JP2009212817A - Mobile station, processing module, wireless communication system, and connection establishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save wireless resources used for establishment of connections between mobile stations and a wireless base station and also improve response in data communication. <P>SOLUTION: This mobile station 30 repeatedly decides normality of a wireless link, after entry process (registration of location) to a wireless base station 10, depending on whether DL-MAP is extracted or not within the time of timer value Lost DL-MAP with a control signal extracting unit 33B. However, if DL-MAP cannot be extracted within the time of timer value Lost DL-MAP after synchronization of the wireless link, this synchronization of the wireless link is maintained by utilizing DL-MAP newly extracted from the wireless frame, after successive scanning of the wireless frame by a signal searching unit 33A and the other control signal, such as, UL-MAP previously extracted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile station, a processing module, a wireless communication system, and a connection establishment method.

Conventionally, a mobile communication system using OFDMA (Orthogonal Frequency Division Multiple Access) that realizes multiple access between a radio base station and a mobile station by dividing a carrier signal into a plurality of orthogonal subcarriers is known. ing. Details of this communication method are described in the following Non-Patent Document 1, and a procedure for establishing a connection between a mobile station and a radio base station is also defined. In this mobile communication system, after the location registration from the mobile station to the radio base station, the mobile station continuously monitors the reception of the downlink control signal, and when the downlink control signal cannot be received, the mobile station Rescan (signal search) radio frames from
“IEEE Standard for Local and metropolitan area networks Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands and Corrigendum 1”, IEEE Std, February 2006

  However, in the above communication method, the mobile station and the radio base station after re-scanning the radio frame and acquiring the control signal again when the reception of the control signal is interrupted regardless of the monitoring interval of the plurality of control signals Various control signals are exchanged between them, and a communication link between them is established again. In general, short-time disconnection of a radio link can occur frequently. As a result, a large amount of control signals are transmitted and received between the mobile station and the radio base station. Tend to occur.

  Therefore, the present invention has been made in view of such problems, and it is possible to reduce radio resources used when establishing a connection between a mobile station and a radio base station, and to improve response during data communication. An object is to provide a possible mobile station, a processing module, a wireless communication system, and a connection establishment method.

  In order to solve the above problems, a mobile station of the present invention is a signal for searching for a radio frame from a radio base station in a mobile station that transmits and receives uplink data and downlink data to and from the radio base station by orthogonal frequency division multiple access. A search means; a control signal extraction means for extracting a control signal including a downlink data reception control signal and an uplink data transmission control signal from the radio frame searched by the signal search means; and a radio base station after extracting the control signal Connection establishment means for establishing a communication connection for data communication with the radio base station by requesting location registration to the wireless base station, the connection establishment means after the communication connection is established, the control signal extraction means performs downlink data Whether the control signal for reception can be extracted within the predetermined timer value or not repeatedly determines the normality of the communication connection and When the downlink data reception control signal cannot be extracted within the predetermined timer value after the establishment, the downlink data reception control signal newly extracted from the radio frame after the search for the radio frame again by the signal search means The communication connection is maintained by using the control signal excluding the downlink data reception control signal extracted last time.

  Alternatively, the processing module of the present invention searches for a radio frame from a radio base station in a processing module built in a mobile station that transmits and receives uplink data and downlink data to and from the radio base station by orthogonal frequency division multiple access. A signal search means; a control signal extraction means for extracting a control signal including a downlink data reception control signal and an uplink data transmission control signal from the radio frame searched by the signal search means; and A connection establishment means for establishing a communication connection for data communication with the radio base station by requesting a location registration from the station, and the connection establishment means is downloaded by the control signal extraction means after the communication connection is established. The normality of the communication connection is repeatedly judged depending on whether or not the data reception control signal can be extracted within the predetermined timer value. In both cases, when the downlink data reception control signal cannot be extracted within the predetermined timer value after the establishment of the communication connection, the downlink data newly extracted from the radio frame after the radio frame is searched again by the signal search means. The communication connection is maintained using the reception control signal and the control signal excluding the previously extracted downlink data reception control signal.

  Alternatively, the connection establishment method of the present invention is a connection establishment method in a mobile station that transmits and receives uplink data and downlink data to and from a radio base station by orthogonal frequency division multiple access. A signal search step for searching for a radio frame, and a control signal extraction unit for extracting a control signal including a control signal for downlink data reception and a control signal for uplink data transmission from the radio frame searched by the signal search unit A connection establishment step, wherein the connection establishment means establishes a communication connection for data communication with the radio base station by requesting location registration from the radio base station after extracting the control signal. In the establishing step, after the communication connection is established, the control signal extracting means sends the downlink data reception control signal within a predetermined timer value. The normality of the communication connection is repeatedly determined depending on whether it can be transmitted, and if the downlink data reception control signal cannot be extracted within the predetermined timer value after establishment of the communication connection, the A communication connection is maintained using a downlink data reception control signal newly extracted from the radio frame after the frame is searched again and a control signal excluding the previously extracted downlink data reception control signal. And

  According to such a mobile station, a processing module, and a connection establishment method, when a communication connection with a radio base station is established by orthogonal frequency division multiple access, a radio frame from the radio base station is searched, A control signal including a downlink data reception control signal and an uplink data transmission control signal is extracted from the radio frame, and location registration is requested from the radio base station. After the communication connection is established in this way, the reception of the downlink data reception control signal is monitored at a predetermined timer value time interval to determine the normality of the communication connection, and the downlink data reception control signal When reception is interrupted, a downlink data reception control signal is newly extracted from the re-searched radio frame, and the downlink data reception control signal and control signals other than the previously received downlink data reception control signal The communication connection is maintained using. As a result, even if reception of the downlink data reception control signal, which generally tends to have a short monitoring interval, is interrupted for a moment, the communication connection is efficiently maintained in a short time by reusing the control signal received last time. The radio resources used at the time of establishment are also effectively reduced. As a result, it is possible to improve the response at the time of data communication in the mobile station.

  The connection establishment means cannot extract the downlink data reception control signal after establishing the communication connection, and if a response from the radio base station cannot be received when exchanging the control signal in the communication connection, It is preferable to newly establish a communication connection by newly extracting all control signals from the radio frame and using the control signals.

  In this way, if reception of the control signal for downlink data reception is interrupted and a response from the radio base station at the time of control signal exchange cannot be received, the radio signal is extracted by extracting all control signals from the re-searched radio frame. The communication connection with the base station can be reliably restored.

  Further, the connection establishment means cannot extract the downlink data reception control signal after establishing the communication connection, and if the response from the radio base station cannot be received when the control signal is exchanged in the communication connection, It is also preferable that after the search, all control signals are newly extracted from the radio frame and a handover is requested to the radio base station by using the control signals.

  If such a configuration is adopted, if reception of the control signal for downlink data reception is interrupted and a response from the radio base station at the time of control signal exchange cannot be received, all control signals are extracted from the re-searched radio frame and connected. By executing switching (handover) of the partner radio base station, it is possible to reduce control signals transmitted and received at the time of reconnection, so that the communication connection with the radio base station can be reliably and efficiently recovered.

  The radio communication system of the present invention includes the above-described mobile station and a radio base station that transmits and receives uplink data and downlink data to and from the mobile station.

  Alternatively, the connection establishment method of the present invention is a connection establishment method in a wireless communication system in which uplink data and downlink data are transmitted and received between a mobile station and a radio base station by orthogonal frequency division multiple access. A signal search step for searching for a radio frame from the station, and a control signal for the mobile station to extract a control signal including a downlink data reception control signal and an uplink data transmission control signal from the radio frame searched by the signal search step A connection step comprising: an extraction step; and a connection establishment step in which the mobile station establishes a communication connection for data communication with the radio base station by requesting location registration from the radio base station after extracting the control signal. In the establishing step, after establishing the communication connection, the control signal extracting step transmits the downlink data reception control signal to a predetermined timer value. If the control signal for downlink data reception cannot be extracted within the predetermined timer value after establishment of the communication connection, the signal search step is performed. A communication connection is maintained using a downlink data reception control signal newly extracted from the radio frame after the search for the radio frame again and a control signal excluding the downlink data reception control signal extracted last time. And

  When the radio base station receives a control signal for securing the data communication band from the mobile station and the communication connection is in an open state, the radio base station sends a control signal for requesting the mobile station to release the communication connection. It is preferable to send it out. In this case, even when a mismatch occurs in the management state of communication connection between the radio base station and the mobile station, the state can be matched, and the reconnection with the mobile station is facilitated to further improve the communication response. be able to.

  According to the present invention, it is possible to reduce radio resources used when establishing a connection between a mobile station and a radio base station, and to improve response during data communication.

  Hereinafter, preferred embodiments of a mobile station, a processing module, a wireless communication system, and a connection establishment method according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  1 to 3 are schematic configuration diagrams of a radio communication system 100, a radio base station 10, and a mobile station 30, respectively, according to a preferred embodiment of the present invention. As shown in FIG. 1, a radio communication system 100 according to the present embodiment includes a radio base station 10 and a mobile station 30, and includes orthogonal frequency division multiple access (OFDMA: Orthogonal Frequency Frequency) compliant with IEEE802.16e. This is a communication system that transmits and receives uplink data and downlink data between the radio base station 10 and the mobile station 30 using Division Multiple Access. OFDMA is a type of multicarrier transmission in which the entire band of a transmission carrier is divided into subcarriers on the frequency axis, and a radio signal is transmitted as a bundle of a plurality of narrowband subcarriers. For example, 5 MHz, 10 MHz, or 20 MHz is selected as the bandwidth of the transmission carrier. Here, the radio communication system 100 may include a plurality of radio base stations and a plurality of mobile stations.

  First, functional configurations of the radio base station 10 and the mobile station 30 will be described in detail.

As illustrated in FIG. 2, the radio base station 10 includes an error correction encoding unit 11 _{1 to} 11 _N , a modulation unit 12 _{1 to} 12 _N , a multiplexing unit 13, a channel assignment control unit 14, an OFDM signal generation unit 15, a transmission Unit 16, receiving unit 17, OFDM signal detecting unit 18, channel allocation analyzing unit 19, separating unit 20, demodulating units 21 _{1 to} 21 _N , and error correction decoding units 22 _{1 to} 22 _N.

Each piece of transmission information (downlink user data) to be transmitted to a plurality of mobile stations 30 is subjected to error correction coding processing by the error correction coding units 11 _{1 to} 11 _N , and each error correction coding unit 11 ₁ redundant bit information after outputted error correction coding processing from to 11 _N, as a division multiplexed DL user data time via a modulation unit 12 ₁ to 12 _N and the multiplexing unit 13 (downlink data) Generated. The DL user data output from the multiplexing unit 13 is set in a radio frame by the channel assignment control unit 14, and these radio frames are converted into radio signals for OFDMA by the OFDM signal generation unit 15. Is transmitted to the external mobile station 30 by the transmitter 16 using OFDMA.

In addition, a radio signal including a radio frame in which reception information (uplink user data) transmitted from a plurality of mobile stations 30 to the radio base station 10 is set is received by the reception unit 17 using OFDMA. The received radio signal is detected by the OFDMA signal detection unit 18 so that a radio frame is extracted from the radio signal. Then, after the user data is separated from the radio frame into time-division multiplexed UL user data (uplink data) by the channel allocation analysis unit 19, the UL user data is separated from each mobile station 30 by the separation unit 20. To UL user data. Each UL user data is demodulated by the demodulating units 21 _{1 to} 21 _N , and then subjected to error correction decoding processing by the error correction decoding units 22 _{1 to} 22 _N to be restored to received information from each mobile station 30. Is done.

  Next, the configuration of a radio frame generated by the radio base station 10 will be described. FIG. 4A conceptually shows a data arrangement on the time axis of radio frames assigned by the channel assignment control unit 14 of the radio base station 10. As shown in the figure, a subchannel is assigned to a radio frame on a predetermined basis for each subchannel logical number. Specifically, a plurality of sets of subcarriers are selected from a plurality of subcarriers distributed on the frequency axis within a frequency band that can be transmitted by the radio base station 10 by the channel assignment control unit 14, and the plurality of sets of subcarriers are selected. A subchannel identified by a subchannel logical number is assigned to each group. Various data are set on the subchannel of the radio frame by time division multiplexing.

In addition, the radio frame is transmitted to the downlink unit DL that stores downlink data transmitted from the radio base station 10 to the mobile station 30 and the uplink unit UL that stores uplink data transmitted from the mobile station 30 to the radio base station 10. Are generated separately. In this downlink part DL, a preamble part D _P for synchronizing the radio frame on the receiving side, a control data part D _C in which a control signal for notification from the radio base station 10 to the mobile station 30 is set, and user data part D _U is arranged to store the DL user data of a plurality of mobile stations 30 for. The FIG. 4 (b), the is a conceptual diagram illustrating in greater detail the data sequence on the time axis of the control data part D _C of the radio frame. As shown in the figure, the control data section D _C includes a frame control header (FCH) D _C1 for identifying a sub-channel used in the radio frame, other control signal for notifying the mobile station 30 is set Mapping information _DC2 is included.

More specifically, as the control information set in the mapping information _{D C2, DL-MAP, UL} -MAP, DCD , and the like. DL-MAP is a downlink data reception control signal indicating a setting area of DL user data in a subchannel specified by FCH. UL-MAP is an uplink data transmission control signal indicating a setting area of UL user data in a subchannel specified by FCH. The DCD (Downlink Channel Descriptor) is for notifying the mobile station 30 of the physical characteristics of the DL channel at a predetermined cycle (for example, 10 seconds). Here, DL-MAP and UL-MAP are control information that is always set in a radio frame, and are referred to when DL user data is extracted from a radio frame and when UL user data is set in a radio frame. The

  Next, moving to FIG. 3, the mobile station 30 includes a receiver 31, an OFDM signal detector 32, a communication controller 33, a demodulator 34, an error correction decoder 35, an error correction encoder 36, a modulator 37, An OFDM signal generation unit 39 and a transmission unit 40 are included. The mobile station 30 includes a processing module in which a CPU, a memory, a communication module, and the like are mounted, and the above-described units are configured to operate on the processing module.

  The receiving unit 31 receives a radio signal including a radio frame transmitted from the radio base station 10 using OFDMA. The received radio signal is detected by the OFDM signal detector 32, and a radio frame is extracted from the radio signal. Then, the demodulator 34 extracts DL user data from the radio frame. Further, the DL user data is demodulated from the time-division multiplexed data by the demodulator 34, and then subjected to error correction decoding processing by the error correction decoding unit 35 to be restored to reception information addressed to the mobile station 30. Further, the error correction decoding unit 35 outputs the radio frame after the data demodulation processing and error correction decoding processing to the communication control unit 33.

  Further, transmission information to be transmitted from the mobile station 30 to the radio base station 10 is subjected to error correction coding processing by the error correction coding unit 36, and error correction coding processing output from the error correction coding unit 36 is performed. The subsequent redundant bit information is modulated by the modulation unit 37. Further, the UL user data subjected to the modulation processing is set in a radio frame by the modulation unit 37, and the radio frame is converted into an OFDMA radio signal by the OFDM signal generation unit 39. Then, the radio signal is transmitted to the radio base station 10 by the transmitter 40 using OFDMA. Further, various control signals output from the communication control unit 33 are output to the OFDM signal generation unit 39 via the error correction encoding unit 36 and the modulation unit 37, and are set in the radio frame.

  The communication control unit 33 has a function of executing synchronization establishment processing of a communication connection (radio link) with a radio base station when transmitting / receiving UL user data and DL user data to / from the radio base station 10. The signal search unit (signal search unit) 33A, the control signal extraction unit (control signal extraction unit) 33B, and the connection establishment unit (connection establishment unit) 33C are included.

The signal search unit 33A scans (searches) a radio frame from the radio base station 10 when establishing radio link synchronization with the radio base station 10 and determining a radio link synchronization establishment state. . The scan of the radio frame is performed, for example, by the preamble part D _P in the radio frame is analyzed whether it normally acquired.

Control signal extraction section 33B is used from among the control data part _{D C} of the radio frame is scanned by the signal search section 33A DL-MAP, UL-MAP, when transmission and reception of the DL user data and UL user data DCD such as control Extract the signal. The extracted control signal is passed to the connection establishment unit 33C.

  The connection establishment unit 33C requests the radio base station 10 to perform an entry process (Initial Entry) that is a location registration process in order to make the communication service by the radio base station 10 available. Wireless connection, that is, synchronization establishment of the downlink wireless link. Further, once the entry process is completed, the connection establishment unit 33C determines the wireless synchronization state with the entry target wireless base station 10, and executes the entry process again when the synchronization is lost. Specifically, the connection establishment unit 33C determines the normality of the synchronization establishment state based on whether or not DL-MAP and DCD can be periodically extracted from the radio frame every time specified by a predetermined timer value. . When the DL-MAP or DCD cannot be extracted, the connection establishment unit 33C newly extracts a DL-MAP (Scan for DL Channel) from the radio frame scanned again by the signal search unit 33A. Then, using the extracted DL-MAP and the control signal excluding the DL-MAP extracted in the previous entry process, the establishment of the synchronization of the radio link and the entry state are maintained without executing the entry process. Operate. In addition, the connection establishment unit 33C did not obtain a response from the radio base station 10 when exchanging control signals other than DL-MAP and DCD executed to start data communication with the radio base station 10. In this case, it also has a function of executing the entry process to the radio base station 10 again.

  Next, with reference to FIGS. 5 to 9, the radio link synchronization establishment operation of the radio communication system 100 including the radio base station 10 and the mobile station 30 will be described, and the connection establishment method in the radio communication system 100 will be described in detail. Describe.

  FIGS. 5 and 6 are flowcharts showing operations when the mobile station 30 executes entry processing (InitialEntry) for the radio base station 10.

  First, as an initial stage of entry processing, DL synchronization establishment processing (Scan for DL Channel) is performed by the mobile station 30 (steps S101 and S201 to S209). This DL synchronization establishment process is a process for receiving DL-MAP. First, the connection establishment unit 33C starts counting the timer value T20 (step S201). Then, the radio frame is scanned on the frequency axis of the channel i by the signal search unit 33A (step S202). When the radio frame scan is successful (step S203), the connection establishment unit 33C starts counting the timer value T21 (step S204). On the other hand, if the scan of the radio frame fails before the timer value T20 times out, the next channel i + 1 scan is repeated (step S208). Next, after the DL-MAP is extracted from the radio frame by the control signal extraction unit 33B (step S205), the connection establishment unit 33C starts counting the timer values Lost DL-MAP, T1, T12 (step S206). . In this way, DL synchronization establishment is completed (step S207). On the other hand, if the DL-MAP cannot be extracted before the timer value T21 times out (step S209), the radio frame of the next channel i + 1 is scanned again.

  After executing the DL synchronization establishment, the control signal extracting unit 33B acquires UL parameters for uplink data transmission such as UL-MAP from the radio frame (step S102). Further, the connection establishment unit 33C sends a ranging process request to the radio base station 10 (step S103). The ranging process is a process for adjusting the transmission timing, transmission power, and transmission frequency so that an uplink signal can be transmitted with an optimum quality. Thereby, an adjustment parameter is received from the radio base station 10. After completion of the ranging process, other control information exchange process (step S104), authentication process (step S105), location registration process to the radio base station 10 (step S106), and IP connection establishment process (step S107) Subsequently, a connection for data communication is established (step S108).

  After the entry process is completed as described above, the synchronization establishment state is monitored by the mobile station 30 to perform a process for maintaining the synchronization establishment. FIG. 7 and FIG. 8 are flowcharts showing the operation when the mobile station 30 executes the radio link synchronization establishment maintaining process.

  After shifting to the synchronization state upon completion of entry processing (step S301), DL-MAP is periodically extracted from the radio frame newly scanned by the connection establishment unit 33C (step S302). When the DL-MAP extraction is successful, the timer value Lost DL-MAP is reset by the connection establishment unit 33C (step S303), and the radio link synchronization establishment state is maintained (step S306). At the same time, the DCD is also extracted from the radio frame newly scanned by the connection establishment unit 33C (step S304). When the DCD extraction is successful, the timer value T1 is reset by the connection establishment unit 33C (step S305), and the wireless link synchronization establishment state is maintained (step S306).

  On the other hand, when the DL-MAP or DCD extraction fails before the timer value Lost DL-MAP or the timer value T1 times out (steps S307 and S308), only the control signal for downlink data reception is again transmitted by the connection establishment unit 33C. The extracted DL resynchronization establishment process (Scan for DL Channel) is executed (steps S309 and S401 to S409). For example, 600 msec is set as the timer value Lost DL-MAP, and a maximum of 10 sec is set as the timer value T1. From this, it can be seen that DL-MAP and DCD are parameters monitored at a relatively short time interval.

  The DL re-synchronization establishment process (see FIG. 8) is almost the same as the DL synchronization establishment process shown in FIG. 6, but reuses radio parameters such as channel information used in the previous DL synchronization establishment process in step S401. The difference from the DL synchronization establishment processing is that the wireless frame is scanned, and the wireless frame of the same channel is continuously scanned even if the scanning of the wireless frame fails in step S408. This takes into account that if the radio link is disconnected in a short time, it is highly likely that a radio frame of the same channel can be scanned again.

  When the DL resynchronization establishment process is completed, the state transitions to a DL synchronization establishment state (step S310), and the process returns to step S301 to periodically monitor the DL-MAP and DCD by the connection establishment unit 33C. In addition, when the DL resynchronization establishment process is completed, a periodic ranging request is transmitted from the mobile station 30 to the radio base station 10, and when there is no response to the ranging request between the timer values T4 (steps) In step S311), the connection establishing unit 33C releases the wireless link connection (step S313). As the timer value T4, for example, a relatively long time such as 30 to 35 seconds is set. Further, even when there is no response from the radio base station 10 in response to a predetermined number of response requests from the mobile station 30 during uplink data and downlink data retransmission control (ARQ Retry) after the DL resynchronization establishment processing is completed. (Step S312), the wireless link connection is released (Step S313). Thereafter, the entry process (see FIG. 5) is executed again (step S314), and the state shifts to the synchronization established state in step S301.

  On the other hand, if the synchronization release signal (DREG-CMD) is received from the radio base station 10 while the mobile station 30 is in the synchronization established state (step S315), communication within the mobile station 30 is performed by the connection establishing unit 33C. The connection state, that is, the entry of the radio link is released (step S316). Such entry release is performed by updating entry information held in a memory in the mobile station 30. Then, entry processing is executed by the connection establishing unit 33C (step S314). This synchronization release signal (DREG-CMD) is used to forcibly match the connection state of the radio link when there is a mismatch in the connection state of the radio link between the radio base station 10 and the mobile station 30. Command.

  Here, FIG. 9 shows an operation when the radio base station 10 transmits a synchronization release signal (DREG-CMD). When the radio base station 10 is waiting for a signal from the mobile station 30 in a normal state (step S601), the radio base station 10 can receive a band request signal and a ranging request for securing a data communication band from the mobile station 30. Here, when a ranging request is received from the mobile station 30 (step S602), a ranging process is performed according to the request (step S603), and the process returns to step S601.

  On the other hand, when the band request signal is received from the mobile station 30 (step S604), the radio base station 10 transmits an uplink signal transmission control signal such as UL-MAP to the mobile station 30 (step S605). Next, when the radio base station 10 receives a bandwidth request signal (BRH) for notifying the requested bandwidth from the mobile station 30 (step S606), the entry of the radio link with the mobile station 30 is “connected state”. It is determined by referring to the entry information held in the internal memory of the radio base station 10 (step S607). As a result, when the entry of the radio link is in the “open state” (step S607; NO), the radio base station 10 sends a synchronization release signal (DREG−) to the mobile station 30 in order to eliminate the mismatch of the entries. CMD) is transmitted (step S610). On the other hand, when the entry of the radio link is in the “connected state” (step S607; YES), the radio base station 10 transmits the UL-MAP to the mobile station 30 (step S608) and then moves. UL user data is received from the station 30 (step S609).

  According to the wireless communication system 100 and the connection establishment method using the wireless communication system 100 described above, when the wireless link between the mobile station 30 and the wireless base station 10 is established, the mobile station 30 The radio frame is scanned, a control signal including DL-MAP, UL-MAP, and the like is extracted from the radio frame, and an entry is requested from the radio base station 10. After the radio link is established in this way, the reception of DL-MAP is monitored at the time interval of the timer value Lost DL-MAP to determine the normality of the radio link, and the reception of DL-MAP is interrupted. In this case, DL-MAP is newly extracted from the re-scanned radio frame, and establishment of the radio link is maintained using the DL-MAP and other control signals such as UL-MAP received last time. The As a result, even if DL-MAP reception, which generally tends to have a short monitoring interval, is interrupted for a moment, the radio link can be efficiently made in a short time by reusing the control signal and radio parameters of the radio base station received last time. The radio resources used when establishing the radio link are also effectively reduced. As a result, the response at the time of data communication in the mobile station 30 can be improved.

  In addition, when the reception of DL-MAP is interrupted after the connection of the radio link is established and a response from the radio base station 10 at the time of control signal exchange in the ranging process or the retransmission process cannot be received, the radio frame scanned again by the mobile station 30 By extracting all control signals from, the communication connection between the radio base station 10 and the mobile station 30 can be reliably recovered.

  Further, when the radio base station 10 receives the bandwidth request signal (BRH) from the mobile station 30 and the radio link entry is in the “open state”, the radio base station 10 requests the mobile station 30 to open the radio link. Since the synchronization release signal (DREG-CMD) is transmitted, even if a mismatch occurs in the entry state of the wireless link between the wireless base station 10 and the mobile station 30, the state can be matched. It is possible to further improve the communication response by facilitating reconnection.

  In addition, this invention is not limited to embodiment mentioned above. For example, if the mobile station 30 stops receiving the DL-MAP after establishing the wireless link connection and cannot receive a response from the radio base station 10 at the time of control signal exchange in the ranging process and the retransmission process, the mobile station 30 The base station 10 may be operated to request a handover.

  FIG. 10 is a flowchart showing an operation when the mobile station 30 executes the radio link synchronization establishment maintaining process in such a case. The operations in steps S501 to S505 in the figure are the same as the operations in steps S301 and S307 to S310 in FIG. If no response is received during the timer value T4 with respect to the ranging request after the DL resynchronization establishment process is completed (step S506), the DL establishment process (FIG. 6) is performed by the connection establishment unit 33C. Radio frame scanning and DL-MAP re-extraction are performed (step S508). In addition, even when there is no response from the radio base station 10 in response to a predetermined number of response requests from the mobile station 30 during uplink data and downlink data retransmission control (ARQ Retry) after the DL resynchronization establishment processing is completed. (Step S507) The DL establishment process (FIG. 6) is performed by the connection establishment unit 33C (Step S508). Thereafter, another downlink control signal is acquired from the radio base station 10 by the connection establishment unit 33C (step S509). Then, the connection establishing unit 33C determines whether or not the operator ID included in the acquired DL-MAP matches the operator ID at the previous synchronization establishment (step S510). As a result of the determination, if it matches the previous operator ID (step S510; YES), after the handover is requested to the radio base station 10 (step S511), further downlink control is performed from the radio base station 10. A signal is acquired and a ranging request is made to shift to a synchronization established state (step S512). On the other hand, if it does not match the previous operator ID (step S510; NO), the connection establishment unit 33C executes the entry process again with the radio base station 10 (step S513).

  Thus, by extracting all control signals from the radio frame scanned again when the radio link is out of synchronization and requesting switching (handover) of the radio base station 10 from the mobile station 30, a new one is newly created. Since control signals transmitted and received at the time of reconnection can be reduced as compared with the case of performing radio link synchronization establishment processing (Initial Entry), the connection of the radio link between the mobile station 30 and the radio base station 10 is ensured and efficient. Can be recovered. In addition, since the location registration in the radio base station 10 is not deleted by switching the radio link by handover, an efficient radio link connection is realized.

1 is a schematic configuration diagram of a wireless communication system according to a preferred embodiment of the present invention. It is a schematic block diagram of the radio base station concerning suitable one Embodiment of this invention. It is a schematic block diagram of the mobile station concerning suitable one Embodiment of this invention. FIG. 3 is a conceptual diagram showing a radio frame created by the radio base station of FIG. 2. 4 is a flowchart showing an operation when the mobile station of FIG. 3 executes wireless link entry processing (Initial Entry). 4 is a flowchart showing an operation when the mobile station of FIG. 3 executes wireless link entry processing (Initial Entry). 4 is a flowchart showing an operation when the mobile station 30 of FIG. 3 executes a synchronization establishment maintenance process of a radio link. 4 is a flowchart showing an operation when the mobile station 30 of FIG. 3 executes a synchronization establishment maintenance process of a radio link. 3 is a flowchart showing an operation when the radio base station of FIG. 2 transmits a synchronization release signal (DREG-CMD). It is a flowchart which shows the operation | movement at the time of performing the synchronization establishment maintenance process of the radio link by the mobile station concerning the modification of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wireless base station, 30 ... Mobile station, 33A ... Signal search part (signal detection means), 33B ... Control signal extraction part (control signal extraction means), 33C ... Connection establishment part (connection establishment means), 100 ... Wireless communication system.

Claims (8)

In a mobile station that transmits and receives uplink data and downlink data to and from a radio base station by orthogonal frequency division multiple access,
Signal searching means for searching for a radio frame from the radio base station;
Control signal extraction means for extracting a control signal including a downlink data reception control signal and an uplink data transmission control signal from the radio frame searched by the signal search means;
Connection establishment means for establishing a communication connection for data communication with the radio base station by requesting location registration to the radio base station after the extraction of the control signal;
The connection establishment means repeats normality of the communication connection depending on whether the control signal extraction means can extract the downlink data reception control signal within a predetermined timer value after the communication connection is established. And when the downlink data reception control signal cannot be extracted within the predetermined timer value after establishment of the communication connection, the radio frame is searched after the radio frame is searched again by the signal search means. Maintaining the communication connection using the downlink data reception control signal newly extracted from and the control signal excluding the downlink data reception control signal previously extracted,
A mobile station characterized by that. The connection establishing means cannot extract the downlink data reception control signal after establishment of the communication connection, and if the response from the radio base station cannot be received at the time of control signal exchange in the communication connection, Newly extracting all the control signals from the radio frame after the search for a frame again, and newly establishing the communication connection by using the control signals;
The mobile station according to claim 1. The connection establishing means cannot extract the downlink data reception control signal after establishment of the communication connection, and if the response from the radio base station cannot be received at the time of control signal exchange in the communication connection, Newly extracting all the control signals from the radio frame after the search for the frame again, and requesting handover to the radio base station by using the control signal,
The mobile station according to claim 1. In a processing module built in a mobile station that transmits and receives uplink data and downlink data to and from a radio base station by orthogonal frequency division multiple access,
Signal searching means for searching for a radio frame from the radio base station;
Control signal extraction means for extracting a control signal including a downlink data reception control signal and an uplink data transmission control signal from the radio frame searched by the signal search means;
Connection establishment means for establishing a communication connection for data communication with the radio base station by requesting location registration to the radio base station after the extraction of the control signal;
The connection establishment means repeats normality of the communication connection depending on whether the control signal extraction means can extract the downlink data reception control signal within a predetermined timer value after the communication connection is established. And when the downlink data reception control signal cannot be extracted within the predetermined timer value after establishment of the communication connection, the radio frame is searched after the radio frame is searched again by the signal search means. Maintaining the communication connection using the downlink data reception control signal newly extracted from and the control signal excluding the downlink data reception control signal previously extracted,
A processing module characterized by that.   A radio communication system comprising: the mobile station according to claim 1; and a radio base station that transmits and receives uplink data and downlink data between the mobile station. The radio base station requests the mobile station to release the communication connection when the communication connection is in an open state when receiving a control signal for securing a data communication band from the mobile station. Send control signal,
The wireless communication system according to claim 5. In a connection establishment method in a mobile station that transmits and receives uplink data and downlink data to and from a radio base station by orthogonal frequency division multiple access,
A signal search step for searching for a radio frame from the radio base station by a signal search means;
A control signal extracting step for extracting a control signal including a control signal for downlink data reception and a control signal for uplink data transmission from the radio frame searched by the signal search means;
A connection establishing step for establishing a communication connection for data communication with the radio base station by requesting location registration to the radio base station after the control signal is extracted;
In the connection establishing step, after the communication connection is established, the normality of the communication connection is repeated depending on whether or not the control signal extracting means can extract the downlink data reception control signal within a predetermined timer value. And when the downlink data reception control signal cannot be extracted within the predetermined timer value after establishment of the communication connection, the radio frame is searched after the radio frame is searched again by the signal search means. Maintaining the communication connection using the downlink data reception control signal newly extracted from and the control signal excluding the downlink data reception control signal previously extracted,
A connection establishment method characterized by the above. In a connection establishment method in a radio communication system that transmits and receives uplink data and downlink data between a mobile station and a radio base station by orthogonal frequency division multiple access,
A signal search step for the mobile station to search for a radio frame from the radio base station;
A control signal extraction step in which the mobile station extracts a control signal including a downlink data reception control signal and an uplink data transmission control signal from the radio frame searched in the signal search step;
A connection establishment step for establishing a communication connection for data communication with the radio base station by requesting location registration to the radio base station after the mobile station extracts the control signal;
In the connection establishing step, after the communication connection is established, the normality of the communication connection is repeated depending on whether the control signal extraction step can extract the downlink data reception control signal within a predetermined timer value. And when the downlink data reception control signal cannot be extracted within the predetermined timer value after the establishment of the communication connection, the radio frame is searched after the radio frame is searched again by the signal search step. Maintaining the communication connection using the downlink data reception control signal newly extracted from and the control signal excluding the downlink data reception control signal previously extracted,
A connection establishment method characterized by the above.

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