EP2198546A2 - Système radio point à point à efficacité spectrale élevée et procédé de fonctionnement apparenté - Google Patents

Système radio point à point à efficacité spectrale élevée et procédé de fonctionnement apparenté

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Publication number
EP2198546A2
EP2198546A2 EP08803229A EP08803229A EP2198546A2 EP 2198546 A2 EP2198546 A2 EP 2198546A2 EP 08803229 A EP08803229 A EP 08803229A EP 08803229 A EP08803229 A EP 08803229A EP 2198546 A2 EP2198546 A2 EP 2198546A2
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EP
European Patent Office
Prior art keywords
point
receive
antennas
transmission
transmit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08803229A
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German (de)
English (en)
Inventor
Baccio Baccetti
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DRAGONWAVE S.A R.L
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Baccetti Baccio
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Publication date
Application filed by Baccetti Baccio filed Critical Baccetti Baccio
Publication of EP2198546A2 publication Critical patent/EP2198546A2/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/10—Polarisation diversity; Directional diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
    • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0036—Systems modifying transmission characteristics according to link quality, e.g. power backoff arrangements specific to the receiver

Definitions

  • the present invention relates to point-to-point radio system according to the preamble of claim 1.
  • the present invention finds applicability in radio configurations utilizing multiple transmit antennas and multiple receive antennas, that are namely called "MIMO" (Multiple Input Multiple Output) configurations, and realize multiple transmission paths between the transmit and the receive side of a link.
  • MIMO Multiple Input Multiple Output
  • MIMO configurations can be symmetrical, of the type MIMO(N 5 N), as well as asymmetrical, for instance the MIMO(1, 2) configurations, with single input and two outputs, commonly known also as configurations with receive diversity.
  • MIMO(1, 2) configurations with single input and two outputs, commonly known also as configurations with receive diversity.
  • the term “adaptivity” one refers to the dynamic and automatic process of changing the transmission modalities over the hop, as a consequence of the time variations of the propagation conditions, so as to be “adapted” in the best way to said propagation conditions. More specifically, the Physical Level (“PHY Level”) is varied between two or more available options so as to optimally counteract the unwanted effects of the propagation in terms of quality degradation of the received signal.
  • PHY Level Physical Level
  • PtP point-to-point
  • MIMO(1, 1) multiple input, single output MIMO(1, 1) configurations
  • PHY Level adaptivity in radio systems is up to now limited to cellular Point-to- Multipoint (PMP) systems, whereby a plurality of peripheral terminal stations spread over a certain geographical area (called “Cell") is connected to a center station (the "Master Station”).
  • PMP Point-to- Multipoint
  • Cell peripheral terminal stations spread over a certain geographical area
  • Master Station the center station
  • a miscellanea of service typologies is supported, with data services being anyhow predominant.
  • the various peripheral stations are enabled to transmit in different, non- overlapping time intervals in order to maintain mutual orthogonality.
  • the information to be transmitted by each peripheral station in direction to the Master Station is consequently segmented in elemental blocks.
  • Such blocks are mapped with suitable modulation formats over packets (or bursts) of signal, transmitted in distinct times.
  • the transmission times are properly adjusted in order do not to have any overlapping at the Master Station receiver, and avoid this way any mutual interference.
  • the system traffic modality is based on the principle of "capacity assignment on request”, resulting in practice in a variable number of bursts transmitted in a given time interval by each peripheral station, so as to realize a variable transmission capacity over time ("time varying throughput").
  • MISO(N, 1) Single Output
  • Modulation Adaptivity that is that type of adaptivity limited to the change of the Modulation format only, without any variation to the transmission modality.
  • MIMO configurations for PtP radio systems are described in the Patent Applications EP 1 229
  • the Document WO 2007/069071 describes PMP and PtP links based on MIMO configurations, also operated in an adaptivity regime. However the concept is applied to OFDM modulation formats because finalized to lower frequency bands ( ⁇ 6GHz) in NLoS (Non Line of Sight) propagation environments and high incorrelation between the various propagation paths due to the antennas multiplicity.
  • ⁇ 6GHz lower frequency bands
  • NLoS Non Line of Sight
  • the spectral efficiency boost offered by the present invention becomes very important for high frequency (>6GHz), LoS, PtP, MW radio systems, based on Single Carrier Modulation formats.
  • the objectives of the present invention are twofold, namely:
  • the second objective is furthermore reached by an operating method in accordance with Claim
  • Figure 1 shows the vectorial relationship between the various signals in a MIMO(2,2) configuration
  • Figure 2 shows a block diagram of a MIMO(2,2) configuration
  • Figure 3 shows a principle block diagram of a Combiner/Canceler, at the receive side
  • Figure 4 shows the vectorial relationship between signals in a lxMIMO(2,2) configuration
  • Figure 5 shows the vectorial relationship between signals in a 2xMIMO(2,2) configuration
  • Figure 6 shows the vectorial relationship between signals in the IxMIMO(1, 2) configuration, alternative to the configuration of Figure 4,
  • Figure 7 shows an example of signal segmentation for the two transmit antennas, for modulation formats up to 64QAM, and in particular for formats carrying 2, 4 and 6 bits per QAM symbol,
  • Figure 8 shows a schematics relevant to the control of PHY Level switchovers in the MIMO
  • Figure 9 shows a comparison between adaptive PtP systems using various PHY Level profiles
  • Figure 10 and 11 show the exemplary performance of some system configurations according to the present invention
  • Figure 12 shows exemplary antenna separations with one of the system configurations of Figure
  • FIG. 13 shows a general block diagram of a PtP radio system according to the invention
  • Figure 14 shows an example of PHY Level adaptivity process flow, given a certain PHY Level profile.
  • the PHY Level is varied among two or more available PHY Levels, and "adapted" in real time to the variable propagation conditions in order to counteract in the best possible way the signal quality degradations caused by said variable propagation conditions.
  • PHY Level indicates in a more general sense the combination of all the operations performed on the signals to be transmitted, jointly defined in particular by: the selection of a specific Modulation/Coding format ("Modulation Mode”) among two or more available formats, and concurrently the selection of a specific transmission modality (“Transmission Mode”) among at least two available Modes
  • the Transmission Mode also sets the multiplexing factor m of the signal.
  • a generic PHY Level allows for the transmission of a net capacity T (also indicated as “Payload” or "Net Troughput”), related to BW by the following simple relationship:
  • m is the signal multiplexing factor
  • BW is the RF occupied bandwidth (channel bandwidth)
  • ⁇ is the net spectral efficiency (due to both the QAM format and the frame overhead)
  • p is the roll-off factor of the signal shaping (in practice 0,2 ⁇ p ⁇ 0,5)
  • the multiplexing factor m can be 1 or 2, depending on the selected Transmission Mode.
  • polarization reuse also possible
  • the spectral efficiency is further doubled and m can be 2 or 4
  • Bit Error Rate changes with the complexity of the PHY Level.
  • two parameters ( ⁇ , ⁇ ) can be associated to any PHY Level, which are mutually interrelated, in the sense that to realize more performing ⁇ values, one has also to rely on higher threshold values ⁇ .
  • PHY MIN the minimum PHY Level, representing the most robust level (minimum ⁇ )
  • PHY MAX the maximum PHY Level, representing the most efficient one (maximum ⁇ ).
  • the PHY Level adaptivity also implies the time variation of the instantaneous throughput carried by the system. Consequently this solution can only be adopted for the transmission of digital signals that can tolerate the short-term variation of the transmission rate, so typically for the transmission of payloads containing, at least for a significant fraction, "best effort" data services not linked to a real-time transmission, be they of the so called “Cell oriented” type (for instance ATM mapped on IMA-NxEl physical interfaces), or of the so called “Packet oriented” type (for instance IP over Ethernet 10/100 Base T physical interfaces, as typically found in the IP access network).
  • Cell oriented for instance ATM mapped on IMA-NxEl physical interfaces
  • Packet oriented for instance IP over Ethernet 10/100 Base T physical interfaces, as typically found in the IP access network.
  • the PtP radio system operates at high MW frequency bands (typically >6GHz and more commonly >13GHz), benefitting of the quite large frequency blocks offered by the relevant standardized channel plans and of the limited hop lengths to bridge (few kilometres in urban/suburban environments and typically ⁇ 15/20Km in rural environments).
  • the links we consider are in full LoS, with highly directive antennas, and negligible dispersive effects within the channel band BW. This is due to the non-selective (flat) in-band response of the supplementary attenuation, predominantly due to the following two propagation phenomena:
  • R2 w 22 *S2 + W2i*Sl*e J ⁇ 12 ⁇ w o *(Sl*e J ⁇ ° +S2)
  • NF(dB) is the receive noise figure
  • B N (MHZ) is the equivalent receive noise bandwidth ⁇ is the threshold (SfN) ratio between the static peak power of the received signal and the thermal noise, for the wanted BER objective B N is obviously related to the channel bandwidth BW.
  • SfN threshold
  • ⁇ SG (dB) - ⁇ that is equal to the difference between the relevant values of ⁇ , but with sign inverted.
  • the threshold for a given PHY Level is simply given by the condition of having the system gain SG (offered by that PHY Level) equal to the total attenuation present over the link. In other words it holds for the threshold :
  • ASL (dB) is the free space attenuation (inclusive of the gain of transmit antennas Tl and
  • (dB) is the supplementary attenuation due to the propagation.
  • ASL and the remaining parameters (PPTX, B N , NF) are set, so that the condition for the switchover from a PHY Level with threshold ⁇ down to a lower (more robust)
  • the value of the constant KK depends on all the "fixed parameters" of the link, that is all the parameters which do not change with the PHY Level switchover (L, PPTX, NF, B N , BW, F S ).
  • PHY Level adaptivity is essentially to introduce an additional degree of freedom in the system, so as to independently select the values of the two "effective" parameters which govern the overall link performance:
  • PHY MAX the ⁇ value of the highest PHY Level
  • the radio system comprises a PHY Level Transmit Processor 1 (in charge of transmit segmentation, Service insertion and FEC encoding, mapping and dual modulation), two RF transmission modules 4 and 5 (each including an IF /RF up-conversion module and a power amplifier) driving the relevant transmit antennas Tl and T2, two RF receive modules 6 and 7, connected to the relevant receive antennas Rl and R2 (each module including a low noise RF amplifier, and a RF /IF down-conversion module), a Combiner/Canceler 8, and a PHY Level receive Processor 11 (in charge of dual demodulation, demapping, FEC decoding and service extraction and data serialization).
  • PHY Level Transmit Processor 1 in charge of transmit segmentation, Service insertion and FEC encoding, mapping and dual modulation
  • two RF transmission modules 4 and 5 each including an IF /RF up-conversion module and a power amplifier
  • two RF receive modules 6 and 7, connected to the relevant receive antennas Rl and R2 each module including
  • NS number of states of the QAM constellation
  • N,M number of used inputs and, respectively, outputs of the MIMO configuration.
  • N,M number of used inputs and, respectively, outputs of the MIMO configuration.
  • the notation "1x4(1,2)” will indicate a PHY Level using 4QAM with simple RX diversity, for the Transmission modality "Ix”.
  • the Combiner/Canceler structure can be represented by the principle block diagram of FIGURE 3, valid for all MIMO Transmission modalities.
  • each of the received signals Rl and R2 is multiplied by a proper coefficient (C 12 and
  • Ix The by far preferable "Ix" modality is in fact lxNS(2,2) which provides a System Gain advantage of about 6 dB over the IxNS(1, 2) alternative, having only the modest drawback of requiring a return channel to optimize the TX diversity.
  • PHY Level Adaptivity being the PHY Level jointly defined by a Modulation Format and a Transmission Modality.
  • the modality 2xNS(2,2) requires a good coherence of the receive MW LOs to optimize the cancellation.
  • the modality lxNS(2,2) in turn requires good phase coherence in the transmit side to optimize the TX diversity.
  • the first functionality required at the receive side is the fine level adjustment of Rl and R2 (e.g. through individual AGC stages AGCl and AGC2, respectively), to obtain equal average powers and compensate for possible gain differences in all the blocks responsible to convert said signals down to baseband (to DC) (imperfect antenna pointings, resulting in slightly different antenna gains on the two ways, slightly different gains of the RF/IF conversion stages, and similar).
  • the phase shifter by ⁇ has to be controlled in the reverse direction from the remote receive side through the return channel inserted in the system telemetry, with the target to bring to zero the difference between the modules of Rl and R2.
  • FIGURE 4 The situation is presented in FIGURE 4.
  • the loop control signal C is obtained by the difference of the modules of Rl and R2, and conventional In-Phase-Combination (IPC) is used at the receive side to compensate for possible latency differences or misalignments of the RX blocks.
  • IPC In-Phase-Combination
  • Rl wo*Sl + woSle l( ⁇ 44>o)
  • R2 wo*Sle l( ⁇ o) +wo* Sl e> ⁇
  • R2 has to be phase-shifted by a proper angle ⁇ and then summed to Rl.
  • S2 0, hence ⁇ ⁇ (- ⁇ o) if then a sum of the two signals is actually made.
  • control loops and algorithms updating the values of the various involved variables shall not suffer of any discontinuity at PHY Level switchovers.
  • the control loops to be managed are the following: - AGC1.
  • AGC2 AGC2
  • UW Unique word
  • the service field SRV can be provided only for the two most significant bits (4QAM), and left available to the payloads for the less significant bits.
  • the modulation format for the UWs (both U and A) is here imagined to be 4QAM, but an even more robust 2PSK format could be selected, to increase the probability of correct UW detection, thus making the frame synchronization more reliable.
  • the Payload transmission would be organized as follows for the two Transmission modalities of the profile:
  • AGCl AGC2 can be permanently controlled with the U word regardless from the used modality.
  • the Canceler can be controlled by a “continuous" MMSE algorithm running also during the payload fields, and the receive IPC is kept updated with the U word.
  • the receive IPC can be controlled continuously during the payload and the canceler is updated on the U word, thanks to the identical convergent value ⁇ ⁇ * ( ⁇ - ⁇ o) for both the "Ix" and the "2x” modalities.
  • FIGURE 8 presents a detailed scheme of the TX and RX functionalities, for what concerns in particular the management of the PHY Level switchover of this (2,2) profile.
  • QAM Modulators and Demodulators IF AGCs (coarse), Cable Interfaces, and similar.
  • Block 101 is in charge to prepare the data on the two transmission ways for the successive D/A conversions and IF modulations.
  • Clearly Block 101 is configured under the external PHY Level selection command provided by the PHY Level Controller, not shown in the Figure.
  • the T2 way is phase rotated by an angle CC with respect to the Tl way by the Block 102, to properly optimize the TX Diversity.
  • Block 102 is controlled in remote loop from the
  • Rl and R2 undergoes fine level adjustments to achieve the same power level out of the amplifiers 203 and 204 (AGCl and AGC2).
  • the relevant control signals are obtained by power measurements (I 2 +Q 2 ), performed at the output of the AfD converters by the power detectors 106 and 107 , enabled only in correspondence of the
  • A-type UWs (Al and respectively A2), that are specifically dedicated to the Dual Payload Mode.
  • This operation is controlled by an enabling waveform (S A ) provided by the Synchronizer Block
  • the control signal for the phase shifter ⁇ in the TX side is provided by the comparator 105 which computes the difference of the modules of Rl and R2 , enabled by the proper enabling waveform (Su), only during the U-type UWs (U on both antennas), that are specifically dedicated to the Single Payload Mode.
  • the "In-Phase" sum (IPC Block) of Rl and R2 provides the combined output for the lxNS(2,2) Transmission Mode (PHYmin).
  • the signals are further processed by a (2,2) cancellation structure, performing the sum of the signals Rl and R2 with the respective phase shifted and cross-exchanged versions.
  • the phase shifts ⁇ l2 and ⁇ 21 provided by the Blocks 108 and 109 are controlled by the MMSE processors of Block 112 that can compute stochastically updated values continuously, even during the payload fields, when the operating PHY Level is 2xNS(2,2), but are enabled only in correspondence of the A-type UWs (Al and respectively A2), when the operating PHY Level is lxNS(2,2).
  • the step size of these processes is also adaptively changed with the PHY Level, being suitably low to properly average-out the high noise fluctuations present when PHYmin is selected, and conversely suitably high when PHYmax is selected and the noise becomes low.
  • the key for proper operation of the overall structure stays obviously in the quantization size and in the precision of the used arithmetics, and in the correct operation of the Synchronization Block 115.
  • Block 115 has to provide for correct and reliable receive frame synchronization, utilizing by the way conventional synchronization techniques well known to the expert of the art, in the field of digital multiplexing/demultiplexing techniques or of decoding synchronization techniques for FEC block coding.
  • Block 116 includes the functionalities of Demapping, Demodulation, FEC Decoding, Service Extraction and Serialization of received data.
  • PHY Level Profile that can be used with the MIMO(2,2) configuration.
  • the modulation formats include 4QAM, 16QAM and 64QAM, this last reasonably assumed as
  • the modality for PHYmin is the lxNS(2,2) one, based on combined TX and RX diversity.
  • RS (Read Solomon) block coding is assumed with a short block (86 bytes) and a correction capability of up to 3 errors per block.
  • a moderate frame efficiency (0,86) is required to accommodate the overall frame Overhead, estimated in 12 bytes (for the two unique words U and A, the EOW, the MAC telemetry and return channels and for FEC error correction).
  • the uuencoded level of BER 1E-3 (corresponding to a coded BER ⁇ 1E-7) is taken as BER threshold for the link.
  • TL Throughput Loss
  • ⁇ > J ⁇ (A s )*pdf(A s )*d(As) where ⁇ (As) represents the "efficiency staircase" offered by the selected PHY Level profile.
  • an excellent "carrier class" quality objective for a MW link using PHY Level Adaptivity with a BER threshold of, say, BER ⁇ 1E-6 can be set at:
  • the STND(1,1) configuration is not based on static modulation, but also uses adaptive modulation, operated over the same PHY Level profile.
  • the basic advantages the invention provides are:
  • a 4-state profile would offer only marginal advantages over the corresponding 2-state profile (it would about halve TL, or it would only allow for a marginal 10% reduction of the antenna separation, at equal TL).
  • the probability distribution of the rain attenuation As (the only effective propagation component at 23GHz) is provided by ITU-R P.1057-1 "Probability distributions relevant to radio wave propagation modelling".
  • CCDF (As) 0,01*exp ⁇ -14,62 + 0,02326*sqrt[395145,16 - 99011,16*Ln(8,33X)] ⁇ valid for latitudes > 30 degrees, with the notation CCDF indicating "Complementary Cumulative Distribution Function" . The following assumptions are then made concerning the main system characteristics.
  • FEC Coding Shortened RS (86,74), with triple error correction capability
  • PPTX variabile in the range from 10 to 20 dBm
  • the MIMO (2,2) configuration has an additional parameter to select, namely the antenna separation.
  • FIGURES 10 and 11 namely provide these results for the examined configurations A) through
  • FIGURE 12 shows two sets of curves: one in the assumption of adopting a "Constant ⁇ o" design for all hop lengths below Lmax, the other one by adopting a "Minimum ⁇ o" design, yielding the minimum separation able to meet the TL objective.
  • the separation is less than 2,3m and can even be significantly smaller for hop lengths lower than Lmax.
  • Exemplary embodiment In the following the description is provided of an exemplary, possible embodiment of the system, mainly with the purpose of highlighting the technical problems and to discuss the relevant technical solutions.
  • the described embodiment has to be considered "typical" in the sense that, even if alternative solutions would be available or possible, they would have anyhow to guarantee the practical realization of the process with the same functionalities and characteristics as commented here below
  • the transmit signal is represented by the combination of the useful information signal (the data
  • Such combination of signals is usually obtained by means of well known digital multiplexing techniques, by realizing the segmentation of the "on air” signal in successive frames, all of the same duration and structure.
  • the segmentation is such that a small portion of the frame (the "service field") is reserved first to the required UWs (U and A), then to the error correction (FEC), and finally to the other services
  • Block 201 TX PHY Level Processor, which also includes the functionalities of FEC Encoding, Dual Modulation and TX Distribution to the two antennas for the generation of the PHY Level in the transmit side.
  • Block 201 generates two modulated signals for Block 202, Dual RF transmitter.
  • the real time selection of the PHY Level is performed under the control of Block 203, Telemetry
  • the two signals are then translated to the wanted RF frequency through IF/RF conversions and suitably amplified by Block 202, that includes the two RF transmitters feeding the relevant antennas.
  • the signals received by the two RX antennas are first amplified by low-noise amplifiers and then re-translated down at intermediate frequency through RF/IF conversions in
  • Block 204 Dual RF Receiver. Subsequently the signals are processed by Block 205, RX Combiner/Canceler and RX PHY Level Processor (Dual Demodulation, FEC Decoding and Telemetry extraction).
  • Methods to obtain the real time estimate of the CSI include the measure of one of the following parameters:
  • the real time CSI estimate is performed in Block 206, Channel Quality Measure and provided to
  • Block 207 has the intelligence to manage the link adaptivity by controlling : - from remote, the distant transmission side (Block 201, through Block 203) via the the telemetry channel (Block 208, Return Telemetry), and
  • external parameters are also provided (normally SW configurable parameters), representing programmable thresholds to be compared with the real time value of the estimated
  • the TX/RX PHY Level synchronization can for instance be implemented by locating exactly at the beginning of each frame the instants for possible switchovers, by cyclically numbering the successive frames and by transmitting to the processor 201 the frame number selected for the next switchover. For better reliability a backward confirmation message can be foreseen, before actuating the switchover.
  • FIGURE 14 shows in particular the behaviour of the receive (S/N) ratio as a function of the supplementary attenuation As over the hop.
  • the available (S/N) ratio at the receiver proportionally decreases in dB. This ratio is monitored with adequate precision through the CSI estimate performed by block 206 (FIGURE 13). As soon as the CSI value drops below a certain threshold s2, the controller 207 decides to switch the PHY Level down the more robust
  • Controller 207 sends to the remote terminal 201 the first available frame number for the switchover and configures the local receiver 205 to switch at the same time.
  • the ATPC is a well known technique allowing to dynamically reduce the transmit power PPTX when As is particularly low in good propagation conditions (situation by the way occurring for a very high percentage of the time).
  • the benefit is to reduce the interference level generated on other links utilizing the same RF frequency and located in the same geographical area.
  • Zone at PHYmax for values of As in the range from point A to point B. In this zone the link still operates at PHYmax with a constant PPTX value, equal to the maximum available transmit power.
  • Hysteresis zone for values of As in the range from point B to point C.
  • the switchovers between PHYmax and PHYmin occur for conveniently different (S/N)avg values, depending on the sense of the As variation, increasing or decreasing.
  • Zone at PHYmin for values of As in the range from point C to point D. In this zone the link operates at PHYmin with a PPTX value equal to the maximum available one. As can continue to grow until the link threshold (point D) is exceeded and the link enters the next zone 5).
  • receive processing whose task is always to orthogonalize all the available dimensions, a conceptually simple "dimensionality expansion" has to be applied, in the sense of cancelling for each signal output the (ND-I) existing interference components.
  • ND 2
  • CPIC Copolar Interference Canceler
  • the Point-to-Point system and the relevant operating method according to the present invention allow to satisfy challenging requirements and to overcome the problems and limitations commented in the initial part of this description, relevant to the state-of-the art technology.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
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  • Radio Transmission System (AREA)
  • Radio Relay Systems (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

L'invention porte sur un système radio point à point comprenant une pluralité d'antennes de transmission et une pluralité d'antennes de réception, qui peuvent être utilisées avec une modalité de transmission sélectionnée parmi une pluralité de modalités de transmission disponibles, toutes mises au point pour transmettre et recevoir des signaux numériques radiofréquence à modulation à une seule porteuse, à des fréquences supérieures à environ de 6 GHz. Le signal modulé a un format de modulation/codage à une seule porteuse sélectionnable parmi une pluralité de formats de modulation/codage disponibles. La modalité de transmission d'antenne et le format de modulation/codage identifient tous deux un niveau physique de transmission. Le système comprend plus particulièrement, à la fois du côté de la transmission et du côté de la réception, des circuits appropriés de traitement du signal couplés à l'entrée des antennes de transmission et, respectivement, à la sortie des antennes de réception, mises au point au changement adaptatif en temps réel du niveau physique de transmission en fonction de la qualité variable dans le temps des signaux reçus par les multiples antennes de réception.
EP08803229A 2007-08-31 2008-08-26 Système radio point à point à efficacité spectrale élevée et procédé de fonctionnement apparenté Withdrawn EP2198546A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI20071713 ITMI20071713A1 (it) 2007-08-31 2007-08-31 Sistema radio punto-punto e metodo per il funzionamento di tale sistema.
PCT/EP2008/061162 WO2009027408A2 (fr) 2007-08-31 2008-08-26 Système radio point à point à efficacité spectrale élevée et procédé de fonctionnement apparenté

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EP2198546A2 true EP2198546A2 (fr) 2010-06-23

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EP08803229A Withdrawn EP2198546A2 (fr) 2007-08-31 2008-08-26 Système radio point à point à efficacité spectrale élevée et procédé de fonctionnement apparenté

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EP (1) EP2198546A2 (fr)
IT (1) ITMI20071713A1 (fr)
WO (1) WO2009027408A2 (fr)

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Publication number Priority date Publication date Assignee Title
US8391399B2 (en) * 2009-05-13 2013-03-05 Elbit Systems Of America, Llc Single carrier waveform system with frequency domain equalization
US8422540B1 (en) * 2012-06-21 2013-04-16 CBF Networks, Inc. Intelligent backhaul radio with zero division duplexing

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US7139324B1 (en) * 2000-06-02 2006-11-21 Nokia Networks Oy Closed loop feedback system for improved down link performance
KR100591890B1 (ko) * 2003-04-01 2006-06-20 한국전자통신연구원 다중 안테나 무선 통신 시스템에서의 적응 송수신 방법 및그 장치
US8116262B2 (en) * 2004-06-22 2012-02-14 Rockstar Bidco Lp Methods and systems for enabling feedback in wireless communication networks

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See references of WO2009027408A3 *

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ITMI20071713A1 (it) 2009-03-01
WO2009027408A2 (fr) 2009-03-05
WO2009027408A3 (fr) 2009-05-22

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