MXPA98010014A - Method and device for the transmission of high speed data in an amp spectrum communications system - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting high-speed data packets in a CDMA communication system. The transmission system transmits a first channel allocation message indicating the at least one additional channel that will be used to support the high speed data packet. The first channel assignment message is sent in advance at the start of high-speed data communications. In addition, the present invention provides, within the first high-speed data frame, a duplicate channel allocation message. A remote receiver uses the channel assignment message to initialize its demodulation elements (114 and 120) to receive the additional information carried in the at least one additional channel.

Description

METHOD AND DEVICE FOR THE TRANSMISSION OF HIGH SPEED DATA IN A BROAD SPECTRUM COMMUNICATIONS SYSTEM FIELD OF THE INVENTION .f The present invention relates to communications. More particularly, the present invention relates to a novel and improved communications system, wherein a user transmits data in a primary channel. However, when the user's transmission exceeds the capacity of the primary channel, the user is provided with the use of an additional channel or a set of additional channels to be used in conjunction with the primary channel, to allow high-speed data transmission. . The present invention provides dynamic channel allocation for high speed data transmission and provides a very efficient system for data transmission at a variable speed.

BACKGROUND OF THE INVENTION The present invention is related to multiple users who share a communication resource, as for example in a cellular system of CDMA. The use of code division multiple access modulation (CDMA) techniques is one of the P1761 / 98MX various techniques to facilitate communication in which a large number of users of the system are present. Other multiple access communication techniques are known in the art, such as time division multiple access (TDMA), frequency division multiple access (FDMA), and AM modulation schemes, such as the single sideband Compared in amplitude (ACSSB). However, the CDMA wide-spectrum modulation technique has significant advantages over these other modulation techniques for multiple access communication systems. The use of CDMA techniques in a multiple access communication system is disclosed in U.S. Patent No. 4,901,307, entitled "SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS", assigned to the assignee of this invention and incorporated herein by reference. The use of CDMA techniques in a multiple access communication system is further disclosed in U.S. Patent No. 5,103,459, entitled "SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM", assigned to the transferee. of the present invention and incorporated herein by reference. CDMA, because its inherent nature is a broadband signal, offers a form of diversity P17S1 / 98MX in frequency when propagating the power signal over a wide bandwidth. Therefore, selective frequency fading affects only a small part of the bandwidth of the CDMA signal. Path diversity is obtained by exploiting or exploiting the multipath or multipath environment by means of broad spectrum processing by allowing a signal arriving with different propagation delays to be received and processed separately. Additionally, diversity in space or trajectory is obtained by providing multiple signal paths through simultaneous links between a mobile user and two or more base stations. Examples of the use of the diversity of trajectories are illustrated in U.S. Patent No. 5,109,390, entitled "DIVERSITY RECEIVER IN A CDMA CELLULAR TELEPHONE SYSTEM", and in U.S. Patent No. 5,101,501, entitled "SOFT HANDOFF IN A CDMA CELLULAR TELEPHONE SYSTEM ", both assigned to the assignee of the present invention and incorporated herein by reference. An additional technique that can be used to increase the efficiency of the allocation of the communication resource, is to allow the users of the resource to provide data at variable speeds, using in this way only the minimum amount of the resource of communication.

P1761 / 98MX communication to meet your service needs. An example of a variable rate data source is a variable speed vocoder which is detailed in U.S. Patent No. 5, 414,796, entitled "VARIABLE RATE VOCODER", assigned to the assignee of the present invention and incorporated herein by reference. Since the voice inherently contains periods of silence, ie pauses, the amount of data required to represent these periods can be reduced. Variable speed vocoding exploits or takes advantage in the most effective way this fact by reducing the data rate during these periods of silence. A variable speed voice coder provides voice data at full speed when the speaker or speaker is actively speaking, thus utilizing the full capacity of the transmission frames. When a voice coder with variable speed is providing the voice data at a speed lower than the maximum, there is an excess of capacity in the transmission frames. A method for transmitting additional data in transmission frames of a fixed size, where the data source is supplying data at a variable speed, is described in detail in U.S. Patent No. 5,504,773, entitled "METHOD AND APPARATUS FOR THE P1761 / 98MX FORMATTING OF DATA FOR TRANSMISSION ", assigned to the assignee of the present invention and incorporated herein by reference In the aforementioned patent application, a method and an apparatus for combining data of different types from different sources in a data packet for transmission.

SUMMARY OF THE INVENTION A communication resource is usually divided into communication channels. The present invention is described in the context of a CDMA communication system, wherein each channel is provided by dispersing the data in a different propagation sequence. In the exemplary embodiment, the propagation sequences used are orthogonal Walsh sequences. In the present invention, each user is provided with a dedicated or exclusive channel, referred to herein as the primary channel. In addition, each user is provided with selective access to a reservation of common channels, referred to herein as additional channels, which may be shared by all users of the communication system. When the speed of the user's transmission P_7ei / 98MX exceeds the capacity of the primary channel, the communication system determines whether sufficient additional channels are available for high-speed data transmission. If sufficient additional channels are available, they are assigned to the user for high-speed data transmission. In the present invention, after determining that sufficient channels are available but before the start of the high-speed transmission, the transmitter sends a message, referred to herein as the first channel assignment message, to the receiver indicating a next high speed data transmission. In the exemplary embodiment, the channel assignment message identifies the additional channels that will be used to support the high-speed data service. In the exemplary embodiment, the first channel assignment message is transmitted two frames in advance of the high-speed transmission. When using the first channel allocation message, the receiving system does not need to demodulate all possible channels at all times, which greatly reduces the power consumption of the mobile station. In an improved embodiment, a secondary channel assignment message containing the same information as the first channel assignment message is P1761 / 98MX supplies the primary channel at the start of high-speed data communication. This provides a second indication of the high-speed data transmission that can be depended on if the frame carrying the first channel allocation message is not properly received. In the present invention, the receiving system initializes a set of additional demodulators to demodulate the data at high speed in accordance with the information provided in the first channel assignment message. The high-speed data is demodulated by the primary channel demodulator and the additional channel modulators and the demodulated frames are combined and supplied to the user. If deletion of a frame occurs, the receiving system demodulates all possible additional channels as if the first channel assignment message had been received in the deleted frame. The receiving system then uses the secondary channel allocation message to reassemble the frame and to initialize the additional demodulators for reception of the following frames.

BRIEF DESCRIPTION OF THE DRAWINGS OR FIGURES The particularities, objectives and advantages of the P1761 / 98MX present invention, will be more apparent from the detailed description set forth below when considered together with the drawings, in which like reference characters are identified correspondingly throughout, and where: Figure 1 is a diagram illustrating an exemplary implementation of the present invention in a mobile communication system. Figure 2 is a block diagram of the transmission system of the present invention; and Figure 3 is a block diagram of a receiver system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES A multiple access communication resource is divided into channels. This division is usually called multiplexing or multiplexing, of which three specific types are: multiplexing by frequency division (FDM), time division multiplexing (TDM) and code division multiplexing (CDM). The basic unit of information transmitted and received in a communication system is referred to as a table. Referring now to the figures, Figure 1 illustrates an exemplary implementation of the present invention in a mobile communication system. The station Mobile P17S1 / 98MX 10 transmits information to the base station 12 of the cell and receives information therefrom. The base station 12 of the cell transmits information in turn and receives it from the mobile telephone switching center (MTSO) 14. The MTSO 14 in turn transmits information to a public switched telephone network and receives information therefrom (not shown) ). In the exemplary embodiment, the signals transmitted by the base station 12 of the cell to the mobile station 10 are broad spectrum signals such as the signals transmitted from the mobile station 10 to the base station 12 of the cell. The generation of broad spectrum communication signals is described in detail in the aforementioned US Patents Nos. 4,901,307 and 5,103,459. The exemplary embodiment of the present invention is described in terms of a method for providing high-speed data packets from the base station 12 of the cell to the mobile station 10 referred to herein as uplink transmissions. However, the present invention is equally applicable to the transmission of downlink data from the mobile station 10 to the base station 12 of the cell. In the exemplary embodiment, the mobile station 10 is assigned a primary channel for the P1761 / 98MX communications with the base station 12. In the exemplary embodiment, a single channel is provided by a unique Walsh propagation sequence, as described in detail in the aforementioned U.S. Patent Nos. 4,901,307 and 5,103,459. In the present invention, the base station 12 of the cell uses additional channels to supply or provide high-speed data transmission to the mobile station 10. As referred to herein, the high-speed data packets are those that require more capacity than the primary channel for its transmission. In the exemplary embodiment, the data is transmitted in packets. If a packet contains data at high speed, its content is divided into a plurality of frames, each of which can be transmitted in single channel and recombined in the receiver. Figure 2 illustrates a block diagram of the exemplary embodiment of the transmission system of the present invention. The data source 20 supplies the data packets for transmission from the base station 12 of the cell to the mobile station 10. The data source 20 is provided for illustrative purposes. It should be noted that the base stations 12 normally retransmit information from the remote location and the data source 20 is simply a convenient form P1761 / 98KX to illustrate a source of data packets for transmission. The data source 20 can provide both data packets less than the capacity limit of the primary channel and high-speed data that require the use of the primary channel plus one or more additional channels to transport the packet. When the data packet for transmission can be transmitted using only the assigned primary channel, the data source 20 provides the data packet through the demultiplexer (DE-MUX) 22 to the formatting element or primary formatter 24. In the exemplary embodiment, the primary formatter 24 generates a set of redundant bits for the packet in accordance with error correction and detection methods that are well known in the art. In the exemplary embodiment, the formatter 24 generates a set of cyclic redundancy check bits (CRC) and a set of code queue bits and attaches these sets of bits to the output packet, the generation of which is detailed in the aforementioned United States Patent No. 5,550,773. The primary formatter 24 outputs the packet to the primary encoder 26 that encodes the packet to provide coded symbols. ~ In the exemplary embodiment, the primary encoder 26 is a P1761 / 98MX convolutional speed coder, whose design and implementation are well known in the art. In an exemplary embodiment, the convolutional encoder is implemented using a digital shift register. The primary encoder 26 provides the encoded data packet to the primary interleaver 28. The primary interleaver 28 reorders the binary digits of the encoded packet in accordance with a predetermined reordering format. In the exemplary embodiment, the primary interleaver 28 is a block interleaver. In a block interleaver, the data is recorded or recorded in memory in columns and issued in rows. In conjunction with the error correction code, interleaving increases the time diversity of the data and, therefore, increases the robustness against burst channel errors. The interleaved packet is supplied by the primary interleaver 28 to the primary modulator 30. The primary modulator 30 modulates the frames in order to provide the frame in the assigned primary channel. In the exemplary embodiment, the modulator 30 is a code division multiple access modulator (CDMA) as described in detail in U.S. Patent Nos. 4,901,307 and 5,103,459. In the exemplary mode, each frame is propagated by a P1761 / 98HX Walsh sequence (Wn) which is unique to that channel and orthogonal to all other Walsh sequences used by all other channels in which the data is transmitted from the base station 12. In the exemplary embodiment, the data in the Primary channel can be variable speed in accordance with the industry standard TIA / EIA / IS-95-A Mobile Station-Base Station Co patibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System, where the data supplied in the additional channels are programmed at a fixed speed. In the exemplary embodiment, the propagated frame is then covered using a pseudorandom (PN) noise sequence that provides greater separation in the code space and identification of each base station 12. Each channel is distinguished uniquely by its Walsh sequence . There is a limited number of orthogonal sequences available, so that the greater the number of users transmitting at high speeds, the lower the number of users that can be admitted by the base station 12. The modulator 30 provides the modulated frame to the transmitter (TMTR) 36, which overconverts the frequency and amplifies the modulated frame and transmits the signal through the antenna 38. When the data source 20 prepares to transmit the data packet at high speed, P1761 / 98MX provides a request signal (REQ) to the controller 40 of the cell of the base station 12 of the cell. The controller 40 of the cell responds by supplying an acknowledgment or acknowledgment (ACK) of the request. The controller 40 of the cell selects additional channels that will be used for high-speed data transmission. In the exemplary embodiment, the reservation of possible additional channels that can be used for high-speed data transmission is pre-defined, so that the selection can be made by a simple masking technique as is well known in the art. In another exemplary embodiment, additional channel sets are pre-defined and channel allocation messages simply identify one of the pre-defined sets. In an improved modality, pre-defined sets consist of different numbers of additional channels. The controller 40 of the cell generates a channel assignment message, which indicates the additional Walsh channel or channels that will be used to transport the data at high speed two frames (40 ms) later and provides that message to the primary formatter 24. The message channel assignment can be supplied with its own CRC check bits for P1761 / 98MX provide additional reliability or can be transmitted without their own check bits using only a minimum number of additional bits. If the present invention will be used in a time division multiple access communication system, then the channel allocation messages would specify additional time slots where the data would be delivered to the mobile station 10. Similarly, if the present invention were applied to a frequency division multiple access communication system, then the channel allocation messages would specify additional frequencies that would be used to supply the data to the mobile station 10. In the exemplary embodiment, the channel assignment message is supplied as additional signaling data that is combined with the output data in the primary channel. The channel assignment message transmitted in advance at the start of the high-speed data transmissions is referred to herein as the first channel assignment message. A method for combining the output traffic data with the signaling data is described in detail in the aforementioned United States Patent NO. 5,550,773. In an alternative mode, the first channel assignment message is punched in the output data box in the P1761 / 98HX primary channel by methods well known in the art. The frame containing the first channel assignment message is formatted or formatted as described above by the primary formatter 24 and is encoded by the primary encoder 26 as described above. The coded symbols are then supplied to the primary interleaver 28 which reorders the symbols as described above. In the exemplary embodiment, the channel assignment message, the signaling messages (if any), the control messages (if any) and part of the data are all transmitted on the primary channel by the modulator 30 primary, additional channels only carry data. In the exemplary embodiment, the power control bits, if used, are drilled into the primary channel data to provide closed circuit power control of the type described in the aforementioned U.S. Patent No. 5, 109, -501. The primary channel can be fixed or variable speed or can be used as a dedicated or exclusive control channel. The modulated frame is overconverted and amplified by the transmitter 34 and transmitted through the antenna 36. In the exemplary embodiment, the first P1761 / 98MX channel assignment message is supplied two frames in advance at the start of the high-speed data transmissions to provide sufficient time for the receiver (illustrated in Figure 3) to prepare its reception. In the exemplary embodiment, during the call set-up, the additional channels are grouped by the controller 40 of the cell and transmitted to the mobile station 10. In the exemplary embodiment, this group of additional channels can be updated during the call. The definition of the set of possible additional channels in advance, allows the channel allocation message to require only a few bits to identify the channels that will be used. Instead of sending a signal identifying the channels that will be used, the base station can send a mask signal that will allow the high-speed demodulation controller 117 to identify the additional channels. Because there is a likelihood that the frame carrying the first channel allocation message may be received in error, the present invention provides the channel allocation information redundantly in a secondary channel allocation message transmitted on the channel primary. At the start of high data transmissions P1761 / 98MX speed, the data source 20 provides the high-speed data packet to the demultiplexer 22. The demultiplexer 22 divides the high-speed data packet into two parts. The first part is contained in a table that will be transmitted in the primary channel. The second part is contained in tables that will be transmitted in additional channels. The frame that will be transmitted on the primary channel is processed as described above. The data bits of the additional channels are supplied to the additional formatter 25. The additional formatter 25 generates a set of CRC bits for the input data and a set of code tail bits. The formatted data of the additional formatter 25 is supplied to the additional encoder 27 which encodes the data to provide the encoded symbols. In the exemplary embodiment, the additional encoder 27 is a convolutional encoder. The coded symbols are supplied to the additional interleaver 29, which as described above, rearranges the coded symbols in accordance with a predetermined ordering format. In a first mode of primary interleaver 28 and of additional interleaver 29, the interleavers use the same number of addresses but a size of words P17S1 / 98 X variable to support blocks of data of different sizes for their collation. In an alternative mode of primary interleaver 28 and additional interleaver 29, the interleavers use a variable number of addresses and a fixed word size to support a variable block size. The re-ordered coded symbols are supplied to the demultiplexer (DE-MUX) 35 which divides the additional frame into frames, each of which is transported in an additional channel. Each of the additional frames of the demultiplexer 35 is supplied to a different modulator from the additional modulators 32a-32n. In the exemplary embodiment, the additional modulated frames of the additional modulators 32a-32n are combined with the modulated frame of the primary modulator 30 by the transmitter 34 before transmission. The transmitter 34 overconverts and amplifies the combined signal and transmits that signal through the antenna 36. Referring now to Figure 3, the signal broadcast through the antenna 36 of Figure 2 is received by the antenna 110 and supplied to the receiver (RCVR) 112. The receiver 112 subconverts, filters and amplifies the received signal and supplies the received signal to the demodulation circuit 111. The demodulation circuit 111 represents a P1761 / 98MX "finger or tooth" of a rake or comb receiver, if this design is used. In a rake receiver or comb implementation, the multipath or multipath signals received at the base station 10 with different propagation path delays are demodulated separately and the results of the demodulation operations are then combined in the combiner of finger or tooth 128. The design and implementation of a rake receiver or comb is described in detail in the aforementioned U.S. Patent No. 5,109,390. In the exemplary embodiment, the primary demodulator 114 and the additional demodulators 120a-120n are CDMA demodulators as disclosed in the aforementioned U.S. Patent Nos. 4,901,307 and 5,103,459. In the exemplary embodiment, the primary demodulator 114 and the additional demodulators 120a-120n are phase quadrature shift manipulation (QPSK) demodulators. The primary demodulator 114 de-propagates or desdisperses the received signal in accordance with the assigned primary channel Walsh sequence and the PN code. The depropagated or disperse primary frame is supplied to the tooth combiner 128 which combines the soft decision of the primary frame of the finger or tooth demodulator 111 P1761 / 98HX with the soft decisions of the other teeth to provide an improved soft decision. The improved soft decisions are supplied to the primary deinterleaver 118, which reorders soft demodulated decisions in accordance with a predetermined reordering format. The design and implementation of deinterleavers is well known in the art. In the exemplary embodiment, deinterleavers 118 and 124 operate using either a fixed number of addresses and a variable word size or a fixed word size and a variable number of addresses to support data packets of different sizes. The deinterleaver 118 supplies the rearranged frame to the primary decoder 122, which decodes the frame. In the exemplary embodiment, the primary decoder 122 and the additional decoder 126 are Viterbi decoders, whose design and implementation are well known in the art. The decoded frame from the primary decoder 122 is supplied through the multiplexer 127 to the data sink 130 which could be the user of the mobile station 10 or to additional processing elements. If the frame containing the first channel assignment message is received without error, then the decoded channel assignment message is supplied P1761 / 98MX to the high-speed data controller 117. The high-speed data controller can be implemented using a microprocessor programmed to perform the necessary functions. The high-speed data controller 117 provides the necessary Walsh sequence identification and the PN code information to the additional demodulators 120a-120n to demodulate the additional data. The RF signal is received by the antenna 110 and supplied to the receiver 112. The receiver 112 amplifies and subverts the received signal and supplies the received signal to the primary demodulator 114 and the additional demodulators 120a-120n. The demodulated primary frame from the primary channel is supplied to the finger or tooth combiner 128 to provide improved demodulated soft decisions as described above. The improved smooth decisions are supplied to the primary deinterleaver 118 which reorders the soft decisions as described above. The reordered frame is supplied to the primary decoder 122 which decodes the deinterleaved frame and supplies the decoded frame to the multiplexer (MÜX) 127. The received signal is also supplied to the additional demodulators 120a-120n, which demodulate the P1761 / 98MX signals in accordance with the channel information supplied in the first channel assignment message. The demodulated data frames of the additional demodulators 120a-120n are supplied to the finger combiner 128 to generate improved smooth decisions for each of the additional frames. The enhanced soft decisions of the demodulated frames are supplied to the multiplexer (MUX) 123 which reassembles the packet containing the additional data. In the exemplary embodiment, the multiplexer 123 operates in accordance with a signal from the high-speed demodulation controller 117, which indicates the additional demodulators that will be used and the manner of reassembling the packet containing the additional data. The reassembled packet of additional data is supplied to the additional deinterleaver 124 which reorders the smooth decisions in accordance with a predetermined deinterleaving format. Reordered soft decisions are provided to the additional decoder 126. Although illustrated as two separate blocks, the primary decoder 122 and the additional decoder 126 may be implemented using the same hardware, such as a microprocessor programmed to perform the specified function or as an integrated circuit of application P17S1 / 98MX specific (ASIC) designed to perform the specified function. The additional decoder 126 decodes the additional data packet and supplies the decoded bits to the multiplexer 127. The multiplexer (MUX) 127 combines the decoded data transmitted in the primary channel with the decoded data transmitted in the additional channels. The reassembled data packet is supplied to the data sink 103. If a frame erasure occurs and the content of the first channel allocation message is unknown, the receiving system will operate based on the worst case scenario. The receiver will demodulate the maximum set of possible additional channels and demodulate the last of these sets used. It will then decide which frames of the additional channels will be used as valid data once the secondary channel allocation message of the present data packet is appropriately decoded. If the two frames containing the primary and secondary channel assignment messages are received with error, then the corresponding received data will be discarded and the deletion will be declared. The present invention is equally applicable to the transmission of data at variable speed and the P17S1 / 98MX fixed speed transmission. For transmission at fixed speed, the channel assignment message data will normally remain constant throughout the service. NeverthelessIf the need for additional channels for signaling or other data traffic arises, channel allocation messages will be allowed to vary to indicate the additional channel that will be used for the transmission of that data. For variable speed transmissions, scheduling is done so that only the necessary number of additional channels are allocated for the size of the present data packet. The number of additional channels that will be assigned, depends on the amount of data that will be sent. This could be done frame by frame. The above description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. The various modifications to these embodiments will be readily apparent to those skilled in the art and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. In this way, it is not intended that the present invention be limited to the modalities shown herein but that it be in accordance with the P1761 / 98MX broad scope consistent with the principles and novel features disclosed herein. P17S1 / 98MX

Claims (5)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. An apparatus for transmitting data in a high-speed package, comprising: cell controller, for generating a first channel allocation message indicating at least one additional channel that will be used to support the transmission of the high-speed data packet; and a transmission means for transmitting the first channel allocation message and for transmitting the data packet at high speed on a primary channel and at least one additional channel. The apparatus according to claim 1, wherein the first channel allocation message is transmitted in advance to the high-speed data packet. The apparatus according to claim 2, wherein the first channel allocation message is transmitted two frames in advance to the high speed data packet. The apparatus according to claim 1, wherein the first channel assignment message is transmitted in advance to the high-speed data and, where the P1761 / 98HX transmission means is furthermore for transmitting a secondary channel allocation message in a first frame of the high speed data packet. 5. A system for receiving the high-speed data packet, comprising: a first receiving means for demodulating a primary data frame and for providing a channel allocation message from the primary data frame; and a second receiving means for demodulating at least one additional data channel in accordance with the channel assignment message. P17S1 / 98MX