JP2004266854A - Wireless terminal device, base station, and random access method of backward common channel in code division multiple access method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve network efficiency by decreasing unnecessary data transmission and interference signals and to create more appropriate power level with a retransmission in a unit of preamble more faster to improve time delay characteristic. <P>SOLUTION: When multiple terminal devices use code division multiple access method to transmit data via a common channel, the terminal device 100 selects one of available preamble signatures and one of available access slots to transmit the preamble to a base station 200. The base station 200 attempts preamble acquisition and informs all the terminal devices 100 of the acquisition whatsoever. The terminal device either transmits the data or retransmits the preamble depending on the acquisition result of the preamble. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a wireless terminal device, a base station, and a random access method in which a plurality of terminal devices transmit data via a common channel in a code division multiple access scheme.

  More specifically, the present invention selects one of the preamble signatures available to the terminal device and one of the available access slots to access the preamble based on the selected preamble signature. To the station, the base station attempts to acquire the preamble, and informs all the terminals whether or not the preamble has been successfully acquired, and the terminal transmits data or acquires the preamble according to the result of the acquisition of the preamble. By retransmitting the data, unnecessary data transmission is reduced, interference signals are reduced, network efficiency is improved, and a fast retransmission of only the preamble allows quick access to an appropriate power level, thereby delaying time. The present invention relates to an apparatus and method for random access of a reverse (upward) common channel in a code division multiple access system having excellent characteristics. Is shall.

  Currently, the demand for mobile communication services is rapidly increasing, and mobile communication services that support data services as a service form that enables voice information transmission while moving are not yet activated. In a simple and simple form of data transmission, there is an increasing demand for receiving a moving image signal while moving. In particular, the IMT-2000 for 3G mobile communication services that supports not only voice signals but also simple data to video, and can be accessed anywhere in the world through internationally integrated standards. (International Mobile Telecommunication-2000) has been actively studied in Japan and overseas. In addition, although mobility is somewhat limited, research on high-speed data transmission has been conducted. In particular, the wireless LAN proposed in the IEEE 802.11 standard draft already has a data rate of 2 Mbps (Mega bit per sec). Has been commercialized as a product that can transmit data.

  Generally, in performing such high-speed data transmission, a limited number of channels are inefficiently used in the circuit-switching system currently used in the public switched network, digital cellular and personal mobile communication systems. It is not desirable. IMT-2000, which has been studied as a standard for short-distance regional networks and next-generation mobile communication systems, has been developing a packet-switching method for high-speed data transmission. (packet-switch) is applied.

  On the other hand, the spread spectrum system of the CDMA (Code Division Multiple Access) signal system applied to the digital cellular system currently in service has an increased capacity and cannot be eavesdropped from the outside, so that it can be used while moving. There is a feature that stable communication can be performed in a multipath environment generated by a rapidly changing wireless channel.

  The IMT-2000 system, which is currently undergoing active standardization activities, has a basic requirement to support not only existing voice data but also packet data.However, due to the aperiodic nature of packet data, existing The method of using the dedicated channel has a problem that resources cannot be used efficiently. That is, data generated continuously, such as voice data, is allocated to a dedicated channel and used. On the other hand, in the case of packet data that is discontinuous and has a variable amount of data to be transmitted, data such as voice data is used. If a dedicated channel is used, a problem arises in that the capacity supported by the system cannot be satisfied.

  Therefore, if an appropriate number of reverse (upstream) channels are used in common, not only can resources be used efficiently, but also voice services and services with variable amounts of data to be transmitted can be accommodated within the capacity of the system. can do. In addition, since the number of subscribers is expected to increase in the future as the number of subscribers increases, efficient use of resources using the reverse (upward) common channel should be an essential matter.

  The ALOHA method is known to be the simplest method for channel connection and data transmission using such a reverse (upward) common channel. The ALOHA method was developed as a typical random access method at the University of Hawaii in 1970 as a protocol for wireless networks between islands in Hawaii. In the ALOHA method, data is transmitted without a separate time schedule between the base station and the terminal device, so that the data transmission efficiency is reduced. Especially when there are many terminal devices, frequent collision between transmitted data occurs frequently. So a network overload phenomenon occurred. Therefore, in order to determine this problem, a slot ALOHA in which a standard time is set between a base station and a terminal device has been studied. In the slot ALOHA, when data to be transmitted is generated in the terminal device, the data transmission efficiency is increased by permitting transmission only within the reference time. The reason for this is that the probability of being disturbed by its own data transmission due to data generated by another terminal device is reduced, and overall network efficiency is improved.

  Next, a conventional ALOHA protocol using a code division multiple access system will be described with reference to FIG.

  FIG. 9 illustrates a data transmission process in the ALOHA protocol using a conventional code division multiple access system.

  According to FIG. 9, in the terminal device, data transmission is performed through one access attempt (access attempt). This connection attempt is composed of a plurality of access sub-attempts (access sub-attempts). The access probe sequence includes a plurality of access probe sequences, and the access probe sequence includes a plurality of access probes.

  The connection probe includes a connection channel message or a preamble transmitted in the form of a simple pilot before transmission of user data to capture terminal device timing, and includes connection information and user data following the preamble. This is done with an access message capsule.

  A terminal transmitting a connection message or data on a reverse common channel through the connection attempt process thus configured first transmits one connection probe at a predetermined power level. The power level used at this time not only reduces the influence of interference on other terminals transmitting data through the dedicated channel or transmitting data through other reverse common channels, but also reduces the number of retransmissions. Use the best to reduce processing time through.

  The terminal device that has attempted to transmit data with the first connection probe monitors an indication of whether or not the connection probe has been detected from the base station for a fixed time (TA). However, if data transmission of the first connection probe fails, retransmission is performed at a power level increased by a certain level (PI) from the power level of the first connection probe after waiting an arbitrary time (RS). become.

  Through such a process, the terminal device continuously attempts a connection probe including data transmission. However, if the data transmission cannot be successfully performed within the preset number of connection probes, the terminal device terminates one connection probe sequence, waits for another arbitrary time (RS), and then executes the second connection probe sequence. It will start in the same way as when transmitting the first connection probe.

  Japanese Patent Application Laid-Open No. H11-163873 provides a mobile communication system that significantly reduces the time required to process a random access call originating from a mobile device. At the time of connection setup, the mobile devices (16, 18) use a preamble. And transmits a random access packet including a plurality of fields.The information provided in these fields is used by the base station (12), thereby promoting more efficient connection setup and allocating channel resources faster. The invention also provides a system for detecting, identifying, and receiving a plurality of random access requests, wherein each of the mobile stations (16, 18) includes one of a plurality of different preamble symbol patterns in a random access request packet. The base station receiver (14) includes a plurality of accumulators (126), one for each. Are tuned to different preamble symbol patterns, so that the base station receiver (14) can identify multiple random access requests at the same time. This preamble symbol also has the same power as used in IS-95 and CODIT systems. It can also be used in conjunction with gradient processing to control the power of each of the mobile stations attempting multiple random accesses. "

WO 98/18280 pamphlet (Reference patent family: JP-T-2001-502866, FIG. 3)

  However, since the ALOHA method basically transmits data with an appropriate power level in a contention mode, it is inevitable that a connection probe fails due to an insufficient power level and collision between transmission data, Useless transmission failure results.

  On the other hand, there is a method of using a large number of preamble signatures in order to improve the preamble acquisition probability. The preamble signature is a sequence composed of a plurality of symbols that modulates a common spreading code used for a preamble for a reverse (upward) common channel. Since orthogonality is maintained between the preambles, the base station can simultaneously capture a large number of preambles with different preamble signatures.

  As long as the preamble is a signal for capturing the synchronization of the reverse common channel, the longer the preamble, the more stable synchronization can be obtained, but it is not effective in terms of transmission efficiency.

  In view of the above, an object of the present invention is to solve one or more of the problems described above by selecting one of preamble signatures available to a terminal device and one of available connection slots (access slots). One is selected, the preamble is transmitted to the base station, the base station attempts to acquire the preamble, and notifies all the terminal devices whether or not the preamble has been successfully acquired, and the terminal device acquires the preamble. By transmitting data or retransmitting the preamble according to the result, it reduces unnecessary data transmission and reduces interference signals, thereby improving network efficiency and performing fast retransmission of only the preamble. This provides a fast approach to the appropriate power level, which results in a code division multiple access system with excellent time delay characteristics. It is an object of the present invention to provide a random access apparatus and method for a reverse (upward) common channel in a formula.

  Therefore, according to the apparatus and method for random access of a reverse common channel in a code division multiple access scheme according to the present invention, when a terminal apparatus transmits a preamble modulated with a preamble signature, it effectively manages various packet data. For this purpose, one preamble signature is randomly selected from a subset of the preamble signatures classified according to traffic characteristics.

  In addition, after the base station captures preambles for all available preamble signatures, the base station reports the captured preamble signature to all terminal devices using a forward link common channel, and transmits the preamble. The transmitting terminal device can confirm whether or not the preamble sent by itself has been captured (that is, whether or not the preamble has been captured). If the preamble is captured, the terminal device transmits information data to the user at a predetermined time at a power level appropriately set according to the power level at which the preamble is transmitted. However, if the preamble is not captured, the terminal device randomly selects an access time and a preamble signature, and is increased by a predefined power step compared to the power level of the previous preamble. The determined power level is determined and the preamble is retransmitted.

  In order to achieve the above object, in a random access apparatus and method for a reverse (upward) common channel in a code division multiple access system according to the present invention, the base station transmits a reverse signal to all available preamble signatures. A preamble transmitted from a plurality of terminal devices is captured via a common channel, and a signal indicating whether the preamble signature transmitted from the plurality of terminal devices is captured (that is, whether or not the preamble signature has been captured) is forwarded ( Downlink direction) Transmit to a terminal device via a common channel, and a plurality of terminal devices randomly select a preamble signature classified according to characteristics of data to be transmitted, modulate a preamble, and transmit a common channel from the base station. Receiving the signal representing the preamble capture indication transmitted via the When the signature is captured, the user information data is transmitted at a predetermined time at a power level appropriately set by the power level at the time of the preamble transmission, and if the transmitted preamble signature is not captured, the connection slot is used. Will retransmit the preamble with the preamble signature randomly selected.

  As described above, according to the wireless terminal device, the base station, and the random access method of the reverse common channel in the code division multiple access system according to the present invention, the preamble signature is classified according to the characteristics of the data, and thus the dedicated channel is classified. Various types of reverse (upward) common channels, such as channel requests for assignment, packet access for transmitting short data, and medium-sized data, can be used.

  In addition, the present invention improves network efficiency by reducing unnecessary data transmission and interference signals, and can quickly approach an appropriate power level by retransmitting in preamble units, thereby achieving excellent time delay characteristics. Obtainable.

  Hereinafter, a random access device for a reverse (upward) common channel in a code division multiple access system according to the present invention will be described with reference to the drawings.

  FIG. 1 is a network configuration diagram of a general code division multiple access system to which the present invention is applied. The network generates a data and transmits the preamble data via a reverse (upward) common channel to the terminal device 100, and code capture using the preamble transmitted from the terminal device 100 via the reverse common channel. And notifies the terminal device 100 whether or not the preamble has been captured, and receives the corresponding user information data from the terminal device and manages the base station 200 linked with the upper layer protocol and the plurality of base stations 200 and 210. CDMA network 300 linked with other networks, PSTN (Public Switched Telephone Network) 400 linked terminal device 100 and ordinary telephone subscribers linked with CDMA network 300, and terminal device 100 linked with CDMA network 300. Interface that connects Internet users with And Tsu (500) is constituted by a PSDN (Public Switched Data Network) 600 to couple the data server in conjunction with the CDMA network 300 receive the support of the terminal apparatus 100 and the data service.

  In the network configured as described above, the random connection device for the reverse (upward) common channel includes a transmission unit for an acquisition indication signal in the base station, and a reception unit for the acquisition indication signal in the terminal device. And transmission determination means.

  The transmission means of the base station 200 determines whether the transmitted preamble signature has been captured after code capture of the preamble has been performed for all available preamble signatures via the reverse (upstream) common channel. And transmitting the captured display signal to be displayed on the terminal device. The receiving means of the terminal device receives the captured indication signal from the base station via the forward (downward) common channel, and the determining means of the terminal device transmits the user information data by the captured indication signal or retransmits the preamble again. Decide whether to transmit.

  If it is indicated that the preamble signature has been captured, the terminal device transmits user information data, otherwise the terminal device generates a preamble with a randomly selected preamble signature and increased power in the newly selected connection slot. Transmit again.

  FIG. 2 is a functional block diagram of a terminal device and a base station in a random access device of a reverse (upward) common channel by a code division multiple access system according to the present invention.

  The terminal device 100 randomly selects one of the available preamble signatures classified according to the traffic characteristics and a connection slot to be transmitted, and determines a forward path loss and an interference signal reported from the base station. A terminal first determining unit 110 that determines the power of the preamble using the level and the like; and a terminal 1 that generates and transmits a preamble signal based on the preamble signature and power level in the connection slot selected by the terminal first determining unit 110. A transmission unit 120, a terminal first processor 170 activated by the terminal first determination unit 110 to format user information data to be transmitted, and a formatted user information signal are input from the terminal first processor 170. Chan corresponding to preamble signature A terminal second transmission unit 180 that spreads and outputs a channelization code, and a preamble signal generated by the terminal first transmission unit 120 according to a capture indication signal transmitted from the base station 200, or a terminal (2) A terminal selection unit 130 for selecting one of the data generated by the transmission unit 180, and a signal selected by the terminal selection unit 130 is converted into an RF signal and transmitted to the base station 200 via a wireless channel. A terminal second processor 140 for converting a captured indication signal of an RF signal transmitted from the base station 200 into a baseband signal, and a preamble signature transmitted by receiving the baseband captured indication signal from the terminal second processor 140 and transmitting the captured signal. The terminal receiving unit 150 for confirming whether or not the transmission preamble signature confirmed by the terminal receiving unit 150 has been captured. The terminal first determining unit 110 is enabled / disabled I, and a terminal second determination unit 160 for outputting a signal for switching the switch of the terminal selection unit 130.

  As shown in FIG. 3, the terminal first determining unit 110 receives and stores information on a preamble signature classified according to traffic characteristics transmitted from a base station via a forward (downlink) common channel. The storage unit 111 divides the characteristics of the generated data in consideration of the characteristics of the traffic and the requirements of the upper layer, and selects a preamble signature by a random method from available preamble signatures corresponding to the traffic characteristics. A signature selecting unit 112, a slot selecting unit 113 for randomly or deterministically selecting a connection slot when a preamble is transmitted, an interference signal level of a base station, and a forward direction (downward direction). ) Consider path loss and previously transmitted preamble power level etc. And a power determining unit 114 that determines the power of the preamble to be transmitted.

  The power determining unit 114 determines the interference signal level of the base station transmitted from the base station via the forward (downlink) common channel, the forward (downlink) path loss, the predetermined power increase step, and the The power level is determined in consideration of the power level of the preamble and the like.

  Referring again to FIG. 2, the terminal first transmission unit 120 uses the connection slot, the preamble signature and the power level determined by the terminal first determination unit 110 to generate a common spreading code using the preamble signature. The preamble is transmitted by modulation, and a complex spread-spectrum signal having a real value equal to an imaginary value is generated by using the selected preamble signature and the common-band spreading code.

  The terminal receiving unit 150 receives the capture indication signal using the code used for the capture indication transmission on the forward link and the same signature as the transmitted preamble signature.

  In addition, the terminal second determining unit 160 enables the terminal first determining unit 110 when indicating that the preamble signature transmitted by the capture display signal received by the terminal receiving unit 150 has been captured, and the terminal selecting unit 130 A signal for combining the output of the first transmission unit 120 is generated, while otherwise, the terminal first determination unit 110 is disabled, and the output of the terminal second transmission unit 180 is transmitted to the terminal selection unit 130. Join.

  The base station 200 receives an RF signal transmitted from the terminal device 100 and transmits the RF signal to the terminal device 100. The base station processor 210 receives the RF signal from the terminal device 100 and transmits the RF signal to the terminal device 100 via the reverse common channel. A base station synchronizing unit 220 which receives the preamble with all available preamble signatures input from the station processor 210, and a base station determining unit 230 which confirms the acquisition and determines and outputs the captured preamble signature. A base station transmission unit 240 that generates a plurality of capture indication signals corresponding to the capture preamble signature input from the base station determination unit 230, and outputs them to the terminal device 100 via the base station processor 210; The multipath time delay information acquired by the station synchronization section 220 is input, and the base station determination section A despreading code is generated using the information on the acquisition preamble signature received from the base station 30 and data transmitted from the terminal device 100 via the reverse common channel is received from the base station processor 210 and demodulated and channel decoded. And a base station transceiver 250 for transmitting the data.

  The base station synchronizing unit 220 receives a preamble transmitted from the terminal device 100 via the reverse common channel by the base station processor 210 and acquires the preamble with all available preamble signatures. A time delay characteristic output unit that makes the base station transceiver 250 recognize all the time delay characteristics corresponding to the signature and prepares the transceiver 250 to receive the data to be transmitted at an arbitrary predetermined time; and a base station determination unit. And an output unit for outputting a capture display signal for reporting the preamble signature captured in 230.

  The base station determining unit 230 notifies the base station transceiver 250 of a band spreading code corresponding to the preamble signature received from the base station synchronizing unit 220 and prepares to receive data transmitted immediately at a predetermined time. It comprises a generator and a capture display signal generator that generates a capture display signal corresponding to only the captured preamble signature and outputs the signal to the base station transmitter 240.

  The base station transmitter 240 divides the available time by the number of available signatures, assigns the time obtained by the division to each available preamble signature, and assigns the obtained time to the captured preamble signature. An on-off signal format (# 1) in which the captured indication signal is transmitted only at the time and the captured indication signal is not transmitted at the time assigned to the uncaptured preamble signature, and the number of signatures that can use the available time , And assigns each available preamble signature a respective divided time, and the preamble signature captured for all the divided times assigned to the available preamble signatures has a positive acquisition indication signal. The preamble signature that was transmitted and not captured An antipodal signal format (# 2) for transmitting a negative acquisition indication signal, and an orthogonal code assigned to a preamble signature and set as a symbol to be transmitted, and an orthogonal symbol corresponding to the captured preamble signature Only the on-off signal format (# 3) that transmits only the preamble signature and the symbol that is transmitted by allocating an orthogonal code to the preamble signature are transmitted, and a positive capture indication signal is transmitted for the captured preamble signature and is not captured The preamble signature is configured to transmit a capture indication signal based on any one of an antipodal signal format (# 4) for transmitting a negative capture indication signal. Further, it is also possible to combine four signal formats to create and use another signal format.

  The transmission system of the captured indication signal includes a puncturing method applied to the existing forward common channel, a method using an orthogonal code in the forward common channel, and an orthogonality method in the forward common channel. And selecting one of the methods using a code having no.

  Further, the base station 200 performs packet access for transmitting short data, a channel reservation request for transmitting data of an intermediate size, and dedicated channel allocation for transmitting large and continuous data such as voice data. , Which determines the nature of data transmitted through the reverse common channel. Then, the base station 200 classifies all possible preamble signatures according to the nature of the data to be transmitted, and broadcasts them through a forward common channel so that all terminal devices can recognize them.

  In order to access a packet to the base station 200, the terminal device 100 uses a preamble signature with one preamble signature from among preamble signatures classified according to data characteristics such as a length and a transmission rate of data transmitted via the packet access. , And considering the indication of the preamble transmitted from the base station 200, it is determined whether to retransmit the preamble or to transmit the user information data. If user information data is transmitted, one or more frames conforming to the frame structure are transmitted continuously, and the operation for packet access is performed on the transmitted frames of which transmission failed. Do again.

  For the channel reservation request, the terminal device 100 randomly selects one of the preamble signatures allocated for the channel reservation request and transmits the preamble in the same manner as the packet access. The transmitted preamble is captured, and the captured preamble is notified to all terminals through the forward common channel. If a negative capture indication is displayed or there is no capture indication on the terminal device 100, the terminal device randomly selects one of the preamble signatures allocated for channel reservation, determines a connection slot, and determines a preamble. When the terminal device 100 transmits the preamble in which the preamble signature is captured, the terminal device 100 transmits the user information data for the reservation request and transmits the channel reservation data to thereby reserve the channel. . In the base station 200, after correctly receiving the data transmitted for the channel reservation from the terminal device, the base station 200 uses the forward (downlink) common channel to determine whether or not the channel has been reserved (that is, whether the reservation can be made) and the reserved time. The corresponding terminal device notifies the corresponding terminal device of the spreading code and the transmission rate, and the corresponding terminal device transmits the data to be transmitted using the reserved time, the spreading code, the transmission rate, etc. A closed loop power control is performed using a power control command transmitted on a (downward) channel. When transmitting the last frame, the terminal device transmits information indicating that data transmission has been completed, together with the data, and cancels the channel reservation.

  One method for changing the channel reservation condition during reservation is a method in which the terminal device 100 transmits data for changing the channel reservation condition together with data transmission in the same manner as an operation for packet access or a channel reservation request. There is. Another method is a method in which the terminal device 100 multiplexes data for changing the channel reservation condition together with the user information data, and transmits the multiplexed data. In both methods, the base station 200 must transmit information related to the acceptance or rejection.

  Hereinafter, the operation of the random access device for the reverse (upward) common channel in the code division multiple access system according to the present invention will be described.

  FIG. 4 is a schematic diagram illustrating the operation between the terminal device and the base station in the random access device according to the present invention.

  Referring to FIG. When data to be transmitted temporarily occurs, the terminal device 100 transmits a preamble to the base station 200, and the base station 200 performs preamble code acquisition and transmits a preamble code acquisition indication signal to all the terminal devices 100. As a result, each terminal device 100 monitors the captured display signal, retransmits the preamble when the transmitted preamble is not captured, and transmits user information data when the transmitted preamble is captured. . The base station 200 that has received the data receives the user information data and transmits an acknowledgment signal of the user information data to the terminal device 100 after an error check. The time at which the preamble was not caught is called idle time (IT).

  As shown in FIG. 5, when the data to be transmitted is generated (S101), the terminal device 100 transmits one of the available preamble signatures corresponding to the traffic characteristics to transmit the preamble, as shown in FIG. Then, a connection slot is randomly selected (S102), and a step of determining the power of the preamble to be transmitted using information on forward path loss, the level of an interference signal transmitted from the base station 200, and the like (S103). Next, a preamble is generated and transmitted with a randomly selected preamble signature and a determined power level in a randomly selected connection slot (S104).

  Then, the terminal device 100 receives the preamble capture indication signal broadcast to all the terminal devices 100 from the base station 200 (S105), and confirms whether or not the preamble signature transmitted by itself has been captured (S106).

  If the preamble transmitted by itself is captured in the capture indication signal receiving process, the terminal device 100 formats the user information data into a predetermined format, performs data transmission for selecting a message or a preamble, and generates a preamble signature. If the preamble transmitted by itself is not captured in the capture indication signal receiving process, the terminal device transmits the preamble signature, the connection slot, and the power level (S107). The steps starting from the step of determining the transmission resources are repeated to retransmit the preamble (S108).

  On the other hand, the base station 200 controls the transmission of the preamble capture indication signal as shown in FIG. First, the base station 200 receives an RF signal at the terminal device (S201), and performs preamble code acquisition to acquire synchronization with the preamble with all available preamble signatures (S202). Next, the base station confirms whether the preamble has been captured, determines the captured preamble signature (S203), generates a capture display signal corresponding to the captured preamble signature, and transmits this to all terminal devices (S204). ).

  Then, the base station 200 acquires the multipath time delay information and the fading phase information acquired in the preamble code acquisition step, generates a despread code using the acquired preamble signature information, and prepares for reception ( S205) The terminal device receives data transmitted through the reverse common channel, and receives user information data through a demodulation and channel decoding process (S206).

  The above operation will be described in more detail. When the terminal first determining unit 110 is externally enabled, one preamble signature is randomly selected from a set of preamble signatures classified according to characteristics of data transmitted by the enabled terminal first determining unit 110, and connected simultaneously. Slots are also randomly selected. Next, the terminal first transmission unit 120 generates a preamble to be transmitted by spreading the preamble signature using the common band spreading code, and transmits the preamble in the selected transmission slot. At this time, the terminal selector 130 is coupled to the terminal first transmitter 120, outputs the preamble by the terminal second processor 140, and transmits the preamble to the base station 200.

  As a result, in the base station 200, the base station processor 210 receives the preamble transmitted from the terminal device 100 and outputs it to the base station synchronization section 220, and the base station synchronization section 220 uses the preamble with all available preamble signatures. After performing the code acquisition, the information about the acquisition is output to the base station determination unit 230. Then, the base station determining unit 230 determines the preamble signature obtained by receiving the information on each preamble signature from the base station synchronizing unit 220, and outputs this to the base station transmitting unit 240 and the base station transceiver 250. Next, the preamble signature captured by the base station transmission unit 240 is received, a signal corresponding to the captured preamble signature is generated, and a signal is output to the terminal device 100 through the base station processor 210 using the forward common channel. At the same time, the base station transceiver 250 receives the preamble signature captured from the base station determination unit 230 and prepares to receive data transmitted from the terminal device 100 using the spread spectrum code corresponding to the captured preamble signature. .

  On the other hand, the terminal receiving unit 150 receives the captured indication signal transmitted from the base station 200 through the forward common channel via the terminal second processor 140 and checks whether the transmitted preamble has been captured. Is output to the terminal second determining unit 160.

  At this time, if the terminal second determining unit 160 confirms that the transmitted preamble has been successfully captured, the determining unit 160 disables the terminal first determining unit 110 and the terminal first transmitting unit 120 and the terminal second transmitting unit 120. 180 spreads the user information data formatted by the spread spectrum corresponding to the preamble signature transmitted by the terminal first processor 170 and outputs the spread data to the terminal selection unit 130. The terminal selection unit 130 receives the preamble signature capture indication signal from the terminal second determination unit 160, closes the switch for the terminal second transmission unit 180, and transmits the signal to the base station 200 through the terminal second processor 140. Will be. Next, the transmitted data is input to the base station transceiver 250 through the base station processor 210, and the base station transceiver 250 performs demodulation and decoding processes using a band spreading code previously identified through the reverse common channel. Will be restored.

  On the other hand, if the terminal second determining unit 160 determines that the transmitted preamble signature has not been captured, the terminal first determining unit 110 and the terminal first transmitting unit 120 are enabled. That is, the terminal first determining unit 110 randomly selects one new preamble signature from the set of preamble signatures, and at the same time, randomly or deterministically selects a connection slot.

  Similarly to the initial preamble transmission, the terminal first transmission unit 120 generates a preamble to spread and transmit the preamble signature determined using the common band spreading code, and transmits the preamble in the selected connection slot. Let it. At this time, the terminal selection unit 130 connects to the terminal first transmission unit 120, outputs the preamble to the terminal second processor 140, and transmits this preamble to the base station 200. The operation and the like are repeated with a limited number of repetitions, and the number of repetitions depends on the balance of traffic loaded on the system and other system conditions.

  FIG. 7 shows an example of the operation of a random access device for a reverse (upward) common channel in a code division multiple access system.

  First, as shown in FIG. 7, assuming that the frame period is 10 ms and one slot is 1.25 ms, one frame period has eight connection slots, and one preamble is 1 ms. Will occupy. Therefore, the connection slot is composed of a preamble duration of 1 ms and an idle time (idle time) of 0.25 ms. In the base station 200, the connection slot is configured with a capture display signal duration of 1 ms and an idle time of 0.25 ms. Also, to simplify the description, only the case where there are two preamble signatures within one frame duration and only short data is available is considered.

In FIG. 7, it is assumed that three of the certain terminal devices randomly select the same transmission slot as a certain preamble signature in data to be transmitted before the first connection slot start time (T ₀ ). At this time, the base station 200 does not capture a preamble because there is no preamble having a sufficient power level. At this time, the base station 200 transmits only the negative captured display signals of the signal formats # 2 and # 4 and the non-captured display signals of the signal formats # 1 and # 3. Thus, each terminal must retransmit each preamble with a randomly selected or randomly selected preamble signature and an increased power level in a given connection slot.

Terminal device determines a sufficient power level by open loop power control (open loop power control), in the next connection slots T _1, and transmits each preamble another preamble signatures. All two preambles are fully captured and a positive or on-acquisition indication signal is received at all terminals. Therefore, the terminal device for 10ms in connection slot T _2, will transmit the user information data. Of course, access time of data transmission may extend T ₃ or T _4.

Any time slot T _2, 2 pieces of terminal equipment transmits a preamble with the same preamble signature, there is a case where the base station has successfully captured the preamble code synchronization. Therefore, the two terminal devices receive a positive or on-capture indication signal corresponding to their preamble signature and transmit their user information data at a predetermined time. In this case, if all the power levels of the captured preamble and the like are enough to perform the preamble code acquisition at the base station, the base station transmits the user information to the receiver so as to synthesize the multipath signal from other user information data. Data cannot be successfully received. However, if only one preamble has a sufficient power level, the receiver of the base station combines the multipath signal of only one user information data with a sufficient power level, and successfully demodulates the user information data. It is possible to decrypt.

  FIG. 8 shows an example of an interference signal level of the reverse common channel apparatus according to the present invention. In FIG. 8, the level shown by the solid line is the interference level of the conventional reverse common channel arbitrary connection device, and the level shown by the broken line is the interference signal level of the reverse common channel random connection device according to the present invention. The hatched portion indicates the amount of decrease in the interference signal level by the reverse connection common channel random connection device according to the present invention as compared with the related art.

  As can be seen from FIG. 8, the reverse common channel optional connection apparatus according to the present invention reduces the interference signal level by increasing the amount of unnecessary data transmission, and increases the overall capacity. The effect on users using other channels can be minimized, and retransmission can be performed on a preamble basis, so that faster data transmission is possible.

  Next, transmission services for short data of various sizes using operations similar to the above-described operations will be described. At this time, if the data length exceeds a predetermined level, a dedicated channel or a reservation request is required. Therefore, the data length accepted by the arbitrary connection method is an integral multiple of the existing frame unit. Is also restrictive. For example, if the random access scheme can accommodate data whose length is four times the frame length, the terminal device must request a dedicated channel assignment or reserved channel for data whose length exceeds four times the frame length. .

  At this time, first, the preamble signature assigned for packet access in the base station must be classified according to the data length, and all terminal devices must recognize the preamble signature. In this way, it is easy to dynamically assign a preamble signature while taking into account the balance of traffic depending on the length of other data.

  When the terminal device attempts to transmit data on the reverse common channel, these determine characteristics of data traffic such as a length and a transmission rate of data to be transmitted. If the terminal device wants to transmit data through the random access method and device according to the present invention, it transmits a preamble with a preamble signature and transmits a message signal containing data by a capture indication. If the terminal attempts to transmit data via the dedicated channel or the reserved channel, the terminal transmits a preamble with the preamble signature and transmits a message signal requesting the dedicated channel or the reserved channel according to the acquisition indication signal. For example, if the terminal device attempts to transmit 40 ms of data using the random access method and device, the terminal device transmits a preamble using one of the preamble signatures allocated to the 40 ms data and forms four 10 ms frames. Then, this frame is transmitted continuously. And if one of the consecutively transmitted frames fails to transmit, only one is retransmitted. At this time, the terminal device selects a new preamble signature assigned to the data characteristic to be retransmitted in the same manner as described above, and transmits the preamble and the message signal.

  Next, an operation of requesting a channel reservation using a reverse common channel when the terminal apparatus needs to temporarily reserve a channel for transmitting data of an intermediate length will be described.

  That is, if the base station 200 correctly receives the data for channel reservation, the base station 200 notifies the corresponding terminal device of the channel reservation, the reserved time, the spreading code, and the allowable maximum transmission rate. The terminal device that has received the data transmits the data within the allowable maximum transmission rate using the spread spectrum code at the reserved time. At this time, the base station 200 performs a closed loop power control by transmitting a power control command signal (Power Control Command) using the forward common channel or a dedicated channel to the reserved terminal device.

  If the terminal device attempts to change the channel reservation condition during the channel reservation, the terminal device transmits data on the channel reservation condition to be changed in the same way as transmitting the preamble for the initial channel reservation. . Also, when the current data rate is lower than the maximum allowable data rate, the current message to be transmitted using data on the changed channel reservation condition can be multiplexed. Then, when the channel reservation is completed, the terminal device piggybacks the completion information in the last predetermined field, transmits the piggyback to the base station, and the base station 200 releases the reserved channel and time, This is notified to all terminal devices.

  The above-described method of reserving a channel of medium length data can also be used in an application field such as a packet voice service expected to be provided in the future.

  On the other hand, if the transmission data is long or a dedicated channel is required to service an audio signal, a method similar to the above-described channel reservation is used. First, the terminal device randomly selects one of the preamble signatures allocated for the dedicated channel, transmits the preamble, and receives the preamble code capture indication signal from the base station 200 to request the dedicated channel. Will be transmitted. Then, the terminal device transmits and receives data using the dedicated channel after the base station 200 notifies the base station 200 of how to allocate the dedicated channel (that is, whether the allocation is possible) and information on the spread spectrum code and the like. Also in this case, unlike the channel reservation request (that is, one of the preamble signatures allocated for channel reservation is selected and the preamble is transmitted), the terminal device is not limited to the frame length. , Can transmit data. In addition, since one or more dedicated channels are allocated to both the backward direction and the forward direction, closed loop power control can be easily realized.

  While the preferred embodiment of the invention has been illustrated and described, various changes, modifications and the like can be made. The detailed description does not limit the scope of the invention, which is defined by the appended claims.

FIG. 1 is a diagram illustrating a network configuration of a code division multiple access system to which the present invention is applied. FIG. 3 is a block diagram illustrating a configuration of a terminal device and a base station in a random access device for a reverse common channel in a code division multiple access system according to the present invention. FIG. 3 is a block diagram illustrating a configuration of a terminal first determining unit 110 in FIG. 2. FIG. 5 is an explanatory diagram for explaining an operation between a terminal device and a base station in a random access device according to the present invention. 4 is a flowchart illustrating an example of a connection control procedure of the terminal device according to the present invention. 4 is a flowchart illustrating an example of a connection control procedure of a base station according to the present invention. FIG. 4 is a diagram illustrating an operation of a random access device for a reverse common channel in a code division multiple access system according to the present invention. FIG. 3 is a diagram illustrating an example of an interference signal level due to a reverse common channel in the code division multiple access system according to the present invention. FIG. 3 is a diagram illustrating ALOHA data transmission using a reverse common channel in a conventional code division multiple access scheme.

Explanation of reference numerals

Reference Signs List 100 terminal device 110 terminal first determination unit 111 signature storage unit 112 signature selection unit 113 slot selection unit 114 power determination unit 120 terminal first transmission unit 130 terminal selection unit 140 terminal second processor 150 terminal reception unit 160 terminal second determination unit 170 terminal first processor 180 terminal second transmission unit 200 base station 210 base station processor 220 base station synchronization unit 230 base station determination unit 240 base station transmission unit 250 base station transceiver

Claims (32)

In a wireless terminal device that transmits data to a base station using a code division multiple access system,
Preamble generating means for generating a preamble signal using one preamble signature randomly selected from a plurality of available preamble signatures,
Data generating means for generating data for transmission;
Preamble transmission means for transmitting only the preamble signal generated from the preamble generation means using a randomly selected connection slot to the base station via a reverse common channel,
Transmitting the data to the base station or retransmitting another preamble signal in response to an acquisition indication signal indicating acquisition of the transmitted preamble signal received from the base station via a forward common channel. And a transmission control means for controlling the transmission.   When the transmission control means does not receive the capture indication signal, the transmission control means selects a new preamble signature by the preamble generation means, and uses the selected new preamble signature in the selected one preamble signature to generate the preamble signature. The wireless terminal device according to claim 1, wherein a preamble is transmitted to the base station at a preset time.   The wireless terminal device according to claim 1 or 2, wherein the preamble is transmitted using a connection slot randomly selected from available connection slots. The preamble generating means,
Under the control of the transmission control means, the selected one preamble signature corresponding to the traffic characteristics and a slot to be transmitted are randomly selected, and a forward path loss, an interference signal level transmitted from a base station, and the like are used. Terminal first determining means for determining the power of the preamble to be transmitted by
4. The wireless terminal device according to claim 3, further comprising: a terminal first transmission unit that generates a preamble signal using a slot to be transmitted, a preamble signature, a power level, and the like determined by the transmission resource determination unit.   The transmission control unit responds to a capture indication signal transmitted from the base station and selects a signal to be transmitted from a preamble generated by the preamble generation unit and data generated by the data generation unit. The wireless terminal device according to claim 1, further comprising signal selection means. The data generating means includes:
A terminal first processing unit that is enabled by confirming whether data transmission is performed from the transmission determination unit and that is adapted to transmit data to be transmitted;
And terminal second transmission means for receiving data to be transmitted from the terminal data processing means, selecting a code corresponding to a preamble signature to spread a band, and outputting the spread signal to the transmission signal selection means. The wireless terminal device according to claim 5, wherein The terminal first determining means,
A signature receiving unit that receives and stores information on a preamble signature assigned according to traffic characteristics, transmitted from the base station via a common channel,
Considering the characteristics of the generated data and the requirements in the upper layer, classifying the traffic characteristics and randomly selecting a preamble signature from the corresponding preamble signature, a signature selecting means,
Connection slot selection means for selecting a slot to be transmitted at random,
Including a base station interference signal level, a forward path loss, and a previously determined preamble power level, including power determining means for determining the power of the preamble to be transmitted according to a preset reference. The wireless terminal device according to claim 3, wherein: In a base station that receives data from a wireless terminal device using a code division multiple access method,
Receiving a preamble signal transmitted via the reverse common channel from the wireless terminal device, confirming whether or not the preamble signature has been captured, generating a capture confirmation signal corresponding to the captured preamble signature, and Preamble signature capturing means for outputting to the wireless terminal device via a common channel,
A base station data transmission / reception means for receiving data transmitted from the wireless terminal device using a despread code generated by using the preamble signature captured by the preamble signature capture means. . The preamble signature capturing means,
Base station synchronization means for receiving a preamble transmitted from the terminal device via a reverse common channel, and performing initial synchronization according to all available preamble signatures,
Notifying the base station data transmitting / receiving means of the total time delay characteristic corresponding to the captured preamble signature, and a base station and a transceiving means for preparing to receive immediately transmitted data,
The base station according to claim 8, further comprising: a capture indication signal output unit that outputs the captured preamble signature. The preamble signature capturing means,
Using the captured preamble signature to notify the corresponding band spreading code to the data transmitting / receiving unit, and a band spreading code generating unit that prepares to receive immediately transmitted data,
9. The base station according to claim 8, further comprising: the acquisition indication signal generating unit that inputs the acquisition preamble signature from the acquisition indication signal output unit and indicates the acquisition preamble signature. 10.   The capture indication signal generating means sets a corresponding time to a preamble signature, and outputs a capture indication signal as an on-off signal system for transmitting the capture indication signal only for a time corresponding to the capture preamble signature. The base station according to claim 9.   The capture indication signal output means sets a corresponding time to the preamble signature, and outputs a capture indication signal as an antipodal signal system that always transmits the capture signal at a time corresponding to all preamble signatures regardless of capture. The base station according to claim 9, wherein:   The capture indication signal output means assigns a corresponding orthogonal code to a preamble signature and sets the symbol to be transmitted, and outputs a capture indication signal as an on-off signal system for transmitting only the orthogonal code corresponding to the capture preamble signature. The base station according to claim 9, wherein:   The capture indication signal transmitting means assigns the orthogonal code to the preamble signature and sets the symbol to be transmitted, and sets the capture indication signal as an antipodal signal system that always transmits the symbol corresponding to all preamble signatures regardless of capture. The base station according to claim 10, wherein the base station is configured to output a signal. In a random connection method in which a plurality of terminal devices transmit data using a code division multiple access method,
In each terminal device, when data to be transmitted is generated, a preamble signature and a connection slot are each randomly selected, and only each preamble is transmitted to the base station via the reverse common channel. When,
In the base station, perform initial synchronization for all preamble signatures transmitted from the terminal device, generate a preamble capture confirmation signal corresponding to the captured preamble signature, and to all terminals via the forward common channel A terminal-to-terminal transmission step of transmitting;
Transmitting the data to the base station or retransmitting another preamble in response to an acquisition confirmation signal received from the base station via a forward common channel. A random access method for a reverse common channel in a code division multiple access system. In the transmitting to the base station, when data to be transmitted is generated, a preamble signature corresponding to traffic characteristics and a connection slot to be transmitted are randomly selected for transmitting a preamble, and the preamble is transmitted according to a preset method. A transmission resource determining step of determining the power of the preamble;
The code division multiplexing method according to claim 15, further comprising: a preamble transmission step of generating and transmitting a preamble signal using a transmission slot, a preamble signature, a power level, and the like determined in the transmission resource determination step. A random connection method for the reverse common channel in the connection method. The transmission resource determining step includes:
A signature information receiving step of receiving and storing information on a preamble signature assigned according to a traffic characteristic transmitted from the base station via a common channel,
A traffic characteristics determining step of classifying the traffic characteristics in consideration of the characteristics of the generated data and the requirements at the higher hierarchy;
A preamble signature selecting step of randomly selecting any one of the available preamble signatures;
A connection slot selection step of randomly selecting a connection slot to transmit randomly,
17. The method of claim 16, further comprising: determining a power of a preamble to be transmitted in open loop power control.   The previously set method may be set in consideration of an interference signal level of a base station transmitted from a base station via a common channel, a forward path loss, a power level previously transmitted from a preamble, and the like. 17. The method of claim 16, wherein the power level is adjusted by an amount.   The transmitting step to the base station uses the transmission slot, preamble signature and power level determined in the transmission resource determining step to spread and transmit a preamble signature using a common band spreading code. The random access method of the reverse common channel in the code division multiple access system according to claim 16. The step of transmitting to the base station,
20. The method of claim 19, wherein a complex band spread signal is generated using two common band spreading codes.   The code division multiple access system according to claim 15, wherein the retransmitting step receives a capture indication signal using a code used for a forward common channel and a code corresponding to a transmitted preamble signature. Random access method of reverse common channel in.   In a terminal device in which the preamble signature transmitted by itself is not captured, the transmission step to the base station, the transmission step to the terminal, and the retransmission step are repeated a preset number of times, wherein A random access method for a reverse common channel in the code division multiple access system described above. The terminal transmission step,
Initial synchronization step of receiving a preamble transmitted from the terminal device via a reverse common channel and performing initial synchronization according to all available preamble signatures,
A determination step of confirming whether or not the initial synchronization is performed from the initial synchronization step, determining and outputting an acquisition preamble signature,
Generating a capture indication signal corresponding to the capture preamble signature input from the determination step, and sending a capture indication signal to the terminal device;
Input the multipath time delay information obtained in the initial synchronization step, generate a despread code using information for the acquisition preamble signature input from the determination step, and from the terminal device via a reverse common channel 16. The random access of a reverse common channel in a code division multiple access system according to claim 15, further comprising a base station data transmission / reception step of receiving the transmitted data through a demodulation and channel decoding process. Method. The initial synchronization step includes:
An initial synchronization step of inputting a preamble transmitted from the terminal device via the reverse common channel and performing initial synchronization according to all useful preamble signatures,
A data reception preparation step of notifying the base station data transmission / reception step of all time delay characteristics corresponding to an acquisition preamble signature and preparing to receive data immediately transmitted;
24. The method according to claim 23, wherein the determining step includes a step of notifying a capture preamble signature. The determining step includes:
Using the capture preamble signature input from the initial synchronization step, informing the data transmitting / receiving means of the corresponding band spreading code, and preparing to receive immediately transmitted data,
24. The method according to claim 23, further comprising an output step of generating a signal only with an acquisition preamble signature and outputting the signal to the acquisition indication signal transmission step.   The capture indicating signal transmitting step includes four signal systems, namely, a first on-off signal system for setting a time corresponding to a preamble signature and transmitting a capture signal only during a time corresponding to the capture preamble signature, and a preamble. A first antipodal signal system in which a corresponding time is set in a signature and a capture signal is always transmitted at a time corresponding to all preamble signatures regardless of capture, and a corresponding orthogonal code is allocated to the preamble signature and transmitted. A second on-off signal system that sets only the symbol corresponding to the acquisition preamble signature, and assigns the corresponding orthogonal code to the preamble signature, and sets the symbol to be transmitted. Second antipodal signal transmitting a symbol corresponding to the preamble signature of Select any one of the signal system of the system, reverse common channel random access method in a code division multimeric connection system according to claim 23, wherein the transmitting to the acquisition indication signal transmission system.   The acquisition indicating signal transmission system includes a method of puncturing an existing forward common channel, a method of dedicating a separate channel having orthogonality to another forward common channel, and an orthogonality to another forward common channel. 27. The method of claim 26, wherein the transmission is performed by selecting one of a method dedicated to a channel not having the channel and a method of transmitting the selected channel. In the base station,
A channel reservation request for requesting a dedicated channel assignment to transmit large data;
Packet access for transmitting short data,
In response to a reservation request for transmitting data of an intermediate size, the characteristics of data to be transmitted through the reverse common channel are classified, and a preamble signature corresponding thereto is appropriately allocated so that all terminal devices can recognize the characteristics. The method according to claim 15, wherein the transmission is performed via a directional common channel.   29. The code division multiple access according to claim 28, wherein in the packet access, a preamble signature assigned to packet access for transmitting short data is further subdivided and assigned according to a length of data transmission. Random access method of reverse common channel in the scheme. For the channel reservation request,
One of the preamble signatures allocated for channel reservation from the terminal device is randomly selected and the preamble is transmitted in the same manner as the packet access, and the base station performs initial synchronization using the preamble transmitted from the terminal device. To inform all terminals via the forward common channel of the acquisition preamble signature,
The terminal device that has transmitted the preamble signature that is not captured, randomly selects one of the preamble signatures allocated for channel reservation, determines a time slot to transmit, and retransmits the preamble,
The terminal device that has transmitted the acquisition preamble signature transmits data for channel reservation, and then transmits data for reservation and attempts channel reservation.
The base station, after correctly receiving the data for channel reservation transmitted from the terminal device, informs the corresponding terminal of the reserved time and spreading code, the transmission rate, etc., using a common channel,
The corresponding terminal transmits data to be transmitted using a reserved time, a spreading code, a transmission rate, and the like, and performs closed-loop power control using a power control command transmitted to a forward channel,
29. The code division multiple access system according to claim 28, wherein when transmitting the last frame, information indicating that data transmission has been completed is included in the data and transmitted, and the channel reservation is canceled. Random connection method for common channels.   While the reserved channel is being used, in order to change the channel reservation condition, data for changing the channel reservation condition is transmitted simultaneously with the data transmission in the same manner as the operation for the packet access and the channel reservation request. 31. The random access method of a reverse common channel in the code division multiple access system according to claim 30. Upon receiving the acquisition confirmation signal transmitted from the base station, in the terminal device in which the preamble signature transmitted by itself is not acquired, the preamble signature and the slot are reset at random, and the preamble whose power has been adjusted by the already set amount is set. The method of claim 15, further comprising: a retransmission step of retransmitting the common channel.

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