.e., a series of frequency multiplication circuits, thereby generating a millimeter wave local oscillator signal. In addition to the frequency multiplication chain, a frequency division chain, or a combination of a frequency multiplication chain and a frequency division chain may be considered for generating a signal in a frequency range of, for example, 30 GHz to 300 GHz or 500 GHz from any lower or higher signal frequency. The combiner may be as simple as a summer, which calculates the sum of the signals from the in-phase path and the orthogonal path, respectively. How the functional modules are connected and receive the filtered baseband signal depends on the specific embodiment. Several exemplary embodiments will be discussed in more detail below. The millimeter wave signal to be transmitted is derived from these functional modules.

[0051] In a preferred embodiment, a transmitter module in a communication system generally includes a clock and data recovery (CDR) circuit for recovering the clock of an input signal. This allows a discrete time filter, in particular a pre-equalization filter, to be implemented with the recovered clock signal.

[0052] In an advantageous embodiment, a millimeter wave coupler is provided at the output of the transmitter, the millimeter wave coupler being operable in the millimeter wave frequency range of 30 GHz to 300 GHz, preferably in the range of 30 GHz to 500 GHz, for coupling the transmission millimeter wave signal to the polymer millimeter wave optical fiber.

[0053] Millimeter wave signals are transmitted in low-cost polymer (e.g., plastic) media as waveguides. Waveguides can be solid, hollow, contain chambers of other materials, or a combination thereof. Polymer waveguide media serve as directional channels for guiding electromagnetic waves and provide large bandwidth for data communications using millimeter wave carrier frequencies. It can be bent and twisted without significantly affecting the transmitted signal. Polymer waveguide interconnections do not require expensive electro-optical conversion equipment and optical-electrical conversion equipment or precise alignment, and provide long transmission distances due to good field confinement and low path loss at millimeter wave frequencies. Multiple plastic waveguides can be used in parallel, and modulated data of different frequencies can be multiplexed to increase data rates. Various types of plastics can be considered for use as PMFs. Example materials can be non-conductive materials such as polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE) and other fluoropolymers, but are not limited thereto.

[0054] The receiver of the communication system according to the invention is a receiver commonly encountered in radio communication systems. It can be a non-coherent receiver, in which no local oscillator signal is present for demodulation, or a coherent receiver, in which carrier signal recovery is performed, or in some other way the carrier signal is shared between transmitter and receiver. In a preferred embodiment, a millimeter wave coupler (22) is provided at the receiver input (see Figure 2 ). A millimeter wave coupler similar to that which may be used on the transmitter side may be used, although this is not a strict requirement. The receiver structure typically includes a low noise amplifier (24) which boosts the received signal to a sufficiently high level for further processing in a millimeter wave detector module (26) which is responsible for demodulation. The resulting baseband signal is then applied to a baseband amplifier (28) to produce a baseband output signal. An alternative receiver implementation may use an intermediate down-conversion stage which uses a fixed local oscillator to an intermediate frequency. The IF signal may then be demodulated as described above.

[0055] The filter coefficients of the pre-equalization filters in the in-phase path I and the quadrature path Q are determined so that the complex channel impulse responses hi(t) and hq(t) are pre-compensated for the degradation that occurs when traveling on the channel, and the signal is received in the receiver module without inter-symbol interference distortion or with at least a reduced amount of inter-symbol interference distortion and can then be demodulated. As is known, the pre-equalization filters (12, 14) actually represent the estimated inverse channel given by the receiver-side adaptive equalizer. Channel estimation needs to be performed. In practice, inter-symbol interference is usually limited to a finite number of samples. Therefore, for equalization, a finite impulse response filter with a finite number of taps (symbol-spaced taps or fractionally-spaced taps) can be used.

[0056] The pre-equalization filter coefficients can be obtained in an open-loop configuration or a closed-loop configuration. In an open-loop configuration, the channel frequency response can be pre-characterized by electromagnetic simulation of the channel or via measurement. The optimal time-domain filter coefficients for a given distance and an ideal impulse response target can be calculated and loaded into the filter in the transmitter. Alternatively, in a closed-loop configuration, the pre-equalization filter is implemented as an adaptive filter, for example, using an advanced stochastic gradient algorithm based on, for example, a minimum mean square error (MMSE) criterion, such as a minimum mean square filter (LMS), a recursive least squares (RLS) filter, or a constant modulus algorithm (CMA). For example, the error signal can be obtained by observing the opening in the eye diagram of the received signal on an oscilloscope. The error signal must be fed back to the transmitter through a reverse channel. The reverse channel can be implemented using the same optical fiber as the main communication channel or in any other way.

[0057] As already mentioned, in embodiments of the present invention, there are many possible ways to connect the main functional modules in the transmitter (i.e., modulator (16), amplifier (17), combiner (18)), to which the filtered signals output by the various pre-equalization filters are fed. Some preferred embodiments are described in detail below.

[0058] exist Figure 2 In the invention, mixed signal pre-equalization filters (12, 14) output analog signals in the in-phase path (8) and the quadrature path (9), respectively. Each path includes an RF up-conversion mixer, which mixes the analog filter output signal with the in-phase signal (43) and the quadrature signal (45), respectively. The in-phase signal and the quadrature signal can be obtained by conventional means, such as a millimeter wave VCO, a frequency multiplication chain or a frequency division chain, and a 90° hybrid coupler. The up-converted in-phase signal and the quadrature signal are then combined in an RF combiner (18), and the resulting signal is applied to a linear power amplifier (17), which then outputs a transmit signal.

[0059] Via the millimeter wave coupler, the transmission signal is applied to the PMF (30). On the receiver side, a millimeter wave coupler (22) is preferably also provided to couple the signal received from the PMF to the receiver structure. The latter essentially comprises the already described Figure 1 Functional modules discussed.

[0060] The filter coefficients can be determined using the methods discussed above.

[0061] Figure 3 Another preferred architecture of the transmitter of the system of the present invention is shown in FIG. The figure shows the incoming baseband signal and the (optional) clock and data recovery module (4). The module passes the incoming signal and reaches the pre-equalization filter via the in-phase path and the quadrature path respectively. The clock and data recovery module (if present) further recovers the clock signal from the input signal and forwards the clock signal to the corresponding pre-equalization filter. Figure 3 The pre-equalization filter in the embodiment is a finite impulse response filter. In another embodiment, an infinite impulse response filter may be used. The digital signal output by the pre-equalization filter is then applied to the RF-DAC in each path. The RF-DAC (47) further receives the in-phase signal (43) and the quadrature signal (45) respectively. The in-phase signal and the quadrature signal can be obtained by conventional means, as described above. Each RF-DAC mixes the two signals at its input to obtain an RF signal and performs digital-to-analog conversion. The signals from the I path and the Q path are then combined in the RF combiner (18) to obtain the transmitted millimeter wave signal.

[0062] The rest of the program is similar to Figure 2The transmission signal is applied to the PMF via a millimeter wave coupler. On the receiver side, a millimeter wave coupler is preferably also provided for coupling the signal received from the PMF to the receiver structure. The receiver structure basically comprises the Figure 1 Functional modules discussed.

[0063] Here the filter coefficients can also be determined using the method discussed above.

[0064] Depend on Figure 3 The scheme of provides the advantage that the amplitude linearity requirements can be relaxed. In this scheme, only a constant amplitude signal flows in the amplification chain, and the signal amplitude is only modified in the stage including the RF-DAC. In addition, the RF-DAC can be operated in switch mode because the digital-to-analog conversion linearity depends only on the number of devices turned on or connected to the output, and not on the inherent transconductance linearity of the devices. This allows for better performance in terms of linearity in this architecture.

[0065] Figure 4 Another possible architecture of the transmitter is shown in FIG. Again, the baseband signal enters and a clock and data recovery module (4) may be optionally provided. This module passes the incoming signal and reaches the pre-equalization filter via the in-phase path and the quadrature path respectively. The clock and data recovery module (if present) further recovers the clock signal from the input signal and forwards the clock signal to the corresponding pre-equalization filter. Figure 4 The pre-equalization filters (12, 14) in the embodiment depicted in are also finite impulse response filters. The in-phase filtered digital signal and the quadrature filtered digital signal output by the pre-equalization filter are then applied to module (11) where these signals are converted into a polar coordinate representation. The phase digital signal in this representation is used to directly modulate the phase of the generated LO signal by a digital phase shifter circuit (13). The resulting phase shifted signal is fed to the RF-DAC which modulates the amplitude of the transmitted signal using the amplitude signal calculated in the I / Q to polarity module (11). This produces the final signal for transmission.

[0066] Figure 4 The rest of the program is similar to Figure 2 The transmission signal is applied to the PMF (30) via the millimeter wave coupler (19). On the receiver side, a millimeter wave coupler (22) is preferably also provided for coupling the signal received from the PMF to the receiver structure (20). The receiver structure basically comprises the Figure 1 Functional modules discussed.

[0067] Here the filter coefficients can also be determined using the method discussed above.

[0068] Figure 4The scheme may be advantageous in terms of linearity characteristics. This is due to the very linear characteristics of the digital phase shifter. In addition, this architecture alleviates the need for a combiner after the RF-DAC, allowing its output power to be higher. Therefore, it is well suited for longer distances.

[0069] Now we show some simulation results. Figure 2 The system depicted in is simulated where the channel is a 7-meter polymer microwave fiber. The transmitter is an IQ transmitter and the receiver is a non-coherent receiver with envelope detection only. In both, all modules are assumed to be ideal. Therefore, the signal is only affected by the channel response and the equalization filter response. The system transmits a PAM-4 signal at a 28 Gigabaud symbol rate. Figure 5a The resulting eye diagram for a system without any equalization is shown in . In this case, the eye is completely closed, meaning that there is a lot of inter-symbol interference and no data can be recovered. Figure 5b In , the results obtained with a 5-tap equalization filter are shown. In this case, most of the ISI has been compensated, but there is still residual ISI, especially affecting the lower eye, which is the most sensitive in the power detection system due to its nonlinearity. Finally, in Figure 5c In Figure 1, a 10-tap equalization filter is used. The channel has been adequately compensated. Clearly, a pre-equalization system can compensate for channel non-idealities and improve performance and achievable data rates.

[0070] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary, rather than restrictive. The foregoing description describes certain embodiments of the present invention in detail. However, it will be appreciated that no matter how detailed the foregoing description appears in text, the present invention can be practiced in many ways. The present invention is not limited to the disclosed embodiments.

[0071] By studying the drawings, the present disclosure and the appended claims, those skilled in the art may understand and implement other variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude pluralities. A single processor or other unit may perform the functions of several items recited in the claims. The mere fact that certain measures are stated in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. The computer program may be stored / distributed on a suitable medium (such as an optical storage medium or solid-state medium supplied together with or as part of other hardware), but may also be distributed in other forms (such as via the Internet or other wired or wireless telecommunications systems). Any reference numerals in the claims should not be interpreted as limiting the scope.

Claims

1. A communication system (1) capable of operating in a millimeter wave spectrum, comprising: - a transmitter (10) arranged to transmit a millimeter wave signal, - a polymer millimeter wave optical fiber (30) arranged to propagate the transmission millimeter wave signal, - a receiver (20) arranged to receive the propagated transmitted millimetre wave signal, The transmitter (10) is arranged to receive an input signal (3) and comprises: - an in-phase path (5) and a quadrature path (7) for said input signal, - modulation means (16) for performing modulation by means of a millimeter wave carrier signal, - an amplifier device (17), - a combiner device (18), And it is characterized in that the in-phase path and the quadrature path each include a pre-equalization filter (12, 14) to filter the input signal, and then the transmission millimeter wave signal is obtained by applying the filtered input signal to the modulator device, the amplifier device and the combiner device.

2. A communication system as claimed in claim 1, comprising a millimeter wave coupler (19) for coupling the transmission millimeter wave signal to the polymer millimeter wave optical fiber.

3. The communication system as claimed in claim 1 or 2, further comprising a clock and data recovery module (4), wherein the clock and data recovery module (4) is used to derive a clock signal of the input signal.

4. A communication system as claimed in any one of the preceding claims, wherein the modulator device (16) comprises a generator device and a mixing device, wherein the generator device is used to generate the millimeter wave carrier signal and the mixing device is used to mix the millimeter wave carrier signal with the filtered input signal in the in-phase path and the orthogonal path respectively.

5. A communication system as claimed in claim 4, wherein the combiner means (18) is adapted to combine the mixed signals in the in-phase path and the quadrature path to obtain the transmitted millimeter wave signal.

6. A communication system as claimed in claim 5, wherein the amplifier means (17) is adapted to amplify the combined mixed signal before obtaining the transmit millimetre wave signal.

7. A communication system as claimed in claim 5, wherein said amplifier means and said mixing means are part of an RF digital to analog converter structure.

8. The communication system according to any one of claims 1 to 3, wherein the filtered input signals in the in-phase path and the quadrature path, respectively, are combined and then the modulation is performed with the millimeter wave carrier signal.

9. A communication system as claimed in claim 8, comprising a conversion module (11) wherein the amplitude and phase of the filtered input signal are combined.

10. A communication system as claimed in claim 9, comprising said phase being applied to a phase shifter (13) and said amplitude being applied to said amplifier means (17).

11. A communication system as claimed in any one of the preceding claims, wherein the pre-equalization filter (12, 14) is a digital filter.

12. The communication system of any one of claims 1 to 10, wherein the pre-equalization filter (12, 14) is a mixed signal filter.

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