EP1004213A1

EP1004213A1 - Method, mobile station and base station for packet oriented information transmission

Info

Publication number: EP1004213A1
Application number: EP98947381A
Authority: EP
Inventors: Christian Menzel
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1997-08-12
Filing date: 1998-08-04
Publication date: 2000-05-31
Also published as: KR20010022802A; KR100326483B1; CN1266595A; JP2001513612A; DE19734935A1; CN1112064C; WO1999008462A1; AU9431798A

Abstract

The invention relates to a method for packet oriented critical time-critical information transmission via a radio interface between a base station and mobile stations pertaining to a TDMA mobile communication system. During a logical link, a request for upward radiotechnic resources is sent by a mobile station with a service profile for time-critical information in part of a channel solely assigned to said profile in an upward direction without prior allocation of precise transmission time by the base station. The base station receives the request, evaluates it and carries out a modified allocation of radiotechnic resources for transmission of a useful signal in an upward direction to said mobile station. The invention can be used particularly advantageously in TDD mobile radio telephone services with TDMA/CDMA subscriber separation.

Description

description

Method, mobile station and base station for packet-oriented transmission of information

The invention relates to a method, a mobile station and a base station for packet-oriented transmission of information via a radio interface between a base station and mobile stations of a TDMA mobile communication system, in particular for a GPRS packet data service for time-critical information within a GSM mobile radio network.

Mobile communication systems are used to transmit data using electromagnetic waves over a radio interface between a transmitting and a receiving radio station, with one of the radio stations generally being non-stationary. An example of a mobile communication system is the known GSM mobile radio network (Global System for Mobile Communications), in which a channel formed by a narrow-band frequency range and a time slot is provided for the transmission of a subscriber signal. Since a subscriber signal in a channel is separated in frequency and time from other subscriber signals, the receiving radio station can detect the data of this subscriber signal. The formation of time slots results in a time division multiplex subscriber separation and thus a TDMA (time division multiple access) mobile communication system.

The network-side radio station of a mobile radio network is a base station which communicates with mobile stations via a radio interface. The transmission from a mobile station to the base station is called the upward direction, the transmission from the base station to a mobile station is called the downward direction. A frequency channel is formed by at least one time slot per time division multiplex frame. Several time-division multiplex frames form a macro frame. Furthermore, the carrier frequency and possibly a frequency hopping sequence designate the frequency channel.

Connection-oriented concepts and concepts based on logical connections can be used to transmit data between two communication terminals. In connection-oriented data transmissions, physical resources must be made available between the two communication terminals during the entire time of the data transmission.

A permanent provision of physical resources is not necessary for data transmission via logical connections. An example of such a data transmission is packet data transmission. There is a logical connection between the two communication terminals during the entire data transmission, but physical resources are only made available during the actual transmission times of the data packets. This method is based on the fact that the data are transmitted in short data packets, between which longer pauses can occur. In the pauses between the data packets, the physical resources are available for other logical connections. With regard to a logical connection, physical resources are saved.

The packet data transmission method known from German patent DE 44 02 903 AI is particularly suitable for communication systems with limited physical resources. However, it was developed for the transmission of non-time-critical information, in which delay times for the transmission of the information, in particular in the upward direction, are not relevant. The base station in a mobile communication system can receive time-critical information arriving on the network by appropriately dividing the radio resources into react downward. This is not possible for the upward direction, since the allocation of the radio resources is carried out on the network side, but the knowledge about the presence of time-critical information is decentralized at the mobile stations. A request for an allocation of radio resources to establish a logical connection is sent by an inactive mobile station in an access channel which is assigned to all mobile stations in the radio cell for this purpose.

The invention is based on the object of specifying a method and devices for packet-oriented information transmission which better correspond to time-critical applications. This object is achieved by the method with the features of claim 1 or 10, the mobile station with the features of claim 17 and by the base station with the features of claim 18. Advantageous developments of the invention can be found in the subclaims.

According to the invention, in the method for the packet-oriented transmission of time-critical information via a radio interface between a base station and mobile stations of a TDMA mobile communication system during a logical connection through a mobile station with a service profile for time-critical information within a part of a channel assigned only to this service profile, one is in the upward direction Request for radio resources in the uplink direction without prior assignment of the exact transmission time by the base station. The base station receives the request, evaluates it and then makes a changed allocation of radio resources for a useful signal transmission in the upward direction to this mobile station.

The mobile station is therefore no further from assignments of the base station regarding frequency channels for signaling dependent on an upward resource demand. A mobile station can determine the time of the resource request itself. The delays until the use of radio resources for time-critical information in the upward direction are reduced.

According to an advantageous development of the invention, a first radio block is transmitted in a synchronized manner in a time slot of the radio interface, so that the first radio block arrives at the base station at a predetermined time within the time slot, and that at least a second radio block is transmitted with the request in the same time slot which can be evaluated separately from the first radio block. The requirements can thus be transmitted in addition to the first radio block and do not tie up any further radio resources. Especially in timeslots with shortened access radio blocks there is room for second radio blocks.

A corresponding subdivision of a time slot creates the possibility of transmitting a larger amount of data and thus making better use of the radio resources. A time slot is thus not only assigned to one mobile station, but can be used independently by several mobile stations. The transmission-side synchronization ensures that the radio blocks do not arrive in the time slot at the same time and can therefore be evaluated separately.

The radio blocks transmitted in a time slot could have the same length according to further variants - this creates special time slots with several shortened radio blocks - or they represent different types of radio blocks - this means that an existing time slot structure of the mobile communication system is better used. With the same radio block length, a number of standardized block lengths are introduced which fill a time slot in such a way that There are as few unused transition times as possible and a time slot is filled with two, three or more radio blocks as required. It is advantageous that the time of arrival of the first radio block is based on the beginning of the time slot. As a result, the time duration of a time slot is better used. This means that the already determined values of the time comparison, the lead time (timing advance), can be adopted and additional calculation effort is not necessary.

According to an alternative advantageous development of the invention, the request is sent with an access radio block. Access blocks normally only serve to set a timing advance and are sent by the mobile station at regular intervals. In these

Access radio blocks are, according to the invention, information about the request of radio resources for the upward direction introduced, without there being additional expenditure for signaling.

If this type of request is selected, it is advantageous if a larger number (for example than in the GPRS at the present time) of time slots is provided for access radio blocks. This relieves other signaling options and delays up to

Allocation of radio resources upwards further reduced.

According to a third alternative development of the invention, the request is also sent in time slots that are not intended for packet data transmission. In a mobile communication system, packet data transmission often exists in parallel with other types of transmission (with GSM, in parallel with voice transmission), so the signaling options outside the frequency channel are also used for packet data transmission for faster upward transmission. co O t \) MH

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coordinated sequence of radio blocks (e.g. every second, third etc.) can be assigned for longer periods of time. The mobile station signals to the base station within the information blocks, which of her actually allocated radio blocks ^¬ not required. This type of signaling guarantees the mobile station sufficient uplink radio resources. If they are not required, they can be used by other connections after they have been released.

The assignment of the radio resources is made dependent on the service profiles assigned to the mobile stations according to a further development of the invention. Only mobile stations with certain service profiles for time-critical information can send a request or only their requests are taken into account. This prevents too many mobile stations from using this signaling option and blocking the time-critical applications from their rapid resource requests.

Advantageously, only a predetermined number of mobile stations with a service profile for time-critical information are permitted in a frequency channel. The number is adapted to the signaling options.

If priorities are assigned to the mobile stations in addition to the service profiles, only mobile stations of certain priorities can be allowed to repeat the request within certain time periods. This also prefers the requirements of the particularly time-critical applications.

The described alternative embodiments of the invention can also be combined in order to improve the allocation of radio technical resources in the upward direction. The invention is explained in more detail below with reference to drawings using exemplary embodiments.

Show

1 shows a block diagram of a TDMA mobile communication system for packet data transmission,

2 shows a channel with time-division multiplex subscriber separation,

3 shows a schematic illustration of radio block types,

4 shows a schematic illustration of the structure of an access radio block,

5 shows a schematic illustration of the structure of a normal radio block in the upward direction,

6 shows a schematic illustration of the structure of a normal radio block in the downward direction,

7 shows a schematic illustration of a use of several frequency channels by a mobile station,

8 shows a schematic illustration of the sequence of a transmission of time-critical information,

9 shows a schematic illustration of the radio interface for a TDMA / CMDA transmission,

10 shows a block diagram of a mobile station, and

11 shows a block diagram of a base station. co CJ l \ JMH P-

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The radio interface between the mobile stations MS and a base station BS is characterized by a frequency band and at least one time slot ts. According to FIG. 2, for example, eight time slots ts (ts0 to ts7) are combined to form a frame R. The frame R is repeated cyclically, wherein part of the canal a recurrent ^'time slot for example, the time slot ts = ts4. This time slot ts is used in the following as a channel GPRS-K for packet data transmission in the sense of the service GPRS (General Packet Radio Services). Several time-division multiplex frames R can be combined to form a macro frame.

If a mobile station MS is to use this service, then according to the GSM terminology it carries out an arbitrary access (random access) with a short access block (access burst) and changes to a dedicated control channel. This is followed by authentication and setting the context, for example a temporary identifier (TLLI) with respect to a logical connection (standby state). If the further communication terminal KEG is to communicate with a mobile station MS via the packet data service, the desired mobile station MS is called (paged) on the network side and the described arbitrary access is given to switch to standby state.

For sending packet data in the upward direction, the mobile station MS in turn sends an access block on the control channel, whereupon the mobile station MS receives a short identifier, a GPRS channel GPRS-K and the lead time determined from the access block and used in the GPRS channel GPRS-K ( timing advance). The mobile station MS is then in the ready state. In the waiting state, further access blocks acl are sent at intervals of 1 to 2 s to update the lead time. If the mobile station MS then wants to transmit data in the upward direction, an access block (for example the second radio block fb2 described later or a subsequent access block) is activated again for the time comparison) sent, which is evaluated by a control device SE of the base station BS. Appropriate radio resources will be allocated as soon as possible.

3 shows some types of radio blocks which are common in the GSM mobile radio network. Whereby only one radio block is transmitted per time slot ts, for example ts4. A radio block is initiated and ended by 3 bits each, which are used to settle and swing out the equalizer and other modules. A protection time of 8.25 bits within the time slot ts4 remains unused and compensates for possible, unregulated time differences between radio blocks of different time slots ts4, ts5.

A normal radio block fbn contains two 58 bit useful information, in which a training sequence of 26 bit is embedded in the middle.

Furthermore, a first radio block fbl, which is referred to below as access radio block acl, is shown, which has an introduction of 8 bits and then contains 41 bits of training sequence and 36 bits of useful information. The protection time for the access block acl is extended to a total of 68.25 bits. 60 bits are available for at least one second radio block fb2, as shown later. The access block acl is shortened because it is provided in the GSM mobile radio network for situations in which reliable reception is to be effected in spite of unknown signal propagation times and thus imprecise transmission times.

In FIG. 3, three variants for setting up a second radio block fb2 are also shown as examples, which fill up the time slot ts4. The arrival of the radio blocks acl and fb2 at the receiver is denoted by two points in time t1 and t2, respectively, which are determined after the lead times have been determined Synchronization of the sending mobile station MS can be set. The radio blocks acl, fb2 do not overlap.

The second radio block fb2 according to FIG. 3a) contains a normal training sequence of 26 bits and two data blocks of 17 bits each. According to FIG. 3b), a data block of 34 bits is preceded by a training sequence of 26 bits. Meanwhile in FIG. 4c) the training sequence is extended to 41 bits and thus a data block of only 19 bits follows. The second radio block fb2 thus has a length of 60 bits each. However, other radio block lengths are also possible. For example, the second radio blocks fb2 can in turn be initiated or ended by one or more bits. It is also possible to extend or shorten the protection time at the end of the time slot.

The data blocks of the second radio blocks fb2 can contain useful and signaling information, for example requests reql for an allocation of radio resources in the upward direction.

4 shows an access radio block acl, in the data part of which the request reql for radio resources in the upward direction and information MS-ID1 for identifying the mobile station MS are embedded. This access radio block acl is sent at regular intervals (240 ms or 480 ms) in order to update the lead time. The receiving base station BS evaluates the request reql and assigns the radio resources.

5 shows a normal radio block in the upward direction, in which the mobile station MS contains not only information MS-ID1 for its identification but also information NBI (next block indicator) which indicates which of the subsequent blocks (for example the first, second or third) ) is required in the upward direction. The NBI information can also be used to signal which one is fixed allocated blocks in the upward direction is not used by the mobile station MS. These blocks could therefore be used for other connections. If the connection with time-critical information registers an increased need for radio resources, then all allocated blocks are used again.

A normal radio block in the downward direction according to FIG. 6 is used, for example, to assign a mobile station MS, which is identified with the identification information MS-ID1, to an identifier USF (uplink state flag) for using blocks in the upward direction. The base station BS thus distributes the radio resources in the upward direction. The decision on the allocation is made in the control unit SE according to FIG. 1.

7 shows a frame structure of the radio interface in the upward direction, with two frames R, for example, which contain 8 time slots ts0 to ts7. The time slots tsi and ts4 are frequency channels GPRS-K which are assigned to a packet data service GPRS. Another time slot tsO is a normal GSM frequency channel, which is also used for signaling purposes, e.g. RÄCH is used as the access channel.

A mobile station MS with time-critical information that is to be transmitted via the packet data service GPRS can send reql requests in both frequency channels GPRS-K and, if necessary, can also be allocated resources in both frequency channels GPRS-K in the up and / or down direction. In addition, a mobile station MS can also send requests reql for radio resources upstream in the access channel RACH, which is normally not reserved for the packet data service GPRS.

The measures described above or combinations thereof can also be used to support time-critical use in a GPRS packet data service. The sequence of a transmission of time-critical information is shown in simplified form in FIG.

In a first step (1), the mobile station MS requests a block in the packet data channel GPRS-K uplink (UL).

In a second step (2), the base station BS sends in the downward direction (DL) GPRS-K DL in block B4 (whose radio technical resources may have been intended for another mobile station MS) the USF for the mobile station MS requesting (1) and thus allocates block B6 in the upward direction.

In a third step (3) the mobile station MS sends the time-critical information in the upward direction and at the same time indicates by means of the NBI that it needs another block.

In a fourth step (4), the next block is allocated in the upward direction.

The mobile station MS could also request all further blocks in this way by indicating this with a corresponding value of NBI. NBI reserves blocks B4, B5, B6. If only every second block is required due to the data rate (half rate), this can also be controlled by the mechanism described.

A radio interface for a TDMA / CDMA transmission is shown in FIG. 9, a frame of a broadband channel, for example 5 MHz, comprising 16 time slots tsO to tsl5. For a TDD mode (time division duplex), a first part of the time slots is used for the upward direction and a second part for the downward direction. As an example, the first time slot tsO, which is used in the upward direction, shows that there are several within the time slot tsO Channels can be distinguished by individual feed codes cl to c8.

Some of the feed codes c1 to c6 are reserved for an access channel RÄCH for the mobile stations MS, other spreading codes c7, c8 are used in the user data channels TCH for user data transmission. However, a distinction is made between the mobile stations MS within the access channel RACH. The spreading codes c3 to c6 are assigned to all mobile stations MS, while the remaining spreading codes c1, c2 are assigned to individual mobile stations MS A to L. In this case, a frequency channel formed by spreading code and time slot is subdivided again in time, so that several mobile stations MS can send a request for allocation of radio-technical resources in one time slot by means of short radio blocks that do not overlap in time, without collisions occurring.

The assignment of mobile stations MS to certain parts of a channel, which is used for quick access to radio resources in the upward direction, is based on a service profile. This service profile for a service to be transmitted between the mobile and base station MS, BS can be expressed on the basis of the maximum permitted access delay, the amount of data, the data rate, the priority of the mobile station MS or, in general, the quality of service (QoS quality of service) be determined. The preferred treatment of a mobile station MS takes place if the service profile provides time-critical information in the sense of fast provision of transmission resources in the uplink direction.

Such services are e.g.

Voice services with very little allowed delay, relatively low data rate and pauses between the voice information, - video services with low permitted delays, high data rates (up to 2 Mbit / s), which fluctuate between a minimum and a maximum value,

- Telemetry transmissions with small amounts of data, but depending on the desired application, very little allowed access delay (e.g. alarm message).

If the other parameters of the radio connection, e.g. Transmission power and lead time) remain stored despite pauses in the transmission, it can be indicated according to the invention with a minimum of data from the base station BS that urgent radio resources in the upward direction are urgently needed. The updated parameters prevent the radio blocks from having long training sequences or midambles to signal the access request. As a result, the radio block is very short and can be sent with further radio blocks in one time slot.

A channel is thus segmented into several subunits, which are assigned to exactly one mobile station MS A - then any collision is excluded - or to a group of mobile stations MS I + J. Assigning a channel or part of the channel to a mobile station MS does not mean that the mobile station MS is constantly transmitting therein, but merely that the part has been assigned to it exclusively in the event that it wishes to transmit.

10 contains a control panel T, a signal processing device SP, a control device ST1 and a transmitting / receiving device SE / EE. At the control panel T, the subscriber can make entries, including entries for a priority P1, for a desired service profile DPI, as well as an entry for sending out a data packet by means of the packet data service GPRS or the desired start of a voice connection to a communication terminal KEG via a packet data service GPRS. If there is a voice connection or other connection with time-critical information (video or other services in which the transmission times are not arbitrary) via the packet data service GPRS, a request reql for radio-technical resources in the upward direction is formed in the signal processing device SP in accordance with the presence of time-critical information to be transmitted and transmitted by means of the previously described signaling types via the transceiver SE / EE.

The time slot ts is selected in the control device ST1 and the transmission time is selected after the previously determined lead time. If the signal processing device SP receives assignments for radio resources in the upward direction sent by the base station BS, this is reported to the control device ST1, which controls the subsequent transmission times.

The base station BS according to FIG. 11 contains a transmitting / receiving device SE / EE, which amplifies the received signals, ins

Baseband implemented and demodulated. In an analog / digital converter, the received signals are converted into symbols with a discrete set of values, for example digitized. In the signal evaluation device SA, which e.g. is designed as a digital signal processor, the access blocks acl, the normal radio blocks, etc. processed.

The useful and signaling information of the radio blocks is then fed to further devices, for example within the base station BS or the base station controller BSC. For radio blocks with requirements reql, an evaluation takes place in a control device ST2 in which a table T1 with the priorities P1 to P4 and service profiles DPI, DP2 assigned to the mobile station MS in accordance with their identifier MS-ID1 to MS-ID4. The priority P1 or P2 means that the assigned mobile station MS may send second radio blocks fb2 as requests reql. The other mobile stations MS are not allowed to do this. The difference from priority P1 to priority P2 is that with priority P1 the mobile station MS may immediately repeat the transmission of a second radio block fb2. The mobile station MS with priority P2 has to wait a certain period of time. This prevents the second radio blocks fb2 of different mobile stations MS from canceling each other repeatedly.

In accordance with the priority P1 and the service profile DPI, the base station BS recognizes that the mobile station MS is transmitting time-critical information and that the requirements reql for radio resources in the uplink direction are to be preferred. The information NBI at the times for the radio resources desired by the mobile station MS are also taken into account in the control device ST2.

Claims

claims

1. Method for packet-oriented transmission of time-critical information via a radio interface between a base station (BS) and mobile stations (MS) of a TDMA mobile communication system, in which during a logical connection: a mobile station (MS) with a service profile (Pl, P2) for time-critical information assigned only within a ^'this service profile (Pl, P2) part of a channel in

Upward direction sends a request (reql) for radio resources in the upward direction without prior assignment of a transmission time by the base station (BS), the base station (BS) receives the request (reql), evaluates it and then signals a changed allocation of radio resources in the upward direction this mobile station (MS) carries out.

2. The method of claim 1, in which in a time slot (ts) of the radio interface, a first radio block (fbl) is transmitted synchronized, so that the first radio block (fbl) at a predetermined time (tl) within the time slot (ts) Base station (BS) arrives, and that at least one second radio block (fb2) with the request (reql) is transmitted in the same time slot (ts), which can be evaluated separately from the first radio block (fbl).

3. The method as claimed in claim 2, in which the radio blocks (fbl, fb2) transmitted in a time slot (ts) have the same length or represent different types of radio blocks (fbl, fb2).

4. The method according to claim 2 or 3, wherein the time (tl) of the arrival of the first radio block (fbl) is based on the beginning of the time slot (ts).

5. The method according to any one of the preceding claims, wherein the request (reql) is sent with an access radio block (acl).

6. The method according to claim 5, wherein a larger number of time slots (ts) for access radio blocks (acl) is provided.

7. The method according to claim 1, 5 or 6, in which ^' the request (reql) can also be sent in time slots (ts) which are not provided for packet data transmission.

8. The method of claim 1, wherein the request (reql) can optionally be sent in at least two frequency channels.

9. The method according to claim 8, in which the allocation of the radio resources optionally takes place simultaneously for one or more frequency channels.

10. Method for packet-oriented transmission of time-critical information via a radio interface between a base station (BS) and mobile stations (MS) of a TDMA mobile communication system, in which during a logical connection: between a mobile station (MS) and a base station (BS) is agreed that requests (reql) for radio resources in the uplink direction are transmitted within radio blocks for information transmission, the mobile station (MS) with a service profile (Pl, P2) for time-critical information within a part of a channel assigned only to this service profile (Pl, P2) sends such a request (reql), the request (reql) containing an indication of the point in time at which the mobile station (MS) requests radio resources in the upward direction, the base station (BS) receives the request (reql), evaluates it and then carries out a changed allocation of radio resources in the upward direction to this mobile station (MS).

11. The method according to claim 10, in which the radio resources are allocated in the upward direction to the mobile station (MS) and the request (reql) contains information as to which transmission times are not used.

12. The method according to any one of the preceding claims, wherein the mobile stations (MS) are assigned service profiles (DPI, DP2) and mobile stations (MS) with certain service profiles (DPI) are preferred for time-critical information when allocating radio resources.

13. The method according to claim 12, in which only a predetermined number of mobile stations (MS) with a service profile (DPI) is permitted for time-critical information in a frequency channel.

14. The method according to claim 12 or 13, in which, in addition to the service profiles (DPI, DP2), the mobile stations (MS) are assigned priorities (P1, P2, P3), only mobile stations (MS) having certain priorities (P1) May repeat the request (reql) within certain time periods (td).

15. The method according to any one of the preceding claims, in which the mobile communication system is a GSM mobile radio network and the packet-wise transmission takes place according to the GPRS method.

16. The method according to any one of claims 1 to 14, wherein the mobile communication system is a mobile radio network with TDMA /

CDMA transmission is and the packet-oriented transmission in a broadband frequency channel formed by a time slot (ts) and a spreading code (c).

17. Mobile station (MS) for performing the method according to claim 1 or 10, with a signal processing device (SP) for generating a request (reql) for radio resources within only one service profile (Pl, P2) for time-critical information allocated part of a channel in Upward direction, with a control device (ST1) for synchronizing the sending of the request (reql) within the TDMA structure.

18. Base station (BS) for performing the method according to claim 1 or 10, with a receiving device (EE) for receiving signals sent in a time slot (ts) with a request (reql) for radio resources in the upward direction, with a signal evaluation device (SA ) for processing the request (reql), with a control device (ST2) for allocating upstream radio resources to a requesting mobile station (MS).