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WO1999001945A1 - Procede de detection de signaux pour recepteur cellulaire numerique - Google Patents

Procede de detection de signaux pour recepteur cellulaire numerique Download PDF

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Publication number
WO1999001945A1
WO1999001945A1 PCT/FI1998/000528 FI9800528W WO9901945A1 WO 1999001945 A1 WO1999001945 A1 WO 1999001945A1 FI 9800528 W FI9800528 W FI 9800528W WO 9901945 A1 WO9901945 A1 WO 9901945A1
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WO
WIPO (PCT)
Prior art keywords
channel
signal
adjacent
receiver
useful signal
Prior art date
Application number
PCT/FI1998/000528
Other languages
English (en)
Finnish (fi)
Inventor
Marko Escartin
Pekka Ranta
Esa Malkamäki
Riku Pirhonen
Original Assignee
Nokia Networks Oy
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nokia Networks Oy filed Critical Nokia Networks Oy
Priority to AU77713/98A priority Critical patent/AU741617B2/en
Priority to JP50648499A priority patent/JP2002506594A/ja
Priority to EP98925691A priority patent/EP0990309A1/fr
Publication of WO1999001945A1 publication Critical patent/WO1999001945A1/fr
Priority to NO996262A priority patent/NO996262D0/no

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • H04L25/0242—Channel estimation channel estimation algorithms using matrix methods
    • H04L25/0246—Channel estimation channel estimation algorithms using matrix methods with factorisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/12—Neutralising, balancing, or compensation arrangements
    • H04B1/123—Neutralising, balancing, or compensation arrangements using adaptive balancing or compensation means
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0204—Channel estimation of multiple channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03178—Arrangements involving sequence estimation techniques
    • H04L25/03305—Joint sequence estimation and interference removal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03178—Arrangements involving sequence estimation techniques
    • H04L25/03331—Arrangements for the joint estimation of multiple sequences
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03426—Arrangements for removing intersymbol interference characterised by the type of transmission transmission using multiple-input and multiple-output channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals

Definitions

  • the present invention relates to a signal detection method in a digital cellular network receiver, the method receiving on a desired channel a combination of a desired useful signal and at least one interfering adjacent channel signal originating from a channel adjacent to the desired channel.
  • a cellular network receiver receives a signal transmitted on a par- ticular channel.
  • Signals transmitted on adjacent channels cause interference to the signal, which is referred to as adjacent channel interference.
  • Different frequency division channels are located close to each other. For example, in the GSM system the medium frequencies of the channels are located at a distance of 200 kHz from one another, and the modulation spectrum is slightly wider than 200 kHz. The guard band between channels is thus non-existent. Due to the properties of a GMSK modulation method used adjacent channels leak into the frequency range of each other. Furthermore, signals to be transmitted on the same channel in a cell somewhere further cause interference to the signal, which is known as co-channel interference. In current cellular networks interfering signals are approximated in receivers as random additive white Gaussian noise.
  • the approximation is sufficiently accurate only if interfering signals in relation to a desired signal are sufficiently weak. Adjacent channels thus interfere each other too much, if the difference of powers used thereon is too high. In the GSM system the largest difference of transmission or reception powers allowed of adjacent channels is 9 dB.
  • Cellular networks use a reuse pattern determining how the channels are reused in the cells. When the reuse pattern is for instance 7, then the cell and its six neighbouring cells each use a different channel (or channels).
  • Reuse pattern planning requires thorough planning of radio frequency use. The planning results are tested upon commissioning the network by extensively measuring radio fields. Planning and measuring are important steps also when the network is enlarged.
  • the signal generally propagates along various paths due to reflec- tions caused by obstacles and arrives at a receiver as signal components delayed in different ways.
  • the phenomenon is referred to as multipath propagation. To signal symbols this causes inter symbol interference, in which symbols are partly superimposed.
  • a predetermined reference part, by which a multipath channel through which the signal has propagated can be estimated at the receiver, is generally included in the signal in cellular radio systems. Using a channel estimate thus formed the received signal can be corrected to correspond to the original.
  • CDMA systems use a particular pilot signal and/or a broadband spreading code as the reference part.
  • TDMA systems use a training sequence as the reference part.
  • the GSM system for example, employs eight training sequences, which are selected so as not to resemble the coded data transferred in the signal, but are a unique part of each burst.
  • Transmitters in a particular cell operating on a par- ticular channel all use the same training sequence.
  • the transmitters on an adjacent channel and a co-channel use a different training sequence.
  • a receiver can thus distinguish the correct signal from an interfering signal arriving at the same time. Since interfering signal powers are kept sufficiently low by means of frequency planning, the interfering signals are processed at a re- DCver merely as additive white Gaussian noise. Actual channel estimation, correction and detection are performed without information on interfering signals. This does not cause any problems in cellular networks where frequency planning is correctly performed.
  • the cellular network capacity is also increased by introducing hier- archie cell structures, in which cell sizes vary in diameter from dozens of kilometres to some dozens or hundreds of metres. Such cells are referred to as macro, micro and pico cells. In these cells the power level differences of adjacent channels can be very extensive and cause severe interference.
  • the power control problem of the adjacent channels is solved in such a manner that an attempt is made to attain all signals in the uplink direction to the same power level at a base station re- ceiver. All signals in the downlink direction are transmitted at constant power.
  • a drawback when applying this idea to the GSM system is that the dynamic area of power control should be increased from the current level, 30 dB, up to 60-100 dB. However, this is not possible between different cell types since too much interference would occur.
  • the Finnish patent publication 944 736 describes how co-channel interference cancellation can be implemented at a receiver. However, said publication does not describe how to remove the adjacent channel interference.
  • An object of the present invention is to provide an improvement on signal detection in a cellular receiver by removing an interfering signal caused by an adjacent channel.
  • the invention also relates to a signal detection method in a digital cellular network receiver, the method receiving on a desired channel a combination of a desired useful signal and at least one interfering adjacent channel signal originating from a channel adjacent to the desired channel.
  • the method is characterized according to the invention by determining channel estimates of the useful signal and at least one adjacent channel signal, reconstructing an adjacent channel signal from the useful signal utilizing the channel estimate of the adjacent channel signal, reducing the reconstructed adjacent channel signal from the useful signal, detecting the useful signal utilizing the channel estimate of the useful signal.
  • the invention further relates to a digital cellular network receiver arranged to receive on a desired channel a combination of a desired useful sig- nal and at least one interfering adjacent channel signal originating from a channel adjacent to the desired channel.
  • the receiver is characterized according to the invention by comprising a channel estimator arranged to jointly determine channel estimates of the useful signal and at least one adjacent channel signal, a detection part arranged to detect the useful signal utilizing the channel estimates of both the useful signal and the adjacent channel signal.
  • the invention further also relates to a digital cellular network receiver arranged to receive on a desired channel a combination of a desired useful signal and at least one interfering adjacent channel signal originating from a channel adjacent to the desired channel.
  • the receiver is characterized according to the invention by comprising at least one channel estimator arranged to determine channel estimates of the useful signal and at least one adjacent channel signal, reconstruction means to reconstruct an adjacent channel signal from the useful signal utilizing the channel estimate of the adja- cent channel signal, means to reduce the reconstructed adjacent channel signal from the useful signal, a detection part arranged to detect the useful signal utilizing the channel estimate of the useful signal.
  • interference caused by an adjacent channel signal can also be removed. This enables the use of smaller reuse patterns and facilitates radio frequency planning. Alternatively if there is no need to increase system capacity the invention can improve the radio connection quality or increase the radio connec- tion range.
  • a channel estimate of a useful signal and at least one adjacent channel signal is particularly suitable for implementing a subscriber terminal receiver, since then the invention will not cause additional costs to the implementation of the receiver. Then, when a channel estimate is determined for the adjacent channel signal a generated altered training sequence can be used where a phase distortion caused by the frequency difference between a desired channel and an adjacent channel is taken into account. This improves the accuracy of the channel estimates. Correspondingly the phase distortion can also be taken into account when a desired signal is detected.
  • the channel estimates of the useful signal and at least one adjacent channel signal in parallel, and to reconstruct an adjacent channel signal from the useful signal utilizing the channel estimate of the adjacent channel signal.
  • This procedure is particularly suitable for a base station, since it requires a receiver for each channel to be received.
  • the advantage with this embodiment is quality, as it is easier to remove interference more accurately if the structure of the interference is known.
  • the invention it is also possible to receive in ad- dition to a desired channel at least one channel adjacent to the desired channel, and then filter the desired channel and the adjacent channel apart. Signal estimation and detection is then performed sequentially.
  • This embodiment is well suited for a subscriber terminal due to the relative simplicity thereof compared to the previous embodiment.
  • the invention also enables to determine the channel estimates of the useful signal and at least one adjacent channel signal in such a manner that instead of reference parts symbol or bit decisions made from a received signal are used regarding the useful signal and at least one adjacent channel signal. This known method is referred to as decision feedback.
  • the estimation method of a channel estimate is particularly suitable for
  • the channel estimate for example, in such cellular radio systems, which include channel estimation based on a reference part, but in which the channel has time to change considerably during the time between reference parts (for example, because a transmitter is in a fast moving vehicle or because there is a long time slot between reference parts).
  • a specific modulation method in a GSM-based system in the downlink direction a specific modulation method can be used for the signal enabling substantially better protection against interference caused by an adjacent channel than a conventional modulation method.
  • a conventional modulation method such as a GMSK modulation method, can be used for the signal.
  • the receiver of the subscriber terminal does not, however, require any changes, in which case already existing subscriber terminals can be used in the improved network, where for instance the reuse pattern is reduced.
  • OQAM Offset Quadrature Amplitude Modulation
  • the invention allows the use of a neighbouring frequency in the system, for example, in adjacent cells of a hierarchic cellular radio network, in which the power levels used can be of very different sizes.
  • An example of such a situation is a macro cell covering a wide area and an internal pico cell of an office building in said area. This advantage relates to CDMA, TDMA and various hybrid systems.
  • Figure 1 illustrates a cellular network of the invention
  • Figure 2 illustrates interference caused by an adjacent channel signal to a desired signal
  • Figure 3 shows a discrete time model of signal structure
  • Figure 4A shows a receiver of the invention jointly determining channel estimates
  • Figure 4B shows a receiver of the invention using a set of antennas
  • Figure 5 shows a receiver of the invention separately determining the channel estimates in parallel
  • Figure 6 shows a receiver of the invention receiving a substantially broader frequency band than the desired signal.
  • the present invention is applicable to be used in all digital cellular radio networks that allow interference caused by an adjacent channel.
  • the GSM system is used as an example without restricting the invention thereto.
  • TDMA systems, CDMA systems, SDMA systems and various hybrid systems concurrently using different multiple methods are examples of the cellular radio networks the invention refers to.
  • Figure 1 describes a part of the cellular network of the invention.
  • a base station 100 receives a signal 104 transmitted by a moving station 102 on channel 890.2 MHz.
  • a moving station 106 in another cell transmits a signal 108 to its base station on the same channel 890.2 MHz.
  • a moving station 110 in a neighbouring cell transmits a signal 112 to its base station on channel 890 MHz.
  • a moving station 114 in another neighbouring cell transmits a signal 116 to its base station on channel 890.4 MHz.
  • Signal transmissions substantially occur simultaneously, so as to the receiver 100 the de- sired signal 104 (at 890.2 MHz frequency) is now interfered by
  • Figure 2 shows a frequency on x-axis and a power spectrum on y-axis.
  • Curve 200 is the power spectrum of a signal on a desired channel.
  • Curve 202 is the power spectrum of a signal on a channel below the desired channel, for example at frequency f1 - 200 kHz in the GSM system.
  • Curve 204 is the power spectrum of a signal on a channel above the desired channel, for example at frequency f1 + 200 kHz.
  • the spectrum produced by a GSMK modulation method used in the GSM system is in a sense infinite by nature, and therefore adjacent channels inevi- tably overlap each other; these areas 206, 208 are hatched in the Figure.
  • the adjacent channel signal 202 interferes the desired signal 200.
  • the adjacent channel signal 204 interferes the desired signal 200, respectively.
  • the invention can be used in cellular networks that include a pro- tective frequency area between channels.
  • the invention can also be used in cellular networks where the frequencies are as close as possible to each other, even so close that the channels partly overlap each other.
  • the invention can further be used in cellular networks that use an expanded frequency channel i.e. the channel is considerably broader (e.g. 200 kHz) than a normal channel.
  • the cellular network of the invention can also be semi-adaptive regarding the protective frequency and/or the channel width, i.e. the network operator can place them in any way he/she wants according to situation.
  • the signals to be processed can be described by a discrete time model shown in Figure 3.
  • the system comprises N c transmitters transmitting on the same channel f1 and in the same time slot.
  • the system comprises ⁇ / a transmitters transmitting on channel fO and/or f2 adjacent to channel f1 at the same time as the transmitters of channel f1.
  • the impulse response of each channel is on the same channel L ,n c ⁇ (h 0 ,n c , h ⁇ , nc , ...
  • n a (h 0 ,n a , 1 ⁇ na , ... h L a )
  • ⁇ L is the length of a channel memory in symbols.
  • Vector r ⁇ (r 1 , r 2 , ⁇ "xj is a received signal sequence.
  • Vector n ⁇ consists of independent white Gaussian noise.
  • the model is simplified in the sense that it assumes the channel memory length to be finite and equal for all channels. As for the invention, the model is sufficiently accurate, since in practice the receivers process only finite impulse responses.
  • the receiver has to be able to detect the N c +N a transmitted data sequence a K n from the received signal r ⁇ . This is possible with high probability if the channel states do not overlap. In cellular networks the channels are summed in random phases and amplitudes, the probability of overlapping thus being very small.
  • Figure 4A shows a simplified block diagram of the receiver of the invention.
  • Figure 4A includes only the blocks essential for describing the in- vention, but for one skilled in the art it is obvious that a conventional cellular network receiver also comprises many more functions and structures, the detailed description of which is not necessary in this context.
  • the receiver may be for example a receiver normally used in the GSM system comprising the changes required by the invention.
  • a sum signal received by an antenna 400 and including a desired signal, interference caused by an adjacent channel signal and interference caused by a co-channel signal is applied to radio frequency parts 402 from where the sum signal is applied to a filter 404, where selection filtering of a desired channel is performed for the sum signal by a band-pass filter.
  • the sum signal is converted in further processing means 406 to an intermediate frequency or directly to a base-band.
  • the signal is demodulated into I and Q parts.
  • An A/D transformation is performed for the I and Q signals.
  • the signal can thereafter be more accurately filtered.
  • the signal is applied from the further processing means 406 to a detection part 414 and to a channel estimator 408.
  • the channel estimator 408 estimates channel estimates i.e. for each channel a vector h describing the amplitude and phase of the multipath propagated components of the signal at different delays.
  • a joint channel estimation is performed for the signals. Let us assume that N c synchronic co-channels are received i.e. a desired channel and N c -1 interfer- ing co-channels and in addition N a synchronic interfering adjacent channels.
  • the channel responses of the co-channels are denoted
  • the training sequence divided into preamble and midamble codes is denoted on the n th co-channel by
  • m a ⁇ (m 0 ,n, m ⁇ - ⁇ , m 2 , ⁇ -e J2m , m 3 , n -e J3(2 ⁇ fAT> ,
  • a complex value mixer wave signal is generated by raising term e at a power, and f ⁇ is a frequency difference, or the difference of medium frequencies between the desired channel and the adjacent channel, and j is an imaginary number by which the wave becomes sinusoidal.
  • the formulas include L+P element m p n , where L is the length of the preamble code which equals the length of the channel memory, and P is the length of the midamble code.
  • the first L bits are preamble code bits and the following B bits are midamble code bits.
  • the received signal corresponding to the midamble code bits can thus be presented in the form
  • n Gaussian noise samples with a covariance matrix R
  • a matrix can be formed for the adjacent channels taking the rotated training sequence into account
  • a channel estimator 408 When a channel estimator 408 has estimated a desired channel, channel estimates for co-channels and adjacent channels either sequentially or in parallel for each signal, the channel estimates are applied to means 410 where a receiving power is formed for each signal. The channel estimates are further applied to means 412. From the means 410 the receiving power formed for each signal is applied to the means 412. Interference caused to a useful signal by an adjacent channel signal and a co-channel signal is com- pared in the means 412, and a decision is made concerning which interference or interferences should be removed. From means 414 the channel estimates of the desired signal and at least one of the most interfering signal are applied to a detection part 414. In the detection part 414 the desired signal is detected by removing from the useful signal the effect of the most interfering signal.
  • JMLSE joint maximum likelihood sequence estimation
  • n [l,N]
  • the noise is Gaussian whose average and deviation ⁇ 2 are 0, then the conditional probability density function can be written
  • Equation 12 can be formed using the previous equation 14 into the form
  • This equation returns the minimum sum of the Euclidean distances of all possible sequences.
  • the number of states in the JMLSE trellis diagram is 2 N .
  • the calculation capacity of the receivers limits the number of signals that can be jointly detected or the number of multipaths of the signals.
  • one interferer is more dominating than the others, so it is preferable to remove the effect of at least one of the strongest interferers.
  • a joint estimation and detection provide the best results in a synchronic network. If the network is not synchronic, the interference situation may change in the middle of the burst. Then interference is estimated from the part of the burst it affects. Channel estimation is performed independently for each training sequence, which is assumed to cause interference. Channel es- timation is then a sliding measure by nature as the timing of the interference is not known. Sliding means that according to the timing of the desired signal training sequence a search for the interfering signal training sequence is started.
  • Another solution to the interference synchronization problem is that a receiver is used which can receive, estimate and detect signals in parallel. Such an operation is particularly well applicable to a base station typically re- ceiving several signals concurrently and detecting them.
  • FIG. 5 shows such a receiver.
  • the receiver is in a sense the receiver described in Figure 4A, but provided with several receiver branches and deviating properties described below.
  • the receiver shown in Figure 5 com- prises three receiver branches. Each receiver branch filters the desired channels fO, f1 , f2 apart with filters 404A, 404B, 404C.
  • the channel estimator 408A, 408B, 408C estimating channel estimates for a desired channel and a co-channel. Channel estimation is thus not performed for adjacent channels.
  • the channel estimates and power values are applied to a channel estimate bus and to a power bus 504.
  • the channel estimate bus 506 transmits the channel estimates formed in each receiver branch to reconstruction means 500B of an own receiver branch and to reconstruction means 500A, 500C of other receiver branches, and in addition to a detection part 414B of the own receiver branch.
  • the power bus 504 cor- respondingly transmits the power estimates formed in each receiver branch to the reconstruction means of the own 500B and the other 500A, 500C receiver branches.
  • an adjacent channel signal is generated from a desired signal utilizing the adjacent channel signal channel estimate obtained from the channel estimate bus 506 and the signal sequence received in the second receiver branch obtained from a symbol bus 508.
  • the generated adjacent channel signal is then applied to means 502B.
  • a reconstructed adjacent channel signal, or the adjacent channel signal of channel fO and/or channel f2 is reduced from the received useful signal in the means 502B.
  • a useful signal is detected in the detection part 414B utilizing the channel estimate of the useful signal.
  • the symbols identified from the detection part 414B are applied to be further processed and to the symbol bus 508 transmitting the identified symbols to those adjacent channels (in this case channels fO and f2) to which said channel possibly causes adjacent channel interference.
  • Said receiver in Figure 5 thus utilizes the property that the interfering adjacent channels are desired regarding a receiver branch.
  • One of the channels is likely to be stronger than the others, and therefore easier to detect.
  • the detection of other channels can utilize the fact that based on the content of said strongest channel the interference caused by the strongest channel to adjacent channels can be reconstructed. If a sufficient amount of capacity is available, some receiver branches can detect the signal causing interference also merely because interference cancellation of some channels is thus facilitated in the described manner.
  • the function of the reconstruction means 500B is based on the fact that when the impulse response h and pulse mode p of the adjacent channel are known the interference received at a side frequency of the desired channel in accordance with the equation p * h, where * is a convolution operator.
  • the pulse mode p(t) is formed for an adjacent channel at a lower frequency using a Fourier synthesis or a corresponding convolution in time by equation
  • mf-r ⁇ (t) represents the impulse response of the transmission filter pulse mode
  • e i ⁇ t represents channel difference
  • mf RX (t) represents the im- pulse response of the receiving filter pulse mode
  • * represents a convolution operator
  • pulse mode p(t) is formed for an adjacent channel at a higher frequency by equation
  • mf ⁇ x (t) represents the impulse response of the transmission filter pulse mode
  • e j ⁇ t represents channel difference
  • mf RX (t) represents the impulse response of the receiving filter pulse mode
  • * represents a convolu- tion operator
  • An antenna arrangement employing several antennas, for example 2-20 separate antennas, can be connected to the receiver.
  • the receiver is then like the one described in Figure 4B.
  • the sum signal received by an antenna 400A-400N is applied to its own radio frequency parts 402-402N, from where the sum signal is applied to a filter 404A-404N and further to further processing means 406A-406N.
  • the signals of all antenna branches are in turn multiplexed in a multiplexer 420, for example, in bursts from each antenna branch to a queue.
  • the means 410, the means 412 and the detection part 414 are the same as in Figure 4A and there is only one common set of them for all antenna branches. Manufacturing costs of the receiver are thus saved.
  • the detection part 414 receives N sample bursts.
  • the channel estimates corresponding to each burst are likewise applied to the detection part 414 from the means 412. Detected bits of about one burst come out from the detection part 414.
  • the detection part 414 can be for example a VMLSE type (Vector Maximum Likelihood Sequence Estimation) described in article "Performance of the Vector MLSE Technique for Antenna Arrays in TDMA Mobile Systems" Escartin, Marko and Ranta, Pekka A.
  • the channel estimator 408 and the means 410 can process each burst regardless of the antenna 400A-400N through which it is received.
  • the means 412 make decisions on the basis of all N antenna data and decide on interferences to be removed.
  • the means 412 deliver to the detection means 414 with regard to the N burst the estimates of said interfer- ences with regard to the N antenna
  • Figure 5 shows a receiver which can also be implemented so as to receive a wide frequency band comprising a frequency area of three co- channels. The received frequency band is afterwards digitally filtered to the channels.
  • Figure 6 shows such a receiver, filters 600, 602 and 604 each filter- ing one channel.
  • the adjacent channel signal is transferred using a frequency transmission to a base frequency, the frequency transmission means being 606 and 608 in the Figure.
  • Base frequency signals are multiplexed with one another in means 610 and are sequentially applied to the channel estimator 408 where channel estimates of a desired channel and co-channels are esti- mated for each signal. Then the strongest signal is detected in the detector 414 by which adjacent channel signal interference can be removed on other channels as shown in connection with the receiver in Figure 5.
  • the above described procedures are well suited to be used in future cellular network receivers. In order to apply them in full-scale to existing networks requires changing receivers at both base stations and subscriber terminals.
  • the invention can be employed in current GSM-based systems in such a manner that the receiver to be used in the downlink direction is arranged to receive a signal modulated by a specific modulation method enabling a substantially better protection against interference caused by an adjacent channel than a conventional modulation method.
  • the receiver is arranged to detect the signal modulated according to the specific modulation method in accordance with prior art, i.e. the subscriber terminal receiver does not require any changes.
  • the receiver to be used in the uplink direction is arranged to receive the signal modulated by a conventional modulation method, for example by a GMSK modulation method, and the receiver is arranged to detect the sig- nal modulated according to the conventional modulation method in accordance with the invention.
  • the changes are thus restricted to the base station transmitter and receiver.
  • the OQAM method Offset Quadrature Amplitude Modulation
  • the minimum C/l ratio allowed improves from -9 dB in a GMSK modulation method to -30 dB in the OQAM method.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Noise Elimination (AREA)

Abstract

L'invention concerne un procédé permettant de détecter des signaux dans un récepteur de réseau cellulaire numérique. Une combinaison constituée d'un signal utile désiré et d'au moins un signal de canal adjacent brouilleur, provenant d'un canal adjacent à un canal désiré, est reçue sur le canal désiré. Selon l'invention, des estimations de canal constituées du signal utile et d'au moins un signal de canal adjacent sont déterminées conjointement. L'estimation se fait soit au moyen d'éléments de référence, séquence d'apprentissage par exemple, connus du récepteur, soit au moyen de décisions de symboles ou de bits produites par retour de décision. Puis le signal utile est détecté au moyen des estimations de canal à la fois du signal utile et du signal de canal adjacent. L'estimation peut également se faire séparément, en parallèle ou séquentiellement, auquel cas un signal brouilleur reconstruit est déduit du signal utile avant la détection.
PCT/FI1998/000528 1997-06-19 1998-06-17 Procede de detection de signaux pour recepteur cellulaire numerique WO1999001945A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU77713/98A AU741617B2 (en) 1997-06-19 1998-06-17 Signal detection method in a digital cellular receiver
JP50648499A JP2002506594A (ja) 1997-06-19 1998-06-17 デジタルセルラー受信器の信号検出方法
EP98925691A EP0990309A1 (fr) 1997-06-19 1998-06-17 Procede de detection de signaux pour recepteur cellulaire numerique
NO996262A NO996262D0 (no) 1997-06-19 1999-12-17 Fremgangsmåte for signaldeteksjon i en mottaker i et celledelt, digitalt nett

Applications Claiming Priority (2)

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FI972688A FI104019B1 (fi) 1997-06-19 1997-06-19 Signaalin ilmaisumenetelmä digitaalisen solukkoradioverkon vastaanottimessa
FI972688 1997-06-19

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PCT/FI1998/000528 WO1999001945A1 (fr) 1997-06-19 1998-06-17 Procede de detection de signaux pour recepteur cellulaire numerique

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JP (1) JP2002506594A (fr)
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JP2003092105A (ja) * 2001-09-18 2003-03-28 Denso Corp リチウム二次電池用正極及びリチウム二次電池
EP1786111A1 (fr) * 2005-11-11 2007-05-16 Telefonaktiebolaget LM Ericsson (publ) Filtre et procédé pour supprimer des effets de l'interférence de canal adjacent
EP1642407A4 (fr) * 2003-06-20 2007-05-30 Jan C Olivier Dispositif et procede associe pour systeme de communication a etats de communication variant dans le temps
US8565811B2 (en) 2009-08-04 2013-10-22 Microsoft Corporation Software-defined radio using multi-core processor
US8627189B2 (en) 2009-12-03 2014-01-07 Microsoft Corporation High performance digital signal processing in software radios
US8699424B2 (en) 2008-06-27 2014-04-15 Microsoft Corporation Adapting channel width for improving the performance of wireless networks
US8811903B2 (en) 2009-05-28 2014-08-19 Microsoft Corporation Spectrum assignment for networks over white spaces and other portions of the spectrum
US8929933B2 (en) 2011-05-04 2015-01-06 Microsoft Corporation Spectrum allocation for base station
US8989286B2 (en) 2011-11-10 2015-03-24 Microsoft Corporation Mapping a transmission stream in a virtual baseband to a physical baseband with equalization
US9130711B2 (en) 2011-11-10 2015-09-08 Microsoft Technology Licensing, Llc Mapping signals from a virtual frequency band to physical frequency bands
US9753884B2 (en) 2009-09-30 2017-09-05 Microsoft Technology Licensing, Llc Radio-control board for software-defined radio platform

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FI982857L (fi) 1998-12-31 2000-07-01 Nokia Networks Oy Vastaanottomenetelmä ja vastaanotin
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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003092105A (ja) * 2001-09-18 2003-03-28 Denso Corp リチウム二次電池用正極及びリチウム二次電池
EP1642407A4 (fr) * 2003-06-20 2007-05-30 Jan C Olivier Dispositif et procede associe pour systeme de communication a etats de communication variant dans le temps
EP1786111A1 (fr) * 2005-11-11 2007-05-16 Telefonaktiebolaget LM Ericsson (publ) Filtre et procédé pour supprimer des effets de l'interférence de canal adjacent
WO2007054538A1 (fr) * 2005-11-11 2007-05-18 Telefonaktiebolaget Lm Ericsson (Publ) Filtre et procede permettant de supprimer les effets d'interference de voies adjacentes
US8059772B2 (en) 2005-11-11 2011-11-15 Telefonaktiebolaget L M Ericcson (Publ) Filter and method for suppressing effects of adjacent-channel interference
US8699424B2 (en) 2008-06-27 2014-04-15 Microsoft Corporation Adapting channel width for improving the performance of wireless networks
US9730186B2 (en) 2009-05-28 2017-08-08 Microsoft Technology Licensing, Llc Spectrum assignment for networks over white spaces and other portions of the spectrum
US8811903B2 (en) 2009-05-28 2014-08-19 Microsoft Corporation Spectrum assignment for networks over white spaces and other portions of the spectrum
US8565811B2 (en) 2009-08-04 2013-10-22 Microsoft Corporation Software-defined radio using multi-core processor
US9753884B2 (en) 2009-09-30 2017-09-05 Microsoft Technology Licensing, Llc Radio-control board for software-defined radio platform
US8627189B2 (en) 2009-12-03 2014-01-07 Microsoft Corporation High performance digital signal processing in software radios
US8929933B2 (en) 2011-05-04 2015-01-06 Microsoft Corporation Spectrum allocation for base station
US9918313B2 (en) 2011-05-04 2018-03-13 Microsoft Technology Licensing, Llc Spectrum allocation for base station
US9130711B2 (en) 2011-11-10 2015-09-08 Microsoft Technology Licensing, Llc Mapping signals from a virtual frequency band to physical frequency bands
US8989286B2 (en) 2011-11-10 2015-03-24 Microsoft Corporation Mapping a transmission stream in a virtual baseband to a physical baseband with equalization

Also Published As

Publication number Publication date
FI972688A0 (fi) 1997-06-19
AU7771398A (en) 1999-01-25
JP2002506594A (ja) 2002-02-26
EP0990309A1 (fr) 2000-04-05
AU741617B2 (en) 2001-12-06
FI972688L (fi) 1998-12-20
FI104019B (fi) 1999-10-29
CN1260914A (zh) 2000-07-19
NO996262L (no) 1999-12-17
FI104019B1 (fi) 1999-10-29
NO996262D0 (no) 1999-12-17

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