DE19919545B4 - Method of forming a signal sequence - Google Patents

Abstract

mit
nx = 2^NX...Method for forming a signal sequence K (i) of length n, in which
the signal sequence K (i) with the length n = 256 is based on a first signal subsequence K1 (j) of length n1 = 16 and a second signal subsequence K2 (k) of length n2 = 16, the second signal subsequence K2 (k) n1 is repeatedly and thereby modulated with the first signal subsequence K1 (j), the formation of the signal sequence K (i) by modulation of the second signal subsequence K2 (k) according to the following rule:
K (i) = K2 (i mod n2) * K1 (i div n2), for i = 0 ... n1 * n2-1
wherein at least one of the signal subsequences is a Golay sequence X _n (k) of length nx, which can be formed by the following relationship: X ₀ (k) = δ (k) X _'0 (k) = δ (k) X _n (k) = X _n-1 (k) + W _n · X _'n-1 (k - D _n) X _'n (k) = X _n-1 (k) - W _n · X' _n-1 (k - D _n) k = 0, 1, 2, ..., 2 ^NX - 1 n = 1, 2, ..., NX

With
nx = 2 ^NX ...

Description

In particular, the invention relates to a method for forming a signal sequence to be transmitted for the purpose of synchronizing at least two transmission units.

In signal transmission systems, such as mobile radio systems, it is necessary that one of the communication partners (first transmission unit) recognizes certain specified signals that are sent by another communication partner (second transmission unit). These can be, for example, so-called synchronization bursts (synchronization radio blocks) for synchronization of two synchronization partners, such as radio stations, or so-called access bursts.

In order to reliably detect or identify such received signals relative to the ambient noise, it is known to continuously correlate the received signal over a defined period of time with a predetermined signal sequence and to form the correlation sum over the duration of the predetermined signal sequence. The range of the received signal which gives a maximum correlation sum corresponds to the searched signal. The synchronization signal from the base station of a digital mobile radio system, for example, is preceded by a signal sequence as a so-called training sequence, which is detected or determined in the mobile station in the manner just described by correlation with the stored signal sequence. So the mobile stations can be synchronized with the base station.

Also in the base station, such correlation calculations are required, for example, in Random Access Channel (RACH) detection. In addition, a correlation calculation is also performed to determine the channel impulse response and the signal propagation times of received signal bursts.

wobei E(i) eine aus dem Empfangssignal abgeleitete Empfangssignalfolge und K(i) die vorgegebene Signalfolge ist, wobei i von 0 bis n – 1 läuft. Die Korrelationssumme Sm wird aufeinanderfolgend für mehrere zeitlich versetzte, aus dem Empfangssignal gewonnene Signalfolgen E(i) berechnet, und dann der maximale Wert von Sm bestimmt. Sollen k aufeinanderfolgende Korrelationssummen berechnet werden, so beträgt der Berechnungsaufwand k·n Operationen, wobei eine Multiplikation und Addition zusammen als eine Operation gezählt wird.The correlation sum is calculated as follows:

where E (i) is a received signal sequence derived from the received signal and K (i) is the predetermined signal sequence, where i runs from 0 to n-1. The correlation sum Sm is successively calculated for a plurality of time-shifted signal sequences E (i) obtained from the received signal, and then the maximum value of Sm is determined. If k consecutive correlation sums are to be calculated, the computational effort is k · n operations, a multiplication and addition being counted together as one operation.

The calculation of the correlation sums is therefore very complicated and requires, especially in real-time applications such as voice communication or video telephony or CDMA systems, powerful and therefore expensive processors that have a high power consumption in the calculation. For example, to synchronize the UMTS mobile radio system in the standardization, a known signal sequence of length 256 chips (in the case of CDMA, a transmitted bit is also called a chip) must be determined. The episode is repeated every 2560 chips. Since the mobile station initially operates asynchronously to the chip clock, the received signal must be oversampled in order to obtain a sufficient signal even at an unfavorable scanning position. This results in 256 * 2560 * 2 * 2 = 2621440 operations due to the sampling of the I and Q components.

The invention has for its object to provide methods that allow to form signal sequences, and thus specify signal sequences that are easy to determine in transmitted received signal sequences.

The problem is solved by the features of the independent claims. Further developments can be found in the subclaim.

The invention is based on the idea of forming signal sequences in that a second signal subsequence of length n2 is repeated n1 times, thereby being modulated with the first signal subsequence, and at least one of the signal subsequences being a Golay sequence.

As a result, signal sequences can be formed which, if they are contained in a received signal sequence, can be easily determined. In particular, the use of Golay sequences is advantageous because a very effective algorithm is known for calculating the correlation.

Thus, for example, using a hierarchical correlation sequence of length 256 made up of 2 constituent Golay sequences of length 16, for the PSC of a UMTS system, the computational cost over a conventional realization using a Golay sequence of length 256 is 15 to 14 additions per calculated Correlator output value can be reduced.

A first embodiment of the invention provides that the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ , W ₄ used to form the signal subsequence are the following set of permutation unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;): 3201, + 1-1 + 1 + 1; 3201, -1-1-1 + 1; 3201, -1-1 + 1-1; 3201, + 1-1-1-1; and that the permutation (P ₁ P ₂ P ₃ P ₄ ) used to form the second signal subsequence is 3201.

A second embodiment of the invention provides that the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ , W ₄ used to form a signal subsequence are the following set of permutation unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;) is taken:
3201; + 1-1 + 1 + 1; 3201, -1-1 + 1 + 1; 3201, + 1-1-1 + 1; 3201, -1-1-1 + 1; 3201, + 1-1 + 1-1; 3201, -1-1 + 1-1; 3201, + 1-1-1-1; 3201, -1-1-1-1; 1023, + 1 + 1-1 + 1; 1023, -1 + 1-1 + 1; 1023, + 1-1-1 + 1; 1023, -1-1-1 + 1; 1023, + 1 + 1-1-1; 1023, -1 + 1-1-1; 1023, + 1-1-1-1; 1023, -1-1-1-1 ;.

A third embodiment of the invention provides that the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ , W ₄ used to form a signal subsequence are the following set of permutation unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;) is taken:
0213, + j + j + j-1; 0213, -j + j + j-1; 0213, + 1-j + j-1; 0213, -1-j + j-1; 0213, + 1 + j-j-1; 0213, -1 + j-j-1; 0213, + j-j-j-1; 0213, -j-j-j-1; 0213, + j + j + j + 1; 0213, -j + j + j + 1; 0213, + 1-j + j + 1; 0213, -1-j + j + 1; 0213, + 1 + j-j + 1; 0213, -1 + j-j + 1; 0213, + j-j-j + 1; 0213, -j-j-j + 1; 3120, + 1-j + j-1; 3120, -1-j + j-1; 3120, + 1 + j-j-1; 3120, -1 + j-j-1; 3120, + 1 + j + j + j; 3120, -1 + j + j + j; 3120, + 1-j-j + j; 3120, -1-j-j + j; 3120, + 1 + j + j-j; 3120, -1 + j + j-j; 3120, + 1-j-j-j; 3120, -1-j-j-j; 3120, + 1-j + j + 1; 3120, -1-j + j + 1; 3120, + 1 + j-j + 1; 3120, -1 + j-j + 1 ;.

Through each of these embodiments of the invention, a particularly favorable implementation variant of the invention in ASICs can be made possible.

By specifying the method for forming signal sequences, the signal sequences that can be formed by such a method or are available are within the scope of the invention. In particular, their use in data transmission systems, in particular for the purpose of synchronization of a mobile station with a base station.

In the following the invention will be described in more detail with reference to various embodiments, for the explanation of which serve the figures listed below:

1 schematic representation of a mobile network

2 Block diagram of a radio station

3 conventional method for calculating correlation sums

4 Representation of inventive signal sequences and signal subsequences

5 schematic representation of the formation of the signal sequence according to the invention

6 . 7 and 8th schematic representation of a method for calculating a correlation sum

9 and 10 schematic representation of an embodiment of a method for forming the correlation sum

11 Block diagram of an efficient hierarchical Golay correlator.

In 1 is a cellular mobile network, such as the GSM (Global System for Mobile Communication) system shown, which consists of a plurality of mobile switching centers MSC, which are networked together, or establish access to a fixed network PSTN / ISDN. Furthermore, these mobile switching centers MSC are each connected to at least one base station controller BSC, which may also be formed by a data processing system. A similar architecture can also be found in a UMTS (Universal Mobile Telecommunication System).

Each base station controller BSC is in turn connected to at least one base station BS. Such a base station BS is a radio station, which can establish a radio link to other radio stations, so-called mobile stations MS via a radio interface. Between the mobile stations MS and the base station BS assigned to these mobile stations MS, information can be transmitted by means of radio signals within radio channels f which lie within frequency bands b. The range of the radio signals of a base station essentially define a radio cell FZ.

Base stations BS and a base station controller BSC can be combined to form a base station system BSS. The base station system BSS is also responsible for the radio channel management and allocation, the data rate adjustment, the monitoring of the radio transmission path, hand-over procedures, and in the case of a CDMA system for the allocation of the spreading code sets to be used, and transmits the necessary signaling information to the mobile stations MS.

In the case of a duplex system, FDD (Frequency Division Duplex) systems, such as the GSM system, may have different frequency bands for the uplink u (mobile station (transmitter unit) to the base station (receiver unit) than for the downlink d (base station (base station)). Transmitting unit) to the mobile station (receiving unit)). Within the different frequency bands b, a plurality of frequency channels f can be realized by an FDMA (Frequency Division Multiple Access) method.

In the context of the present application, transmission unit is also understood to mean communication unit, transmitting unit, receiving unit, communication terminal, radio station, mobile station or base station. Terms and examples used in this application also often refer to a GSM mobile radio system; However, they are by no means limited thereto but, based on the description of a person skilled in the art, can also be easily mapped to other, possibly future, mobile radio systems, such as CDMA systems, in particular wide-band CDMA systems.

By means of multiple access methods, data can be efficiently transmitted over a radio interface, separated and allocated to one or more specific connections or to the corresponding subscriber. For this purpose, a time division multiple access TDMA, a frequency division multiple access FDMA, a code division multiple access CDMA or a combination of several of these multiple access methods can be used.

In FDMA, the frequency band b is decomposed into a plurality of frequency channels f; These frequency channels are divided by the time division multiple access TDMA into time slots ts. The signals transmitted within a time slot ts and a frequency channel f can be separated by connection-specific spread codes modulated onto the data, so-called CDMA codes cc.

The resulting physical channels are assigned to logical channels according to a defined scheme. Basically, two types of logical channels are distinguished: Signaling channels (or control channels) for transmitting signaling information (or control information) and traffic channels (TCH) for transmitting user data.

• – Broadcast Channels
• – Common Control Channels
• – Dedicated/Access Control Channel DCCH/ACCH

The signaling channels are further divided into:

• - Broadcast Channels
• - Common Control Channels
• - Dedicated / Access Control Channel DCCH / ACCH

The group of broadcast channels includes the broadcast control channel BCCH, through which the MS receives radio information from the base station system BSS, the frequency correction channel FCCH and the synchronization channel SCH. Common Control Channels include Random Access Channel RACH. The radio blocks or signal sequences transmitted for the realization of these logical channels can contain for different purposes signal sequences K (i) so-called correlation sequences, or on these logical channels signal sequences K (i) can be transmitted for different purposes.

In the following, a method for synchronizing a mobile station MS with a base station BS is explained by way of example: During a first step of the initial base station search or cell search procedure, the mobile station uses the primary synchronization channel SCH (PSC) to generate a Timeslot synchronization with the strongest base station to achieve. This can be ensured by a matched filter or equivalent circuit adapted to the primary synchronization code cp transmitted by all base stations. In this case, the same primary synchronization code cp of length 256 is transmitted by all base stations BS.

The mobile station determines by means of correlation from a receive sequence the received signal sequences K (i) according to a principle that is in the 6 to 11 and associated description is explained. In this case, peaks are output at the output of a matched filter (matched filter) for each received signal sequence of each base station located within the reception range of the mobile station. The detection of the position of the strongest peak enables the determination of the timing of the strongest base station modulo the slot length. To ensure greater reliability, the output of the matched filter can be non-coherently accumulated over the number of time slots. The mobile station thus performs a correlation over a signal sequence of length 256 chips as a matched-filter operation.

The synchronization code cp is in accordance with a signal sequence K (i) according to a principle as in 5 and associated description, or may be formed or may be so obtained. The signal sequence K (i) or the synchronization code cp of length 256 is formed from two signal sub-sequences K1 (j), K2 (k), which each have the length 16, or can be formed in this way. These signal subsequences form a signal subsequence pair (K1 (j); K2 (k)).

A signal sequence K (i) which can be obtained in this way can also be called a "hierarchical signal sequence". A signal subsequence can also be called a "short correlation sequence".

mit
nx = 2^NX
δ(k) Kroneckersche Deltafunktion
P_n, n = 1, 2, ... NX, ist beliebige Permutation der Zahlen {0, 1, 2, ..., NX – 1} für die X Sequenz,
W_n Gewichte für die X Sequenz (+1, –1, +i oder –1).At least one signal subsequence is a Golay sequence X _n (k), which can be formed by the following relationship: X ₀ (k) = δ (k) X _'0 (k) = δ (k) X _n (k) = X _n-1 (k) + W _n · X _'n-1 (k - D _n) X _'n (k) = X _n-1 (k) - W _n · X' _n-1 (k - D _n) k = 0, 1, 2, ..., 2 ^NX - 1 n = 1, 2, ..., NX

With
nx = 2 ^NX
δ (k) Kronecker delta function
P _n , n = 1, 2, ... NX, is any permutation of the numbers {0, 1, 2, ..., NX - 1} for the X sequence,
W _n weights for the X sequence (+1, -1, + i or -1).

W _n can therefore assume the values +1, -1, + i or -i or assume the values +1 or -1 for the generation of binary Golay sequences. In the context of the present application, W _{n is} also referred to as a unit size.

In one embodiment variant of the invention, at least one signal subsequence is a Golay sequence optimized in particular for the frequency error, in particular of length 16, the permutation P ₁ , P ₂ , P ₃ , P ₄ , and unit size W ₁ , W ₂ , W ₃ used to form the sequence , W ₄ , is taken from a set of permutation unit size pairs specified in one and / or more of the independent claims.

By using a signal sequence or synchronization code cp thus formed or formable, the computation outlay in the correlation sum calculation for determining the signal sequence K (i) in the receiving mobile station MS can be considerably reduced for the purpose of synchronization.

The autocorrelation function of a signal sequence K (i) formed by two signal subsequences, however, generally has inferior autocorrelation properties, unlike an orthogonal gold code used in conventional methods. It has, for example, higher secondary maxima and a higher rms value of secondary minima. In addition, UMTS link-level simulations show that when using such signal sequences K (i) in the PSC for slot synchronization at a frequency offset between transmitter and receiver, the synchronization error is generally higher in contrast to the use of an orthogonal gold code.

However, by using complex simulation tools specially created for this purpose, signal subsequence pairs (K1 (j), K2 (k)) consisting of at least one Golay sequence could be determined on the basis of which, as explained above, signal sequences K (i) can be formed or can be formed, which can be reliably determined in particular for synchronization between the base station and mobile station even at a higher frequency offset between transmitter and receiver. The simulations for the UMTS system were also based on a frequency offset of 10 kHz. By using such signal sequences K (i), the calculation effort for calculating the correlation sums is considerably reduced without having to accept a simultaneous increase in the synchronization error. In addition, the use of expensive crystals in the receiver for frequency stabilization can be dispensed with.

Through the elaborate simulations, a set of Golay sequences of length 16 described could be determined by a set of permutation unit size pairs given in one and / or more of the independent claims, on the basis of which signal sequences K (i) can be formed, which have a small synchronization error both at frequency offset zero between transmitter and receiver, as well as at a larger frequency offset when used for synchronization purposes.

In complex simulations, it has been found that the use of a signal sequence K (i), which has good synchronization properties both with smaller and larger frequency errors (frequency offset), is particularly advantageous. This results in a preferred choice of permutation unit size pairs, from which signal subsequences and finally signal sequences K (i) are obtainable or formable. The calculation of the autocorrelation function as a function of the frequency error turned out to be particularly suitable for evaluating the synchronization properties of a signal sequence K (i) formed by a permutation unit variable pair.

• – Autokorrelationsfunktion: Die Berechnung der Autokorrelationsfunktion unter Berücksichtigung eines Frequenzversatzes zwischen Sende- und Empfangseinheit kann dabei auch gemäß folgender Formel durchgeführt werden:
  
  

  ĸ

  Versatz

  n

  Länge der Folge

  i

  Index

  f_d

  Frequenzversatz

  t_a

  Abtastintervall

  []*

  bedeutet konjugiert komplex

The following criteria can also be used to select these signal subsequence pairs (K1 (j); K2 (k)):

• - Autocorrelation function: The calculation of the autocorrelation function taking into account a frequency offset between the transmitting and receiving unit can also be carried out according to the following formula:
  
  

  ÿ

  offset

  n

  Length of the episode

  i

  index

  f _d

  frequency offset

  t _a

  sampling

  [] *

  means conjugated complex

• – Missed Detektion Rate: Wähle die Signalteilfolgenpaare aus durch Vergleich der Missed Detektion Rate bei Durchführung vollständiger Simulationen.
• – Detektionswahrscheinlichkeiten bei gegebenem Frequenzfehler und gegebenem SNR bei AWGN Kanälen.

The values a (ĸ) for ĸ = 0 ... n - 1 can be calculated. If several signal subpulse pairs result, which result in an equally good ratio of main maximum to maximum secondary maximum in the autocorrelation function of the resulting signal sequence K (i), the signal subsequence pairs which result in a lower effective value of the subminals can subsequently be selected. there the ratio of the main maximum to the maximum secondary maximum should be as large as possible and the effective value of the secondary minima should be as small as possible. Subsequent link-level simulations for, for example, the UMTS system signal pairs of signals can be determined that behave at frequency errors 0 kHz and 5 kHz and 10 kHz in terms of synchronization error as well as a conventional orthogonal gold code, which is not hierarchical, and is known to have very good properties for the synchronization.

• Missed Detection Rate: Select the pairs of signal pairs by comparing the Missed Detection Rate when performing full simulations.
• Detection probabilities given given frequency error and given SNR on AWGN channels.

Within the scope of the invention, therefore, there are 10 to 10 ^ 2 permutation unit size pairs selected from a basically possible set of permutation unit size pairs. The selected signal subsequences thus form only a very small subset of the basically possible amount of permutation unit size pairs that can be used to form 16-digit Golay sequences.

The use of a signal sequence K (i) which proved to be particularly advantageous was the use of the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ , W ₄ used to form a partial signal sequence Unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;) is taken:
0213, + j + j + j-1; 0213, -j + j + j-1; 0213, + 1-j + j-1; 0213, -1-j + j-1; 0213, + 1 + j-j-1; 0213, -1 + j-j-1; 0213, + j-j-j-1; 0213, -j-j-j-1; 0213, + j + j + j + 1; 0213, -j + j + j + 1; 0213, + 1-j + j + 1; 0213, -1-j + j + 1; 0213, + 1 + j-j + 1; 0213, -1 + j-j + 1; 0213, + j-j-j + 1; 0213, -j-j-j + 1; 3120, + 1-j + j-1; 3120, -1-j + j-1; 3120, + 1 + j-j-1; 3120, -1 + j-j-1; 3120, + 1 + j + j + j; 3120, -1 + j + j + j; 3120, + 1-j-j + j; 3120, -1-j-j + j; 3120, + 1 + j + j-j; 3120, -1 + j + j-; 3120, + 1-j-j-j; 3120, -1-j-j-j; 3120, + 1-j + j + 1; 3120, -1-j + j + 1; 3120, + 1 + j-j + 1; 3120, -1 + j-j + 1 ;.

The use of a signal sequence K (i) which proved to be particularly advantageous was the use of the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ , W ₄ used to form a partial signal sequence Unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;) is taken:
3201, + 1-1 + 1 + 1; 3201, -1-1 + 1 + 1; 3201, + 1-1-1 + 1; 3201, -1-1-1 + 1; 3201, + 1-1 + 1-1; 3201, -1-1 + 1-1; 3201, + 1-1-1-1; 3201, -1-1-1-1; 1023, + 1 + 1-1 + 1; 1023, -1 + 1-1 + 1; 1023, + 1-1-1 + 1; 1023, -1-1-1 + 1; 1023, + 1 + 1-1-1; 1023, -1 + 1-1-1; 1023, + 1-1-1-1; 1023, -1-1-1-1 ;.

The use of a signal sequence K (i) which proved to be particularly advantageous was the use of the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ , W ₄ used to form a partial signal sequence Unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;) is taken:
3201, + 1-1 + 1 + 1; 3201, -1-1-1 + 1; 3201, -1-1 + 1-1; 3201, + 1-1-1-1, and the permutation (P ₁ P ₂ P ₃ P ₄ ) used to form the second signal subsequence is 3201

Using signal subsequences (constituent sequences) for the PSC of UMTS Golay sequences of length 16, wherein as weights W _n = 1, -1, i -i and as delays any permutation of D _n = {1, 2, 4, 8 } so there are more than 2 ¹² different possibilities for each of the two constituent sequences. So a total of 2 ²⁴ ways. The selected permutation unit size pairs can only be used to form 10 to 10 ^ 2 different constituent sequences and thus only a very small proportion of generally possible constituent sequences of length 16.

2 shows a radio station, which may be a mobile station MS, consisting of an operating unit or interface unit MMI, a control device STE, a processing device VE, a power supply device SVE, a receiving device EE and possibly a transmitting device SE.

The control device STE consists essentially of a program-controlled Mikrocontroler MC, which can read and write access memory modules SPE. The microcontroller MC controls and controls all essential elements and functions of the radio station.

The processing device VE can also be formed by a digital signal processor DSP, which can also access memory modules SPE.

In the volatile or nonvolatile memory modules SPE, the program data required for controlling the radio station and the communication sequence, in particular also the signaling procedures, are stored and information resulting during the processing of signals is stored. In addition, signal sequences K (i), which are used for correlation purposes, and intermediate results of Correlation sum calculations are stored. The signal sequences K (i) lying within the scope of the invention can therefore be stored in the mobile station and / or the base station. It is also possible for one or more of the permutation unit size pairs listed above or signal subsequences or signal subsequence pairs (K1 (j); K2 (k)) derived therefrom to be stored in the mobile station and / or the base station. It is also possible that in the mobile station and / or the base station a signal sequence K (i) is formed from a signal subsequence pair (K1 (j); K2 (k)) and / or a signal subsequence from a permutation unit variable pairs.

In particular, in a base station or in all base stations of a system, a signal sequence K (i) can be stored, which is transmitted at fixed or variable intervals for synchronization purposes. In the mobile station MS, the signal subsequence pair (K1 (j); K2 (k)) from which the signal sequence K (i) stored in the base station can be formed or formed is stored and is used for synchronization of the mobile station with a base station for the computing effort Correlation sum calculation used.

The high-frequency part HF optionally consists of the transmitting device SE, with a modulator and an amplifier V and a receiving device EE with a demodulator and also an amplifier. By analog / digital conversion, the analog audio signals and the analog signals originating from the receiving device EE are converted into digital signals and processed by the digital signal processor DSP. After processing, if necessary, the digital signals are converted by digital / analog conversion into analog audio signals or other output signals and analog signals to be supplied to the transmitting device SE. For this purpose, if necessary, a modulation or demodulation is performed.

The transmitting device SE and the receiving device EE is supplied via the synthesizer SYN the frequency of a voltage-controlled oscillator VCO. By means of the voltage-controlled oscillator VCO and the system clock for clocking processor devices of the radio station can be generated.

For receiving and transmitting signals via the air interface of a mobile radio system, an antenna device ANT is provided. In some known mobile radio systems, such as the GSM (Global System for Mobile Communication), the signals are pulsed in time in so-called bursts received and sent.

The radio station can also be a base station BS. In this case, the loudspeaker element and the microphone element of the operating unit MMI are replaced by a connection to a mobile radio network, for example via a base station controller BSC or a switching device MSC. In order to exchange data with several mobile stations MS at the same time, the base station BS has a corresponding plurality of transmitting and receiving devices.

In 3 is a received signal sequence E (l), which may also be a derived from a received signal signal sequence, the length w shown. To calculate a first correlation sum S0 according to the formula given at the outset, elements of a first section of this received signal sequence E (l) are multiplied in pairs by the corresponding elements of the signal sequence K (i) of length n, and the length of the resulting partial results is added to the correlation sum S0.

In order to calculate a further correlation sum S1, the signal sequence K (i) is shifted by one element to the right as shown in the figure and the elements of the signal sequence K (i) are multiplied in pairs by the corresponding elements of the signal sequence E (l), and by a Summation of the resulting partial results again formed the correlation sum S1.

The pairwise multiplication of the elements of the signal sequence with corresponding elements of the received signal sequence and the subsequent summation can also be described in vector notation as the formation of a scalar product, as long as the elements of the signal sequence and the elements of the received signal sequence are combined to form a vector of a Cartesian coordinate system:

In the correlation sums S thus determined, the maximum can be searched, the maximum of the correlation sums S can be compared with a predetermined threshold value, and it can thus be determined whether the predetermined signal sequence K (i) is contained in the received signal E (l) and, if yes, where in the received signal E (l) it is located, and so two radio stations are synchronized with each other or data to which an individual spreading code in the form of a signal sequence K (i) has been modulated, are detected.

In 4 is again the received signal sequence E (l) and as a correlation sequence, a signal sequence K (i), which is based on the signal sub-sequences K1 (j), K2 (k), represented.

In 5 the formation of a signal sequence K (i) is shown which is based on two signal subsequences K2 (k) of length n2 and K1 (j) of length n1. For this purpose, the signal subsequence K2 (k) is repeated n1 times, and thereby modulated by the signal subsequence K1 (j). The formation of the signal sequence K (i) can also be expressed mathematically by the following formula: K (i) = K2 (i mod n2) * K1 (i div n2), for i = 0 ... n1 * n2-1 mod the integer remainder of a division and div the integer result of a division.

This is illustrated by a sequence f2 which consists of the repeated signal sequences K2 (k) which are shown in succession, and a sequence f1 which is represented by a stretched signal subsequence K1 (j) over the sequence f2.

By multiplying the elements of the sequence f2 by the corresponding elements of the sequence f1 mapped over the sequence f2, the new signal sequence K (i) of length n is created. This generation of a signal sequence K (i) is shown below in the figure once again with reference to an example of two binary signal sequences of length 4 shown.

Signal sequences K (i) thus formed can be used for simplified calculation of correlation sums of these signal sequences K (i) with received signal sequences E (1).

A schematic representation of such a simplified and thus also faster and more cost-effective calculation of correlation sums S is shown in FIGS 6 to 8th presented below.

First, a partial correlation sum TS (z) is formed. For this purpose, for example, for the first element of the partial correlation sum sequence TS (0), the correlation sum of the second signal sub-sequence K2 (k) is formed with the corresponding section of the received signal sequence E (1).

For the second element of the partial correlation sum sequence TS (1), the second signal sub-sequence K2 (k) is displaced by one element as illustrated, and the correlation sum is also formed with the corresponding element of the received signal sequence E (1), etc.

The nth element of the partial correlation sum sequence TS (n1 * n2-1) is correspondingly calculated after n-1 shifts of the second signal subsequence K2 (k) with respect to the received signal sequence E (l).

The resulting partial correlation sum sequence TS (z) is at the top of the 7 shown. From this partial correlation sum sequence, each n.sup.-2 element is selected and multiplied by the corresponding element of the first signal subsequence K1 (j) in pairs.

If the selected elements of the partial correlation sum sequence TS (z) and the first signal subsequence K1 (j) are combined into vectors, the first correlation sum S0 is generated by the scalar product of these two vectors.

7 shows in the lower area the corresponding calculation of further correlation sums S1 and S2 by the selection n2-ter by 1 or 2 to the right of the elements selected as first selected elements:

By storing once calculated partial correlation sums TS, they can be used for the later calculation of further correlation sums, and thus the corresponding calculation steps can be dispensed with.

Depending on the embodiment variant, either the complete partial correlation sum sequence TS (z) can first be calculated over the entire received signal sequence E (1) and then the individual correlation sums or only when necessary to calculate a new correlation sum, the corresponding additional required Teilkorrelationssums be calculated.

8th again shows the two-step method for calculating correlation sums S, this time using the in 5 illustrated example of two binary signal subsequences of length 4.

In a first step, the partial correlation sums TS (z) of the second signal subsequence K2 (k) ++ - + are calculated with corresponding sections of the received signal sequence E (l), and then in a second step every fourth element of the subcorrelation sum sequence TS (z) thus generated is selected, multiplied by the corresponding element of the first signal subsequence K1 (j) + - + and added up to the correlation sequence S0.

The thick drawn lines represent the new calculation steps to be performed for the calculation of a further correlation sum S1, in the event that the remaining partial correlation sums TS have already been calculated and stored beforehand.

This embodiment variant can be carried out as memory-efficient as possible, if first every n2-th partial correlation sum is calculated. For this, the samples are buffered.

The 9 to 10 represent another embodiment for the simplified calculation of correlation sums S based on the already mentioned above example of two binary signal subsequences of length 4.

In this case, first every 4th element of the received signal sequence E (l) is selected and the partial correlation sum sequence TS (z) of the elements thus selected is formed with the signal subsequence K1 (j). From the resulting partial correlation sum sequence TS (z), in each case 4 consecutive elements are selected, multiplied in pairs by corresponding elements of the signal subsequence K2 (k) and the resulting partial results are added up to the correlation sum S. In this case, again the thick drawn lines represent the additionally necessary steps for calculating a further correlation sum S1, in the event that the other partial correlation sums TS have already been calculated and stored previously.

10 shows again the calculation of a first correlation sum S0 in which first every 4th element of the received signal sequence E (l) is selected, these elements are multiplied by corresponding elements of the first signal subsequence K1 (j) + - + and by summing the partial results the partial correlation sum TS (0) is calculated. In a second step, the first four successive elements of the partial correlation sum sequence TS (z) are multiplied by the corresponding elements of the second signal subsequence K2 (k) ++ - + and the resulting partial results are added up to the correlation sum S0.

In this embodiment, less memory is needed for buffering the partial correlation sums when the sums are calculated successively.

A further embodiment of the invention makes use of the regular (almost periodic) structure of the aperiodic autocorrelation function of this signal sequence which is conditioned by the regular design principle of the signal sequence K (i). This means that when searching for a signal not only results in a main maximum, but also at regular intervals, secondary maxima occur. For accelerated search for the signal sequence in the received signal sequence, one can exploit the regularity of the position of the maxima. Once a secondary maxima has been found, one can predict the position of the other maxima due to the periodicity, i. H. one calculates the correlation sum only at these places. In this way you can quickly detect the main maximum. However, the supposed secondary maximum can only be a random value (because of the noise component). In this case, one will not actually find a maximum at the potential locations of the expected major maximum. Therefore, in this case, the hypothesis is rejected and the calculation continues conventionally.

One can exploit the regularity of the secondary maxima due to the design principle of the signal sequences, but also the elimination and correction of disturbing secondary maxima in the correlation result. After the detection of the maximum, one can calculate the secondary maxima from the maximum and subtract this value from the corresponding correlation results. In this way one obtains the correlation result of a (hypothetical) sequence with perfect autocorrelation function. As a result, the regularity of the secondary maxima results in a greatly simplified calculation.

In embodiments of the invention, efficient Golay correlators are used to calculate scalar products, correlation sums, and / or sub-correlation sums.

11 shows an efficient hierarchical correlator for signal sequences, wherein Golay sequences X, Y are used as constituent sequences K1, K2. It consists of two matched filters (a) connected in series, which are each formed as Efficient Golay correlators. b) shows the matched filter for the sequence X and c) shows the matched filter for the sequence Y.

Definition:

• a _n (k) and b _n (k)

  are two complex sequences of length 2 ^N ,

  δ (k)

  is the Kronecker Delta function,

  k

  is an integer representing the time,

  n

  is the iteration number,

  D _n

  is the delay

  P _n , n = 1, 2, ..., N,

  is an arbitrary permutation of the numbers {0, 1, 2, ..., N - 1},

  W _n

  can take the values +1, -1, + i, -i as weights and is also referred to as a unit size.

The correlation of a Golay sequence of length 2 ^N can be carried out efficiently in the following manner:
The sequences R _a ^{( 0 )} (k) and R _b ^{( 0)} (k) are defined as R _a ^{( 0 )} (k) = R _b ^{( 0 )} (k) = r (k), where r (k) the received signal is (or already the output of another correlation stage)

Perform the following step N times, n runs from 1 to N: Calculate R _a ^{( n )} (k) = W ^* _n * R _b ^{( n-1)} (k) + R _a ^(n-1) (k-D _n )

And Rb ⁽ⁿ⁾ (k) = W ^* R _n · _b ^(n-1) (k) - R _a ^(n-1) (k - D _n)

Where W ^* _{n is} the conjugate complex of W _n . If the weights W are real, W ^* _{n is} identical to W _n .

R _a ^{( N )} (k) is then the correlation sum to be calculated.

In the above formula, the quantities R _{b are} multiplied by the weights. Alternatively, it is also possible to multiply the quantities R _b by weights W ', wherein the weights W' can be calculated from the weights W. If necessary, the input signal itself or the output signal is multiplied; but for application as a correlator, one can also omit this multiplication, since a constant factor for the application of the result is often irrelevant. Alternatively one can connect this multiplication with other usually necessary scalings.

To build an Efficient Golay correlator for a PSC code of length 256 (2 ⁸ ) chips in the receiver requires 2 * x 8-1 = 15 complex adders

With the combination of Hierarchical Correlation and Efficient Golay Correlator, for a Hierarchical Code - described by two constituent sequences X and Y - of length 256 (2 ⁴ · 2 ⁴ ) only 2 · 4 - 1 + 2 · 4 - 1 = 14 is needed complex adders (even if you use quadrivalent constituent sequences)

This reduces the calculation effort by 7%. This is enormous, especially since the computational effort for the primary synchronization station in CDMA mobile radio systems is very high.

In the following, embodiments of the invention are given:
Two constituent Golay sequences of length nx = 2 ^NX and ny = 2 ^NY are used to form a code sequence of length 2 ^{NX + NY} and build them up hierarchically as described above.

We use +1 and -1 as weights for the constituent Golay sequences and thus generate binary sequences.

We use as weights for the constituent Golay sequences +1, -1, i or -i and thus generate 4-valued sequences.

You use real Golay sequences.

One uses complex Golay sequences.

One uses two constituent Golay sequences of equal length.

Two complementary Golay sequences are used.

One uses only an efficient Golay correlator, possibly with programmable delays for the optional calculation of one or both complementary Golay sequences.

You use a sequence as described, but add additional values. During the calculation, these values must be accumulated as usual. The rest of the calculation can, however, be carried out efficiently as described. This allows the generation of sequences of any length.

One uses two constituent subsequences.

One uses several constituent subsequences.

One uses only a part of the subsequences of a Golay sequence.

These sequences are used for the synchronization channel in UMTS.

One uses frequency-optimized constituent Golay sequences.

Two filters are used in order to calculate the correlation, one being a matched filter on Golay sequence X and the other a matched filter on Golay sequence Y with spread delays ny * DX _n .

Two filters are used in order to calculate the correlation, one being a matched filter on Golay sequence X and the other a matched filter on Golay sequence Y with spread delays ny * DX _n and the output signals of the filters corresponding to the Efficient Golay sequence. Correlator algorithm can be calculated.

To calculate the partial correlation sums, use the Efficient Golay correlation algorithm and determine the algorithm for the hierarchical correlation to determine the overall correlation.

The invention is not limited to radio transmission systems, but can also be used with other transmission methods z. B. acoustic method (ultrasound), in particular for the purposes of sonography, or optical methods, for example, the infrared measurement according to Lidar principles are used. Another field of application is the investigation of changes in the spectral composition of backscattered signals.

• – zum Zwecke der Synchronisation zweier Übertragungseinheiten, wie beispielsweise Funkstationen, insbesondere die Verwendung dieser Folgen im Synchronisationskanal in CDMA-Mobilfunksystemen, wie das sich in der Standardisierung befindliche UMTS-System,
• – bei der Datenübertragung mittels durch die Signalfolge gespreizte Sendesymbole bzw. Daten in Bandspreiz (spread spectrum)-Systemen, insbesondere zur Ermittlung von Sendesymbolen bzw. Daten, denen eine derartige Signalform aufmoduliert wurde,
• – in der Meßtechnik zur Entfernungs- und Objektvermessung,
• – zur Bestimmung von Übertragungseigenschaften des zwischen Übertragungseinheiten, wie Sendeeinheit und Empfangseinheit liegenden Übertragungskanals, in der Radarmeßtechnik, um die Lage eines Objektes und/oder weitere von der Geometrie und den spezifischen Reflexionseigenschaften des Objektes abhängige Parameter zu bestimmen,
• – zur Bestimmung von Übertragungseigenschaften des zwischen Sender und Empfänger befindlichen Übertragungskanals, in der Radarmeßtechnik zur Bestimmung von Parametern eines rückstreuenden Mediums, insbesondere der Ionosphäre, insbesondere durch inkohärente Streuung,

zur Bestimmung von Übertragungseigenschaften des zwischen Übertragungseinheiten, wie Sendeeinheit und Empfangseinheitliegenden Übertragungskanals, insbesondere zur Bestimmung von Mehrwegeausbreitungen in der Meßtechnik oder Kommunikationstechnik. Dabei werden mittels des Korrelationsergebnisses während der Kommunikation die sich zeitlich ändernden Ausbreitungseigenschaften des Übertragungskanals (Kanalimpulsantwort) ermittelt. Insbesondere werden zusätzliche Pfade der Mehrwegeausbreitung ermittelt. Dazu können die Signalfolgen K(i) auch in Form einer Mittambel innerhalb eines Funkblockes übertragen werden. Diese Kenntnis kann dann in einer ansonsten konventionellen Empfangseinheit weiterverwendet werden.The generation of signal sequences, their transmission, as well as the calculation of correlation sums of these signal sequences with received signal sequences can be used in different technical fields:

• For the purpose of synchronizing two transmission units, such as radio stations, in particular the use of these sequences in the synchronization channel in CDMA mobile radio systems, such as the UMTS system undergoing standardization,
• In data transmission by means of transmission symbols spread by the signal sequence or data in spread spectrum systems, in particular for the determination of transmission symbols or data to which such a signal form has been modulated,
• - in the measurement technique for distance and object measurement,
• For determining transmission characteristics of the transmission channel lying between transmission units, such as transmitting unit and receiving unit, in the radar measuring technique in order to determine the position of an object and / or further parameters dependent on the geometry and the specific reflection properties of the object,
• For determining transmission characteristics of the transmission channel between the transmitter and the receiver, in the radar measurement technique for determining parameters of a backscattering medium, in particular of the ionosphere, in particular by incoherent scattering,

for determining transmission characteristics of the transmission channel between transmission units, such as transmitting unit and receiving unit, in particular for determining multipath propagation in measuring or communication technology. In this case, the time-varying propagation characteristics of the transmission channel (channel impulse response) are determined by means of the correlation result during the communication. In particular, additional paths of multipath propagation are determined. For this purpose, the signal sequences K (i) can also be transmitted in the form of a midamble within a radio block. This knowledge can then be used in an otherwise conventional receiving unit.

Claims (4)

A method for forming a signal sequence K (i) of length n, wherein the signal sequence K (i) of length n = 256 on a first signal subsequence K1 (j) of length n1 = 16 and a second signal subsequence K2 (k) of length n2 = 16, wherein the second signal subsequence K2 (k) is repeated n1 times and thereby modulated with the first signal subsequence K1 (j), the formation of the signal sequence K (i) by modulating the second signal subsequence K2 (k) according to the following The rule is: K (i) = K2 (i mod n2) * K1 (i div n2), for i = 0 ... n1 * n2-1 where at least one of the signal subsequences is a Golay sequence X _n (k) length nx, which can be formed by the following relationship: X ₀ (k) = δ (k) X _'0 (k) = δ (k) X _n (k) = X _n-1 (k) + W _n · X _'n-1 (k - D _n) X _'n (k) = X _n-1 (k) - W _n · X' _n-1 (k - D _n) k = 0, 1, 2, ..., 2 ^NX - 1 n = 1, 2, ..., NX

with nx = 2 ^NX δ (k) Kronecker's delta function P _n , n = 1, 2, ... NX, is any permutation of the numbers {0, 1, 2, ..., NX - 1} for the X sequence, W _n weights for the X sequence (+1, -1, + i or -i), wherein the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ used to form a signal subsequence , W _{4 is taken from the} following set of permutation unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;): 0213, + j + j + j-1; 0213, -j + j + j-1; 0213, + 1-j + j-1; 0213, -1-j + j-1; 0213, + 1 + j-j-1; 0213, -1 + j-j-1; 0213, + j-j-j-1; 0213, -j-j-j-1; 0213, + j + j + j + 1; 0213, -j + j + j + 1; 0213, + 1-j + j + 1; 0213, -1-j + j + 1; 0213, + 1 + j-j + 1; 0213, -1 + j-j + 1; 0213, + j-j-j + 1; 0213, -j-j-j + 1; 3120, + 1-j + j-1; 3120, -1-j + j-1; 3120, + 1 + j-j-1; 3120, -1 + j-j-1; 3120, + 1 + j + j + j; 3120, -1 + j + j + j; 3120, + 1-j-j + j; 3120, -1-j-j + j; 3120, + 1 + j + j-j; 3120, -1 + j + j-j; 3120, + 1-j-j-j; 3120, -1-j-j-j; 3120, + 1-j + j + 1; 3120, -1-j + j + 1; 3120, + 1 + j-j + 1; 3120, -1 + j-j + 1 ;. A method for forming a signal sequence K (i) of length n, wherein the signal sequence K (i) of length n = 256 on a first signal subsequence K1 (j) of length n1 = 16 and a second signal subsequence K2 (k) of length n2 = 16, wherein the second signal subsequence K2 (k) is repeated n1 times and thereby modulated with the first signal subsequence K1 (j), the formation of the signal sequence K (i) by modulating the second signal subsequence K2 (k) according to the following The rule is: K (i) = K2 (i mod n2) * K1 (i div n2), for i = 0 ... n1 * n2-1 where at least one of the signal subsequences is a Golay sequence X _n (k) length nx, which can be formed by the following relationship: X ₀ (k) = δ (k) X _'0 (k) = δ (k) X _n (k) = X _n-1 (k) + W _n · X _'n-1 (k - D _n) X _'n (k) = X _n-1 (k) - W _n · X' _n-1 (k - D _n), k = 0, 1, 2, ..., 2 ^NX - 1 n = 1, 2, ..., NX

with nx = 2 ^NX δ (k) Kronecker's delta function P _n , n = 1, 2, ... NX, is any permutation of the numbers {0, 1, 2, ..., NX - 1} for the X sequence, W _n weights for the X sequence (+1, -1, + i or -i), wherein the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ used to form a signal subsequence , W _{4 is taken from the} following set of permutation unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;): 3201, + 1-1 + 1 + 1; 3201, -1-1 + 1 + 1; 3201, + 1-1-1 + 1; 3201, -1-1-1 + 1; 3201, + 1-1 + 1-1; 3201, -1-1 + 1-1; 3201, + 1-1-1-1; 3201, -1-1-1-1; 1023, + 1 + 1-1 + 1; 1023, -1 + 1-1 + 1; 1023, + 1-1-1 + 1; 1023, -1-1-1 + 1; 1023, + 1 + 1-1-1; 1023, -1 + 1-1-1; 1023, + 1-1-1-1; 1023, -1-1-1-1 ;. A method for forming a signal sequence K (i) of length n, wherein the signal sequence K (i) of length n = 256 on a first signal subsequence K1 (j) of length n1 = 16 and a second signal subsequence K2 (k) of length n2 = 16, wherein the second signal subsequence K2 (k) is repeated n1 times and thereby modulated with the first signal subsequence K1 (j), the formation of the signal sequence K (i) by modulating the second signal subsequence K2 (k) according to the following The rule is: K (i) = K2 (i mod n2) * K1 (1 div n2), for i = 0 ... n1 * n2-1 where at least one of the signal subsequences is a Golay sequence X _n (k) length nx, which can be formed by the following relationship: X ₀ (k) = δ (k) X _'0 (k) = δ (k) X _n (k) = X _n-1 (k) + W _n · X _'n-1 (k - D _n) X _'n (k) = X _n-1 (k) - W _n · X' _n-1 (k - D _n), k = 0, 1, 2, ..., 2 ^NX - 1 n = 1, 2, ..., NX

with nx = 2 ^NX δ (k) Kronecker's delta function P _n , n = 1, 2, ... NX, is any permutation of the numbers {0, 1, 2, ..., NX - 1} for the X sequence, W _n weights for the X sequence (+1, -1, + i or -i), where the permutation P ₁ , P ₂ , P ₃ , P ₄ and unit size W ₁ , W ₂ , W ₃ used to form the signal subsequence , W _{4 is taken from the} following set of permutation unit size pairs (P ₁ P ₂ P ₃ P ₄ , W ₁ W ₂ W ₃ W ₄ ;): 3201, + 1-1 + 1 + 1; 3201, -1-1-1 + 1; 3201, -1-1 + 1-1; 3201, + 1-1-1-1, and the permutation (P ₁ P ₂ P ₃ P ₄ ) used to form the second signal subsequence is 3201. Method according to one of the preceding claims, in which the formation and / or transmission of the signal sequence K (i) takes place for the purpose of synchronizing at least two transmission units.

Images