WO2010043087A1

WO2010043087A1 - Method and apparatus of telecommunications

Info

Publication number: WO2010043087A1
Application number: PCT/CN2008/072740
Authority: WO
Inventors: Guang Liu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2008-10-17
Filing date: 2008-10-17
Publication date: 2010-04-22
Also published as: BRPI0920585A2; WO2010043120A1

Abstract

The present invention relates to conversational service over packet-switched PS network, particularly, to technology for sending and receiving a control message in a PS network. According to the embodiments of the invention, a data structure carrying a control message is sent for sending a control message to a communications network in particular bit interval 5 allocation of a PTCCH/U or an idle frame and a BSS is provided to receive the control message from a UE. Embodiments of the invention also provide a data structure for carrying a control message.

Description

METHOD AND APPARATUS OF TELECOMMUNICATIONS

FIELD OF INVENTION

[0001] The present invention relates to conversational service over packet-switched, PS, networks. Particularly, it relates to technology for sending and receiving a control message in a PS network.

BACKGROUND OF THE INVENTION

[0002] In telecommunications, conversational service is a service that provides two-way, interactive, real-time, end-to-end information transfer. The conversational voice service enables routing of voice conversations over the Internet or any other IP network. The voice data flows over a PS network, instead of traditional circuit- switched, CS, voice transmission lines.

[0003] In a CS network, a user of a voice conversation occupies a fixed bandwidth during the whole conversation. However, in a network supporting packet switched conversational voice service, such as voice over IP, VoIP, ideally a user of a voice conversation occupies bandwidth when the user transmits data but does not occupy bandwidth when not transmitting data. So different users or different services share the same bandwidth, thus, the bandwidth is supposed to be efficiently used.

[0004] Generally speaking, a network supports conversational voice service if the network can send voice frames, for example Adaptive Multi Rate, AMR, frames, half rate, HR, frames and full rate, FR, frames, from a speaking party to a listening party of a voice conversation timely and correctly, with latency less than 300ms and a Frame Error Rate, FER, of less than 2%. However, measures to fulfill the two requirements are often counteracting. For example, to reduce the FER, incorrect data blocks may be retransmitted, but retransmission requires more time and increases the latency. [0005] Downlink is a transmission path for the transmission of signals from the network to the UE while the transmission path in direction from the UE to the network is referred as uplink. If a user equipment device, UE, wants a network to retransmit a downlink data block when the data block is not received correctly, the UE needs to respond to the network whether the data block is received correctly or not. [0006] Usually, a response of acknowledgement, ACK, is made when the data block is correctly received and a response of negative acknowledgement, NACK, is made when the data block is not correctly received. Usually, one bit is used for representing ACK/NACK information, e.g. 1 represents ACK, and 0 represents NACK. To have a small latency, the response must be sent to the network as soon as possible to make the retransmission finish as soon as possible.

[0007] In an example GSM EDGE (Enhanced Data Rates for Global Evolution) Radio Access Network, GERAN, Fast ACK/NACK Report, FANR, function is introduced to support VoIP technology. The FANR refers to the possibility to include, in a radio block for data transfer sent in one direction, piggy-backed ACK/NACK, PAN, information relative to a temporary block flow, TBF, with FANR activated in the other direction.

[0008] In GSM, a TDMA frame is a radio frame containing bursts for eight time slots. Four consecutive appearances of the same time slot within four consecutive TDMA frames is termed one radio block. A radio block carries one Radio Link Control, RLC, or Medium Access Control, MAC, protocol data unit, PDU. Each MAC/RLC PDU may comprise one or more data blocks.

[0009] For transmission of one or more data blocks, resources are reserved on one or more packet data channels, PDCHs. GPRS uses a 52-multiframe structure, where each frame is a TDMA frame. The GPRS resource allocation is done on block level.

[0010] The FANR function is achieved by inserting a PAN field in a radio block. Each PAN responds RLC/MAC data blocks to confirm whether the RLC/MAC data blocks are received correctly or not. The PAN information is usually sent frequently. Thereby, a response can be sent timely for retransmission of incorrect data blocks to be accomplished in time.

[0011] Figure 1 illustrates communication between a UE and Base Station Subsystem BSS when a user participating in a voice conversation is listening but not speaking. A PAN comprises 20 bits and is usually sent for every uplink voice data blocks, if any. As illustrated in figure 1, the UE sends some dummy blocks carrying PAN information to the BSS, although the user is not speaking. A dummy data block has 184 bits, and occupies a whole radio block.

[0012] The UE goes into a discontinuous transmission DTX mode when the user does not speak. In DTX mode, the UE sends uplink data infrequently. No voice data blocks but silence data blocks which contain background noise information are sent in DTX mode. However, when the user starts to speak, the network needs to allocated radio resource for the user as soon as possible.

[0013] When channel quality, in terms of e.g. noise and interference or time-delay spread of the transmission channel, is favorable, the FER of received frames may be less than 2%, which satisfies the requirement of VoIP technology. There is no need of retransmission in such situation and FANR is not used. However, the BSS still has to allocate uplink resources frequently for a user also if the user is not speaking for the user to be capable of reporting a positive voice activity to the BSS when he becomes active speaker. In brief, uplink resources are occupied even if a user is not speaking in prior art.

SUMMARY OF THE INVENTION

[0014] A problem in prior art is that uplink resources are allocated to a user when the user is listening but not speaking. The uplink resource is not efficiently used.

[0015] In an embodiment of the invention, a data structure for sending a control message to a communications network is provided. Preferably, the control message, which is carried in the data structure, comprises at least one of an ACK/NACK message for one or more received data blocks, a voice activity message and a user ID message.

[0016] According to an embodiment of the invention, the data structure is sent to the communications network in particular bit interval allocation of a packet timing advanced control channel/uplink, PTCCH/U, or an idle frame, wherein the PTCCH/U is an uplink channel used for transmission of one or more random access bursts and the idle frame and the idle frame is a periodically arranged time interval in a TDMA frame structure for the UE to measure on or search for neighbor cells.

[0017] Preferred user equipment for sending a control message to a communications network and BSS for receiving a control message from a UE are provided according to embodiments of the invention. The user equipment comprises a data structure generating unit configured to generate a predefined data structure carrying a control message and a data structure sending unit configured to send the data structure in particular bit interval allocation of a PTCCH/U or an idle frame, and the BSS comprises a receiving unit configured to a predefined data structure for carrying a control message from a UE.

BRIEF DESCRIPTION OF THE DRAWINGS [0018] Figure 1 illustrates communication between a UE and BSS when a user in a voice conversation is listening but not speaking.

[0019] Figure 2 illustrates a multiframe structure in prior art.

[0020] Figure 3 illustrates prior art structure of an access burst sent in a timeslot T.

[0021] Figure 4 illustrates communication between a UE and BSS according to a first embodiment of the invention.

[0022] Figure 5 illustrates data blocks received in six radio blocks when downlink TBF is in basic transmission time interval configuration according to an embodiment of the invention.

[0023] Figure 6 illustrates data blocks received in three radio blocks when downlink TBF is in reduced transmission time interval configuration according to an embodiment of the invention.

[0024] Figure 7 illustrates communication between a UE and BSS according to a second embodiment of the invention.

[0025] Figure 8 illustrates an example structure of a piggyback burst according to an embodiment of the invention.

[0026] Figure 9 illustrates structure of an access burst according to an embodiment of the invention.

[0027] Figure 10 illustrates a UE for sending a control message to a communications network according to an embodiment of the invention. [0028] Figure 11 illustrates a BSS for receiving a control message from a UE according to an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

[0029] An embodiment of the invention provides a method for sending a control message to a communications network independently of uplink resource allocation. In this embodiment, a predefined data structure, such as a burst, carrying the control message is sent from a UE participating in a conversational service to the network through a PTCCH/U or an idle frame, where the PTCCH/U is an uplink channel used to transmit one or more random access bursts and the idle frame is periodically arranged in a frame structure to facilitate for the UE to measure on or search for neighbor cells. [0030] The control message comprises at least one of an ACK/NACK message for one or more received data blocks, a voice activity message and a user identity, ID, message. The ACK/NACK message or voice activity message is preferably reported to the network using idle uplink resources without allocating uplink channel resources for data transmission. [0031] Figure 2 illustrates a multiframe structure of prior art. Timeslots BO to BIl (201, 202, 203, 204) are arranged for transmission of data blocks and timeslots T (205), which constitute PTCCH/U, are arranged for UE to transmit access burst AB. During timeslots X (206), which constitute idle frame, a UE measures on or searches for adjacent cells but does not transmit any signal. [0032] In one example embodiment, the data structure carrying the control message is sent in timeslots T (205) forming PTCCH/U. Figure 3 illustrates the structure of an AB sent in timeslot T (205) of the prior art. An AB comprises 8 extended tail bits, TB (301), 41 synchronization sequence bits (302), 36 encrypted bits (303), 3 tail bits, TB(304) and a guard period GP (305) for 68.25 bits. ) It is identified that an AB does not occupy a whole timeslot T and allocation of a GP (305) provides an option to send a data structure for sending the control message.

[0033] In another example embodiment, the data structure is sent in timeslots X (206, 208), forming idle frames. During the timeslots X (206, 208), the UE does not transmit any signal. The timeslot X provides a resource option for sending the data structure carrying the control message.

[0034] Preferably, the control message carried in the data structure comprises at least one of an ACK/NACK message, a voice activity message and a user ID message. The ACK/NACK message represents whether one or more data blocks are received correctly, the voice activity message represents whether a voice activity is detected. [0035] In one example embodiment, the ACK/NACK message is carried in a PAN field, the voice activity message is carried in a cause field and the user ID message is carried in a user ID field.

[0036] The PAN field comprises one or more bits, each bit representing an ACK/NACK message for one or more data blocks. Usually, a UE may receive one or more data blocks in a radio block. Each bit of the PAN field preferably represents an ACK/NACK message for a data block in a radio block, which means that if all data blocks in a radio block are received correctly, the value of the respective bits corresponding to the radio blocks represents ACK; otherwise, the value of the bit corresponding to a radio block for which an error is detected represents NACK. In this situation, each bit of the PAN field corresponds to a radio block, for example, three bits represent an ACK/NACK message for received data blocks in three radio blocks. [0037] In another example embodiment, two bits of the PAN field represent an ACK/NACK message for a radio block. For example, six bits represent ACK/NACK messages for received data blocks in three radio blocks.

[0038] For example, if a user receives two data blocks in a radio block, each of the two ACK/NACK bits preferably corresponds to a data block. If a user receives one data block in a radio block, the two bits preferably represent an ACK/NACK message for the data block, such as "00" representing NACK and "11" representing ACK. If a user receives more than two data blocks in a radio block, the set of data blocks is preferably divided into two groups and each of the respective two bits represents an ACK/NACK message for the groups of data blocks. [0039] Figure 4 illustrates example communication between a UE and BSS according to a first embodiment of the invention. In the first embodiment, a control message carried in the data structure comprises 3 bits of a PAN field. In the example, the BSS sends radio blocks 1, 2 and 3 to the UE (401,402, 403) and the data blocks in radio blocks 1 and 2 are correctly received, but not all the data blocks in radio block 3. The UE then sends a data structure (404) carrying an ACK/NACK message for the received radio blocks 1, 2 and 3. The preferred values of the 3 bits in the PAN field for this non-exclusive example are 1, 1 and 0, where 1 represents ACK and 0 represents NACK.

[0040] The correspondence between the ACK/NACK message and the data blocks are different for different downlink configurations in a non-exclusive embodiment of the invention. Figure 5 illustrates data blocks transmitted from the BSS in six radio blocks when the downlink TBF is in basic transmission time interval, BTTI, configuration. In the six radio blocks, six data blocks are transmitted from a packet data channel PDCH. Data blocks Bl (501), B2 (502) and B3 (503) are transmitted in the first three radio blocks and a first data structure carrying a first ACK/NACK message is sent from UE in timeslot Tl (504). The first ACK/NACK message corresponds to data blocks Bl (501), B2 (502) and B3 (503). During the next three radio blocks, example data block B4 (505), B5 (506) and B6 (507) are received and a second data structure carrying a second ACK/NACK message is sent from UE in timeslot T2 (508). The bit content of the second ACK/NACK message corresponds to receive status of data blocks B4 (505), B5 (506) and B6 (507).

[0041] Figure 6 illustrates data blocks transmitted from BSS in three radio blocks when the downlink TBF is in reduced transmission time interval RTTI configuration. In RTTI configuration, a radio block is sent on a PDCH pair, consisting of PDCHi and PDCHj, in one RTTI block period. The RTTI period is half of a BTTI radio block. In the three radio blocks, data blocks BIa (601), B2a (603) and B3a (605) are sent in the first RTTI block periods and data blocks BIb (602), B2b (604) and B3b (606) are sent in the first RTTI block periods. Data blocks BIa (601) and BIb (602) are transmitted from the BSS in the first BTTI radio block, data blocks B2a (603) and B2b (604) are transmitted from the BSS in the second BTTI radio block, and data blocks B3a (605) and B3b (606) are transmitted from the BSS in the third BTTI radio block. After receiving the three BTTI radio blocks, a first data structure carrying a first ACK/NACK message is sent in uplink direction in timeslot Tl (607) and a second data structure carrying a second ACK/NACK message is sent in uplink direction in timeslot T2 (608). The first ACK/NACK message corresponds to data blocks BIa (601), B2a (603) and Ba (605) and the second ACK/NACK message corresponds to data blocks BIb (602), B2b (604) and B3b (606).

[0042] In a second embodiment of the invention, the control message carried in the data structure further comprises a voice activity message. Figure 7 illustrates example communication between a UE and BSS according to the second embodiment of the invention. The voice activity message is preferably carried in a cause field representing whether a voice activity is detected. E.g. with positive logic, when a voice activity is detected, the value of the cause field is set to 1; otherwise, the value of the cause field is set to 0.

[0043] In the second embodiment, a data structure comprising a control message is sent when any data block in the radio blocks is received incorrectly or when a voice activity is detected. The BSS sends (701,702) example radio blocks 1 and 2 to the UE. The data blocks in radio blocks 1 and 2 are assumed correctly received in the illustrated example, and the BSS sends example radio block 3 (703) to the UE but not all the example data blocks in radio block 3 are correctly received. During the time period of transmission of radio blocks 1, 2, and 3, there is no voice activity detected. Preferably and according to the second embodiment of the invention, for the illustrated example, the UE then sends a data structure (704) to the BSS with 3 bits of PAN field being 1, 1, and 0 and the value content of the cause filed being 0. Then in the illustrated example, the BSS continues to send radio blocks 4, 5 and 6 to the UE (705,706,707) and all the data blocks in radio blocks 4, 5 and 6 are correctly received (705-707). During the period of the radio blocks 4, 5 and 6, a voice activity is detected, the UE then sends a data structure (708) with 3 bits PAN field being 1, 1, and 1 and the value of cause filed being 1. [0044] In the second embodiment, the ACK/NACK message for one or more received data blocks and the voice activity are reported in one or more control messages without allocating any uplink data channel resource. Upon a voice activity being reported, the BSS knows that the user will start to talk and timely allocates uplink data channel resources to the UE.

[0045] In a third embodiment of the invention, the control message carried in the data structure further comprises a user ID message. User IDs are used to distinguish different users sharing an uplink channel.

[0046] The user ID field comprises one or more bits. For example, the user ID field comprises one bit and the value of 0 represents one of two users who share an uplink channel while the value of 1 represents the other user. The user ID field preferably comprises more bits in case several users share an uplink channel. For example, two bits in the user ID field can represent four different users. Usually, there are not too many users sharing an uplink channel due to associated latency increase. A user ID is allocated to a user by the BSS or generated as a default.

[0047] Combining some or all of the above-mentioned embodiments of the invention, a data structure for sending a control message to a network is provided. The data structure preferably provided with redundancy for forward error control during transmission and parity check bits for error detection to enable retransmission upon error detection.

[0048] According to one embodiment, the data structure is a piggyback burst, PB, the PB preferably comprising 16 bits arranged for carrying the control message. The piggyback burst may, in particular, improve utilization of short and otherwise blank periods of e.g. uplink PTCCH/U of legacy systems, such as GERAN systems. The control message comprises at least one of an ACK/NACK message for one or more received data blocks, a voice activity message and a user ID message and the PB carries transmission feedback corresponding to at least one of a PAN field, a cause field and a user ID field as described in detail above. [0049] In a preferred embodiment three fields are represented, a PAN field preferably comprising three bits, each bit representing ACK/NACK for one or more data blocks in a radio block; a cause field preferably comprising one bit and a user ID field preferably comprising one bit. Thus for the preferred example, each PB carries five message bits. The PB comprises encoded bits corresponding to encoding as follows.

[0050] Three parity bits are added according to a cyclic redundancy checking, CRC, code, e.g. defined by generator polynomial g(D) = D³ + D + 1. These 8 bits are input to a rate 1/2 convolutional encoder, providing 16 encoded bits adapted for forward error correction plus possible additional tail bits, TB, providing a well defined encoder/decoder state, well known as such.

[0051] Figure 8 illustrates the structure of a PB according to the embodiment. The following table illustrates detailed example information of fields of the PB.

[0052] In an example embodiment, the GP (801,807) is a time period between every two consecutive active timeslots. The TB fields (802,806) comprise modulating bits as follows: (BNlOO, BNlOl, BNl 02)= (0, 0, 0)

(BN145, BN146, BN147)= (0, 0, 0).

[0053] The Info fields (803, 805) comprise 8 bits carrying the control message of the PAN field, cause field and user ID field, and the TSC field (804) comprises modulating bits according to a training sequence code TSC. [0054] The TSC is e.g. any of the following sequences BNlIl, BN112, ..., BN136:

0,0,1,0,0,1,0,1,1,1,0,0,0,0,1,0,0,0,1,0,0,1,0,1,1,1 0,0,1,0,1,1,0,1,1,1,0,1,1,1,1,0,0,0,1,0,1,1,0,1,1,1 0,1,0,0,0,0,1,1,1,0,1,1,1,0,1,0,0,1,0,0,0,0,1,1,1,0 0,1,0,0,0,1,1,1,1,0,1,1,0,1,0,0,0,1,0,0,0,1,1,1,1,0 0,0,0,1,1,0,1,0,1,1,1,0,0,1,0,0,0,0,0,1,1,0,1,0,1,1 0,1,0,0,1,1,1,0,1,0,1,1,0,0,0,0,0,1,0,0,1,1,1,0,1,0 1,0,1,0,0,1,1,1,1,1,0,1,1,0,0,0,1,0,1,0,0,1,1,1,1,1

1,1,1,0,1,1,1,1,0,0,0,1,0,0,1,0,1,1,1,0,1,1,1,1,0,0.

[0055] Particularly, prior art access bursts comprises inefficiencies in terms of allocation of bit intervals of idle frames. A great number of bits of access bursts also contributes to latency. In a further embodiment of the invention, the control message is carried in an AB. In this embodiment, the control message comprises an ACK/NACK message for one or more received data blocks, a voice activity message and a user ID message. The ACK/NACK message is carried in a PAN field comprising six bits, each bit representing ACK/NACK for a data block. A voice activity message is carried in a cause field comprising one bit and a user ID message is carried in a user ID field comprising one bit. Thus, each AB carries eight message bits. These nine message bits are encoded to form an AB corresponding to encoding as follows. Facilitating more bits for the control message, the AB supports a greater number of simultaneous users than the PB, while still providing a sufficiently small latency.

[0056] Six parity bits of a CRC code, e.g. defined by generator polynomial g(D) = D⁶ + D⁵ + D³ + D² + D¹ + 1 according to CRC-6 of ITU G.704, are added to form a sequence of 14 bits. Four tail bits are preferably added, providing a sequence of length 18. The 18 bits are encoded for forward error control in a rate 1/2 convolutional encoder providing 36 bits plus possible additional tail bits TB, providing a well defined encoder/decoder state, well known as such.

[0057] Figure 9 illustrates the structure of an AB according to the embodiment. The following table illustrates the detailed information of the fields of the AB.

[0058] In an example embodiment, the TB field (901) comprises modulating bits BNO, BNl, BN2, BN3, BN4, BN5, BN6, BN7 equal to 0, 0, 1, 1, 1, 0, 1, 0. [0059] The synchronization sequence bits (902) comprise modulating bits according to one of the following states/sequences:

(BN8, BN9 ... BN48)= (0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0,

1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0) or

(BN8, BN9 ... BN48)= (0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1) or

(BN8, BN9... BN48)= (1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1,

0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1).

[0060] The Info field (903) comprises 36 bits carrying the control message of the PAN field, cause field and user ID field, and the TB field (904) comprises modulating bits with the state of BN85, BN86, BN87 equal to 0, 0, 0.

[0061] Figure 10 illustrates a UE for sending a control message to a communications network according to an embodiment of the invention. The UE comprises a data structure generating unit (1001) and data structure sending unit (1002). The data structure generating unit (1001) is configured to generate a predefined data structure for carrying a control message. The data structure sending unit (1002) is configured to send the predefined data structure carrying the control message in particular bit interval allocation of a PTCCH/U or an idle frame.

[0062] The data structure generated by the data structure generating unit (1001) comprises at least one of an ACK/NACK message for one or more received data blocks, a voice activity message and a user ID message, where preferably the ACK/NACK message is carried in a PAN field, the voice activity message is carried in a cause field and the user ID message is carried in a user ID field. The functions of the units of the UE are implemented in hardware comprising electrical circuitry or a microprocessor, or software including computer-executable program code or instructions.

[0063] Figure 11 illustrates a BSS for receiving a control message form a UE according to an embodiment of the invention. The BSS comprises a receiving unit (1101) and a transmitting unit (1102). The receiving unit (1101) is configured to receive a predefined data structure sent from a UE. The predefined data structure is arranged for carrying a control message comprising at least one of an ACK/NACK message for one or more data blocks, a voice activity message and a user ID message.

[0064] For the case of the control message comprising an ACK/NACK message, the BSS further preferably comprises a transmitting unit (1102), which is configured to retransmit one or more data blocks when the ACK/NACK message represents the one or more data blocks are received incorrectly by the UE. In case that the control message comprises a voice activity message, the BSS advantageously further comprise a resource allocating unit (1103).

The resource allocating unit (1103) is configured to allocate uplink resources for the UE when the voice activity message represents a positive voice activity.

[0065] The BSS optionally also comprises a user ID allocating unit (1104), which is configured to allocate a user ID for each of the users sharing an uplink channel. When the user equipment sends a control message to the BSS, reporting to the BSS, the user ID can then be carried in the report data structure. [0066] The functions of the units of the BSS are implemented by hardware comprising electrical circuitry or a microprocessor, or by software including computer-executable program code or instructions.

[0067] While several example embodiments have been provided in the present disclosure, it should be understood that the disclosed methods, apparatuses and systems might be embodied in many other specific forms without departing from the scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented. [0068] Techniques, systems, apparatuses, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Also, other changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the scope of the following claims.

Claims

1. A method for sending a control message to a communications network, wherein the control message is sent from a user equipment, UE, participating in a conversational service, characterized in that a predefined data structure carrying the control message is sent to the network in particular bit interval allocation of a packet timing advanced control channel for the uplink, PTCCH/U, or an idle frame, wherein the PTCCH/U is an uplink channel used for transmission of one or more random access bursts and the idle frame is a periodically arranged time interval in a TDMA frame structure for the UE to measure on or search for neighbor cells.

2. The method according to claim 1, wherein the control message comprises at least one of an ACK/NACK message for one or more received data blocks, a voice activity message and a user ID message.

3. The method according to claim 2, wherein the ACK/NACK message is carried in a PAN field, the voice activity message is carried in a cause field and the user ID message is carried in a user ID field.

4. The method according to claim 3, wherein the PAN field comprises 3 to 6 bits, the cause field comprises 1 bit and the user ID field comprises 1 or 2 bits.

5. The method according to any of claims 1 to 4, wherein the data structure is a piggyback burst PB or an access burst AB.

6. The method according to any of claims 1 to 5, wherein the data structure is sent when one or more data blocks are received incorrectly or when a voice activity is detected.

7. User equipment for sending a control message of a communications system providing packet switched services, characterized by: a data structure generating unit, configured to generate a predefined data structure for carrying a control message; and a data structure sending unit, configured to send the predefined data structure carrying the control message in particular bit interval allocation of a PTCCH/U or an idle frame, wherein the PTCCH/U is an uplink channel used for transmission of one or more random access bursts and the idle frame is a periodically arranged time interval in a TDMA frame structure for the UE to measure on or search for neighbor cells.

8. The user equipment according to claim 7, wherein the control message comprises ACK/NACK message for one or more received data blocks.

9. The user equipment according to claim 8, wherein the user equipment further comprises a detecting unit, configured to detect a voice activity and the control message comprises a voice activity message.

10. The user equipment according to any of claims 7 to 9, wherein the control message comprises a user ID message.

11. A Base Station Subsystem, BSS, for receiving a control message from a UE in a communications network providing packet switched services, comprising: a receiving unit, configured to receive a predefined data structure for carrying a control message from a UE, wherein the predefined data structure is arranged for carrying a control message comprising at least one of an ACK/NACK message for one or more data blocks, a voice activity message and a user ID message in particular bit interval allocation of a PTCCH/U or an idle frame wherein the PTCCH/U is an uplink channel used for transmission of one or more random access bursts and the idle frame is a periodically arranged time interval in a TDMA frame structure for the UE to measure on or search for neighbor cells.

12. The BSS according to claim 11, comprising: processing circuitry adapted for detecting from the particular bit interval allocation whether a control message comprises feedback information pertaining to one or more data blocks earlier transmitted or a request for uplink data transmission resources.

13. The BSS according to claim 11 or 12, comprising: a transmitting unit, configured to retransmit one or more data blocks when the ACK/NACK message represents the one or more data blocks are received incorrectly.

14. The BSS according to any of claims 11 to 13, comprising: a resource allocating unit configured to allocate uplink resource for the UE when the voice activity message represents a voice activity is detected.

15. The BSS according to any of claims 11 to 14, comprising: a user ID allocating unit configured to allocate a user ID for the UE.

16. A data structure for sending a control message to a communications network, characterized in that the data structure is adapted for transmission in particular bit interval allocation of a PTCCH/U or an idle frame, wherein the PTCCH/U is an uplink channel used for transmission of one or more random access bursts and the idle frame is a periodically arranged time interval in a TDMA frame structure for the UE to measure on or search for neighbor cells and that the control message comprises at least one of an ACK/NACK message for one or more received data blocks, a voice activity message, and a user ID message of packet switched voice services.

17. The data structure according to claim 16, wherein the ACK/NACK message is carried in a PAN field, the voice activity message is carried in a cause field and the user ID message is carried in a user ID field.

18. The data structure according to claim 17, wherein the PAN field comprises 3 to 6 bits, the cause field comprises 1 bit and the user ID field comprises 1 or 2 bits.