Method and communication system for synchronizing subscriber stations

 

The invention relates to a method and communication system for synchronizing subscriber stations, in particular, to the synchronization feature in the mobile radio wideband channels and the separation of subscriber channels at the expense of duplex time division mode multiple access code division. The technical result - ensuring error-free synchronization of subscriber stations in a partially synchronized base stations. To do this, the set of base stations assign a time interval to transmit at least one synchronization sequence, and the neighboring base stations use different shifts over time relative to the beginning of the time interval for transmission of the synchronization sequence, allowing the synchronized base stations to eliminate the overlap. So despite that the subscriber station can determine the beginning of the time interval assigned to a shift on time. The time shift corresponds to the selection of one or more synchronization sequences and/or sequence multiple sequence synchronization. Information about the time shift of soobschaetsa time of reception of the synchronization sequence and indicates the time shift of the detected sequence of synchronization and/or the recognized sequence multiple sequence synchronization performs time synchronization. 2 S. and 11 C.p. f-crystals, 5 Il.

The invention relates to a method and communication system for synchronizing subscriber stations, in particular synchronization in a mobile radio system with a broadband channel and the separation of subscriber channels at the expense of duplex time division (DDA) mode multiple access code division (mdcr).

In radio systems information (e.g., speech signals, information, images, and other data) is transmitted with the aid of electromagnetic waves via a radio interface. The term "radio interface" refers to the connection between the base station and subscriber stations, and subscriber stations can be a mobile station or fixed station. The radiation of electromagnetic waves is performed using carrier frequencies in the frequency band provided for the respective system. For future radio communication systems, for example UMTS (Universal mobile communication system) or other systems of the third generation is provided by frequency in the range of 2000 MHz.

For the third generation mobile radio has two modes, one mode op/98, from 25.8.1998, and the other mode is defined as duplex, time division (DDA), described, for example, in DE 19827700. Various modifications of the modes are used in different frequency bands, and they both involve the use of selected time intervals.

In the above document, ETSI STC SMG2 UMTS-L1, Tdoc SMG2 UMTS-L1 221/98, from 25.8.1998, section 2.3.3.2.3 and 6.3 describes how synchronization for HDR mode, which uses frequency synchronization, which is sent to each selected time interval. Thereby it is possible to synchronize the subscriber stations to the beginning of the time interval. By order of transmission of the second sequence synchronization signal, what is the group of spread spectrum codes used by the base station. In addition, it is possible to detect the beginning of the frame.

This method of synchronization leads, however, in the case of synchronous mode base stations, to the scenario according to Fig.1. Frequency synchronization of base stations of the cells of the radio communication Zl, Z3 overlap in the receiving subscriber station, because the irradiation sequences synchronization of all base stations (see Fig.10 of the above-mentioned document ETSI STC SMG2 UMTS-L1, Tdoc SMG2 UMTS-L1 221/98, from 25.8.1998) Satania is a method and radio system with which error-free synchronization of subscriber stations possible and at least partially synchronized base stations. This problem is solved by a method characterized by signs of paragraph 1 of the claims, and the communication system, characterized by signs of paragraph 13 of the claims. Preferred embodiments of the invention set forth in the dependent claims.

In accordance with the invention, the set of base stations for transmission to a selected one of a time interval and at least one synchronization sequence or upstream control point, or according to their own choice. Neighboring base stations use different shifts over time relative to the beginning of the time interval for transmission of the synchronization sequence. Thereby, it is possible and in synchronized mode base stations to eliminate the overlap.

To subscriber stations, in spite of this, were able to detect the beginning of the time interval, they are informed about the time shift. The time shift associated with the one or more synchronization sequences and/or sequence multiple sequence synchro is animal sequence synchronization and performs time synchronization based on the time of reception of the synchronization sequence and indicates the time shift of the detected sequence of synchronization and/or the recognized sequence of multiple synchronization sequences.

To signal time shift can be, for example, multiple variants of a single sequence synchronization and/or the order of transmission of sequences of synchronization. The preferred way as in the above mode, HDR, in one selected time interval passed two sequences of synchronization. The first synchronization sequence is used to determine the time of reception and coarse synchronization. The sequence of the second sequence synchronization across multiple transmission encodes the time shift.

According to a preferred variant of the invention, specify the time interval between two synchronization sequences in the selected time interval. Thus there is the possibility to detect both sequences synchronization to use only one switchable filter. The second synchronization sequence may also be transmitted before the first, thus the time interval is negative. If you use two filters, both sequences can be transmitted and at the same time.

Also is the preferred transfer other information for MF the spine to the work of the subscriber stations. Specified other information refers to the framing used by the base station metabolim (middle parts of the message structure), spread spectrum codes or configuration data for channel organization. Higher gain due to coding is achieved if the coding of other information by selecting and/or a sequence of sequences of synchronization is distributed into several time intervals. If, for example, are 17 variants of the second synchronization sequence and the estimated sequence of eight parcels of the second sequence of synchronization available 178possible options. Only a small part of them should be used.

Preferably the sequence of synchronization are unmodulated orthogonal codes Golda. Consequently, the method of synchronization mode HDR hardly have to change. The synchronization method is particularly suitable for radio communication systems in which the time intervals are an integral part of the circuit transfer mode DDA with broadband channels. The synchronization can be used several time slots per frame. So for megaregional for the purposes of a broadcast transmission if possible less system resources the synchronization sequence is transmitted during time intervals in which is additionally transmitted information of the service channel. Thus you need only a small number of time slots for downlink (from base station to subscriber station) to maintain constant readiness. The degree of freedom of asymmetry in both directions of transmission is practically not limited. In order to maintain a fairly low level of mutual interference caused by synchronization sequences affecting the other channels, they are transmitted at a power lower in comparison with other transmission base station. By winning, provide encoding, this flaw is easily compensated.

The embodiments of the invention are described below in more detail with reference to the drawings showing the following: Fig.1 - example of overlapping sequences of synchronization in the receiver; Fig. 2 - schematic representation of the interface radio communication between the base station and the mobile stations; Fig. 3 - the pattern of changes over time in the transmission of the synchronization sequences; Fig. 4 is a schematic representation of official channels, is made different on the radio shown in Fig.2. In accordance with the component mode multiple access with time division multiplexing (mdvr) provided by the Department of broadband frequency range, for example with bandwidth B= 5 MHz, at several time intervals ts fixed duration, such as 16 time intervals from ts0 to tsl5. Bandwidth is the frequency range Century. part of the time intervals used in a straight line PL, and part of the time intervals used in the return line OL. For example, the asymmetry ratio 3:1 in favor of a straight line PL. In this way, the transmission mode DDA frequency band for the return line OL corresponds to the frequency band for direct communication line PL. The same is repeated for the other carrier frequencies. Due to the alternating assignment of time intervals ts for the inverse and direct lines of communication can be implemented in various asymmetric distribution of resources.

Within time intervals the data is transmitted multiple connections in blocks radio signals. Data d individually for each connection expands the spectrum fine structure in the form of a code spread spectrum, so that side is Ctra for individual data symbols d provides that, during the duration of Tsymthe transmitted symbol Q code elements of duration Tchip. When this Q code elements forming the code with the expansion of spectrum for individual connections.

Within the broadband frequency range In successive time slots ts are split up in accordance with the frame structure. So, 16 time slots are combined into a frame fr.

As an example, can be selected the following settings interface communication rate code: 4,096 Mega-items per second.

Frame duration: 10 MS.

The number of time intervals: 16.

The duration of one time interval: 625 μs.

Coefficient of expansion: 16.

Modulation type: CPM (quadrature phase shift keying).

Band width: 5 MHz.

The value of the repetition frequency: 1.

These parameters provide a better harmonization with HDR mode for third generation mobile radio.

In a straight line, according to Fig.3, are used, for example, time slots ts0, ts8 for synchronization. So, in the time interval ts8 are transmitted, respectively, two-sequence synchronization, cf, cs, separated by a time period tgap. The separation of ewnost both sequences is better distributed over time. The first sequence cf synchronization in each time slot ts0, ts8 is the first. The second synchronization sequence cs can each time be selected differently from the same time slot ts0 to another time interval ts8.

The choice and sequence of second synchronization sequences cs corresponds to the offset time toff, in which the transmission of the first synchronization sequence cf delayed relative to the beginning of the time slot ts8. By receiving and evaluating sequences of synchronization cs receiving subscriber station MSS can determine the offset time toff and to consider it in sync.

Neighboring base stations BS are synchronized by the frame. In accordance with the invention, the neighboring base stations BS will be assigned a different offset time toff for transmission of the synchronization sequences. For example, we use 32 different time shift, so that you can form a group of cells and at change of shift time toff for one base station BS does not need to change the entire group of base stations.

Due to the choice and sequence second sequence cs synchronization, for example, four frames fr and two time the 256 code points, there 178various possible options for transmission in addition to the offset time toff other information. Due to such a large number of options can be obtained with a high gain of the use of coding, so that the sequence cf, cs synchronization can be transmitted with less power.

Other transmitted information relates framing used by the base station malambo, codes spread spectrum (and midanbury and spread spectrum codes are set independently from each other) and configuration data of the service channel SSN (broadcast control channel - the CABINET). When applying to synchronize two time slots ts to the frame fr to determine the beginning of the frame, according to the recognition data synchronization in the time interval ts is the ratio uncertainty 2. Therefore, the frame synchronization can be easily introduced through a certain order of the second sequence cs synchronization. In addition, the subsequent detection information of the service channel the CABINET is accelerated if midanbury, spread spectrum codes and configuration data are transmitted at the stage of synchronization.

The company is the use of offset time toff due to the priority sequence cs synchronization. According Fig. 4, the service information can be transmitted, for example, in one, two or four channels. Thus, it can speed data service channel of the CABINET to coordinate with specific cell communication needs in accordance with the proposed communication services. Thus, possible future modifications of the service channel of the CABINET. Thus, it is not required to determine the parameters (number of channels, time slots, codes spread spectrum) official channel of the CABINET in advance at the system level. They can be advised during the synchronization process.

In addition to the variants according to Fig. 4, it is also possible to specify additional channels with service information through other information from the data synchronization. So, the service information may occasionally be transferred into additional channels. Official channel of the CABINET is transmitted in parallel with other compounds for the transmission of useful data, however, necessary in the case of more significant coding for error correction.

Send a service channel of the CABINET and sequences cf, cs synchronization are preferably in the same time interval ts, whereby only two time slots ts0,Imperii in this case is somewhat limited.

If the ratio of asymmetry in the system are such that a straight line PL is applied over two time slots ts0, ts8, service information may also be transmitted in the remaining time intervals assigned for direct communication line PL. In this case, it is also possible to send service information only during time intervals ts, in which the sequence cf, cs synchronization is not transmitted. The flexibility of the service channel, the CABINET provides additional advantages, as the distribution on the set of time intervals causes a higher stability of the transmission with respect to interference.

Use multitool transmission in the service channel of the CABINET (i.e., multiple codes with spread spectrum on the time interval ts) within one time interval ts enables adaptive speed data service channel of the CABINET. Such can be achieved by reducing the expansion coefficient of the spectrum, which is also achieved by selecting and sequencing sequences cs synchronization. The choice of time intervals ts for transmission of service information can be coordinated from the upstream control station such as the 1 before the synchronization control device, for example, in the radio resource administrator of RDA, is the assignment of time slots ts0, ts8 for synchronization and various shifts on time toff relative to the beginning of time slots ts0, ts8 for transmission sequences cf, cs synchronization. In the second stage 2 the set of base stations BS transmit sequence cf, cs synchronization in a pre-specified order, for each base station individually and corresponds to the offset time toff.

The subscriber station speaker at the third stage 3 takes the sequence cf, cs synchronization and performs coarse synchronization using the first sequence cf synchronization. Through the use of the second sequence cs synchronization in the fourth stage 4 possible synchronization time intervals at the beginning of the time interval ts, and then by evaluating the other information on the fifth step 5 is also framing and preparing to receive service dripped the CABINET. Stages 3 through 5 are performed using the subscriber station synchronization tools SYNC, which, for example, represent a processor signal processing and correlators, educated filters, consistent with the) in the communication system, wherein the set of base stations (BS) designate the time interval (ts) for transmitting at least one synchronization sequence (cf, cs), neighboring base stations are synchronized and use a variety of shifts over time relative to the beginning of the time slot (ts) for the transmission of the synchronization sequence (cf, cs), the time shift corresponds to the selection of one or more synchronization sequences (cf, cs) and/or a sequence of multiple synchronization sequences (cf, cs), a subscriber station (MSS) receives a sequence of synchronization (cf, cs), the subscriber station based on the time of reception of the synchronization sequence (cf, cs) and indicates the time shift of the detected sequence synchronization (cf, cs) and/or the recognized sequence of multiple synchronization sequences (cf, cs) performs time synchronization.

2. The method according to p. 1, characterized in that the two sequences synchronization (cf, cs) transmit in one time slot (ts).

3. The method according to p. 1, wherein the pre-set time interval between two synchronization sequences (cf, cs) in a time interval is of choice sequences synchronization (Wed, cs) and/or their sequence.

5. The method according to p. 4, characterized in that the said other information relates to the synchronization of frames and/or applied to the base station metabolim and/or spread spectrum codes ().

6. The method according to p. 4, characterized in that the said other information relates to the configuration of the service channel (the CABINET).

7. The method according to p. 6, characterized in that the data related to the configuration, include a variable number of time intervals and/or spread spectrum codes.

8. The method according to any of paragraphs. 4-7, characterized in that the encoding mentioned other information by selecting and/or a sequence of sequences of synchronization (cf, cs) takes several time slots (ts).

9. The method according to any of paragraphs. 1-8, characterized in that the sequence of synchronization (cf, cs) are unmodulated orthogonal codes Golda.

10. The method according to any of paragraphs. 1-9, characterized in that the time slots (ts) are a component of transmission schemes, the corresponding duplex mode with a time division multiplexing (DDA) with the broadband channels, and multiple time slots (ts) in the frame (fr) is used for synchronization.

11. The method according to any who), in which carry additional information of the service channel.

12. The method according to any of paragraphs. 1-11, characterized in that the sequence of synchronization (cf, cs) transmit with less power, in comparison with other transmission base station.

13. Radio system that contains many base stations to transmit at least one synchronization sequence (cf, cs), control device (RDAs) for assignment of the neighboring base stations, which are synchronized, the time interval (ts) and a distinct shift in time relative to the beginning of the time slot (ts) for the transmission of the synchronization sequence (cf, cs), and the shift in time corresponds with the selection of one or more synchronization sequences (cf, cs) and/or a sequence of multiple synchronization sequences (cf, cs), subscriber station for receiving and evaluating the sequence of synchronization (cf, cs), available in the subscriber station synchronization (SYNC), which is based on the time of reception of the synchronization sequence (cf, cs) and indicates the time shift of the detected sequence synchronization (cf, cs) and/or the recognized sequence carried the

 

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