MXPA00001579A - A method for communicating information in a communication system that supports multiple modulation schemes - Google Patents

Abstract

A method of communicating control information in systems that support multiple modulation schemes for communicating voice or data and control information. To provide backward compatibility dedicated control channels use the modulation scheme used in current systems, for example GMSK modulation scheme. Traffic channels and associated control channels use linear modulation schemes that have the same symbol rate. The modulation scheme of the associated control channel uses a reduced signal set of the modulation scheme used for traffic channels. Also, an in-band signalling procedure is used to indicate to a receiving station the modulation type, channel coding and speech coding used for a transmitted burst.

Description

"A METHOD FOR COMMUNICATING INFORMATION IN A COMMUNICATION SYSTEM THAT SUSTAINS MODULATION PROJECTS MULTIPLE " BACKGROUND This invention relates generally to the field of communication systems and, more particularly, to digital communication systems that support multiple modulation projects. Digital communication systems use a variety of linear and nonlinear modulation projects to communicate voice or data information. These modulation projects include Gaussian Minimum Displacement Manipulation (GMSK), Quadrature Phase Displacement Manipulation (QPSK), Quadrature Amplitude Modulation (QAM), etc. The GMSK modulation project is a nonlinear linear bass modulation (LLM) project with a symbol regime that supports a specified user bit rate. In order to increase the user's bit rate, high level modulation (HLM) projects can be used. Linear modulation projects such as QAM projects may have a different level of modulation. For example, the 16QAM project is used to represent the Sixteenth variation of 4 data bits. On the other hand, a QPSK modulation project is used to represent the four variations of 2 data bits. Even though the 16QAM project provides a bit rate higher than QPSK, both of these modulation projects could have the same symbol regime. The application of modulation projects, however, differs in many aspects, for example, the symbol regime and / or the bursting format, which complicates its support or support in systems that use multiple modulation projects. In wireless digital communication systems, standardized air interfaces specify most of the system parameters, including modulation type, burst format, communication protocol, symbol rate, etc. For example, the European Telecommunications Normal Institute (ETSI) has specified a Global System for Mobile Communications (GSM) standard that uses multiple access from. division in time (TDMA) to communicate control, voice and data information through physical radio frequency (RF) channels or links using a GMSK modulation project at a symbol rate of 271 ksps. In the United States, the Telecommunications Industry Association (TIA) has published a number of Interim Standards, such as IS-54 and IS-136 that define different versions of the advanced digital mobile phone service (D-AMPS), a system TDMA that uses a QPSK Differential modulation project (DQPSK) to communicate the data through radio frequency links. TDMA systems subdivide the available frequency band into one or more radio frequency channels. The radiofrequency channels are divided into a number of physical channels corresponding to time intervals in the TDMA frames. The logical channels are formed from one or more of the physical channels, where the modulation and channel coding projects are specified. In these systems, the mobile stations communicate with a plurality of dispersed base stations by transmitting and receiving bursts of digital information through uplink and downlink radio frequency channels. The increasing number of mobile stations in use today has generated the need for more voice and data channels within cellular telecommunication systems. As a result, the base stations have separated more closely, with an increase in interference between mobile stations operating on the same frequency in neighboring or closely spaced cells. Even when digital techniques obtain more useful channels from a given frequency spectrum, there is still a need to reduce the interference, or more specifically to increase the ratio of the intensity or concentration of the carrier signal to interference, (that is, carrier-to-interference ratio (C / I)). Radio frequency links that can handle lower C / I ratios are considered to be more robust than those that can only handle higher C / I ratios. In order to provide various communication services, a corresponding minimum user bit rate is required. For example, for voice and / or data services, the user's bit rate corresponds to the voice quality and / or the data throughput, with a higher bit rate of the user producing better voice quality and / or higher data throughput. The bit rate of the total user is determined by a selected combination of techniques for speech coding, channel coding, modulation project and for a TDMA system, the number of assignable time intervals per call. Depending on the modulation project used, link quality deteriorates more rapidly as C / I levels decrease. Higher level modulation projects are more susceptible to low C / I ratio levels than lower level modulation projects. If an HLM project is used, the performance of the data or quality of service decreases very rapidly with a drop in link quality. On the other hand, if an LLM project is used, the data throughput or quality of service does not decrease as quickly under the same interference conditions. Therefore, the link adaptation methods, which provide the ability to change the modulation and / or coding based on the channel conditions, are used to balance the user's bit rate against link quality. In general, these methods dynamically adapt a combination of the speech coding system, channel coding, modulation, and number of assignable time slots to achieve optimal operation through a wide range of C / I conditions. One evolutionary path for the next generation of cellular systems is to use high level modulation (HLM), e.g., a 16QAM modulation project, to provide increased user bit rates compared to existing standards. These cellular systems include improved GSM systems, improved D-AMPS systems, International Mobile Telecom 2000 (IMT-2000), etc. A high-level linear modulation, such as the 16QAM modulation project, has the potential to be more efficient in appearance than, for example, GMSK, which is a low-level modulation (LLM) project. In addition, the use of the 16QAM modulation project together with a higher symbol rate significantly increases the bit rate of the user compared to the GMSK modulation project. In this way, the maximum user bit rate offered by the HLM project, such as the 16QAM modulation project, can more than double. Because higher level modulation projects require a higher minimum C / I ratio for acceptable operation, their availability in the system becomes limited to certain areas of system coverage or certain parts of the cells, where more robust links can be maintained. However, a system can be planned to provide complete coverage for the HLM project. The modulation projects that are provided in a cell can be a mixture of non-linear and linear modulation with different symbol regimes. In general, two types of logical channels are defined by air interface standards: control channels (CCH) and traffic channels (TCH). CCHs are used to control the transmission of signals such as registration, authentication, call establishment, and the like. The TCHs, which are individual user channels, are used to handle voice or data communication. For the TCHs, some of the standards define several user bit regimes. In GSM systems, the transmission of control signals is carried out using different types of CCH, including dedicated control channels (DDCHs), Broadcast Channels (BCHs), and Common Control Channels (CCCHs). The BCHs include Frequency Correction Channel (FCCH), Synchronization Channel (SCH), and Broadcast Control Channel (BCCH). The CCCHs include the Radiolocation (PCH) channel, the Access Grant Channel (AGCH) and the Random Access Channel (RACCH). DCCHs include Dedicated Control Channel Maintenance Only (SDCCH), Fast Associated Control Channel (FACCH), and Slow Associated Control Channels (SACCH). The FCCH indicates a BCCH carrier signal and allows a mobile station to synchronize to its frequency. He SCH is used to point to the TDMA frame structure in a cell and a Base Station Identity Code (BSIC) that indicates whether a base station belongs to a GSM system or not. The BCCH is transmitted during a predefined time interval (e.g., time slot 0 in individual carrier base stations) of a downlink radio frequency channel, to provide general information to the mobile stations. The SDCCH, which can be transmitted during a time interval adjacent to BCCH, is used for registration, location update, authentication and call establishment. The PCH is a single downlink channel, which is used to inform the mobile station of a requirement to transmit signals from the network, for example when the mobile unit is called. The AGCH is a downlink only channel used for answering access requests to allocate a dedicated control channel for subsequent signal transmission. The RACH is used by a mobile station to request a channel, when it is radiolocated, or when it wishes to initiate a call. The associated control channels, FACCH and SAACH are always associated with traffic channels. The applicable standards specify a number of bits for FACCH and SACCH, which communicate according to a predefined format. The SACCH is used to communicate control and supervision signals associated with traffic channels, including the transmission of parameters corresponding to a bit error rate (BER) measurement or a measure of the concentration of the received signal (RSS) ) in mobile stations. The FACCH steals allocated bursts for traffic channels for control requirements, such as delivery.

Rapid signal transmission procedures are needed to quickly provide signal transmission information to the receiver. For example, in GSM systems, furtive flags, which are multiplexed in time at predefined positions within a burst, are used to distinguish between a burst of FACCH and a burst of TCH. By reading the furtive flags, the receiver determines the type of logical channels. In systems that support multiple modulation projects, especially those that use different symbol regimes, the management control information communicated through the control channels creates many complications. By introducing link adaptation algorithms, coding adaptation and / or modulation project becomes more frequent. Frequent link adaptations result in an effort to transmit increased control signals and, for example, link adaptation commands are transmitted in the FACCHs, causing degradation in communication quality. In addition, it is important to provide backwards compatibility between the improved systems that use high-level modulation projects and current systems that use low-level modulation projects. Therefore, there is a need for an efficient and simple method for communicating control information in systems that support multiple modulation projects. Also, in some systems, there may be a. requirement for an outbreak in order to carry out dissemination information, that is, information addressed to all users within a specific group, as well as user-specific information. For example, GSM systems can support a General Packet Radio Service (GPRS) that provides packet data service. In the GPRS, a current uplink state (USF) flag, a broadcast information, is communicated on a downlink channel in order to multiplex the uplink traffic from the different mobile stations. The same burst may contain a downlink data transfer directed to a specific user. Therefore, a single pop can contain both broadcast and individual user information. Also, in Digital European Wireless Telephone (DECT) systems, control information and broadcast information (eg, cell parameters) are communicated using a portion of each burst and the user's specific voice or data is communicated using another portion. of the outbreak. In systems that support multiple modulation projects, it is difficult to spread the same burst to several mobile stations with different modulation capabilities and different classes of service. Therefore, there is a need for a system that allows broadcast information within a burst to be received by different types of mobile stations independent of the modulation project used to transmit the burst.

COMPENDIUM The present invention that addresses this need is exemplified in a method of communicating control and broadcast information in systems that support multiple modulation projects. By abbreviating, in accordance with the method of the invention, the control information is communicated through a control channel using a first modulation project. The voice or data is communicated through a traffic channel using a second modulation project. The traffic channel has an associated control channel which can be a fast associated control channel or a slow associated control channel, which uses a third modulation project to communicate the control information. According to one embodiment of the present invention, the first modulation project is a non-linear modulation project, for example, a GMSK modulation project, and the second and third modulation projects are linear modulation projects., for example, modulation projects 16QAM, 8PSK and QPSK. The second and third modulation projects may have the same or different modulation levels. If they are different, the third modulation project, which may be a lower level modulation project, uses a reduced signal established in relation to the second modulation project to communicate the control information. Preferably, the second and third modulation projects have the same symbol regime, the same pulse configuration, regardless of the modulation project, the same burst format and the same training sequences. In accordance with another aspect of the invention, a method of transmitting signals in band between the base station and a mobile station, communicates the signal transmission information within the transmitted bursts. Each pop contains one or more reserved bits in predefined positions. The reserved bits are used to indicate at least one or more of a modulation type, a channel coding, or a speech coding used for the transmitted burst. In accordance with still another aspect of the invention, the mobile station and the base station communicate the voice or data through a traffic channel using a first modulation project. If a delivery is requested during a call in progress, a delivery procedure is initiated through the associated fast control channel using a second modulation project. Then, the communication through the traffic channel is resumed using the first modulation project, after the delivery is completed. According to yet another aspect of the invention, a communication method between a base station and a mobile station transmits a burst that communicates at least two types of information. A first type of information is modulated using a first linear modulation project, and a second type of information is modulated using a second linear modulation project using a reduced signal set or apparatus of the first modulation project. The first and second types of information can be a first user specific data and a second user specific data, respectively. Alternatively, the first type of information may be a specific data of the user and the second type of information may be the dissemination information. Other features and advantages of the present invention will become apparent from the following description of the preferred embodiment, which is taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a functional diagram of a communication system that advantageously uses the present invention. Figures 2 (a) and 2 (b) are diagrams of modulation constellations of modulation projects 16QAM and QPSK, respectively. Figure 3 is a diagram of a subdivided radiofrequency channel that is used in the communication system of Figure 1. Figure 4 is a diagram of a normal transmission burst transmitted in the radio frequency channel of Figure 2. Figure 5 is a functional diagram of a mobile station used in the communication system of Figure 1. Figure 6 is a functional diagram of a radio base station used in the communication system of Figure 1.

Figure 7 is a functional diagram of a radio transceiver used in the base station of Figure 6. Figure 8 shows a diagram of the bit format and the symbols of a transmitted burst. Figure 9 shows a diagram of a representation project used to demodulate the transmitted bursts of Figure 8.

DETAILED DESCRIPTION Referring to Figure 1, a communication system 10 in accordance with an exemplary embodiment of the present invention supports multiple modulation projects. In an exemplary embodiment of the invention, the system 10 supports three modulation projects: a first LLM project (LLMl), a second LLM project (LLM2) and an HLM project. In an exemplary modality, the first LLM project (LLMl) is a non-linear modulation project, such as the GMSK modulation project used in GSM systems. A second LLM project (LLM2) is a linear modulation project such as QPSK. Finally, the HLM modulation project is a linear modulation project of the highest level, for example, a 16QAM project or 8PSK project. The LLM2 and HLM projects have the same symbol regime that is different or equal to the symbol regime of the LLMl project. The mode of operation of the GSM communication systems is described in the documents of the European Normal Telecommunications Institute (ETSI) ETS 300 573, ETS 300 574 and ETS 300 578, which have already been incorporated herein by reference. Therefore, the operation of the GSM system is described to the extent necessary for the understanding of the present invention. While the present invention is described as being modified in a GSM system, those skilled in the art will appreciate that the present invention could be used in a wide variety of other digital communication systems such as those based on the PDC or D-AMPS standards. and the improvements of them. The present invention can also be used in CDMA or hybrid communication systems of CDMA and TDMA. The 10 am communication system for a geographic area that is subdivided into communication cells, which together provide communication coverage to a service area, for example, to an entire city. Preferably, the communication cells are modeled according to a cell pattern that allows some of the separate cells to use the same uplink and downlink radiofrequency channels. In this way, the cell pattern of the system 10 reduces the number of radiofrequency channels necessary to cover the service area. System 10 may also employ frequency hopping techniques, for example, to avoid "inactive zones". Referring to Figures 2 (a) and 2 (b), the sets or signal devices in the modulation constellations of the 16QAM project and the QPSK project are shown respectively. The points of the external signal of the project 16QAM are shown by points A, B, C and D, and the signal points of the QPSK project are shown by the points AX BX C and Dd The QSPK project can be seen as having a game or reduced signal device in relation to the 16QAM project. If the symbol schemes of the QPSK and 16QAM projects are the same, a 16QAM demodulator can demodulate the game or reduced signal device of the QPSK modulation project using only signal points A, B, C and D of the 16QAM project. Consequently, the same demodulator can be used to demodulate the signals that are modulated with QPSK and 16QAM projects, if the same burst format and pulse configuration is used for both of these projects. This provision significantly facilitates the change of demodulation between the QPSK and 16QAM projects, for example, during the adaptation of the link. A method of - lí The demodulation is described in a simultaneously filed patent application entitled "A METHOD FOR DEMODULATING INFORMATION IN A COMMUNICATION SYSTEM THAT SUPPORTS MULTIPLE MODULATION SCHEMES", which is incorporated herein by reference. In one aspect, the present invention takes advantage of ease of demodulation switching with modulation projects having the same symbol rate, pulse configuration, burst format, and where one of the modulation projects has a signal set reduced in relation to the other, to effectively communicate control information in systems that use multiple modulation projects. The present invention communicates the control information between a BTS 20 and a mobile station 12 through the control channels (CCHs) and communicates the voice or data through the traffic channels (TCHs). Those CCHs that are associated with TCHs, for example, FACCH and SAACH, are defined herein as associated control channels. The remaining CCHs, which are not associated with TCHs, are defined here as non-associated control channels. Non-associated control channels include all Broadcast Channels (BCHs) (e.g., Frequency Correction Channel (FCCH), Synchronization Channel (SCH), and Broadcast Control Channel (BCCH), all Common Control Channels (CCCH) (eg, Radiolocation Channel (PCH), Access Grant Channel (AGCH) and Random Access Channel ( RACCH), and the Dedicated Control Channel that is Maintained Alone (SDCCH) In order to maintain backwards compatibility with existing GSM systems, the system 10 communicates the control information through non-associated control channels, using a first modulation project, preferably, the GMSK modulation project The system 10 communicates the control information through the associated control channels, i.e., FACCH or SACCH, using a second modulation project, such as QPSK or 16QAM , which is different from the first modulation project, voice and data are communicated through the TCHs using a third modulation project that is different from the first and second modulation projects, for example, if possible, The third preferred modulation project is an HLM project, which can be a 16QAM modulation project. Otherwise, the voice or data is communicated using the LLM2 project, which can be a QPSK modulation project. Preferably, the second modulation project of the associated control channels and the third modulation project of the TCHs have the same symbol regime, even though their modulation levels may be different or they may be the same. In an exemplary embodiment, the second modulation project of the associated control channels is the second lowest level modulation project LLM2, which is a QPSK modulation project. The HLM and LLM2 modulation projects use the same pulse configuration, the same symbol rate and burst format. The LLM2 project, however, uses a reduced signal set or device from the HLM project. As described above, this allows the use of an identical demodulator in the receivers to demodulate the external signal points of the 16QAM project and the signal points of the QPSK modulation project, which are used to communicate the control information in the associated control channels. The identical demodulator demodulates the signals that are communicated using the HLM project. Because the LLM2 project uses a device or reduced signal set from the HLM project, the HLM demodulator can also demodulate the modulated LLM2 signals by detecting the external signal points of the HLM modulation constellations. System 10 is designed as a hierarchical network with multiple levels to handle calls. Using an allocated set of uplink and downlink radio links, the mobile stations 12 operating within the system 10 participate in the calls using allocated time slots. At a high hierarchical level, a group of Mobile Service Switching Centers (MSCs) 14 are responsible for the sending or routing of calls from a person of origin to a destination. In particular, they are responsible for the establishment, control and termination of calls. One of the MSCs 14, known as the access MSC, handles communication with a Public Switched Telephone Network (PSTN) 18, or other public and private networks. The communication system 10 uses the present invention to provide a link adaptation, when the mobile stations 12 within a cell move within coverage areas supporting one or more of the LLM1, LLM2, HLM projects. At a lower hierarchical level, each of the MSCs 14 connects to a group of base station controllers (BSCs) 16. The main function of a BSC 16 is the management of the radio resource. For example, based on the concentration of the received signal given in the mobile stations 12, the BSC 16 determines whether to initiate a delivery. Under the GSM standard, the BSC 16 communicates with MSC 14 under a normal interface known as interface A, which is based on the Mobile Application Part of the CCITT Signal Transmission System No. 7. At a lower hierarchical level still each one of the BSCs 16 controls a group of base transceiver stations (BTSs) 20. Each BTS 20 includes a number of TRXs that use the uplink and downlink radio frequency channels to service a specific common graphics area. The BTSs 20 mainly provide the radio frequency links for the transmission and reception of bursts of data to and from the mobile stations 12 within their designated cell. In an exemplary embodiment, a number of BTSs 20 are incorporated into a radio base station (RBS) 22. The RBS 22 can be configured according to an RBS-2000 product family, which is offered by Ericsson, the concessionaire of the present invention. Referring to Figure 3, a radiofrequency channel 26 (uplink or downlink) is divided into repetitive time frames 27 during which the information is communicated. Each frame 27 is further divided into time intervals 28 carrying information packets. The voice or speech or data is transmitted during time intervals designated as traffic channels (TCH] _, ..., TCHn). All signaling functions related to the management of calls in the system, including initiations, deliveries, and termination, are handled through control information transmitted through the control channels.

In order to provide backwards compatibility with the GSM systems, the system 10 uses the GMSK modulation project to communicate the control information through the non-associated control channels. The mobile stations 12 use the associated slow control channels (SACCHs) to transmit the associated control signals, such as the RX-LEV signal, which corresponds to the signal concentration received in the mobile station 12 and the RX-QUAL signal, which is a measure of the various levels of the bit error rate in the mobile station 12, as defined by the GSM standard. The associated fast control channels (FACCHs) perform control functions such as deliveries, testing the bursts allocated for TCHs. The rapid signaling procedure is used to indicate whether a burst contains control or voice and / or data. In the present invention, the FACCHs and SACCHs can use modulation projects LLM2 or HLMJ to communicate the control information independent of the modulation project used for the TCHs, if LLM2 and HLM are supported. The BSC 16 instructs RBS 22 based on measurements of channel characteristics of the radio frequency links between the mobile stations 12 to RBS 22. As will be described later in detail, the characteristics of the channel can be measured based on a number of parameters, including the concentration of the signal received in the mobile station 12, the bit error rate in the mobile station 12, the multipath propagation property of the uplink radio frequency channel, for example, the time dispersion, or a combination from the same. The system 10 carries out the transmission of information during a time interval in a burst containing a predefined number of encoded bits. The GSM specification defines several types of bursts: normal burst (NB), frequency correction burst (FB), synchronization burst (SB), access burst (AB), and simulated burst. The normal burst, which lasts 576 microseconds, is used both during traffic and some channels of transmission of control signals. The remaining bursts are used primarily for access and to maintain signal and frequency synchronization within the system. As shown in Figure 4, a normal burst 29 includes two separate data portions 30 during which the bits of the digital data are communicated. The normal burst also includes tail and guard sections 31 and 32 as shown. Among other things, the protection section 32 is used to allow the rise of the burst and the descent of the bursts. The tail section 31 is used for demodulation purposes. All burst transmissions, except simulated burst transmissions, including training sequences. The training sequences are modeled with predefined autocorrelation characteristics. During the demodulation process, the autocorrelation characteristic of the training sequence assists in the synchronization of the bit sequences received through the radiofrequency channel. In normal burst 29, a training sequence 33 is placed in the middle of the burst between its data portions. In order to compensate for the propagation delays, the communication system 10 uses a time alignment process by which the mobile stations 12 align their burst transmissions to arrive at the BTSs 20 in appropriate time relation with respect to other transmissions of outbreak. As will be described later, the mobile station 12 and the RBS 22 incorporate equalizers that correlate the baseband bit sequences received through the uplink or downlink radiofrequency channels with the training sequences to provide correlator responses that correspond to the properties of the multipath propagation. Based on the correlator's answers, the section of the BTS receiver 20 generates a synchronization advance parameter (TA), which corresponds to a propagation delay through the uplink radio frequency channel. The mobile station 12 uses the parameter TA, which is transmitted from RVS 22, to advance or delay its burst transmissions in relation to a time reference. With reference to Figure 5, the functional diagram of a mobile station 12 is shown. The mobile station 12 includes a receiver section 34 and a section of the transmitter 36, which are coupled to an antenna 38 through a duplexer 39. The antenna 38 is used to receive and transmit the radio frequency signals to and from the BTS 20 through the radio frequency channels assigned uplink and downlink. The receiver section 34 includes a radiofrequency receiver 40, which includes a local oscillator 41, a mixer 42, and selectivity filters 43 placed in a well-known manner, to down-convert and demodulate the received signals to a baseband level . The radiofrequency receiver 40, which is tuned by the local oscillator 41 to the downlink channel, also provides an RX-LEV signal on the line 44 corresponding to the intensity of the signal received in the mobile station 12.

The radiofrequency receiver provides a baseband signal to a demodulator 46 that demodulates the coded data bits that represent the information received from speech, data and signal transmission. Depending on the type of mobile station 12, the demodulator 46 can support one or more demodulation projects corresponding to the LLMl, LLM2, and HLM projects. For example, the demodulator of the mobile station 12 subscribed to an operator supporting the LLMl project may be able to demodulate only the LLMl modulated signals. On the other hand, the demodulator of a mobile station 12 subscribed to an operator that supports all three modulation projects is preferably capable of demodulating the LLMl, LLM2 and HLM projects. As described above, the demodulator 46 includes an equalizer (not shown) that processes the coded bit pattern placed in the training sequences, to provide the correlator responses that are used for predictive demodulation of the band signal. base. The equalizer uses the correlator responses to determine the most probable bit sequence for demodulation. As defined by the GSM specification, a channel decoder / interleaver 50 also provides an RX-QUAL signal on line 48, which is a measure of the various bit error rate levels in mobile station 12. The mobile station 12 reports the RX-QUAL signal and the RX-LEV signal to the BSC 16 on an SACCH channel. Preferably, the bursts modulated according to the LLM2 and HLM projects, ie the 16QAM and QPSK projects, use the same pulse configuration, symbol rate and burst format, and use the same training sequences. Both modulation projects use the same signal points to modulate the training sequences. For example, a 16QAM modulator modulates the training sequence using the external signal points A, B, C and D, (shown in Figure 2 (a)). Similarly, a QPSK modulated signal, having a reduced signal set relative to the 16QAM modulated signal, uses the signal points AX BX CX and D '(shown in Figure 2 (b)) to transmit the sequence of training. Although the training sequence used in the bursts communicating the control information is the same as the training sequence of the bursts that communicate the voice or data in the present invention, the modulation project used to communicate the training sequence of a control channel different from that of a TCH. Similarly, the information of transmission of signals in band as well as the furtive flags are modulated using the external signal point of the linear modulation constellation. As described above, the mobile station 12 can use the same demodulator, i.e., a 16QAM demodulator, to demodulate the signal transmission information in band, as well as the training sequences. This arrangement significantly facilitates the decoding of both the training sequence and the signal transmission information in band of the modulated signals HLM and LLM2. The channel decoder / deinterleaver 50 decodes and de-interleaves the demodulated signal. The speech data bits are applied to a speech decoder 52 that decodes the speech pattern using an algorithm from a variety of speech decoding algorithms. After decoding, the speech decoder 52 applies an analogue speech signal to an output device 53, eg, a loudspeaker, through an audio amplifier 54. The channel decoder 50 provides the decoded data and the decoder information. transmission of signals to a microprocessor 56 for further processing, for example, presenting the data to a user. The transmitter section 36 includes an input device 57, e.g., a microphone and / or numeric keypad, to support voice or data information. In accordance with a specified speech / data coding technique, a speech coder 58 digitizes and encodes speech signals in accordance with a variety of supported speech coding projects. A channel encoder / interleaver 62 encodes the uplink data in accordance with a specified encoding / interleaving algorithm that improves error detection and correction in .BTS 12. The channel encoder / interleaver 62 provides a bandwidth signal. uplink base to a modulator 64. The modulator 64 modulates the uplink baseband signal according to one or more of the supported modulation projects. Similarly to the demodulator 46, the modulator 64 of the mobile station 12 can support one or more LLMl, LLM2 and HLM projects. The modulator 64 applies the coded signal to an upconverter 67, which receives a carrier signal from the uplink converted local signal oscillator 41. A radio frequency amplifier 65 amplifies the up-converted signal for transmission through the antenna 38. A well-known frequency synthesizer 66, under the control of the microprocessor 56, supplies the operating frequency information to the local oscillator 41. The microprocessor 56 causes that the mobile station 12 transmits the RX-QUAL and RX-LEV parameters to the RBS 22 through SACCH. Referring to Figure 6, an exemplary functional diagram of RBS 22 is shown to include a plurality of BTSs 20 serving different geographic areas. Through a sync bus 72, the BTSs 20 synchronize with one another. The voice and data information is provided to and from RBS 22 via a traffic bus 74 that can be coupled, through the A-bis interface, with a voice and public or private data transmission line such as an IT line. (not shown). Each BTS 20 includes the TRXs 75 and 76 that communicate with the mobile station 12. As shown, two antennas designated 24A and 24B are separated accordingly in the cover cells 77 and 78. The TRXs 76 are coupled with the antennas 24 through the combiner / duplexer 80 which combine the downlink transmission signals from the TRXs 76 to distribute the uplink received signals from the mobile station 12. The RBS 22 also includes a function block 68 as a base station (BCF) which controls the operation and maintenance of the RBS 22. Referring to Figure 7, a functional diagram of a TRX 76 is shown. The TRX 76 includes a section of the transmitter 86, a section of the receiver 87, a baseband processor 88 and a TRX controller 90. Via a corresponding antenna 24 (shown in Figure 6), the section of the receiver 87 receives the uplink signals from the mobile station 12. A downconverter block 91 downconverts the received signal. After the downconversion of the received signals, the receiver section 87 samples its phase and magnitude, through a sampling block 92, to provide the received bit sequence to the baseband processor 88. A calculator 94 RSSI provides an RSSI signal on line 95, which is a measure of the concentration of the received signal. The RSSI 94 calculator can also measure noise alteration levels during empty channels. The TRX controller 90, which is coupled to the traffic bus 74, processes the commands received from the BSC 16 and transmits the related TRX information, such as various TRX measurements, to the VSC 16. Under this arrangement, the TRX 76 in the form periodically the RSSI signal and the noise alteration levels to the BSC 16. The baseband processor 88 includes a demodulator 96 that receives the uplink baseband data from the receiver section 87. The demodulator 96 generates the responses of the correlator that are processed in a well-known manner to recover the uplink baseband data. The demodulator 96 can support the demodulation of signals that are modulated using one or more LLMl projects, LLM2 or HLM. The uplink baseband data is applied to a channel decoder 97 that decodes the baseband signal according to one or more supported channel decoding projects. The channel decoder 97 places the decoded baseband signal on the traffic bus 78, for further processing by the BSC 16. When the downlink baseband data is transmitted, the baseband processor 88 receives the appropriately encoded data or digitized speech information from the BSC 16 through the traffic bus 74 and applies them to a channel encoder 102 that encodes and interleaves the voice and data according to one or more of the coding projects of channel supported. The transmitter section includes a modulator 104 that modulates the supplied data bits according to one or more of the LLMl, LLM2 and HLM projects. The modulator 104 provides downlink baseband signals to an upconversion block 106 for upconversion. A power amplifier 108 amplifies the up converted signal for transmission through a corresponding antenna.

In an exemplary operation, the system 10 establishes a call between a mobile station 12 and a BTS 20 using LLMl in the SDCCH. The system 10, for example, uses one or a combination of parameters RX-QUAL, RX-LEV or TA, which are measures of the radio frequency link channel characteristic, to decide whether or not to initiate a delivery procedure between the cell, an intra-cell delivery, or a link adaptation. The initiation of a link adaptation procedure within the coverage areas supporting LLMl, LLM2 and HLM projects is based on the channel characteristic of the radio frequency link as well. The BSC 16 compares the characteristic parameter of the channel with corresponding thresholds to determine whether a link adaptation is carried out, or an intra-cell or inter-cell delivery. When a call is requested, the TCHs are allocated based on the capabilities of both mobile stations 12 and BTS 20 to use LLM2 and HLM projects. When only one LLMl is sustained, the TCHs use LLMl. If the system 10, including the mobile station 12, can support the LLM2 and HLM projects, the assigned TCHs use LLM2 or HLM projects. If the quality of the link is sufficient for the HLM project, the system 10 uses the HLM project to communicate through the assigned TCHs. Otherwise, the system 10 uses the LLM2 project. After the delivery is complete, a link algorithm for switching modulation within a continuous cell. A simultaneously filed patent application entitled "A LINK ADAPTATION METHOD FOR LINKS USING MODULATION SCHEMES THAT HAFE DIFFERENT SYMBOL RATES", which is incorporated herein by reference, discloses a link adaptation procedure that can preferably be used to carry The link adaptation in the system is carried out. 10. While a call is in progress, the voice or data is communicated through TCHs using the HLM project, whenever possible. If the BTS 20 detects a delivery condition based on the channel characteristic of the radio frequency link, in accordance with an aspect of the invention, a method of communication between the mobile station 12 and BTS 20 initiates a delivery on an associated control channel. using the LLM2 project. After delivery is completed, mobile station 12 and BTS 20 resume communication through TCH using the HLM project. In this manner, the present invention provides an easy delivery method because the delivery commands through FACCHs communicate using sets or reduced signal devices of the LLM2 project which are usually demodulated by the same demodulator used to demodulate the voice or data modulated by HLM through the TCHs. In order to maintain compatibility with existing systems, the number of bits in a FACCH block that must be transmitted must remain the same. In an exemplary embodiment, a modulation project at a higher level, equal to the 16QAM modulation project with a significantly higher maximum number of bits may of course be used. Using the higher bit rate that is provided by the 16QAM modulation project, a greater number of redundancy bits can be used to increase the reliability of communication of the control information. In accordance with another aspect of the invention, the system 10 uses LLM2 to transmit the control information through the associated control channels, eg, FACCH, independently of the modulation project used in the TCHs, which may be one of the projects LLM2 or HLM. The LLM2 project, which has a lower modulation level in relation to the HLM project, uses a reduced signal device from the HLM modulation project to communicate the control information through the associated control channels. For example, the LLM2 project can be a QPSK modulation project and the HLM project can be a 16QAM modulation project. In this way, both QPSK modulated signals and 16QAM modulated signals can be demodulated using a 16QAM demodulator. Consequently, the data reliability through the associated control channels is improved compared to the TCHs by an increased Euclidean distance between the modulation signal points, ie the QPSK modulation project compared to the 16QAM project. In addition, the system 10 uses furtive flags to indicate whether a transmitted burst contains voice and data information or control. The furtive flags contained in the broadcast burst can transmit using either QPSK or 16QAM modulation projects. In case they are transmitted using the QPSK modulation project, no additional bit is transmitted for the furtive flags through TCHs. The advantage of transmitting furtive flags using the QPSK modulation project, that is, the LLM2 project, is that they can be demodulated and evaluated independently of the modulation applied to the voice or data. Generally, SACCHs are transmitted on the same carrier as the TCHs. The position of SACCHs is well defined so that the receiver is able to demodulate the SACCH bursts. In still another aspect of the invention, the LLM2 project is used for transmission through the SACCHs. In this way, the demodulation process is simplified, because the symbol regimes of LLM2 and HLM are equal. The present invention can also use the LLM2 project for some of the non-associated control channels, such as SDCCH, PCH and AGCH, in the same way as it was used for the SACCHs. As described above, the in-band signal transmission method places control signals on each burst, i.e., time slot for the TDMA systems, at predefined positions. In accordance with another aspect of the present invention, the in-band signal transmission is used to indicate at least one or more of a type of modulation, channel coding, and / or speech coding used for a burst transmitted. The present invention reserves a number of bits (or symbols), similar to furtive flags as bandwidth transmission information to indicate which modulation project or channel coding project or speech coding is used in the transmitted burst. The reserved symbols or bits have a predefined location within the burst. In order to use the same demodulation project as that used to demodulate LLM2 or the modulated HLM voice or data, the reserved bits or preference symbols are modulated using the LLM2 project. In this way, the receiver can demodulate and evaluate the signal transmission information in band independently of the modulation project used for the voice or data using identical demodulation projects. Therefore, the present invention can modulate the information of transmission of signals in band and voice or data using separate modulation projects, but demodulates them using the same demodulation project. Referring to Figure 8, a table containing bits and symbols within a burst is illustrated. Each 16QAM symbol comprises four bits. For transmission of data symbols, all four bits contain information that is calculated in the receivers. For symbols that are used for transmission of signals in band, only two bits, bits 1 and 2, carry information of signal transmission and the other two bits, bits 3 and 4, do not graduate to zero. In accordance with the band signal transmission method of the invention, only the four external signal points are used (at the corners of the 16QAM constellation). Referring to Figure 9, a diagram of a representation project used for the demodulation of modulated LLM2 and HLM symbols is shown. As shown in Figure 9, all four points of the external signal have the bit pattern 'xyOOX where x and y are equivalent to bits 0 and 1 of the symbol used for the transmission of in-band signals. In this way, the transmission of band signals is efficiently used for transmission for fast control information, for example, to indicate the modulation project used. In accordance with another aspect of the invention, the method of sending band signals reserves symbols or bits within a burst to communicate at least two types of information. Different types of information can be data addressed to different users or can be disseminated and user-specific information. The system 10 transmits a burst that communicates the two sets of information modulating a first set of information using a first modulation project and modulating a second set of information, using a second modulation project that is different from the first modulation project. In accordance with this aspect, the second modulation project, which may be linear or non-linear, uses a reduced signal set of the first modulation project. In the case of a linear modulation project, the first modulation project can be the 16QAM project, and the second modulation project can be the QPSK project. In case of non-linear modulation, the first modulation project can be the 4GMSK project, and the second modulation project can be GMSK. In this way, the modulation project can be carried out according to the quality of the link and the class of each user. In an exemplary embodiment, the system 10 supports the GSM GPRS extension, which provides packet data service to the users. Under this provision, each burst contains both broadcast information and user-specific information. The broadcast information, for example, may be a USF and user-specific information may include packets of the user's data. This aspect of the invention uses a first modulation project to transmit the broadcast information and a second modulation project to transmit the user-specific information. Preferably the first modulation project, which is a linear modulation project, uses a reduced signal set from the second modulation project, which has a higher modulation level than the first modulation project. For example, the first modulation project is the LLM2 project, e.g., the QPSK project, and the second modulation project is the HLM project, ie 16QAM modulation project. Also, the first and second modulation projects have the same symbol regime and use the same impulse configuration and use the same burst format. As described above, the modulated broadcast information LLM2 can be demodulated by all receivers that are capable of demodulating HLM. Accordingly, the present invention ensures that maximum coverage is obtained for diffusion within cells where either LLM2 or HLM can be used. From the foregoing, it will be appreciated that the present invention significantly facilitates the communication of control information in a system that supports multiple modulation projects by reducing the total gaso associated with the demodulation of the control information, while providing compatibility towards behind. The present invention takes advantage of the higher data throughput advantage that is provided by higher level modulation projects to improve reliability when communicating control information. With modulation projects having the same symbol regime, the same pulse configuration and burst format, the present invention uses the method of transmitting signals in band to identify the modulation, channel coding and speech coding in a burst transmitted. . In this way, the present invention improves the communication quality of the systems that support multiple modulation projects.

Although the invention has been described in detail with reference to only one preferred embodiment, those skilled in the art will appreciate that various modifications can be made without departing from the invention. Accordingly, the invention is defined only by the following claims which are intended to cover all equivalents thereof.

Claims (85)

CLAIMS:

1. A communication method between a transmitter and a receiver comprising the steps of: communicating the control information through a control channel; communicate the voice or data through a traffic channel; use a first modulation project to communicate the voice and data through the traffic channel; and using a second modulation project that is different from the first modulation project to communicate the control information through the control channel.

2. The method of claim 1, wherein the first and second modulation projects have the same symbol regime.

3. The method of claim 2, wherein the control channel is an associated control channel.

The method of claim 3, wherein the associated control channel is a fast associated control channel.

The method of claim 3, wherein the associated control channel is a slow associated control channel.

6. The method of claim 2, wherein both the first and the second modulation projects are linear modulation projects.

The method of claim 6, wherein the first modulation project has a modulation level higher than the second modulation project.

The method of claim 7, wherein the second modulation project uses a reduced signal set of the first modulation project.

9. The method of claim 6, wherein the first and second modulation projects have the same level of modulation.

The method of claim 6, wherein the first modulation project and the second modulation project use the same pulse configuration.

The method of claim 6, wherein the first and second modulation projects use the same burst format.

The method of claim 6, wherein the first and second modulation projects use the same training sequences.

The method of claim 6, wherein the first modulation project is a QAM modulation project and the second modulation project is a QPSK modulation project.

14. The method of claim 1, wherein the first and second modulation projects have different symbol regimes.

15. The method of claim 1, wherein the control channel is a non-associated control channel.

16. The method of claim 1, wherein the first modulation project is a linear modulation project and the second modulation project is a non-linear modulation project.

17. The method of claim 16 wherein the first modulation project is a QAM modulation project and the second modulation project is a GMSK modulation project.

18. The method of claim 16, wherein the first modulation project is an 8PSK modulation project and the second modulation project is a GMSK modulation project.

19. The method of claim 2, wherein the control channel is a non-associated control channel.

20. The method of claim 2, wherein the first modulation project is a linear modulation project and the second modulation project is a non-linear modulation project.

The method of claim 20, wherein the first modulation project is an 8PSK modulation project and the second modulation project is a GMSK modulation project.

22. A communication method between a base station and a mobile station comprises the steps of: communicating the control information through a non-associated control channel; communicate the voice or data through a traffic channel; use a first modulation project to communicate the control information through the non-associated control channel; and using a second modulation project to communicate the voice and data through the traffic channel, wherein the traffic channel has an associated control channel that uses a third modulation project to communicate the associated control information.

23. The method of claim 22, wherein the first modulation project is a non-linear modulation project and the second and third modulation projects are linear modulation projects.

24. The method of claim 23, wherein the second and third modulation projects have the same symbol regime.

25. The method of claim 24 wherein the associated control channel is a fast associated control channel.

26. The method of claim 24, wherein the associated control channel is a slow associated control channel.

27. The method of claim 23, wherein the third modulation project has a modulation level lower than the second modulation project.

28. The method of claim 27, wherein the third modulation project uses a reduced signal set of the second modulation project.

29. The method of claim 23, wherein the second and third modulation projects use the same pulse configuration.

30. The method of claim 23, wherein the second and third modulation projects use the same burst format.

31. The method of claim 23, wherein the second and third modulation projects use the same training sequences.

32. The method of claim 23, wherein the first modulation project is the GMSK modulation project, the second modulation project is a QAM modulation project, and the third modulation project is a QPSK modulation project.

33. A communication method between a base station and a mobile station comprising: communicating the voice or data through a traffic channel using a first modulation project; and communicating the control information through a control channel that is associated with the traffic channel using a second modulation project.

34. The method of claim 33, wherein the first and second modulation projects have the same symbol regime.

35. The method of claim 34, wherein the associated control channel is a fast associated control channel.

36. The method of claim 34, wherein the associated control channel is a slow associated control channel.

37. The method of claim 34, wherein both the first and the second modulation projects are linear modulation projects.

38. The method of claim 37, wherein the first modulation project has a modulation level higher than the second modulation project.

39. The method of claim 38, wherein the second modulation project uses a reduced signal set of the first modulation project.

40. The method of claim 37, wherein the first and second modulation projects have the same level of modulation.

41. The method of claim 37, wherein the first and second modulation projects use the same impulse configuration.

42. The method of claim 37, wherein the first and second modulation projects use the same burst format.

43. The method of claim 37, wherein the first and second modulation projects use the same training sequences.

44. The method of claim 37, wherein the first modulation project is a QAM modulation project and the second modulation project is a QPSK modulation project.

45. A communication method between a base station and a mobile station comprising: communicating the voice or data through a traffic channel using a first modulation project; and communicating the information of transmission of signals in band through the traffic channel using a second modulation project, wherein the information of transmission of signals in band includes reserved bits indicating at least one or more of one type of modulation, one channel coding, or speech coding used with a burst transmitted.

46. The method of claim 45, wherein the first and second modulation projects have the same symbol regime.

47. The method of claim 46, wherein the reserved bits have a predetermined position within the transmitted burst.

48. The method of claim 46, wherein the traffic channel has an associated control channel that uses the second modulation project to communicate the control information.

49. The method of claim 46, where both the first and the second modulation projects are linear modulation projects.

50. The method of claim 49, wherein the first modulation project has a modulation level higher than the second modulation project.

51. The method of claim 50, wherein the second modulation project uses a reduced signal set of the first modulation project.

52. The method of claim 49, wherein the first and second modulation projects have the same modulation level.

53. The method of claim 49, wherein the first modulation project and the second modulation project use the same pulse configuration.

54. The method of claim 49, wherein the first and second modulation projects use the same burst format.

55. The method of claim 49, wherein the first and second modulation projects use the same training sequences.

56. The method of claim 49, wherein the first modulation project is a QAM modulation project and the second modulation project is a QPSK modulation project.

57. A communication method between a mobile station and a base station comprising: communicating the voice or data through a traffic channel using a first modulation project; and initiate a delivery through an associated control channel using a second modulation project.

58. The method of claim 57, wherein the first and second modulation projects have the same symbol regime.

59. The method of claim 58, wherein the associated control channel is a fast associated control channel.

60. The method of claim 59, wherein the fast associated control channel is indicated by allowing information of signals communicating using the second modulation project.

61. The method of claim 58, wherein both the first and the second modulation projects are linear modulation projects.

62. The method of claim 61, wherein the first modulation project has a modulation level higher than the second modulation project.

63. The method of claim 62, wherein the second modulation project uses a reduced signal set in relation to the first modulation project.

64. The method of claim 61, wherein the first and second modulation projects have the same level.

65. The method of claim 61, wherein the first modulation project and the second modulation project use the same pulse configuration.

66. The method of claim 61, wherein the first and second modulation projects use the same burst format.

67. The method of claim 61, wherein the first and second modulation projects use the same training sequences.

68. The method of claim 61, wherein the first modulation project is a QAM modulation project, and the second modulation project is a QPSK modulation project.

69. A method of communication between a base station and a mobile station comprising the steps of: transmitting a burst that communicates at least two sets of information; modulate a first set of information using a first modulation project; and modulate a second set of information using a second modulation project that is different from the first modulation project.

70. The method of claim 69, wherein the first and second modulation projects are linear modulation projects.

71. The method of claim 69, wherein the first and second modulation projects are non-linear modulation projects.

72. The method of claim 69, wherein the first set of information is a first specific data of the user, and wherein the second set of information is a second specific data of the user.

73. The method of claim 69, wherein the first set of information is the specific data of the user, and wherein the second set of information is the information disseminated.

74. The method of claim 70, wherein the first modulation project has a modulation level higher than the second modulation project.

75. The method of claim 74, wherein the second modulation project uses a reduced signal set of the first modulation project to communicate the second set of information.

76. The method of claim 70, where the first modulation project and the second modulation project use the same impulse configuration.

77. The method of claim 70, wherein the first and second modulation projects are the same burst format.

78. The method of claim 70, wherein the first modulation project is a QAM modulation project and the second modulation project is a QPSK modulation project.

79. A method for communicating information between a mobile station and a base station comprising the steps of: communicating user-specific information using a first modulation project; and communicating broadcast information using a second modulation project.

80. The method of claim 79, further comprising the step of communicating dissemination and user-specific information within a burst.

81. The method of claim 79, wherein the first modulation project has a modulation level higher than the second modulation project.

82. The method of claim 81, wherein the second modulation project uses a reduced signal set of the first modulation project to communicate the broadcast information.

83. The method of claim 79, wherein the first modulation project and the second modulation project use the same pulse configuration.

84. The method of claim 79, wherein the first and second modulation projects use the same burst format.

85. The method of claim 79, wherein the first modulation project is a QAM modulation project and the second modulation project is a QPSK modulation project.