FI105306B - Radio - Google Patents

Description

1 105306

radio system

The present invention relates generally to radio networks and in particular to methods for increasing data transmission capacity in a radio network.

The most significant limiting factor for the capacity of radio systems is the limited frequency spectrum available. Thus, the capacity of the radio system depends on how efficiently the radio frequencies assigned to the system can be utilized. In cellular radio networks, the more efficient utilization of radio frequencies is based on frequency reuse: the same frequency is used at several locations far enough apart, resulting in a huge increase in system capacity. This is counterbalanced by increased complexity for both the network and the mobile stations, which must be able to select a base station from a number of possible ones. For example, if the same frequency is reused every nine cells, the N frequency spectrum allocation allows the N / 9 carrier to be used simultaneously in any cell. Reducing the cell size or reducing the distance between the same frequency cells increases the capacity but also the co-channel interference. Therefore, the choice of a frequency reuse factor is often a trade-off between the same-20 channel interference in the system and the traffic capacity.

* ·. Because the frequency spectrum allocated to the cellular radio network is fixed and the number of subscribers is growing rapidly, efficient use of the allocated frequency spectrum * · * · ': · is vital for every network operator. Thus, the various traffic capacity-enhancing features in the cellular network provide much needed • •:: 25 impact on operators, particularly in crowded urban areas. Radio: ·:: The evolution towards high-capacity radio networks mainly involves: increasing the number of channels, -

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lut), microcell networks, multilayer networks, underlay overlay networks, and • · «other capacity-enhancing solutions such as half rate channels, frequency hopping, and power control. These are discussed in more detail below

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. ··. options.

The simplest way to increase capacity is to increase the number of channels

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Since the frequency spectrum allocated to the network operator is very limited, this method does not alleviate the capacity problems. So-35 cell division involves design problems and investment in base station location and transmission. Cell division is a good method to ease the capacity problem. Unfortunately, in urban areas, capacity requirements are so high that this method does not provide long-term help, and cell division can only be used as a short-term relief 5 Micro-cellular networks also have the same problems.

An underlay overlay network has two (or more) distinct cell layers, one of which, e.g., a macrocellular layer, provides total coverage and the other, e.g., a microcellular layer, provides capacity. The "Coverage Layer" uses the traditional frequency reuse pattern and cell range to provide a seamless total coverage of 10. The "capacity layer" uses a very dense frequency reuse pattern and a shorter cell range to achieve high capacity over a few channels. In an underlay overlay network, a handover between network layers is a critical factor in increasing capacity. Another known and effective way to increase the capacity of a cellular network is cells having 15 different frequencies with reuse coefficients. Higher reuse coefficient frequencies achieve comprehensive coverage and lower reuse coefficient frequencies provide additional capacity in the center of the cells.

In digital mobile communication systems, voice transmission is entirely digital. In this case, the bandwidth required for one radio link on the radio path can be reduced by using speech size in speech transmission. a data rate which achieves a lower transmission rate, e.g. 16 or 8 kbit / s, than the 64 kbit / s rate typically used in telephone networks. As well as travel T *. of course that the mobile network must have a speech codec for speech coding. On the network side, speech coding functions may be located in 25 alternative locations, such as a base station or a mobile switching center. In this case, each incoming or outgoing voice call to the mobile station is coupled to the voice connection on the network side by a speech codec which «k · decodes the uplink speech signal from the mobile station and encodes

Kl downlink (downlink) speech signal to the mobile station.

··. 30 In some digital mobile communication systems, voice

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. ···. there is also a discontinuous transmission mode DTX (Discontineous Transmission). It aims to increase the efficiency of the system through interference reduction t '; ** [by preventing the transmission of a radio signal when it is not needed for information purposes.

In addition, the DTX reduces mobile power consumption, an important consideration in 35 battery-powered portable terminals. This DTX mode is usually alternate to the normal mode, and the choice between the two modes is made on a call-specific basis in the mobile network. In DTX mode, speech is normally encoded e.g. at 13 kbit / s when the user is speaking, and during speech breaks a significantly lower bit rate is used, e.g. about 500 kbit / s. This lower bit rate 5 is used to encode the background noise information on the transmission side. For example, in a pan-European digital mobile communication system, a GSM transmitter (mobile or base station) normally transmits one traffic burst per TDMA frame (i.e., 96 bursts / 480 ms) until the speech codec detects a silent period in the speech signal. Then the transmitter only transmits 12 bursts-10 t / 480 ms. On the receiving side, this background noise is regenerated for the listener, which is why it is called comfort noise so that he or she does not think that the connection has been lost during transmission breaks. The function that monitors at the transmission end whether or not there is speech activity is called Voice Activity Detection VAD. The decision whether a signal contains speech or background noise is typically based on a threshold and a comparison of the measured signal energy.

Comfort noise is generated because experience has shown that the listener is greatly disturbed when the background noise behind the speech suddenly stops. This would happen regularly in discontinuous transmission. One way to avoid this listener interference is to generate artificial noise when no sig-20 is received. The properties of this noise are regularly updated and: j transmitted to the receiving end by a speech encoder located in the transmitter; off.

• *. Discontinuous transmission may also be applied to data transmission if the data rate or amount of data varies during a call. In multi-channel high-speed 25 ”circuit switched data transmission (HSCSD for high-speed data * * · · connection, two or more parallel traffic channels are used on the • · · * (subchannel) radio path. This may result in a situation where ... is less than the maximum data rate allocated to the connection, and traffic channels have to transmit incomplete or empty data files. • In the discontinuous data transfer method of PCT / FI96 / 00669: the problem has been alleviated by the fact that data frames are transmitted '' 'tightly only over certain subchannels when allocated to the data connection. ·! ·, maximum transmission capacity is not required. Other subchannels allocated to the connection have no transmission or have subchannel-specific discontinuous transmissions * 35 Hours The number of active subchannels RAN reduction leads to a reduction in the transmitter 4 105306 in power consumption, a reduction in the thermal problems, and the simpler the reception, transmission and neighbor cell measurement scheduling. In addition, as unnecessary transmissions at the radio interface are reduced, interference levels in the mobile communication network also decrease.

5 In circuit switched data transmission services, a dedicated circuit switched connection (e.g., a radio interface traffic channel) is allocated to a data call. In this case, the number of concurrent users is limited to the maximum number of traffic channels. In a packet or packet switched data transfer service, individual data packets are transmitted based on their addresses or via a virtual connection 10. At the radio interface, the traffic channel can be shared by multiple users for packet data transmission, which increases the capacity of the radio network as measured by the number of users. The packet data service is advantageous especially when the data transmission is random but the connection is to be maintained continuously to enable high speed data transmission. The packet switched data transmission can be implemented in a dedicated packet radio network or as an additional service in a traditional circuit switched radio network.

For example, a Global Packet Radio Service (GPRS) is being developed for the Global System for Mobile Communication (GSM), a new service for the GSM system 20 and is one of the topics of GSM Phase 2+ standardization work in ETSI (European Telecommunication Standard Institute). The GPRS environment consists of a single. . ·. One or more sub-network service areas interconnected by a GPRS backbone network. The subnet comprises a plurality of packet data service nodes SN, referred to herein as serving GPRS support nodes · · .I, * 25 other SGSNs, each connected to a GSM mobile communication network (typically • · · base station systems) so as to be able to provide packet data service to mobile data via multiple base stations, i.e. cells. The intermediate mobile network ... provides packet data communication between the support node and mobile data terminal equipment. The different subnets, in turn, are connected to an external data network, e.g., a public switched data network, PSPDN, through dedicated GPRS gateway support nodes GGSN. Thus, the GPRS service provides packet data transmission between mobile data terminals and external data networks while the GSM network is an access network. Base station transceivers and channels are allocated for circuit-switched calls 35 and packet-mode calls as needed.

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An object of the invention is to increase the data transmission capacity in radio networks supporting both circuit switched and packet transmission services.

The object is achieved by a radio system comprising mobile stations, a base station network in which each base station supports both circuit-switched calls 5 and packet data transmission, and a discontinuous transmission mode which is activated for a circuit-switched call in the downlink direction. The invention is characterized in that the downlink traffic channel of a base station having a circuit switched call in discontinuous transmission mode can be allocated for separate packet data transmission for the circuit disconnected call transmission mode 10 (DTX).

The invention also relates to a data transmission method for a radio system comprising mobile stations and a base station network in which each base station supports both circuit-switched calls and packet data transmission and comprises a discontinuous transmitting state that ; establishing a circuit-switched call; transmitting circuit switched information on said downlink traffic channel from said base station; initiating discontinuous transmission mode on said circuit-switched call. The method is characterized in that it further comprises the steps of allocating said downlink traffic channel allocated to a circuit switched call in discontinuous transmission mode, also for packet data transmission in discontinuous transmission mode of a circuit switched call, to transmitting packet data in said discontinuous state. said downlink traffic channel, terminating the transmission of packet data on said downlink * '* * traffic channel and returning the downlink traffic channel to the circuit-switched call when said discontinuous transmission mode ends.

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The invention also relates to a transmission system for a radio system which. * ··· '30 supports both circuit-switched calls and packet data transmission, whereby: · a discontinuous transmission mode can be activated for a switched call. The apparatus is characterized in that the traffic channel of the transmission apparatus having a circuit switched call in a · · · continuous transmission state can be allocated for separate packet data transmission for the circuit switched call discontinuous transmission (DTX) mode · · 35.

6 105306

In the present invention, moments requiring pauses or lower transmission capacity in the circuit switched call information stream (speech or data signal), i.e., moments in which the call is in discontinuous transmission mode (DTX), are utilized for transmitting packet information from the base station over the same downlink traffic channel. When the circuit switched call enters DTX mode (information transmission is interrupted), packets of packet data call (s) are transmitted on the allocated traffic channel until the discontinuous transmission mode ends. The traffic channel may be allocated to packet data transmission (calls) separately for each DTX mode, or may be allocated over a longer period. Pi-10 lower allocation may be advantageous, for example, when the packet call has at least one other downlink traffic channel and the invention increases capacity in the downlink direction. The traffic channel is allocated for DTX modes for packet mode transmission to typically different mobile stations than the mobile station to which the traffic channel is allocated for circuit switched transmission. 15 This allows the transmission capacity to be allocated as efficiently as possible to the users in need on the network. Mobile stations may belong to different systems, such as packet data radio network and circuit switched radio network. The mobile station (s) for which the traffic channel is allocated for packet data transmission is directed to receive on the allocated channel. It receives the data packets assigned to it by nor-20 and discards any circuit-related information it may receive: ··· connected. Similarly, a mobile station having; said circuit switched call in progress, receiving DTX- * * * as normal. mode but discards all packet information as incorrect. Otherwise

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. ·. : that is, each (each) mobile station receives on the traffic channel as a line: ·. * 25 kennel channels would be in its own use all the time, so it does not require any • ·· [... capability to handle or understand traffic from another mobile station.

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In its simplest form, the invention can be implemented without modifications to terminals, which facilitates implementation in existing networks. Changes are required • · only on the access point or other network element. The traffic channel may also be allocated to the same mobile station for both circuit switched and packet <f; j * traffic, but the mobile station must be modified specifically for this purpose. This type of allocation is also much less efficient in terms of capacity utilization of the network than the DTX mode dy-! allocation allocation to a large number of users for packet transfer according to their * * 35 transfer needs. The advantage of the data transmission packet form is that during the same 7,105,306 DTX mode, data of many users can be transmitted and thereby more efficiently utilize the capacity provided by the entire DTX mode.

The method according to the invention can significantly improve the utilization of the capacity of the radio network in the downlink direction. It can be estimated 5 that a normal voice call is up to 40-50% of the call time in DTX mode in one transmission direction (in normal conversation, the speakers alternate, overlapping is rare). In any case, there are pauses in the speech which can transfer thousands of bytes of data (eg about 500 bytes / 0.5 seconds). It is precisely in the downlink direction that all 10 available capacities are needed, since in this direction the data traffic is the highest. Typically, mobile stations subscribe to services and information in the upplink direction and receive subscribed data, such as the World Wide Web (WWW) or file, in the downlink direction.

The invention will now be described by means of preferred embodiments 15 with reference to the accompanying drawings, in which Fig. 1 illustrates the architecture of a GSM / GPRS system, Figs. 2A, 2B and 2C illustrate different placement alternatives of a packet control unit PCU. Fig. 3 is a block diagram of a base station according to the invention; Fig. 4 is a flow chart illustrating the base station diagram of Fig. 3. . ·. operation of the navel controller 31,. FIG. 5 is a flowchart illustrating the operation of the PCU / CCU of FIG. 3; FIG. 6 is a signal diagram illustrating the signals of the base station of FIG. 3.

The present invention is applicable to various types of radio systems that support both circuit-switched transmission service and packet-switched transmission service. Particularly advantageously, the invention is suitable for use in a 5 * ·; ·: 30 pan-European digital mobile communication system (GSM) or equivalent mobile communication systems, such as DCS1800 and PCS (Personal Communication System), in conjunction with a general packet radio service. (GPRS = General Packet Radio Service). In the following, the preferred embodiments of the invention will be described by means of the GPRS / GSM radio system, without limiting the invention to such a particular radio system.

Figure 1 illustrates the basic architecture of a GSM system and the architecture of a GPRS packet radio network implemented in a GSM system.

5 The basic structure of the GSM network consists of two parts: the base station system BSS and the network subsystem (NSS). The BSS and the mobile stations MS communicate via radio links. In the base station system BSS, each cell is served by the base station BTS. A plurality of base stations are connected to a base station controller BSC whose function is to control the radio frequencies and channels used by the BTS. The 10 BSCs are connected to the mobile services switching center MSC. However, for a more detailed description of the GSM system, reference is made to the ETSI / GSM Recommendations and the book "The GSM System for Mobile Communications", by M. Mouly and M. Pautet, Palaiseau, France, 1992, ISBN: 2-9507190-07-7.

In the GSM system, voice and data transmission as a whole takes place via digital circuit-switched transmission connections. The speech coding method currently used in speech transmission is RPE-LTP (Long Term Prediction), which utilizes both long-term and short-term prediction. The encoding produces LAR, RPE, and LTP parameters that are transmitted instead of the actual speech. Speech transmission is dealt with in the GSM Recommendations Chapter 20 06, and speech coding in particular in Recommendation 06.10. In the near future will be used for other encoding methods such as half-rate methods. methods in which the invention can also be used as such. Because • Λ the actual invention is not directed to the speech coding method itself and is V 'of it. independent, it will not be discussed further here.

Of course, the mobile station must have a speech encoder and decoder for speech coding. Since the implementation of the mobile station is not essential to the invention and is not deviated from, it will not be described in further detail here.

'···' On the network side, various speech coding and rate adaptation functions are centralized in the Transcoder / Rate Adapter ··· Unit (TRCU). The TRCU may be located in several alternative locations within the system, »depending on the choices made by the manufacturer. The transcoder unit interfaces are 64 <31 kbit / s PCM (Pulse Code Modulation) interface (A interface)

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\ MSC and a 16 or 8 kbit / s GSM interface to the base station BTS. In connection with these interfaces, the GSM recommendations also use the terms uplink and 9 105306 downlink, of which the uplink is from the BTS to the base unit and out to the MSC, while the downlink is the opposite.

Typically, the transcoder unit TRCU is located within the mobile communications switching center MSC but may also be part of a base station controller BSC or a base station BTS. When the transcoder unit TRCU is separated from the base station BTS, information is transferred between the base station BTS and the transcoder unit TRCU in a so-called. TRAU frames. TRAU frames are defined in GSM Recommendation 08.60 (or 08.61). Depending on the information content, the frame may include a speech, access / maintenance and data frame, and so-called. idle speech frame. To perform synchronization, the first two octets of each frame contain 16 synchronization bits. In addition, the first bit of the 16-bit words (2 octets) forming the frame is the synchronization check bit. In addition to the actual speech, data or usage / maintenance information bits, each frame contains control bits that convey information about the frame type as well as a variable amount of other type-specific information. In addition, for example, in the speech and idle frames, the last four bits T1-T4 are reserved for the aforementioned timing control. The TRAU speech frame has 21 control bits C1-C21, in addition to which the last 4 bits T1-T4 of the frame are reserved for timing control. The actual pu-20 information transfer bits are in octets 4-38. In practice, the transmitted speech information is the LAR, RPE and LTP parameters of the Regular Pulse Exitation (Long Term Prediction) RPV-LTP speech coding method. The idle speech frame is similar to the speech frame of Figure 2 except that all traffic bits in the frame are in logical state "1". Bits C13-C14 form the SID (Silence • * ·· 25 Descriptor). C17 is a downlink DTX bit that indicates whether discontinuous transmission is possible: T: DTX uses downlink (DTX = 1) or not (DTX = 0). C16 is an SP bit indicating in the downlink whether the TRAU frame contains speech (SP = 1) or is it a so-called SID frame (SP = 0) which contains information about the transmission · ««: * '; side background noise.

· Continuous Transmission DTX, as used herein, generally refers to a method by which transmission to a radio path is traditionally interrupted during speech (or • '' • y '' breaks in other information streams). In the GSM system, the downlink DTX is implemented by three main building blocks. Transcoder TRCU requires Voice Activity Detection, or VAD (Voice Activity Detection) 35, which is used to investigate whether the observed speech signal contains speech or whether it is pure background noise. In normal transmission mode, the TRCU transmits speech frames (SP = 1) to the base station. When speech is no longer detected, the TRCU begins to send SID frames (SP = 0) to the base station BTS after the time required to calculate background noise parameters, the BTS transmits the speech frames directly to the radio path. When the 5 BTS receives the first SID frame, it still transmits this SID frame to the radio path and enters downlink DTX mode. In DTX mode, the BTS continuously receives the SID frames from the transcoder TRCU but transmits them to the radio path only at predetermined intervals (480 ms) to update the noise parameters. The DTX mode continues until the BTS receives the transcoder TRCU speech frame 10 (SP = 1), whereupon the BTS switches back to continuous transmission.

The primary benefit of the Downlink DTX is lower interference in the cellular network and enabling intermittent reception in the mobile station. However, according to the inventors' realization, the physical traffic channel reserved for the call is unused capacity during DTX mode, which can be made available for 15 other downlink transmissions. In the preferred embodiment of the invention, this other downlink transmission is GPRS packet data transmission.

Again, with reference to Figure 1, the GPRS system comprises one GPRS network having two serving GPRS support nodes (SGSN) and one GPRS gateway support node (GGSN). These different support nodes SGSN and GGSN 20 are interconnected by an intra-operator backbone network 13 (Intra-operator Backbone II Network). It will be appreciated that the GPRS network can have any number of support nodes and gateways. GPRS Gateway Support Node GGSN connects an operator's GPRS network to other operators' GPRS systems and · data networks 11-12, such as the Inter-Operator Backbone Network, IP Network (Internet) or X.25 -network.

: T: The serving GPRS support node SGSN is a node serving the mobile communication MS. Each support node SGSN manages packet data negotiation in the area of one or more cells in a cellular packet radio network. To this end, each support node SGSN is connected (Gb interface) to a specific local part * * * ·. 30 GSM mobile communication systems. This connection is typically made with a base station - «· · ;;; system BSS, i.e., the base station controller BSC (as in Figure 1) or one of the base stations BTS. The mobile station MS in the cell communicates over the radio interface with the base station BTS and further through the mobile network with the support node SGSN to which the cell belongs. In principle, the mobile communication network between the support node 35 SGSN and the mobile station MS merely transmits packets of 105306 between the two. To this end, the mobile communication network provides a physical connection for transmitting data packets between the mobile station MS and the serving support node SGSN.

A cell that supports GPRS may allocate radio resources on one or more physical channels to support GPRS traffic. A physical channel (e.g., a time slot) is called a packet data traffic channel PDTCH. It is temporarily allocated to one GPRS-MS or set of GPRSs. In multi-slot operations, a single GPRS-MS may use multiple PDTCH channels (up to eight time slots on the same carrier) in parallel for its own packet transmission. The Al-10 localized physical channels are taken from a common channel pool available in the cell. The allocation of physical channels to circuit switched GSM and GPRS services is done dynamically according to the capacity on demand principle. The common signaling required by the GPRS is transmitted on the packet switched control channel PCCCH, if allocated, or on the GSM common control channel 15 CCCH.

GPRS does not require permanently allocated PDTCH channels. Capacity allocation for GPRS can be based on the needs of the actual packet transmission, referred to herein as the "on demand" principle. The advantage of dynamic allocation is that, in a load situation, the operator can allocate unused channels 20 to GPRS traffic to increase the quality of the GPRS service. However, the operator may • * »> dedicate, permanently or temporarily, some channels for GPRS use.

·:. * The base station system and SGSN are connected by a Gb interface, which enables the exchange of signaling information and data. This signaling also includes packet channel allocation signaling, e.g., setting up a virtual connection from the SGSN to the radio resource group located in the base station BTS. The connection may be i'X: may also be a circuit-switched connection.

More specifically, the Gb interface is defined to be located between the packet control unit PCU and the SGSN. The PCU is a functional unit responsible for the various GPRS MAC (Medium Access Control) and RLC (Radio Link • · 30 Control) layer protocols defined in GSM 03.64.

# · «· ;;; These include e.g. Creating RLC blocks for downlink transmission, I ('access request and access grants) and radio channel management functions such as power control, radio channel allocation and release,' \ i broadcasting control information, etc.

12 105306 The PCU, in turn, is connected via the Abis interface to the channel codec unit CCU. CCU functions include channel coding functions (including forward error correction FEC and interleaving) and radio channel measurement functions. The CCU also generates GPRS radio blocks, i.e. GPRS packets, in which data and signaling information is transmitted over the radio interface. As shown in Figures 2A-C, the CCU is always housed in a base station BTS, but the PCU has several alternative locations: a base station BTS (Fig. 2A), a base station controller BSC (Fig. 2B) or a base node SGSN (Fig. 2C). Once the PCU is located away from the BTS, the CCU can control some of the PCU's functions.

The invention is applicable to all different PCU placement options. However, the implementation becomes the simplest and most efficient in terms of radio path utilization when the PCU is located on the base station. Figure 3 illustrates a base station BTS according to the invention including a PCU / CCU unit (combined PCU and CCU), a GSM traffic channel controller 31 and a radio unit 30.

The GSM channel control unit generally represents the base station BTS baseband signal processing that is performed on the downlink signal prior to transmission: e.g., channel coding, interleaving, etc. The most important function of the invention is the control of the downlink DTX. The channel controller 31 receives downlink GSM traffic from the digital transmission link 20 (Abis interface) from the base station controller. This GSM traffic comprises TRAU frames which are processed and transmitted by the channel controller • · · · '' by the radio interface 30 to the radio unit 30 via line 32. The channel controller 31 performs baseband processing of eight GSM traffic channels. The channel controller 31 is further provided with the inventive device! · · ·. * ·: An additional feature that indicates the start and end of downlink DTX mode • * ·· 25 lines using DTX_DETECTED mode. Each GSM traffic channel has its own DTX_DETECTED line and its own line 32.

The PCU / CCU contains the combined functions of the PCU and CCU. The PCU / CCU receives GPRS traffic over a digital connection 35 (Gb interface).

• · ·; * ··; The connection 35 may be connected via a base station controller BSC or other route from the base station SGSN. The PCU / CCU is connected via line 33 to the radio unit 30, from which it • · · * ;;; can allocate traffic channels for GPRS. For each traffic channel, <c has its own line 33. In addition, the PCU is provided with the additional feature of the invention that it can allocate to GPRS traffic a DTX mode traffic channel allocated to a circuit switched GSM call.

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The radio unit 30 generally represents the radio frequency parts of one radio frequency channel and the baseband signal processing directly associated therewith. Because one radio frequency channel has eight time slots (GSM), the radio unit 30 has a capacity of eight traffic channels. These traffic channels can be allocated to GSM traffic or GPRS traffic as needed. In addition, radio unit 30 is provided with the feature of the invention that it transmits GPRS information provided by the PCU / CCU on a traffic channel allocated to a circuit switched GSM call if a corresponding DTX_DETECTED line is set.

The operation of the base station BTS 10 according to the invention will now be described by way of example.

It is first assumed that a circuit-switched GSM voice call established through a base station BTS according to standard GSM call set-up procedures and allocated a traffic channel ch4. The GSM channel controller unit 31 receives the voice and SID frames of Figure 6 from line 34 and processes them as required by GSM. In addition, the channel control unit performs the operation according to the block diagram of Figure 4 for each channel. Initially, in step 41, the control unit 31 checks whether the frame received from line 34 is a SID frame. If it is not an SID frame, proceed to step 44, where the continuous transmission state is maintained or restored. Thereafter, in step 45, the DTX_DETECTED line is reset (deactivated). In the example of Figure 6, steps 44 and 45 are performed on the first three speech frames. When the frame received from line 34 is the SID frame in step 31, the channel controller 31 enters the downlink DTX mode in step 41. When entering the DTX mode, the channel controller transmits the first SID frame to the radio unit 30. The channel controller 31 then sets (activates) the DTX_DETECTED line for that traffic channel, as illustrated in Figure 6.

The radio unit 30 has so far transmitted on the traffic channel: * ·; ch4 GSM information, i.e. three speech frames and one SID frame because • · ·. ···; the DTX_DETECTED line corresponding to the traffic channel has been reset. When the DTX_DETECTED line is set, the radio unit 30 will start transmitting traffic information.

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· ;;! the GPRS information received from line 33 on channel ch4.

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Referring to the flowchart of Figure 5, when the PCU / CCU detects that the DT4_DETECTED line of the traffic channel ch4 is established (step 51), it initiates a temporary allocation of the traffic channel as a GPRS traffic channel for one or 35 more GPRS_MSs (if further downlink transfers are required). 105306 Step 52. Transmission of packet data to the mobile station MS in GPRS Ready mode is initiated by the PCU by transmitting a Packet Resource As-Singment or Reassignment message, Step 53, according to GPRS procedures. If the MS is in a state other than GPRS-Ready, first signaling according to the GPRS-5 recommendations will be performed to initiate the Ready state. Because the invention seeks to provide additional capacity, it is very likely that the MS is in Ready state (even receiving on one or more other traffic channels). If a PCCCH is allocated in a cell, a Packet Resources Assignment message is sent by PAGH. If the cell does not have 10 PCCCHs allocated, the Packet Resources Assignment message is sent via AGCH. The Packet Resources Assignment message includes a list of the packet traffic channel (s) PDTCH (channel ch4 in this example) used for downlink transmission and the PDTCH used to carry uplink PACCH. Timing Advance and Power Control are also included if available. Otherwise, the MS may be requested to respond with an access burst. The PCU / CCU then begins to supply the GPRS packet data to the radio unit 30 via line 33, step 54. The radio unit 30 forwards the GPRS data on the downlink traffic channel ch4 on the radio path, as shown in Figure 6. The multiplexing of radio blocks allocated to different mobile stations MS to the same downlink-PDTCH is made possible by an identifier included in each radio block. Selective acknowledgment can be used for data transmission. The PCU may from time to time request (polling) the MS to send a Packet Ack / Nack in an uplink direction.

The PCU / CCU will continue to send GPRS data until it is detected in step 55 Ιοί * · .. 25 that the DTX_DETECTED line has been reset. In the exemplary case (Fig. 6): T: The channel controller 31 enters the continuous transmission mode and resets the DTX_DETECTED line when the channel controller receives the first speech frame in DTX mode. In this case, the channel controller 31 again starts transmitting speech frames. Since the. "" DTX_DETECTED line is reset, the radio unit 30 proceeds to transmit the GSM information from the channel controller 31 on the traffic channel.

When the PCU / CCU has found in step 55 that DTX is DETECTED

* * f - line reset, stops GPRS packet data input to radio unit 30. In addition, the PCU / CCU releases the allocation of traffic channel ch4 to GPRS according to the PDTCH GPRS procedures. Resource release * · 35 is initiated by the PCU by terminating the downlink transfer and requesting MS 15 105306 for the final acknowledgment. When the downlink transfer on the PDTCH ends, the MS proceeds to listen to the PCCCH, whereupon a new PDTCH can be assigned to it by sending a Packet Resources Assignment message. It is also possible for the PCU to change the current downlink PDTCH assignment by sending a Packet Resources Reassignment message 5 acknowledged by the MS. For example, the reassignment can be made to another GSM traffic channel in DTX mode.

In the preferred embodiment of the invention, the GPRS allocation takes only one DTX mode. GPRS allocation can also take longer, i.e. 10 multiple DTX modes. In this case, the Packet Resources Assignment message only needs to be sent at the beginning of the first DTX state before data transfer begins. In the following DTX modes, data transmission can be initiated directly without signaling. Longer-term allocation may be advantageous, for example, when the invention provides additional capacity for data transmission on one or more other traffic channels. The channel controller 31 may also reset the DTX_DETECTED line to periodically transmit the SID frame in DTX mode. This can lead to GPRS allocation after each SID update frame (about 0.5 sec). This can be avoided if the PCU / CCU waits for at least one frame to confirm whether it is a SID update or speech start. In the case of an SID-20 upgrade, the DTX DETECTED line will be reset and the PCU / CCU may resume transmission with the same allocation.

GSM_MS can receive GPRS data, but rejects it as incorrect. GPRS_MS may also receive GSM voice and SID frames, but again reject them as invalid. Therefore, the invention should not require modifications to the terminals.

: '· ** In one embodiment of the invention, the channel controller 31 and the PCU / CCU

is connected to the radio unit 30 via a common time division bus. On the fairway one- · · *. if the interval corresponds to one traffic channel. The radio unit 30 reads the time slot content from the bus and forwards it on the traffic channel in question. When the channel controller * · * 30 31 writes to the bus in continuous transmission mode and PCU / CCU in DTX mode, collisions ·· ♦ - · do not occur. In this embodiment, the DTX_DETECTED line does not need to be connected to the radio unit 30.

The invention has been described above by means of an example in which a speech codec and «II VAD and DTX functions are placed in a» 35 transcoder unit separate from the BTS. Of course, the codec and DTX functions can be “105306

ID

also located in the base station, whereby DTX status information is available directly without identifying the SID frames. Otherwise, the invention may be applied to any base station structure or other transmission apparatus for transmitting packet information during DTX states of a circuit switched call.

The invention has been described above in connection with voice calls, but it can also be applied in the context of DTX for data calls. For example, in multichannel transmission of PCTVFI95 / 00669, some of the allocated channels do not always have any transmission or have subchannel-specific discontinuous transmission. These "underutilized" traffic channels can be used as additional capacity for GPRS data transmission according to the invention.

The figures and the description related thereto are intended only to illustrate the invention. The details of the invention may vary within the spirit and scope of the appended claims.

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Claims (20)

A radio system comprising mobile phones (MS), a base station network in which each base station (BTS) supports both circuit switched calls and data transmission in packet form, and a discontinuous transmission state that can be activated for a circuit switched call in downlink transmission direction, characterized by the downlink of the base station traffic channel, with a pointing circuit switched call in a discontinuous transmission state, can be allocated for a separate packet data transmission for the time the discontinuous transmission state (DTX) pays the circuit switched call. 2. The radio system according to claim 1, characterized in that the radio system comprises an allocation unit (PCU) for allocating the radio resources in the data transmission in packet form, which allocation unit has been arranged for allocating the data transmission in the data transfer to the downlink in the DT package form requires extra capacity in the downlink direction. Radio system according to claim 1 or 2, characterized in that: the circuit-switched call is a voice call, and that the system:: '' comprises a separate base transcoder (TRCU) from a base station (BTS). transmitting to the base station (BTS) speech parameter frames or noise parameter frames according to whether tai is present or not, and the base station (BTS); ·. * 25 has been arranged to start the downlink DTX state on the downlink traffic channel and activate the "DTX state detected" signal in response to receiving a noise parameter frame, and the base station has been arranged to terminate the downlink DTX state on the downlink traffic channel and disable "DTX the signal "in response to the reception of a speech frame in the DTX state, and that the radio system further comprises a. allocation unit (PCU) for allocating the radio resources in the data transfer! ···. in packet form, which allocation unit in response to an activated "DTX to * * * permanently detected" signal allocates the downlink traffic channel for data transfer IM V • · • • • • «« · «· · • M • · 105306 23 in packet form eat at least for the time the DTX state pays off. Radio system according to claim 1, 2 or 3, characterized in that the data transmission in packet form is packet transmission according to the GPRS system. Radio system according to claim 4, characterized in that said allocation unit for allocating the radio resources comprises a packet controller (PCU) in the GPRS system. Radio system according to claims 1, 2, 3, 4 or 5, characterized in that the circuit-switched call is a call in a GSM mobile telephone system. A data transmission method for a radio system comprising cellular telephones (MS) and a base station network in which each base station (BTS) supports both circuit switched calls and packet data transmission, and includes a discontinuous transmission state which can be activated for a circuit switched call at least in the downlink direction. the method comprising the following stages of the downlink traffic channel being allocated for the circuit switched call in the base station (BTS), a circuit switched call is formed, circuit switched information is transmitted on said downlink: · a traffic channel from said base station (BTS),. the discontinuous transmission state is started in said, "circuit-switched call, characterized in that the method further comprises the phase in which said downlink traffic channel is allocated for a circuit-switched call in a discontinuous transmission state. , even for packet data transmission for the time of the discontinuous transmission state of the circuit switched call, data in packet form is transmitted during said discontinuous transmission state on said downlink traffic channel, transmission of data in packet form terminates on said downlink traffic channel to the circuit switched at the disposal of the call when said discontinuous transmission state ceases. Method according to claim 7, characterized by downlink traffic channel allocated for packet data transfer 5 separately during each discontinuous transmission condition, the allocation is signaled to a packet data terminal separately at the beginning of each discontinuous transmission state before packet data transfer is started. Method according to claim 7, characterized in that the downlink traffic channel is allocated for packet data transmission for the time of several discontinuous transmission states, the allocation is signaled to a packet data terminal at the beginning of the first discontinuous transmission state before the data transmission is transmitted in the packet form, the packet form is started. the traffic channel is restored to the disposal of the circuit-switched call when the continuous transmission state begins, the data transmission in packet form starts immediately at the beginning of the subsequent discontinuous transmission state. Method according to claim 7, 8 or 9, characterized in that the circuit-switched call is a voice call, and that the method. includes the stages where * «. "L. From a base station (BTS) separately located speech transcoder <(TRCU) is transmitted to the base station (BTS) speech parameter frames or noise-saving frames" 25 meter frames according to whether tai is present or not, • downlink DTX is started at the base station (BTS) the state of the * · * 'downlink traffic channel and the "DTX state detected" signal is activated when a noise parameter frame is received, the downlink DTX state terminates on the downlink traffic channel: ***: 30 and the "DTX state detected" signal is deactivated when the base station receives a speech frame in the DTX state. , * - '!!! allocates the allocation unit for the radio resources in the data transfer *: ** packet form downlink the packet data transfer channel «« · • «« # * · · t · · • · · · · · At least for the time DTX state operation, which is separately from the allocation of the radio resources for the circuit switched calls, the discontinuous transmission state is detected in the circuitry information flow on the traffic channel, the downlink traffic channel for data transmission in packet form is allocated for the further, the transmission pauses in the circuit, transmission pauses. 10 11. A method according to any of claims 7-10, characterized in that the data transmission in packet form is packet transmission according to the GPRS system. Method according to claim 11, characterized in that the traffic channel is allocated for packet data transmission and the allocation is signaled to a packet data terminal according to a procedure according to the GPRS system. Method according to any of claims 7-12, characterized in that the circuit-switched call is formed and the discontinuous transmission is carried out in accordance with a procedure in a GSM mobile telephone system. . 14. transmission luminaire in a radio system, which also supports, yes, circuit switched calls as packet data transmission, and there for the V *. circuit-switched call a discontinuous transmission state can be activated, characterized in that • · * · .// the transmission equipment (BTS) traffic channel, with a pointer: ·:: circuit-switched call in a discontinuous transmission state, can be allocated for a separate data transmission in packet the time the Discontinuous Transmission State (DTX) charge for the circuit switched call. 30 15. Transmission equipment according to claim 14, characterized in that the transmission equipment is a base station (BTS) and the discontinuous transmission can be activated on the downlink traffic channel. 16. Broadcasting apparatus according to claim 15, characterized in that the base station (BTS) comprises an allocation unit (PCU / CCU). ) for the radio resources of the data transmission in packet form, which allocation unit has been arranged to allocate for the data transmission in packet form the downlink traffic downlink traffic channels which are in the DTX state where for the data transmission in packet form additional capacity is required in the downlink direction. 17. Transmission apparatus according to claim 15 or 16, characterized in that the circuit-switched call is a voice call, and that the base station (BTS) has been arranged to receive speech parameter frames or noise parameter frames from a separate base station (BTS) as the base station (TRCU). (BTS) transmits speech parameter or noise parameter frames according to whether tai occurs or not, and that the base station (BTS) has been arranged to start the downlink DTX state on the downlink traffic channel and activate the "DTX state detected" signal in response to receiving a noise pair meter base, and that the base station (BTS) has been arranged to terminate the downlink DTX state on the downlink traffic channel and deactivate the "DTX state detected" signal in response to receiving a speech frame in the DTX state, and that the base station (BTS) comprises an allocation unit (PCU / CCU) ) for allocating the radio resources in the data transmission in packet form, which allo key in response to an activated "DTX state detected" signal: .i .: allocates the downlink traffic channel for data transmission in packet form!!: 'at least for the time the DTX state pauses. Transmission apparatus according to any of claims 14-17, characterized in that the data transmission in packet form is: 1 · 1: 25 packet transmission according to the GPRS system. 19. Transmission apparatus according to claim 18, characterized in. ···. because the allocation unit for allocating the radio resources comprises a packet controller (PCU) in the GPRS system. • · “1 Broadcasting apparatus according to any of claims 14 - 19, 30, characterized in that the circuit-switched call is a call in a GSM mobile telephone system. · · · • · 9 9 9 9 9 9 9 9 9