FI105516B - Method and packet radio system for transmitting modulation and signaling data - Google Patents

Description

105516

Method and packet radio system for transmitting modulation and signaling information ψ

Field of the Invention

The present invention relates to a method and a packet radio system for transmitting signaling and modulation signal Signa-5 in training sessions of a radio system using packet transmission.

Background of the Invention

Packet radio system refers to a radio system using packet switched technology known from the fixed network side. Packet-10 switching is a method of establishing a connection between users by transferring information in packets containing address and control information. Multiple connections can use the same transfer connection at the same time. The use of packet switched radio systems has been the subject of special research because the packet switching method is well suited for data transmission in which burst data is generated. In this case, the data connection need not be reserved all the time, but only for packet transmission. This results in significant cost and capacity savings both during the deployment and operational phases of the network. Packet radio networks are currently of particular interest for the further development of the Global System for Mobile Communication (GSM) system, referred to as GPRS 20 (General Packet Radio Service), and Enhanced General Packet Radio Service (EGPRS).

In designing known radio systems, the effort has been made to secure · signal quality even when channel quality is poor. One essential parameter when designing communication systems is the modulation method used on the transmission path. The information symbols to be transmitted as such cannot be transferred over the transmission path due to the loss of the transmission path and the capacity of the transmission path, but the symbols must be modulated by a suitable method in order to obtain satisfactory transmission capacity and transmission quality. Thus, when designing known systems, the focus in selecting the modulation method has been to safeguard transmission quality 30, whereby the performance of the modulation methods in poor channel conditions is important. As a result, the ability of current methods to transmit high data rate signals is quite poor. Thus, in order to ensure transmission quality, capacity has to be compromised.

One example of known modulation methods is GMSK 35 (Gaussian Minimum Shift Keying), which is used in a GSM cellular radio system. It has a narrow frequency spectrum and good performance, but data rates are not very high.

One solution to optimize performance and transfer rate is to change the modulation method used according to the particular need. When good interference resistance is needed, for example, the GMSK method may be used, and when the channel quality is good, for example, the 8-PSK method may be used, which achieves a triple data rate over GMSK.

In known radio systems, the problem is to change the modulation method seamlessly during continuous communication. Changing the modulation method 10 causes particular problems in the receiver because the transmitter can change the modulation method without notifying the receiver in advance. However, a seamless change of modulation method is required, for example, in packet switched data transmission.

A packet radio system is known for transmitting blocks consisting of bursts, for example four bursts. Packet radio systems employ a variety of burst modulation and need a method to identify the modulation method used in the downlink. The modulation remains the same for one block of four bursts. For example, if one-burst modulation is misinterpreted, one quarter of the block data is lost. This prevents the block from being received at most coding rates.

Several subscriber terminals may use the same time slot. The base station transmits an uplink status field on a downlink. The status fields indicate which subscriber terminal is allowed to send signals in the uplink. A slot can only be utilized if it is used by exactly one subscriber terminal for transmitting information. For this to happen, all slave subscriber terminals should be able to receive the uplink status fields correctly. The required detection capability does not depend on modulation or data coding rate.

30 For example, in GPRS, an uncoded uplink! the status field consists of three bits for each quad burst per radio block.

The uncoded uplink status field (USF, Uplink State Flag) is encoded into 6 or 12 bits interleaved with the data, depending on the coding rate of the data.

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Brief Description of the Invention. It is thus an object of the invention to provide a method and a packet radio system implementing the method so that the above problems can be solved. This is achieved by the following method and packet radio system. This is a method of coding signaling information in a packet radio system, the packet radio system comprising at least one base station and a subscriber terminal, wherein the signals transmitted in a radio link between the base station and the subscriber terminal form blocks, blocks comprising symbols bursts comprising In the method, the signaling information, together with modulation information for the whole block, is coded into the block training sequences.

It is also a packet radio system comprising at least one base station and a subscriber terminal, wherein the signals to be transmitted in a radio link between the base station and the subscriber terminal 15 form blocks, comprising bursts of symbols, bursts comprising a training sequence, and training modules included therein. The packet radio system is adapted to encode the signaling information together with modulation information for the entire block into block training sequences.

Preferred embodiments of the invention are claimed in the dependent claims.

A training sequence refers to a set of predetermined symbols that the receiver knows. By comparing the received training sequence with the known training sequence by certain methods, the receiver can provide information about the kind of distortions caused by the non-ideal radio connection between the base station and the subscriber terminal, and utilizing this information can more easily demodulate the received signal.

The present invention thus relates to a method and a packet radio system for transmitting signaling and modulation information in training cycles of a packet radio system. Modulation remains the same in all bursts in the block, so that modulation information does not need to be included in each training cycle separately. Thus, opus sequences can be used according to the invention in addition to modulation information to transmit signaling information.

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The training sequence used in the method of the invention can be detected, for example, by comparing channel estimates calculated over different training periods.

The method and system of the invention provide several advantages. The method of the invention is particularly well suited for coding uplink path fields. The coding is effective because a large number of symbols are used to encode the uplink path fields. Coding also allows for higher data rates since data bits do not need to be reserved for uplink path encoding, so encoding preferably saves about three symbols per burst, for example. The coding can be easily implemented for different coding rates and modulations. The coding also allows for the same time slot to be allocated to the near and far subscriber terminals due to the efficiency of the coding.

The system of the invention has the same advantages as described above for the process. It is obvious that the preferred embodiments and the detailed embodiments may be combined into different combinations to achieve the desired technical effect.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a cellular radio network as a block diagram illustrating the connection of a base station and base station controller to a packet transmission network, illustrates an example burst construct according to the invention for USF encoding.

DETAILED DESCRIPTION OF THE INVENTION

The method of the invention can be applied to any digital packet radio system in which the transmitted signals comprise bursts of symbols, which bursts comprise a known training sequence, and in which the bursts are transmitted in blocks. Most preferably, the invention is applicable to GSM-based cellular radio networks in further developed networks in which data transmission is performed using an Enhanced General Packet Radio Service (EGPRS). In this case, the data transfer i '35 thus takes place in packet form.

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Referring to Figure 1, a typical structure of a cellular radio network according to the invention and its interfaces to a fixed telephone network and a packet transmission network will be described. Figure 1 is limited to the essential aspects of explaining the invention, but it will be apparent to one skilled in the art that the conventional cellular wireless network also includes other functions and structures that need not be further described herein.

The cellular radio network comprises a network part 100, 102, 132, 140 and a wide-area terminal 150. The network part 100, 102, 132, 140 includes mm. base stations 100 having a bidirectional radio link 170 between the base stations 100 and the subscriber terminal 150, in which the radio link 170 transmits a radio signal at a specific carrier frequency. The subscriber terminals 150 may be fixed, in-vehicle, or portable portable terminals. The plurality of base stations 100, in turn, are centrally controlled by the base station controller 102 associated with them. The base station 100 has transceivers 114.

Typically, base station 100 has one to sixteen transceivers 114. One transceiver 114_ provides radio capacity for one TDMA frame, typically eight time slots.

The base station 100 has a control unit 118 which controls the operation of the transceivers 114 and the multiplexer 116. The multiplexer 116 locates the traffic and control channels used by the plurality of transceivers 114 on a single transmission link 160. The structure of the transmission link 160 is well defined and is called the Abis interface. Transmission connection 160 is typically implemented using a 2 Mbit / s connection, or PCM (Pulse Coded Modulation) link.

From the transceivers 114 of the base station 100, there is a connection to the antenna unit 112, which provides a bidirectional radio connection 170 to the subscriber terminal 150. The bidirectional radio connection 170 is used for connection and packet transmission. Also, in bidirectional radio communication 170, the structure of the frames to be transmitted is well defined and is called the air interface.

The subscriber terminal 150 may be, for example, a standard GSM mobile phone and may, for example, be equipped with an additional card to connect a laptop 152 which may be used for packet transmission to order and process packets. Protocol processing may be located on the subscriber terminal 150 and / or on my computer 52 connected to the subscriber terminal 150.

The base station controller 102 establishes a connection to the subscriber terminal 150 by requesting the base station 100 to send a message to establish a connection. The base station controller 102 comprises a group switching field 6 105516 120 and a control unit 124. The group switching field 120 is used for switching speech and data and for combining signaling circuits. The base station subsystem (BSS) formed by the base station 100 and the base station controller 102 further includes a transcoder or rate adapter unit (TRAU 5) 122. The transcoder 122 is generally located as close as possible to the mobile switching center 132, since voice can be transmitted in cellular between encoder 122 and base station controller 102.

The transcoder 122 converts the different digital coding formats of speech used between the public telephone network and the cellular radio network 10, for example, from a 64 kbit / s fixed network to another (e.g., 13 kbit / s) format and vice versa. The control unit 124 performs call control, mobility management, statistical data collection and signaling.

As shown in Figure 1, group switching field 120 can be used to connect (depicted with black balls) to both a Public Switched Telephone Network (PSTN) 134 via a mobile switching center 132 and a packet data network 142. In a public switched network 134, a typical terminal 136 is a standard or ISDN Services 20 Digital Network).

A connection node 140 (SGSN = Serving GPRS Support Node) establishes the connection between the packet transmission network 142 and the group switching field 120. The function of the support node 140 is to transfer packets between the base station system and the gateway GPRS support node (GGSN) 144 and keep a record of the location of the subscriber terminal: 25,150 in its area.

The gateway node 144 connects the public packet transmission network 146 and the packet transmission network 142. For example, the Internet protocol or the X.25 protocol may be used at the interface. The port node 144 conceals the internal structure of the packet transmission network 142 from the public packet transmission network 146, so that the packet transmission network 142 appears to the public packet transmission network 146 as a subnet where the subscriber terminal 150 may assign packets to and receive packets.

The packet transmission network 142 is typically a private internet protocol network that carries signaling and tunneled user data. The structure of the Ver-35 kon 142 may vary from operator to operator, both in architecture and protocol, below the internet protocol layer.

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The public packet transmission network 146 may be, for example, a global Internet network to which the terminal 148, for example a server computer, wishes to transfer packets to the subscriber terminal 150.

Thus, a portable computer 152 is connected to the subscriber terminal 150.

Of course, data can also be transmitted in the opposite direction of transmission, i.e. from server computer 148 to laptop computer 152. The data passes through the system at air interface 170, from antenna 112 to transceiver 114, and from multiplexer 116 to multiplexer, where a connection is made to the output going to the support node 140, the data from the support node 140 is transported over the packet transmission network 142 through the gateway node 144 to a server computer 148 connected to the public packet transmission network 146.

In digital radio systems, a predetermined symbol sequence, a training sequence, can be placed in the signal bursts, for example, to calculate an impulse response. Figure 2 illustrates, by way of example, a normal burst of a digital GSM cellular radio system. A normal burst of a GSM system comprises symbols comprising bits or bit combinations. The burst symbols are in periods comprising start symbols 20, information symbols 202, instruction symbols 204, information symbols 206, and end symbols 208.

Let us now examine the method of the invention. It may be used in a digital packet radio system for signaling between base station 112 and a subscriber terminal 150, wherein the signals transmitted in a radio link 170 between base station 112 and subscriber terminal 150 comprise bursts of symbols comprising bursts of known training station 150. The connection symbol 170 is given two different training periods 204, then the symbol representing the data to be transmitted may have two different values, for example 30 to 0 and 1. If more than two different training periods 204 are used, the symbol representing the information to be transmitted may receive so many different values than the number of different training sessions 204 in use. It is characteristic of the method according to the invention that the training sequence is not completely known, but there are several alternatives. One lesson is used for the lesson set of the 35 hour lesson set, but it is not known which set it is.

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It is previously known to include modulation information, i.e., to transmit information about the modulation used in training sessions 204, to bursts comprised in training sequences 204. In the method of the present invention, modulation of the entire block remains the same. The modulation information is most preferably encoded 5 for only a portion of the training sequences, and the other training cycles are most preferably coded for signaling. Different bursts of a block may have different number of training cycle options 204.

Each training sequence can contain log / ι bits of information, where variable n represents the number of 10 different training cycle options available. According to the most preferred embodiment, the three training sequences are used to transmit block coded uplink status fields. The structure of the block code is determined by variable n, that is, the structure depends on the number of different training periods available. Thus, each training session is one of a number of predetermined options. For example, if 15 n = 2, the three-bit USF can be transmitted without coding.

Different bursts of a block may have different number of possible training sequence options. Figure 3 shows a burst structure for USF encoding according to the invention. The four bursts of the block are shown. The burst structure is divided into periods, the first and last sections 300 and 20 304 of modulated data including data periods. The middle section 302 comprises instructional sections. Each course is one of n different possibilities. Preferably, the training sequences of the middle section 302 are first, for example, a training / modulation indicator 306, and subsequent training periods include a coded USF 308, a coded USF 25 section 2 (training / modulation indicator 306). part 2 of coded USF) 310 and part 3 of coded USF (training / part 3 of coded USF) 312.

Thus, the coding of uplink state fields by the method of the invention has e.g. The following benefits. The uplink status fields are coded using a large number of symbols, so the coding is relatively efficient. The coding allows the subscriber terminals located near and far to be granted the same time slot due to this coding efficiency.

Encoding allows for better throughput since data bits do not have to be reserved for uplink status field encoding, so encoding advantageously saves, for example, about three symbols per burst. The coding can also be easily implemented for various coding rates and modulations.

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Although the invention has been described above with reference to the example of the accompanying drawings, it is clear that the invention is not limited thereto, but can be modified in many ways within the scope of the inventive idea set forth in the appended claims.

Claims (16)

An encoding method for signaling data in a packet radio system, the packet radio system comprising at least one base station (112) and a subscriber terminal (150), wherein signals transmitted in a radio connection between the base station (112) and the subscriber terminal (150) form blocks comprising blocks formed by symbols, which bursts comprise a learning period (302) and which learning periods (302) comprise modulation data, characterized by decreased signaling data being coded together with modulation data relating to the entire block during the learning periods of the block (302). The method of claim 1, characterized by the method, comprising modulation data relating to the entire block, only in a portion of the learning periods (302) included in the bursts of the block in the packet radio system and the signaling data being encoded in the other block learning periods (302). Method according to Claim 1, characterized in that, in most cases, the method encodes state fields for a rising transmission path during the learning periods (302) of the packet radio system. Method according to claim 2, characterized in that the modulation data is included only in the first burst of the block. 5. A method according to any of the preceding claims, the signature of the scrubbers is demodulated immediately upon receipt. 25 Method according to any of the preceding claims, characterized in that the bursts which follow the first cut are demodulated using the same modulation method as in demodulation of the first cut. Method according to any of the preceding claims, characterized in that the learning periods (302) of the bursts following the first burst are used to transmit block-coded state fields for the ascending transfer path. Method according to claims 1,2,3 or 4, characterized in that the learning periods (302) for the bursts following the first burst are used for any other desired signaling other than modulation of a burst. Packet radio systems comprising at least one base station (112) and a subscriber terminal (150), wherein signals transmitted in a radio connection between the base station (112) and the subscriber terminal (150) form blocks, which blocks comprise characters formed by symbols which bursts comprise a learning period (302) and which learning periods (302) comprise modulation data, characterized in that the packet radio system is arranged to encode signaling data along with modulation data relating to the entire block, during the learning periods of the block (302). . Packet radio system according to claim 9, characterized in that the packet radio system is arranged to comprise modulation data relating to the entire block, only during a part of the learning periods (302) which are part of the block bursts in the packet radio system and that the packet radio system is arranged to encode signaling data in the the other learning periods of the block (302). Packet radio system according to claim 9, characterized in that the packet radio system is arranged to encode state fields for the ascending transmission path during the packet radio system's study periods (302). Packet radio system according to claim 10, characterized in that the packet radio system is arranged to include modulation data only in the first cut in the block. Packet radio system according to any of the preceding claims 9-12, characterized in that the system is arranged to demodulate the bursts immediately after they have been received. Packet radio system according to any of the preceding claims 9-13, characterized in that the system is arranged to demodulate the bursts following the first cut, using the same modulation method as in demodulation of the first cut. Packet radio system according to any of the preceding claims 9 to 14, characterized by the learning periods (302) for the bursts following the first burst, arranged to transmit block-coded state fields for the ascending transmission path. Packet radio system according to claims 9, 10, 11 or 12, characterized in that the packet radio system is arranged to use the learning periods (302) for the bursts following the first burst, for any other desired signaling than modulation of a burst. •