EP1935160A1

EP1935160A1 - Method and device for transmitting organisation information to a multi-carrier communication system

Info

Publication number: EP1935160A1
Application number: EP06778355A
Authority: EP
Inventors: Jürgen MICHEL; Martin DÖTTLING; Heino Gerlach; Rüdiger Halfmann; Thomas Hindelang; Axel Klein; Jörn KRAUSE; Andreas Lobinger; Bernhard Raaf; Ingo Viering; Wolfgang Zirwas
Original assignee: Nokia Siemens Networks GmbH and Co KG
Current assignee: Nokia Solutions and Networks GmbH and Co KG
Priority date: 2005-10-05
Filing date: 2006-08-24
Publication date: 2008-06-25
Also published as: CN101322372A; RU2008117410A; EP1773016A1; WO2007039353A1

Abstract

The invention relates to a method for transmitting information (ORG) to a radiocommunication system receiver (MS), wherein a frequency band splitted into several sub-carriers is used for communications. The transmitter (BS) transmits a signal to at least two sub-carriers, respectively, wherein the information (ORG) is encoded in such a way that it is transmissible to an addressee by knowledge of the frequency location of two or more sub-carriers associated with the knowledge of a phase difference between two or more signals. The transmitter (BS) and the receiver (MS) for carrying out the inventive method are also disclosed.

Description

description

METHOD AND DEVICE FOR SUBMITTING ORGANIZATION INFORMATION IN A MULTI-COMPLIANCE COMMUNICATION SYSTEM

The invention relates to a method for transmitting information from a transmitter to a receiver in a radio communication system, in which a frequency band split into a plurality of subcarriers is used for communication.

In radio communication systems, messages, for example with voice information, image information, video information, SMS (Short Message Service), MMS (Multimedia Messaging Service) or other data, are transmitted by means of electromagnetic waves via a radio interface between transmitter and receiver. Depending on the specific configuration of the radio communication system, the radio stations may be various subscriber-side radio stations or network-side radio devices such as repeaters, radio access points or base stations. In a mobile radio communication system, at least part of the subscriber-side radio stations are mobile radio stations. The radiation of the electromagnetic waves takes place with carrier frequencies which lie in the frequency band provided for the respective system.

Mobile radio communication systems are often designed as cellular systems, for example according to the standard GSM (Global System for Mobile Communication) or UMTS (Universal Mobile Telecommunications System) with a network infrastructure consisting for example of base stations, facilities for controlling and controlling the base stations and other network-side facilities. In addition to these widely organized (supralocal) cellular, hierarchical wireless networks, there are also wireless local area networks (WLANs, Wireless Local Area Networks) with a generally much more spatially limited radio coverage. coverage area. Examples of different standards for WLANs are HiperLAN, DECT, IEEE 802.11, Bluetooth and WATM.

In order to achieve the most efficient transmission of data, the entire frequency band available is split up into several subtrans- porters (multicarrier or multicarrier methods). The idea behind the multi-carrier systems is to convert the initial problem of transmitting a broadband signal into the transmission of several narrowband signals. This has the advantage, among other things, that the complexity required at the receiver can be reduced. Furthermore, splitting the available bandwidth into several narrowband sub-carriers allows a significantly higher granularity of the data transmission in terms of the distribution of the data to be transmitted to the different sub-carriers, i. the radio resources can be distributed with a great fineness to the data to be transmitted or to the subscriber stations. In particular, in the case of variable data rate transmissions or bust-like data traffic, the available bandwidth can be efficiently utilized by allocating a number of sub-carriers to different subscriber stations.

An example of a multi-carrier transmission method is an Orthogonal Frequency Division Multiplexing (OFDM) system, in which the subtransagers use approximately rectangular pulse shapes. The frequency spacing of the sub-carriers is chosen such that in the frequency space at the frequency at which the signal of a Subtragers is evaluated, the signals of the other Subtrager have a zero crossing. Thus, the sub-carriers are orthogonal to each other. Due to the usually very small distance of the sub-carriers and the narrow-band nature of the signals OFDM transmitted on the individual sub-carriers, it is to be ensured that the transmission within the individual sub-carriers is generally not frequency-selective. This simplifies signal equalization at the receiver. The object of the invention is to present efficient methods for transmitting information in a radio communication system, wherein a frequency band split into a plurality of subtransagers is used for the communication. Furthermore, a transmitter and a receiver for carrying out the method will be presented.

This object is achieved by a method having the features of claim 1, and by a method and apparatus having features of independent claims. Advantageous embodiments and further developments are the subject of subclaims.

In the inventive method for transmitting information from a transmitter to a receiver in one

Radio communication system, a frequency band split into a plurality of sub-carriers is used for communication. The transmitter sends a signal to at least two sub-carriers. The information is coded such that it can be determined on the receiver side using the knowledge of the frequency positions of the at least two subtransagers in combination with the knowledge of the phase relationship between the at least two signals.

The transmitter may itself be an arbitrarily configured radio station, preferably this is a network-side radio station of the radio communication system. For communication, a multi-carrier method such as e.g. OFDMA or IFDMA (Interleaved Frequency Division Multiple Access). The transmission of information according to the invention may be a dedicated transmission from the transmitter to the receiver or also a transmission from the transmitter to a plurality of receivers.

The information is transmitted in coded form. This means that a coding rule exists, which the sender applies before sending the information, and which the receiver is known so that it can make a decoding of the information. The encoding rule used at least concerns, inter alia, the frequency positions of at least two sub-carriers and the phase relationship of the signals transmitted on these two sub-carriers. For decoding the receiver therefore requires knowledge of these frequency positions and this phase relationship, which he can obtain by measurements on the received signals. The frequency positions may relate here to the absolute frequency position of the subtractor or to the position of the subtransformers within the frequency band, and / or to the relative frequency position of the subtransformers relative to one another, ie to the frequency spacings of the subtransagers. The phase relationship of the signals indicates whether or by how much the phase of one signal is shifted relative to the phase of the other signal.

The invention is applicable to the use of two or more sub-carriers for encoding the information.

It is possible that the information can be determined solely from the knowledge of the frequency positions and the phase relationship, or also that further knowledge is required for this purpose, such as, for example, Knowledge of the amplitude ratio between the at least two signals and / or knowledge of the number of at least two subtragers.

In a further development of the invention, a part of the frequency band is available to the transmitter for transmitting the information, wherein the at least two subtransagers represent a subset of the part of the frequency band. The transmitter does not use the sub-carriers of the part of the frequency band not used to send the at least two signals for signal transmission. It thus selects a subset for signal transmission from a plurality of sub-carriers available to it, this selection taking into account the information to be transmitted or the coding rules for the information to be transmitted. From- Selected subset is used to send the information, the unselected Subtrager not.

It is advantageous if the method is additionally carried out by another transmitter for sending other information, wherein the transmitter for transmitting the information, a part of the frequency band and the other transmitter to transmit the other information is another part of the frequency band available. This provisioning of the part and the other part of the frequency band and the transmission of the information and the other information may take place simultaneously or sequentially. The two parts of the frequency band differ, preferably they have no overlaps, so that the signals which transmit the information and the other information do not interfere with each other at the time of transmission. The two parts of the frequency band preferably each consist of adjacent sub-carriers, wherein they may contain the same number of sub-carriers. The procedure described with respect to two transmitters can also be applied to a larger number of transmitters, under which the frequency band is split.

In the second inventive method for transmitting information from a transmitter to a receiver in a radio communication system, a frequency band split into a plurality of sub-carriers is used for communication. The receiver in each case receives a signal on at least two sub-carriers and determines the information using the knowledge of the frequency positions of the at least two subtransagers in combination with the knowledge of the phase relationship between the at least two signals. The above explanations regarding the method according to the invention first described are accordingly also applicable to the second method according to the invention. It is advantageous if the receiver uses at least one of the at least two signals, except for determining the information for time synchronization and frequency synchronization.

According to a development of the invention, associations between frequency positions of the at least two subtransagers in combination with phase ratios between the at least two signals on the one hand and information contents on the other hand are used. The assignments are used on the transmitter side for coding and on the receiver side for decoding or for determining the information.

In an embodiment of the invention, different numbers of phase ratios are used in the assignments for different frequency distances between the at least two sub-carriers. That There is a first frequency spacing, which can be used in combination with a first number of phase relationships, and at least one frequency spacing different from the first frequency spacing, which can be used in combination with a number other than the first number of phase relationships. It is possible that for a group of several different frequency spacings a first number of phase relationships is possible, and for one or more further frequency spacings one or more further numbers of phase relationships. With preference, a first number of phase ratios is used for a first frequency spacing between the at least two sub-carriers, and a second frequency ratio smaller than the first number for a second frequency spacing greater than the first frequency spacing. The tuning of the frequency distances to numbers of allowed phase relationships makes it possible to take into account correlation properties between the transmission channels of the different subtragers.

In an embodiment of the invention, the transmission of the information is an IFDMA transmission, wherein in the assignments at least for some frequency distances exactly two possible phase relationships are used between the at least two sub-carriers. In the case of IFDMA transmission, signals are processed on the transmitter as well as on the receiver side in accordance with IFDMA. The use of exactly two phase ratios proves to be advantageous in terms of the transmitter-side power efficiency and the receiver-side detectability of the IFMDA signals.

It is advantageous if a maximum frequency spacing between the at least two sub-carriers is used in the assignments, which depends on characteristics of the transmission channel between transmitter and receiver. This makes it possible to adapt the coding of the information to the current radio propagation conditions.

In an embodiment of the invention, the information is information required by the receiver to send messages to the transmitter and / or to decode messages from the transmitter, e.g. cell-specific information of a radio cell of a cellular radio communication system.

Each of the at least two signals may be preferably one of constant phase and amplitude oscillation, i. a non-phase and amplitude modulated oscillation.

The transmitter according to the invention has means for using sub-carriers of a frequency band split into a plurality of sub-carriers for communication, as well as means for sending in each case one signal to at least two sub-carriers, and means for coding the information such that it uses the receiver side Knowledge of the frequency positions of the at least two Subtrager in combination with the knowledge of the phase relationship between the at least two signals can be determined. The receiver according to the invention has means for using subcarriers of a frequency band split into a plurality of subcarriers for communication, and means for receiving in each case one signal on at least two subcarriers, and means for determining the information using the knowledge of the frequency positions of at least two subcarriers in combination with the knowledge of the phase relationship between the at least two signals.

The transmitter according to the invention and the receiver according to the invention are particularly suitable for carrying out the respective method according to the invention, and this can also apply to the refinements and developments. For this they may have other suitable means.

In the following the invention will be explained in more detail with reference to an embodiment. Showing:

FIG. 1 shows a section of a radio communication system,

FIG. 2a shows a first distribution of a frequency band,

FIG. 2b shows a second division of a frequency band,

FIG. 3 shows a signal transmission on a part of the subcarriers,

FIG. 4 shows a first assignment of subcarrier spacings to phase shifts;

FIG. 5 shows a second assignment of subcarrier spacings to phase shifts.

The detail of a radio communication system shown in FIG. 1 shows a radio cell of a base station BS. This is connected to other network-side devices NET, for example to a device for controlling base stations. the. The radiocommunication system under consideration is preferably a cellular system, eg according to a further developed UMTS standard, which comprises a large number of radio cells, of which, for the sake of clarity, only the radio cell of the base station BS is shown. The

Base station BS may communicate via radio with subscriber stations within its radio cell, e.g. with the subscriber station MS. As radio technology, at least for the downlink direction, i. for the transmission of signals by the base station BS to subscriber stations, a Mehrtragerverfah- ren such. OFDM used. For this exists a frequency band which is divided into a plurality of equally wide Subtragern.

The base station BS sends organization information ORG, which the subscriber stations must evaluate before a communication between the base station BS and the respective subscriber station can take place. Organizational information ORG allows a subscriber station to frequency and time synchronization; They also contain cell-specific information. The cell-specific information may be e.g. to trade one or more of the following big names:

The frequency position or sub-carrier information of certain channels, e.g. a synchronization channel and / or a broadcast channel,

The number and frequency position of the subtranslators available for communication in the radio cell,

The scrambling code used in the radio cell with which the base station and subscriber stations are messaging messages,

Structure information concerning physical channels, e.g. the length of a cyclic prefix of OFDM messages, identification information of the radio cell or of the radio cell sector of the base station BS,

• general signal and channel configurations. The organizational information ORG is required, for example, when a subscriber station searches for the base station in its environment to which it has the best radio channel. If the subscriber station currently does not communicate with another base station and if it has no information concerning the surrounding base stations, for example regarding the scrambling codes used, then this search is referred to as "initial search".

FIGS. 2a and 2b show the frequency band FB used in the radio communication system. The frequency band FB is divided between the base stations for the purpose of sending the organization information ORG. According to FIG. 2a, the frequency band FB is divided into seven equal parts, a first part of a first base station BS1, a second part of a second base station BS2, a third part of a third base station BS3, a fourth part of a fourth base station BS4 fifth part of a fifth base station BS5, a sixth part of a sixth base station BS6, and a seventh part of a seventh base station BS7 for sending the respective organization information ORG is available. The seven base stations BS1, BS2, BS3, BS4, BS5, BS6 and BS7 are a group of neighboring base stations, in a representation of the radio cells as hexagons, for example, one base station and the six neighboring base stations whose radio cells are connected to the base stations Adjacent radio cell of the base station. In the same way, the other base stations are grouped together. Although the division between seven base stations is advantageous in this case, it is only an example, other group sizes can also be used.

The division of the frequency band FB among the base stations BS1, BS2, BS3, BS4, BS5, BS6 and BS7 has only for the

Dispatch of organizational information ORG validity. There is a period of time which is required by the base stations for sending the organizational information ORG. see is. During this time period, the frequency band FB is divided among the base stations BS1, BS2, BS3, BS4, BS5, BS6 and BS7 as shown in FIG. 2a. The division of the frequency band FB means that the individual parts of the frequency band FB are not available to adjacent radio cells during the period of the transmission of the organization information ORG, and thus the frequency repetition distance 1 of 7 is not used. The division of the frequency band FB during the period of transmission of the organization information ORG has the advantage that the signals of neighboring base stations which contain the organizational information ORG do not interfere and thus are more easily detectable by the subscriber stations or can be assigned to a base station.

The use of the frequency band FB with respect to the allocation of the radio resources between the base stations outside the time periods used for the transmission of the organization information ORG can be handled differently.

While in FIG. 2 a the entire frequency band FB has been subdivided into seven equal large parts, it is alternatively possible according to FIG. 2 b to divide only a portion of the frequency band FB into seven equal parts and the base stations BS 1, BS 2, BS 3, BS 4 , BS5, BS6 and BS7 for sending the organizational information ORG. The remaining bandwidth in FIG. 2b by way of example at the right edge of the frequency band FB can be used for purposes other than the transmission of the organizational information ORG.

According to the previous explanations, the transmission of the organizational information ORG by the different base stations takes place simultaneously, different frequency ranges being used for the separation of the signals of the different base stations. Additionally or alternatively to the separation of Organizational information ORG different base stations in the frequency domain, a separation in the time domain is possible.

The frequency width which is available to the base stations BS1, BS2, BS3, BS4, BS5, BS6 and BS7 for sending the organization information ORG depends on the width of the frequency band FB and the desired frequency repetition distance. Furthermore, when deciding on the frequency range to be used for the organizational information ORG, it can be taken into consideration that subscriber stations may exist which, due to the configuration of their receivers, are not able to transmit signals over the entire width of the frequency band FB, but only in a narrower one Frequency range to receive. In order to ensure that each subscriber station can listen to the organizational information ORG of all base stations in their immediate vicinity, it is advantageous to consider only the bandwidth that can be received by the subscriber station that can be received with respect to its "weakest" receivable bandwidth The base stations BS1, BS2, BS3, BS4, BS5, BS6 and BS7 can also be considered as a further effect, since filtering takes place at the edge of this bandwidth, so that only 90% of this bandwidth can be used. On receivable bandwidth, for example, 1.25 MHz, resulting from the calculation - = \ 60.7 kHz a bandwidth of 160.7 kHz for each of the base stations BSL, BS2, BS3, BS4, BS5, BS6 and BS7 for sending the organization information ORG. If there is a division of the frequency band FB into subcarriers of a width of 15 kHz each, then each of the B stands Asstations BS1, BS2, BS3, BS4, BS5, BS6 and BS7 have ten subcarriers for sending the organizational information ORG.

FIG. 3 shows ten adjacent subcarriers, numbered 1 to 10, which are available to a base station for the purpose of sending their organizational information stand. The sending of the organization information does not take place on all the sub-stations available to the base station for this purpose; instead, the base station uses only a subset of these sub-carriers for sending the organization information. FIG. 3 illustrates the case in which the base station uses the sub-carrier 2 for sending a first signal ORG 1, and the sub-carrier 5 for sending a second signal ORG 2. This transmission is a so-called "double-tone" overdrive On the remaining sub-contractors 1, 3, 4, 6, 7, 8, 9 and

10 no signals are sent during the dispatch of the organization information. The signals ORG 1 and ORG 2 emitted on the two sub-carriers 2 and 5 are sinusoidal oscillations which in themselves do not carry any information, i. their amplitudes are not in accordance with a

Amplitude modulation with time change, and whose phases do not change according to a phase modulation with time.

The use of only a portion of the sub-carriers to send the organization information has the advantage over the use of all available sub-carriers that the organization information can be radiated on the few Subtragern with a higher performance, whereby the subscriber station side detection is facilitated.

A subscriber station detects the two signals ORG1 and ORG2. Thus, it is known that the respective base station uses a certain frequency range for sending its organization information. Because of the knowledge of this

Frequency range, the subscriber station using a mapping table determine certain information regarding the base station. This base station specific information may be e.g. to a group of scrambling codes, which are part of the respective

Base station used scrambling code is to act. In this case, there are at least 7 groups of scrambling codes which as well as the frequency ranges according to FIGS 2b are distributed among the base stations BS1, BS2, BS3, BS4, BS5, BS6 and BS7. Thus, by assigning the frequency ranges for the organization information to the base stations, a part of the cell-specific information can already be coded.

The subscriber station performs time and frequency synchronization with respect to the base station using signals ORG1 and ORG2. For frequency synchronization, using the frequency positions of the two subcarriers 2 and 5, it sets its oscillator, which is used to generate the radio-frequency signals to be radiated, so that the subcarrier frequencies used by the subscriber station coincide with those of the base station. For time synchronization, it sets its internal time using the reception timing of the signals ORG1 and ORG2 so that the time slots used by it match those of the base station. In addition to the time and frequency synchronization, a further evaluation of the signals ORG1 and ORG2 takes place in order to determine further cell-specific information transmitted by the base station. The following describes how this information is coded into the two signals ORG1 and ORG2.

The two signals ORG1 and ORG2 have a fixed, with time constant, phase relationship to one another. This means that on the two subcarriers 2 and 5 per se, the same vibrations are emitted, but phase-shifted against each other. In this case, it is favorable to permit different phase relationships or to use different modulation methods, depending on the distance of the subcarriers used for the emission of the signals ORG1 and ORG2. It is proposed to use no phase shift for large frequency spacings between the two subcarriers, for medium distances phase shifts, which in the case of a BPSK

Modulation are possible, and at small distances phase shifts, which are possible with a QPSK modulation. FIG. 4 shows in tabular form the possible phase shifts as a function of the spacing of the subcarriers used for the signals ORG1 and 0RG2. The left column contains the subcarrier distance DIST between the subcarriers used for the signals ORG1 and 0RG2, the right column contains the usable phase shifts PHASE. For the subcarrier distances DIST of 1, corresponding to the use of adjacent subcarriers, as well as of 2 and 3, QPSK is used. Accordingly, for the subcarrier distances DIST of 1, 2 and 3, one of the phase differences PHASE of 0, -π, π and -3π between the

2 2

Signals ORGl and ORG2 are set. For the subcarrier distances DIST of 4, 5 and 6 BPSK is used. Accordingly, one of the phase differences PHASE of 0 and π between the signals ORG1 and 0RG2 can be set for the subcarrier distances DIST of 4, 5 and 6, respectively. For the subcarrier spacings DIST of 7, 8 and 9, no coding of information into the phase relationship of the signals ORG1 and ORG2 takes place, so that only the phase difference PHASE 0 is possible for this purpose. For those subcarrier distances DIST of 7, 8 and 9, for which no encoding of information in the

Phase differences PHASE occurs, the receiver does not need to evaluate the phase relationship. It is therefore possible that, on the transmitter side, the phase differences PHASE for the subcarrier spacings DIST of 7, 8 and 9 can be set as desired.

Allowing different phase differences as a function of the distance between the subcarriers used for the signals ORG1 and ORG2 can be justified as follows: during the signal transmission via the radio channel, the emitted signals are changed, whereby i.a. in a

Phase rotation of the signals expresses. That is, the received signal has an unwanted phase rotation with respect to the transmitted signal. This rotation is more similar for two subcarriers, the smaller the frequency spacing of these subcarriers. This means that the channels of two subcarriers are the more correlated the closer they are together in the frequency domain. The higher the modulation method used and thus the larger the number of the possible phase relationships, the more difficult it is to detect the correct phase relationships for a given radio channel. On the other hand, with given phase relationships, the different detection of the radio channels is the more difficult the correct detection. It is therefore advantageous to match the subcarrier spacings and the modulation methods used.

To estimate what numbers of phase shifts are appropriate for particular subcarrier distances, the coherence bandwidth can be used as a measure of the correlation between different subcarriers. For example, considering a channel with a delay spread of 3.33 μs, the 50% coherence bandwidth is approximately 60 kHz. With a subcarrier width of 15 kHz, this corresponds to the width of 4 subcarriers. It follows that the QPSK modulation method according to FIG. 4 should be applicable at least for subcarrier spacings of up to 3 subcarriers, and the BPSK modulation method according to FIG. 4 at least for the three larger subcarrier spacers up to 6 subcarriers.

The information content IC, which can be transmitted by means of the coding according to FIG. 4, results from / C = log ₂ [(9 + 8 + 7) -4 + (6 + 5 + 4) -2 + (3 + 2 + 1 ) -l] bits = 7.1 bits.

Here, the 9th of the first parenthesis corresponds to the subcarrier distance DIST of 1, since there are 9 ways to arrange two adjacent subcarriers within 10 subcarriers. The 9th of the first round bracket is multiplied by 4, because for the subcarrier distance DIST of 1 four phase differences

PHASE are approved. Similarly, the 8th of the first parenthesis corresponds to the subcarrier distance DIST of 2, the 7th of the first parenthesis to the subcarrier distance DIST of 3, the 6th of the second parenthesis to a subcarrier distance DIST of 4, and so on.

The subscriber station determines the subcarrier distance DIST and the phase shift PHASE between the signals of the two Subcarriers. It is aware of an association between these variables, ie between each line of FIG. 4 and a cell-specific information, so that it can determine the respective information from the knowledge of the sub-carrier distance DIST in combination with the phase shift PHASE. For example, the 7.1 bits transmitted from the base station to the subscriber station in this manner can be used to signal a cell-specific scrambling code.

In order to achieve a low Peak to Average Power Ratio (PAPR) when sending the organization information to multiple sub- scribers, IFDMA (Interleaved Frequency Division Multiple Access), described, for example, in • A Filippi, E. Costa, E Schulz: "Low Complexity Interleaved Sub-Carrier Allocation in OFDM Multiple Access Systems", Proc. IEEE VTC ^S 04, Los Angeles, California, USA, September 2004,

• T. Frank, A. Klein, E. Costa, E. Schulz: "Interleaved Orthogonal Frequency Division Multiple Access with Variable Data Rates", OFDM Workshop, Hamburg, 31.8.-1.9.2005.

As in the past, it is considered that two sub-carriers are used to transmit the organizational information of a base station. In IFDMA, in this case there is a sequence of two complex symbols z1, z2 in the time domain at the transmitter end, which are converted into the two complex symbols p1, p2 in the frequency domain via a 2-point discrete Fourier transformation, where: pl = zl + z2 and p2 = zl-z2.

The complex symbols p1 and p2 are then converted into the time domain and sent by an inverse Fast Fourier transformation.

In order to ensure that the "double tone" signal can be detected as reliably as possible in the receiver and the probability of a "missed detection" can be reduced, it is advantageous if the absolute values of p1 and p2 in the receiver Frequency range are equal because then the fingers for the inverse discrete Fourier transform in the receiver can be set with low error probability. In order to obtain the equality of the quantities, we must hold that xl ■ x2 = -yl ■ yl with xl the real part of zl, yl the imaginary part of zl, x2 the real part of z2, and y2 the imaginary part of z2. For example, if zl is 1, ie xl = 1 and y \ = 0, then x2 = 0 and y2 can be chosen arbitrarily.

In order to continue to obtain a desired low PAPR of the transmitted signal, it should be understood that the absolute amounts of zl and z2 are equal. For example, zl is 1, i. xl = 1 and yl = 0, then y2 = ± l in this case. Overall, this results in zl = 1 and z2 = + j. Thus, the phase shifts of π and -π are possible between the two signals.

The example described shows, without limiting the generality, if one of the two symbols to be transmitted is known or fixed, and the absolute values of p1 and p2 in the frequency range are to be the same, and furthermore the absolute values of z1 and z2 in the time domain are the same Due to the double possibility for the phase relationship between the two signals, one bit of information can be transmitted.

As already explained above, it is advantageous to use the encoding of information in the phase shift only if the subtranslators used are not too far away from each other. Figure 5 shows as well as Figure 4 in the left column, the Subtragerabstand DIST between the two subcarriers used, and in the right column, the phase shift PHASE between the signals of the two Subtrager. For the IFDMA transmission, exactly two phase relationships are allowed for the sub-carrier distances DIST of 1, 2, 3 and 4 as described above, namely the two phases PHASE of π and -π, for the sub-carrier distances DIST of 6, 7, 8, and 9, however, no phase difference. Because If the subcarrier distance DIST between the two subcarriers used is less than 50% coherence bandwidth, the phase shift between z1 and z2 can easily be detected at the receiver end. With a larger sub-carrier distance DIST, however, this is no longer necessarily true.

The information content IC, which according to the use of the coding. 5, the result is: / C = log ₂ [(9 + 8 + 7 + 6) -2 + (5 + 4 + 3 + 2 + 1) -1] bits = 6.2 bits. 9 in the first round bracket corresponds to the subcarrier spacing of 1, since there are 9 different ways of distributing two adjacent subcarriers to 10 subcarriers. The 9 is multiplied by 2 because there are 2 possible phase relations. The same applies to the subcarrier spacings of 2 -corresponding to 8 in the first round staple, from 3 -corresponding to 7-in the first round staple-and of 4 -corresponding to 8 in the first round staple. For the larger subcarrier spacings of 5 -corresponding to the 5 in the second round bracket, to 9 -corresponding to the 1 in the second round bracket-, no phase difference is coded and evaluated on the receiver side, since only the phase difference of 0 is permitted for this purpose.

The following is an extension of the previous IFDMA

Procedure described. It can be deviated from the fact that the amount of zl should be equal to the amount of z2. This corresponds to a waiver of a favorable low PAPR. In order to ensure the equality of the amounts of p1 and p2 in the frequency domain, z2 = jk can be chosen with k of an arbitrary integer, as explained above. In this case, as explained above, two phase differences, namely π and -71, are possible. In addition, the amplitudes of the two signals differ, since the amplitude of the first xl, since zl = xl, and that of the second k is. This amplitude difference allows further information to be transmitted. Each line of Figure 5 can in this case in a A plurality of rows are split, according to the various legal values of k.

According to the last-described extension of the IFDMA method, the subscriber station detects the frequency position and the frequency spacing of the sub-carriers used for the organization information, as well as the phase difference between the signals of the two sub-carriers, and the amplitude ratio between these signals. From this information, she can determine cell-specific information using a mapping table known to her. While the use of the amplitude ratio in addition to the use of the phase difference has been explained by IFDMA technology, it is not limited to IFDMA but is applicable to other multi-carrier transmission methods.

In order to reduce the likelihood of false detection, it is advantageous if only certain subtrager intervals are allowed. For example, referring to Figures 4 and 5, which show the use of all possible sub-carrier distances for two sub-carriers, all lines relating to odd sub-carrier distances could be deleted. However, this reduces the number of transferable bits.

Using the methods described, it is possible to realize a certain number of bits by sending signals once on multiple sub-carriers. If the number of bits actually required exceeds this number, multiple sending is possible. These multiple

Shipments can follow one another directly or at a certain time interval. If a large amount of cell-specific information is to be transmitted by a base station, the base station can use a plurality of time slots, which are available for sending the organization information, in order to transmit the entirety of its cell-specific information. When using several consecutive shipments, one is Further coding possible by linking information contents to the phase difference and / or the relative frequency position and / or the amplitude ratio of signals of successive transmissions.

Previously, it was assumed that the organizational information would be transferred to 2 subcarriers. However, this is only an example, the use of larger plural numbers of subcarriers is additionally or alternatively possible. For example, it can be specified that the organizational information is transmitted on 2, 3 or 4 subcarriers. In addition to the sub-carriers used in Figures 4 or 5 concerning 2 sub-carriers used in this case, there are two further tables relating to 3 and 4 sub-carriers used. As a result, a larger amount of information can be coded or transmitted by a single transmission of the organization information.

It is advantageous if a determination of a maximum subcarrier distance is made, which is e.g. may correspond to the coherence bandwidth of the radio channel. This is particularly advantageous if different numbers of usable subcarriers are possible. By limiting the maximum subcarrier spacing it is e.g. It is unlikely that a use of 3 subcarriers will be confused with the use of 2 subcarriers on the receiver side, due to the proximity of subcarriers i.d.R. either all subcarriers are affected by a strong attenuation due to poor radio transmission conditions, or none of the subcarriers. The larger the permitted subcarrier spacings, the more likely it is that a smaller number of subcarriers are detected on the subscriber side than was used on the sender side, since it is easily possible with increasing subcarrier spacings that only a subset of the subcarriers used are in a so-called "fading In this case, correct decoding of the transmitted information can not occur.

Claims

claims

1. A method for transmitting information (ORG) from a transmitter (BS) to a receiver (MS) in a radio communication system in which a frequency band (FB) split into a plurality of sub-carriers is used for communication, the transmitter (BS ) on at least two Subtragern in each case a signal (ORG 1, ORG 2), wherein the information (ORG) are coded such that they at the receiver side using the knowledge of the frequency positions of the at least two Subtrager in combination with the knowledge of the Phasensenhaltnisses between the at least two signals (ORG 1, ORG 2) can be determined.

2. The method of claim 1, wherein the information (ORG) are encoded such that they can be determined on the receiver side using in addition to the knowledge of the amplitude ratio between the at least two signals (ORG 1, ORG 2).

3. The method of claim 1 or 2, wherein the information (ORG) are coded such that they can be determined on the receiver side using in addition to the knowledge of the number of at least two Subtrager.

4. The method according to any one of claims 1 to 3, wherein the transmitter (BS) for transmitting the information (ORG) is a part of the frequency band (FB) available, the at least two subtrager a subset of the part of the frequency band (FB) and the transmitter (BS) does not use the sub-carriers of the part of the frequency band (FB) not used to send the at least two signals (ORG 1, ORG 2) for signal transmission.

5. The method according to any one of claims 1 to 4, wherein the method is additionally performed by another transmitter (BS) for sending other information, wherein the transmitter (BS) for transmitting the information (ORG) part of the frequency band (FB) and the other transmitter (BS) for transmitting the other information another part of the frequency band (FB) is available.

6. A method for transmitting information (ORG) from a transmitter (BS) to a receiver (MS) in a radio communication system in which a frequency band (FB) split into a plurality of sub-carriers is used for communication, the receiver (MS) At least two Subtragern each receiving a signal (ORG 1, ORG 2) and the information (ORG) using the knowledge of the frequency positions of the at least two Subtrager in combination with the knowledge of the phase relationship between the at least two sig- nals (ORG 1, ORG ).

7. The method of claim 6, wherein the receiver (MS) determines the information (ORG) using additionally the knowledge of the amplitude relationship between the at least two signals (ORG 1, ORG 2).

8. The method of claim 6 or 7, wherein the receiver (MS) determines the information (ORG) using düng of additionally knowing the number of at least two Subtrager.

9. The method according to any one of claims 6 to 8, wherein the receiver (MS) at least one of the at least two signals (ORG 1, ORG 2) except for the determination of the information (ORG) used for time synchronization and frequency synchronization.

10. The method according to any one of claims 1 to 9, are used in the associations between frequency positions of the at least two Subtrager in combination with Phasenverhaltnissen between the at least two signals (ORG 1, ORG 2) on the one hand and information contents on the other hand.

11. The method of claim 10, wherein in the assignments for different frequency distances between the at least two Subtragern different numbers of Phasenverhaltnissen be used.

12. The method of claim 11, wherein for a first frequency spacing between the at least two Subtragern a first number of Phasenverhaltnissen is used, and for a second compared to the first frequency spacing between the at least two Subtragern greater frequency spacing a second compared to the first number smaller number of Phase relationships is used.

13. The method according to any one of claims 10 to 12, wherein the transmission of the information (ORG) is an IFDMA transmission, wherein in the assignments at least for some frequency distances between the at least two Subtragern exactly two possible Phasenbehhalt- be used.

14. The method according to any one of claims 10 to 13, wherein in the assignments a maximum frequency spacing between see the at least two Subtragern is used, which depends on characteristics of the transmission channel between transmitter (BS) and receiver (MS).

15. The method according to any one of claims 1 to 14, wherein the information (ORG) is information which the receiver (MS) for sending messages to the transmitter (BS) and / or for decoding messages from the Sender (BS) required.

16. The method according to any one of claims 1 to 15, wherein each of the at least two signals (ORG 1, ORG 2) is a vibration of constant phase and amplitude.

A transmitter (BS) for transmitting information (ORG) to a receiver (MS) in a radio communication system, comprising means for using sub-carriers of a frequency band (FB) split into a plurality of sub-carriers for communication,

Means for sending on at least two sub-carriers of each one signal (ORG 1, ORG 2), means for encoding the information (ORG) such that it uses the knowledge of the frequency positions of the at least two subtransagers in combination with the knowledge of the phase relationship between the at least two signals (ORG 1, ORG 2) can be determined.

A receiver (MS) for receiving information (ORG) from a transmitter (BS) in a radio communication system, comprising means for using sub-carriers of a frequency band (FB) split into a plurality of sub-carriers for communication,

Means for receiving on at least two sub-carriers of each one signal (ORG 1, ORG 2),

Means for determining the information (ORG) using the knowledge of the frequency positions of the at least two subtransagers in combination with the knowledge of the phase relationship between the at least two signals (ORG 1, ORG 2).