RU2285350C2 - Protocol for controlling radio-channel and/or controlling access to transfer environment - Google Patents

Abstract

FIELD: technology for realization of message transfer service, wherein user data may be transferred between transfer of signaling, such as short messages service, in accordance with protocol for controlling radio-channel and/or controlling access to transmission environment (RLC/MAC) in mobile communication system.

SUBSTANCE: in case of access protocol to channel for Dm-channel (LAPDm protocol) short message service is realized due to usage of each second signaling message, in case, when short message for transfer is present. It also required in case, when at data transfer level instead of LAPDm protocol RLC/MAC protocol is used. This is provided for by determining at least two different identifiers for use with frames, transferred along signaling channel, and primarily with use of frames in accordance to MAC protocol at least on basis of identifier, related to frame. Identifiers are identified on basis of radio channel, carrying signaling of frame.

EFFECT: possible transfer of short messages without borrowing speech frames for transfer of short messages.

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Description

Technical field

The present invention relates to the implementation of a messaging service in which user data may be transmitted between the transmission of a valid signaling, such as a short message service, in accordance with the RLC / MAC protocol (radio channel control / media access control) in a mobile communication system, in particular, to implement the messaging service according to the RLC / MAC protocol over the SACCH (slow connected control channel), which has a DPSCH subchannel (dedicated physical subchannel). The SACCH is a linked control channel in which one frame is available for signaling control in the direction in which the linked channel carries traffic.

State of the art

A mobile communication system is generally understood to mean any telecommunication system that provides wireless communication when the user is in the service area of the system. Examples of such systems are cellular mobile communication systems such as GSM (Global System for Mobile Communications) or corresponding systems such as PCS (Personal Communication System) or DCS 1800 (1800 MHz Digital Cellular System), third generation systems such as UMTS (Universal Mobile Communication System) and systems based on the aforementioned systems, such as GSM 2+ systems and future fourth-generation systems. A typical example of a mobile communication system is PLMN (Public Land Mobile Network).

In addition to conventional voice and data connections established via traffic channels in digital mobile communication systems, short digital data messages containing user data can be transmitted between actual signaling via the control and signaling channels of the system. The main reason for this is to avoid borrowing frames from the traffic channel. These short digital data messages containing user data are commonly referred to as short messages. In the GSM system, the control channels used for transmitting short messages are SACCH channels used for transmitting measurement results performed by the mobile station MS during the connection, and an SDCCH (separate dedicated control channel) carrying a valid signaling. If the mobile station has a connection on the traffic channel, short messages are sent on the SACCH, otherwise they are sent on the SDCCH.

In the GSM system, the short message service is implemented using the LAPDm protocol (channel access protocol for the Dm channel) at the data channel level, that is, at level 2. The LAPDm protocol provides services for a higher level, that is, level 3, through access points to the service (SAP), which are identified by the service access point identifier (SAPI). LAPDm has two different meanings for the SAPI. The signaling is carried in frames SAPI = 0, using the operation mode without acknowledgment on the SACCH channel associated with the traffic channel. Short messages are carried in SAPI = 3 frames using the acknowledgment mode of operation on the SACCH associated with the traffic channel. The acknowledgment mode of operation according to the LAPDm protocol sets the priority of messages from an object of level 3, so that if the SAPI = 3 frame, that is, a short message, is waiting for transmission, then two SAPI = 0 frames are not sent in successive frames. It is also guaranteed that at least one SAPI = 0 frame is transmitted after the SAPI = 3 frame. In other words, short messages are transmitted on the SACCH associated with the traffic channel by preemptively using (occupying) every second signaling frame, i.e. SAPI frame = 0.

However, in a GSM 2+ system called GERAN (GSM / EDGE (Advanced Data Rates for Global Evolution) Radio Access Network), version 5, it is proposed to use the RLC / MAC protocol instead of the LAPDm protocol to make protocol stacks less complex. One of the problems associated with replacing the LAPDm protocol with the RLC / MAC protocol is that the RLC / MAC protocol does not support the frame preemptive mechanism described above.

SUMMARY OF THE INVENTION

The present invention is the creation of a method and system for implementing the method to solve the above problem. This result is achieved using the method and system, which are characterized by the characteristics given in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on formulating the problem and providing the RLC / MAC protocol with a mechanism for the preferential use of signaling frames by defining at least two different identifiers, preferably identifiers of the signaling radio carrier, the first indicating a signaling message, and the second indicating possible short messages, and modifications protocol for the preferential use of every second frame with a first identifier.

An advantage of the invention is that it enables the transmission of short messages, as if the LAPDm protocol was used, and therefore there is no need, for example, to borrow speech frames for transmitting short messages. Another advantage is that the physical layer of the SACCH can be stored as it is.

Brief Description of the Drawings

The invention is described below in more detail by way of examples of preferred embodiments with reference to the drawings, which show the following:

Figure 1 - the main components of the communication system;

2 is a protocol architecture according to a first preferred embodiment of the invention;

3 is a flowchart illustrating media access control operations in accordance with a first preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention can be applied in any communication system where a short message service or a corresponding user data service transmitted between signaling via signaling channels is provided via the RLC / MAC protocol. Such systems include, for example, the aforementioned systems. In the following, the invention is described using, by way of example, a GERAN system, without limiting the invention to this embodiment.

Figure 1 presents a very simplified architecture, illustrating only the main parts of the communication system 1. For specialists in the art it is obvious that the system 1 contains network nodes, functions and structures, which are not necessary to describe here in detail.

The mobile station MS comprises a real terminal and a removable SIM identification card, also called a subscriber identity module. In this context, a mobile station typically denotes an entity formed by a subscriber identity module and a real terminal. The mobile station MS may be any device capable of communicating in a mobile communication system and supporting a short message service or a corresponding service.

In the example of FIG. 1, system 1 comprises a core network CN and a radio access network GERAN. The GERAN network is formed by a group of subsystems of the radio communication network (not shown in FIG. 1) that are connected to the main network CN via the lu interface 2. The GERAN network can be a GSM / SDGE radio access network, and the CN network can be a main GSM network / UMTS.

For the short message service, system 1 comprises an SMSGW short message service gateway having a connection with the SMSC short message service center. SMSGW Short Message Service Gateway is a generally accepted term for the Gateway Mobile Switching Center for SMS-SMSC Short Message Service and Mobile Gateway Switching Center for SMS-IWMSC Short Message Service. SMS-GMSC receives short messages from SMSC, requests routing information, and delivers short messages via CN and GERAN to mobile station MS. Accordingly, the SMS-IWMSC can receive short messages from the mobile station for forwarding to the SMSC short message service center.

FIG. 2 illustrates a protocol architecture of an SACCH lu interface having a DPSCH in accordance with a first preferred embodiment of the invention. The protocol stack shown in FIG. 2 is a protocol stack of a control plane. Corresponding layers and sublevels implemented in accordance with the invention can also be used in other interfaces. Bold lines between levels and sublevels illustrate possible data streams, and circles indicate service access points for peer-to-peer data transfers.

The lu interface protocol architecture shown in FIG. 2 contains three protocol layers: a physical layer L1, a data link layer L2, and a network layer L3. The data link channel layer L2 contains the following sublevels below the RRC (radio resource control) of the L3 layer: RLC — radio channel control and MAC — media access control.

The RRC layer has a control interface (not shown in FIG. 2) between the RRC layer and the RLC protocol sublayer, between the RRC layer and the MAC protocol sublayer and between the RRC layer and L1. These interfaces allow the RRC layer to control the configuration of the lower layers.

The RRC layer in accordance with the invention provides at least two different signaling carrier channels 0, 3 in the control plane, one of which is used, inter alia, for the short message service or the corresponding user data service, and the other is used for signaling. Each signaling radio bearer is identified by an SRBid of the signaling radio bearer, or the corresponding identifier may be displayed in a one-to-one relationship with the associated signaling bearer. In the first and second preferred embodiments of the invention, the identifier SRBid 0 corresponds to the identifier SAPI = 0 protocol LAPDm, and the identifier SRBid 3 corresponds to the identifier SAPI = 3 protocol LAPDm. The RRC layer according to the invention configures the RLC and MAC protocol sublevels accordingly through the interfaces. The signal carrier radio channels can be configured when the RRC connection is established and stored until, for example, the RRC connection is released. Another possibility is that the alarm radio channels use a predefined default configuration. In other words, the RRC layer according to the invention differs from the known RRC level in that it reserves two signaling radio channels for the connection.

The RLC protocol sublayer provides the upper layer L3, inter alia, data transmission with acknowledgment and without acknowledgment. The RLC sublayer according to the invention provides acknowledgment data transmission for those messages for which the frame header contains the identifier of the signaling radio carrier, also used for short messages, i.e. frames with the identifier SRBid 3 in the first and second preferred embodiments of the invention. Data transfer without acknowledgment is provided for signaling messages, that is, frames with the identifier SRBid 0 in the first and second preferred embodiments of the invention. The RLC protocol sublayer object 4 is preferably set for each radio signaling carrier channel, that is, for each identifier, as soon as a frame for transmission appears, and this object exists preferably until the corresponding DSPCH is released.

The MAC protocol sublayer processes access and multiplexing to physical subchannels, thereby determining, among other things, the logical channels to be used for each radio signal carrier. The sublayer of the MAC protocol also provides the transmission of messages about the measurement results of mobile stations MS. For the mobile station MS, there is one MAC protocol entity on the mobile station side and one on the network side. The MAC protocol sublayer, in accordance with the first preferred embodiment of the invention, will advantageously advantageously use (borrow, borrow) every second frame having an identifier of a signaling radio carrier indicating a signaling message in the case when there is a frame having a different identifier of the radio channel -carrier alarm. In other words, the MAC protocol sublayer provides, in the lu-interface mode, priority processing between traffic flows based on identifiers of the signaling radio channels.

The operation of the MAC protocol in a first preferred embodiment of the invention is shown in FIG. For clarity, the drawing does not mention header information and the like, which is added by the MAC protocol to the received information. The functionality described in FIG. 2 is implemented in each cycle, that is, in GERAN something is transmitted on the SACCH every 480 ms. If there are no measurement results to be transmitted, a fill frame is transmitted. In a first preferred embodiment, it is assumed that a pad frame is generated at the MAC protocol level. In some other embodiments, a pad frame may be generated at the RLC protocol level or at the RRC level.

In a first preferred embodiment of the invention, there are two inputs to the MAC protocol layer: input 0 for frames with the identifier SRBid 0 and input 3 for frames with the identifier SRBid 3, and three buffers: one input buffer called InBuffer 0 for frames with the identifier SRBid 0, another input buffer called InBuffer 3 for frames with the identifier SRBid 3, and an output buffer called OutBuffer. The InBuffer 3 buffer is a FIFO (first come, first served) buffer.

3, in step 301, the MAC protocol reads input 3 for frames with the identifier SRBid 3, and if input 3 is not empty (step 302), then adds the contents of input 3 to InBuffer 3 in step 303 and reads input in step 304 0 for frames with the identifier SRBid 0. Then the MAC protocol proceeds to the same step 304 if input 3 was empty (step 302). If input 0 is not empty (step 305), then the MAC protocol adds at step 306 the contents of input 0 to the InBuffer 0 buffer. After that, the MAC protocol at step 307 checks to see if the InBuffer 3 buffer is empty. If not, the MAC protocol checks at step 308 whether the frame sent in the previous cycle had a frame with the identifier SRBid 0. If so, the MAC protocol deletes at step 309 the first element in the InBuffer3 buffer from the InBuffer 3 buffer to the OutBuffer buffer and clears the InBuffer 0 buffer in step 310 and transmits the contents of the OutBuffer buffer in SACCH in step 311. In other words, the preferential use of the frame with the identifier SRBid 0 in the first preferred embodiment of the invention is carried out at step 310. It is performed by the extrusion function, which can be defined as the preemptive function (means).

If the frame transmitted in the previous cycle was not a frame with the identifier SRBid 0 (step 308), or if the InBuffer 3 buffer is not busy (step 307), then the MAC protocol deletes, in step 312, the InBuffer 0 buffer element from the InBuffer 0 buffer to the OutBuffer buffer and transmits at 311 the contents of the buffer to the SACCH.

If input 0 was empty (step 305), then the MAC protocol adds a fill frame to InBuffer 0 at step 313 and proceeds to step 307 to check whether the InBuffer 3 buffer is not occupied. A pad frame is added (step 313) for continuous transmission on the SACCH.

In another embodiment, frames with an identifier of SRBid 3 are not buffered in the MAC protocol. In this embodiment, the MAC protocol acknowledges receipt of the corresponding RLC protocol entity when a frame with the identifier SRBid 3 has been sent, and the RLC protocol sends another frame with the identifier SRBid 3 only after an acknowledgment has been received. Confirmation of receipt may be performed, for example, between steps 309 and 310 of FIG. 3.

Thus, the MAC protocol according to the first preferred embodiment of the invention does not account for half of the frames with the identifier SRBid 0, whenever there is a frame with the identifier SRBid 3 for transmission, simply by replacing one frame with the identifier SRBid 0 on the frame with the identifier SRBid 3. In other words, the frame with the identifier SRBid 3 takes the bandwidth of the frames with the identifier SRBid 0 in the channel SACCH.

In accordance with a second preferred embodiment of the present invention, the MAC protocol uses the principles of a round-robin (round-robin) service algorithm, which are well known to those skilled in the art. Thus, in a second preferred embodiment, the MAC protocol sends a frame from InBuffer 0, then from InBuffer 3 if it contains a frame, then again a frame from InBuffer 0, and so on. The InBuffer 0 buffer has frames with the identifier SRBid 0. The InBuffer 3 buffer has frames with the identifier SRBid 3. InBuffer buffers are cleared according to the FIFO principle.

Although the invention is described under the assumption that buffers are used in the MAC protocol, those skilled in the art will understand that the invention can be applied without buffers.

Although the invention is described under the assumption that there are only two signaling radio carrier channels (and signaling carrier radio channel identifiers), the invention can be applied to any preferential use (occupation) mechanisms between different carrier radio channels by preemptively occupying low priority frames with higher priority frames .

In addition to the means known from the prior art, a system that implements the functions of the present invention and network nodes of this system contain means for providing preferential use of user data sent over signaling channels. More specifically, network nodes may comprise means for implementing the functions described above. Modern network nodes contain processors and memory that can be used in the functions of the invention. All changes necessary to implement the invention can be implemented as an addition or modernization of software routines using application-oriented (specialized) integrated circuits (ASICs) and / or programmable circuits such as EPLD (Erasable Programmable Logic Device), FPGA (valve matrix, user programmable).

For specialists in this field of technology should be clear that with the development of technology, the principle underlying the invention can be implemented in various ways. The invention and its embodiments are not limited to the described examples, but may vary within the scope of the claims.

Claims (10)

1. A method of prioritizing frames transmitted over a signaling channel in a communication system using a medium access control protocol (MAC) at a data channel level, characterized in that it includes steps in which at least two different identifier to be used with frames transmitted over the signaling channel, one of the identifiers indicating that the frame related to the said one identifier may contain user data, and advantageously at least, frames related to the aforementioned one identifier are used over the MAC protocol, at least based on the identifier relating to the frame. 2. The method according to claim 1, characterized in that the signaling frame is indicated by a first identifier, a frame that may contain user data is indicated by a second identifier, and every second frame related to the first identifier is advantageously used whenever there is a transmission frame related to the second identifier. 3. The method according to claim 1 or 2, characterized in that they reserve the same number of signaling radio channels for the connection as many identifiers are determined, display each identifier on the signaling radio channel and identifying the frame identifier in the MAC protocol based on the signaling radio channel frame. 4. A method of prioritizing frames transmitted over a signaling channel in a communication system using the MAC protocol at the data channel level, characterized in that it includes the steps of reserving at least two different carrier radio channels for connecting to the signaling channel moreover, each carrier channel is identified by an identifier, one of the identifiers indicates that the frame related to the one identifier may contain user data, and advantageously use at least frames relating to said one identifier for MAC protocol, at least based on the radio bearer frame identifier. 5. The method according to claim 4, characterized in that the radio carrier channels are radio carrier signaling with a slow connected control channel (channel SACCH), and the method further includes the step of determining at least one radio carrier signaling, which an acknowledgment radio channel that can be used to transmit user data between alarms and must be identified by the same identifier. 6. A communication system that provides services for the transmission of user data on the signaling channel, comprising an interface that uses the MAC protocol at the data transmission level, characterized in that the system further comprises at least two carrier radio channels (0.3) for connection, moreover, each carrier channel is identified by an identifier, one of the identifiers indicates that the frame related to the one identifier may contain user data, preferential use (MAC), designed for the preferential use of at least frames related to the aforementioned one identifier, according to the MAC protocol, at least based on the identifier of the radio bearer of the frame. 7. The communication system according to claim 6, characterized in that at least one of the carrier radio channels is also used for transmitting user data, and at least one of the carrier radio channels is used only for signaling transmission and with respect to the latter carries out the aforementioned preferential use of personnel. 8. The communication system according to claim 6 or 7, characterized in that the carrier radio channels are signaling radio channels. 9. A network node in a communication system providing a service transmitting user data via a signaling channel, the network node comprising an interface using the MAC protocol at the data transmission layer, characterized in that the interface provides two or more different carrier radio channels (0, 3) for the connection, each carrier channel being identified by an identifier, one of the identifiers indicates that the frame related to the one identifier may contain user data, and a network node further comprises a preferential use tool (MAC) intended for preferential use of at least frames related to the aforementioned one identifier via the MAC protocol, at least on the basis of the identifier of the radio carrier. 10. An interface for a communication system providing a service transmitting user data on a signaling channel, the interface being configured to use the MAC protocol at the data transmission layer, characterized in that the interface provides two or more different carrier radio channels (0.3) for connection, moreover, each carrier channel is identified by an identifier, one of the identifiers indicates that the frame related to the said one identifier may contain user data and the interface will complement flax comprises means preferential use (MAC), intended for primary use, at least frames of MAC protocol, at least based on the radio bearer identifier.

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