JP2007060145A - Wireless communication system and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain an efficient transmission/reception processing and a re-transmission processing when fragmentarily transmitting/receiving a large capacity of content data to be downloaded from a master set to a slave set. <P>SOLUTION: The master set includes: a means that divides the contents data of a large capacity into fragments of a size D and gathers N fragments sequentially from the top fragment to form M sequences; a means that consecutively transmits N fragments of one sequence and records transmitted fragments to a transmission fragment table as transmission complete fragments; and a means that receives a contents ACK informed from the slave set within a prescribed time Tack after the transmission of all the fragments of one sequence, retransmits fragments not received yet by the slave set on the basis of the information of the contents ACK if there are unreceived fragments, resets the transmission fragment table when receiving the contents ACK denoting reception completion of N fragments, and sequentially transmits the fragments of the M sequences. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication system and a wireless communication method for dividing and transmitting and receiving large-capacity data downloaded from a parent device to a child device in a wireless LAN system that performs wireless communication between the parent device and a child device.

  Conventional packet communication includes a method of dividing and transmitting large-capacity data (Patent Document 1). That is, when a transmitting terminal (master unit) transmits large-capacity data, it is divided into a plurality of packets (fragments) and a sequential number is assigned to each packet. The receiving terminal (slave unit) monitors the sequence number of each packet, and transmits the missing information to the transmitting terminal when the missing packet is found. The transmitting terminal recognizes the sequence number of the missing packet from the missing information transmitted from the receiving terminal, and retransmits the packets after the sequence number.

  For example, when the sequence number of the packet received at the receiving terminal is “1, 2,..., N−1, n + 1”, the receiving terminal determines that the packet with the sequence number n is missing and transmits the missing information to the transmitting terminal. To do. The transmitting terminal transmits packets after sequence number n, that is, packets with sequence numbers n, n + 1, n + 2,. When a large amount of data is divided and transmitted / received, packet communication without data loss is possible by using a retransmission protocol of such a simple procedure.

Now, when TCP / IP (Transmission Control Protocol / Internet Protocol) is used when sending and receiving large volumes of data separately, transmission quality and reliability are improved by retransmission processing, but a reception response (ACK) is awaited. Since the next packet is transmitted after that, the throughput decreases. In addition, when the above retransmission protocol is applied to a protocol such as UDP / IP (User Datagram Protocol / Internet Protocol) that does not guarantee transmission quality, communication with high throughput and reliability is possible. In any case, however, since the receiving terminal transmits missing information every time it finds a missing packet, the efficiency is poor. In addition, when retransmitting, not only the missing packet but also subsequent packets are retransmitted, which is inefficient.
Japanese Patent No. 3533715

  By the way, services that can bring wireless LAN devices into the public wireless LAN service area and download content data such as newspaper articles, route search, English conversation learning software, electronic book software, etc. from access points in the public wireless LAN service area have become widespread. It's getting on. Furthermore, a service is also provided in which necessary content data can be automatically downloaded just by a user passing through a public wireless LAN service area. Here, it is necessary to complete the reception of the content data in a short time while the user passes through the public wireless LAN service area. However, if the data size is large, the download may take time and the download may not be completed. .

  On the other hand, since the size of data that can be transmitted at a time is limited, when downloading large-capacity data from the master unit to the slave unit, the master unit divides it into multiple packets (fragments) and sends it to the child unit. The method of synthesizing them with a machine is taken. At this time, there is a need for a transmission / reception method that efficiently transmits / receives and retransmits a plurality of divided packets (fragments) and enables downloading of large-capacity data in a short time.

  There is a technique called “block ACK” in which a plurality of packets are continuously transmitted and received, and then reception responses of the plurality of packets are collectively collected. With this technique, throughput can be improved as compared with a method in which a reception response is performed for each packet. However, as shown in FIG. 25, when the parent device transmits a plurality of packets, transmission starts according to the polling packet (CF-Poll) from the child device. Further, the master unit transmits a block ACK request at the end of a plurality of continuously transmitted packets, and notifies the slave unit that it is the last of a plurality of continuously transmitted packets (fragments). The slave unit transmits a block ACK describing the reception result of the received packet from the transmission of the polling packet to the reception of the block ACK request. The base unit appropriately performs retransmission processing according to the reception result of this block ACK. As described above, in the “block ACK” technology, it is necessary to exchange a polling packet and a block ACK request for specifying a continuous transmission period between the slave unit and the master unit, and a reduction in throughput is unavoidable. It was.

  It is an object of the present invention to provide a wireless communication system and a wireless communication method that enable efficient transmission / reception processing and retransmission processing when a large amount of content data downloaded from a parent device to a child device is divided and transmitted / received. Objective.

  The first invention establishes a link between the parent device and the child device, and divides the large-capacity content data requested by the child device into a plurality of fragments from the large-capacity content data held by the parent device. In the wireless communication system to be downloaded, the master unit has a transmission fragment table that records the transmission results of N fragments (N is an integer of 2 or more), and the slave unit records the reception results of N fragments. And receiving the fragment size D and the fragment number N of the fragment table between the parent device and the child device at the time of establishing the link. Divide into fragments and combine N fragments as a sequence from the beginning to form an M sequence (M is an integer greater than or equal to 1) Means for continuously transmitting N fragments of one sequence, recording each fragment as transmitted in the transmission fragment table, and within a predetermined time Tack after transmission of all fragments of one sequence, A content ACK having received or unreceived information of N fragments notified from the slave unit is received, and if there is an unreceived fragment, the transmission fragment table is updated based on the information of the content ACK, The fragment is reset to non-transmitted and retransmitted, and is recorded as transmitted in the transmission fragment table. When a content ACK is received in which N fragments have been received, the transmission fragment table is reset, and M sequences Means for sequentially transmitting fragments.

  While receiving each fragment of one sequence, the slave unit records the successfully received fragment in the received fragment table as received, and transmits the reception result of all fragments of one sequence received within a predetermined time as a content ACK. And a means for instructing re-transmission to the master unit using the content ACK until all fragments recorded in the received fragment table have been received, and when all fragments in one sequence have been received, the received fragment table And sequentially receiving M sequence fragments.

  In the second invention, when the base unit of the first invention does not receive the content ACK within a predetermined time Tack after the transmission of all the fragments of one sequence, the transmission fragment table is reset, Means for retransmitting the fragment.

  In the third invention, the child device of the first invention counts the number of times of content ACK transmission Ns including information on unreceived fragments, and does not transmit the content ACK when Ns reaches a specified value. Means for transmitting a connection request signal for reconnection with the parent device.

  In the fourth invention, the master unit of the first invention counts the number of sequence transmissions Np at which all fragments have been transmitted, including retransmission, and does not retransmit the fragments when Np reaches a specified value. Means for transmitting a beacon for reconnection with the slave unit.

  In the fifth invention, when the master unit of the second invention does not receive a content ACK within a predetermined time Tack after transmission of all fragments of one sequence, the content ACK reception failure count Nack is counted, and Nack Includes means for transmitting a beacon for reconnection with the slave unit without retransmitting the fragment.

  In the sixth invention, the child device of the second invention transmits a content ACK including received information of all fragments of the sequence (j-1) (j is an integer of 2 to M), and the next sequence j When the parent device retransmits all fragments of the sequence (j−1) because the content ACK is not received by the parent device when waiting for the reception of the fragment, the content of the sequence (j−1) Including a means for retransmitting the ACK, and the master unit monitors whether or not the content ACK is received when retransmitting all the fragments, and receives the content ACK, and the content is the sequence (j-1). When the received information of all the fragments is included, means for stopping the retransmission of the fragments and shifting to the transmission of the next sequence is included.

  The seventh invention is for reconnecting to the master unit when the slave unit of the first invention does not receive one fragment within a predetermined time from the start of reception of one sequence of fragments. Means for transmitting a connection request signal;

  In an eighth aspect of the present invention, the base unit of the first aspect of the present invention is in the middle of transmitting or retransmitting one sequence of N fragments, or within a predetermined time Tack after transmission of all fragments of one sequence. Includes a means for monitoring a connection request signal transmitted from the terminal and transmitting a beacon for reconnection with the slave unit when the connection request signal is received.

  The present invention makes it possible to efficiently download large-capacity content data by dividing large-capacity content data into a plurality of fragments and performing transmission / reception and retransmission processing in units of sequences in which N fragments are grouped together. Become. In particular, it is necessary to notify the beginning and end of continuous transmission as in the conventional block ACK by notifying the number N of fragments in one sequence and the data size D of each fragment in advance between the parent device and the child device. Thus, transmission / reception and retransmission processing in sequence units can be performed efficiently.

  Further, in the present invention, when the number of retransmissions from the parent device exceeds a specified value, the content ACK does not reach the parent device, and when the number of retransmissions for retransmitting all fragments from the parent device exceeds the specified value, When the number of transmissions of content ACK requesting retransmission exceeds the specified value, by performing reconnection processing between the master unit and the slave unit, avoiding a state where retransmission processing is repeated more than necessary, Efficient downloading of large-capacity content data is possible.

(First embodiment)
FIG. 1 is a flowchart showing the processing procedure of the master unit in the first embodiment of the present invention. FIG. 2 is a flowchart showing a processing procedure of the slave unit in the first embodiment of the present invention. FIG. 3 shows the relationship between fragments and sequences in the division of large-capacity content data.

(Relationship between fragment and sequence)
With reference to FIG. 3, the division of large-capacity content data will be described. The present invention assumes a case where the content data has a capacity exceeding the maximum size that can be transmitted in one wireless packet (for example, the maximum size of the data area of the MAC frame of the IEEE 802.11 standard is 2296 bytes). In the case of content data less than the capacity, it is equivalent to the conventional method.

  The content data is divided into fragments of size D (predetermined size of 2296 bytes or less designated by the child device or the parent device) D that can be transmitted in one wireless packet. Then, a unit in which N fragments are collected in order from the top is defined as a sequence, and M sequences are formed. Here, N is an integer equal to or greater than 2, and is the number of fragments in one sequence determined by the size of the fragment table of the master unit and the slave unit. M is an integer equal to or greater than 1 and determined according to the content data capacity. is there. That is, the content data is divided by a predetermined fragment size D between the parent device and the child device, the number N of fragments in one sequence is determined according to the size of the fragment table, and the content data is one sequence. The number of sequences M is determined by dividing the size by D × N. If the number of fragments of the Mth sequence is less than N, it is supplemented with dummy data. The dummy data is (D × N × M− (content data capacity)).

  A data frame (MAC frame) is formed by adding a header and FCS to each fragment thus divided. In the header, a parent device (transmission source) ID, a child device (destination) ID, a sequence number, a fragment number, and the like are stored. The slave unit recognizes the sequence number and the fragment number from the header of the received data frame.

(Processing procedure of the main unit)
With reference to FIG. 1, the processing procedure of the master unit in the first embodiment will be described.
The parent device broadcasts a beacon at regular or random time intervals, waits for a connection request signal transmitted from the child device (S1), enters a connection operation in response to reception of the connection request signal, and can be connected to the child device If it is a connection request signal from the terminal, a connection response signal for permitting connection is transmitted (S2). The slave unit sets the number N of fragments in one sequence corresponding to the requested content data, the fragment size D, and the size of the received fragment table in the connection request signal. The master unit sets the requested content data capacity and sequence number M in the connection response signal. Note that the fragment size D and the fragment number N may be determined by the parent device and notified to the child device by a connection response signal.

  Next, the master unit divides the content data to be downloaded into fragment units as described above, collects it into M sequences of N pieces, and initializes the sequence number j (j = 1) (S3). Next, N fragments of the sequence j (= 1) are set in the signal processing hardware unit, and the sequence transmission number Np is reset (Np = 0) (S4). Next, the transmission fragment table that records the transmission result for each sequence fragment is reset (S5). In the transmission fragment table, all fragments are in a “not transmitted” state by resetting, and “transmitted” is overwritten in the corresponding area for each fragment transmission.

  Next, until the number Np of sequence transmissions reaches a specified value P, fragments whose “unsent” is recorded in the transmission fragment table are sequentially transmitted (S6, S7 to S14). First, the transmission fragment table is confirmed for the first fragment i (= 1), and since it is “not transmitted”, the fragment i is transmitted, and “transmitted” for the fragment i is recorded in the transmission fragment table (S7, S8, S9, S10). Next, the transmission fragment table is checked, and if all the fragments are not “transmitted”, the measurement of the time Ta until the next fragment is transmitted is started (S11, S12). After the elapse of time Ta from the transmission of the fragment i, the processing returns to the processing for transmitting the next fragment (i + 1) (S13, S6, S7). Here, it is confirmed that the fragments 1 to i are “transmitted”, the next fragment (i + 1) is transmitted, and “transmitted” is recorded in the transmission fragment table (S7, S8, S14, S9, S10, S11).

  When transmission of all fragments of sequence j (= 1) is completed by repeating the processing of S7 to S14, it is confirmed in S11, the sequence transmission count Np is incremented (S15), and transmitted from the slave unit. The measurement of the time Tack awaiting reception of the content ACK is started (S16, S17, S18). When the content ACK is received within the time Tack from the completion of transmission of all the fragments of the sequence j (= 1), the content ACK is confirmed (S19). In the content ACK, a reception fragment table in which the reception state of all fragments of the sequence j in the slave unit is recorded (“received” when correctly received, “unreceived (initial state)” when not correctly received). The parent device confirms the “received / not received” fragment of the sequence j in the child device.

  If it is confirmed in S19 that all the fragments of sequence j have been received from the content ACK, the process returns to the transmission of the next sequence (j + 1) fragment (S19, S20, S21, S4), and the same fragment transmission processing is performed. repeat. When transmission of all the fragments up to sequence M is completed, the process returns from S20 to S1, transmits a beacon, and enters connection waiting.

  On the other hand, if it is confirmed in S19 that there is a fragment that is “not received” in the content ACK, the transmission fragment table of the parent device is updated to the content of the reception fragment table of the child device notified by the content ACK. (S19, S22), the process returns to S6. Thereby, in the fragment table of the parent device, since the fragment that has been “unreceived” in the child device becomes “untransmitted”, the retransmission processing for the “untransmitted” fragment is performed.

  If it is confirmed in S11 that all the fragments of sequence j are “transmitted” but the content ACK cannot be received from the slave unit and the time Tack has elapsed, the process returns from S17 to S5, and the transmission fragment of the master unit is returned. The table is reset to “untransmitted” for all fragments, and all fragments in sequence j are retransmitted.

  When the base unit transmits all fragments of sequence j for the first time, the sequence transmission count Np is 1. Thereafter, when the “unreceived” fragment notified by the content ACK is retransmitted, or when all the fragments are retransmitted because the content ACK is not received, the sequence transmission count Np is incremented. In S6, when the number of sequence transmissions Np (= number of retransmissions−1) reaches the specified value P before starting the retransmission process, it is determined that the communication environment has deteriorated, and no further retransmission process is performed. The connection with the slave unit is disconnected and the process returns to beacon transmission (S6, S1).

(Processing procedure of the slave unit)
With reference to FIG. 2, the processing procedure of the slave unit in the first embodiment will be described.
The slave unit waits for a beacon broadcast from the master unit at a constant or random time interval (S31), and when receiving the beacon, verifies whether or not it can connect to the master unit that transmitted the beacon. If it is a connectable parent device, a connection request signal is transmitted, and a connection response signal transmitted from the parent device is awaited (S32). In the connection request signal, the requested content data, the fragment size D, and the number N of fragments in one sequence corresponding to the size of the received fragment table are set. In the connection response signal, the requested content data capacity and the number M of sequences are set.

  Next, the slave unit initializes the sequence number j (j = 1), resets the received fragment table that records the reception result for each fragment for one sequence, and resets the content ACK transmission count Ns (S33, S34). ). In the received fragment table, all fragments are in a “not received” state by resetting, and “received” is overwritten in the corresponding area for each reception of each fragment.

  Next, measurement of the time Tad waiting for reception of the fragment i of the sequence j (= 1) is started (S35). When the fragment i is received within the time Tad, it is determined whether or not the fragment i is correctly received. When the fragment i is correctly received, it is recorded in the signal processing hardware unit as the fragment i of the sequence j and received. The fragment i is recorded as “Received” in the fragment table (S36, S37, S38, S39, S40). On the other hand, when the fragment i cannot be received correctly, recording to the signal processing hardware unit and recording to the reception fragment table are not performed. Therefore, the fragment i in the received fragment table remains “unreceived”.

Next, the received fragment table is confirmed, and if all the fragments are not “received”, the process returns to the measurement of the time Tad waiting for the next fragment (S41, S35). here,
Tack>Tad> Ta
It is. Normally, fragment (i + 1) is received after fragment i, and when received normally, “received” is recorded in the received fragment table (S35 to S41). Similarly, when “received” of all N fragments for sequence j is confirmed, all fragments recorded in the signal processing hardware unit are moved to the signal processing software unit, and the received fragment table Content ACK storing all the contents (all fragments are “received”) is created and transmitted to the parent device (S42, S43, S44).

  Next, the received fragment table is checked again. If all fragments are “received”, the received fragment table is reset in order to receive the next sequence (j + 1) fragment, and fragment reception processing is performed ( S45, S46, S47, S34). When all the fragments of sequences 1 to M are received, all the fragments in the signal processing software unit are synthesized and recorded in the memory unit, and the download of the large-capacity content data is completed (S46, S48).

  On the other hand, even if the parent device has finished transmitting all the fragments of sequence j, if part or all of the fragments of sequence j are not received by the child device, the time Tad is over in S36. The slave unit creates the content ACK storing the contents of the received fragment table until the specified value S is reached while incrementing the number of times of content ACK transmission Ns, and transmits it to the master unit (S36, S49, S50, S43, S44). After the transmission of the content ACK requesting retransmission, the process returns to the process of receiving the fragment retransmitted in response to the content ACK (S45, S35). If all fragments are not “received” even if the content ACK transmission count Ns reaches the specified value S, it is determined that the communication environment has deteriorated and a content ACK requesting further retransmission is transmitted. First, the process returns to the process of transmitting the connection request signal to the parent machine (S49, S32).

  Here, in the first embodiment, transmission of N fragments in each sequence unit from the parent device to the child device succeeds, the child device transmits a content ACK for which all fragments have been received, and retransmission from the parent device is performed. FIG. 4 shows an operation example in which the next sequence of fragments is transmitted instead. An example of the transmission fragment table of the parent device and the reception fragment table of the child device in this time chart is shown in FIG.

  Further, in the first embodiment, the slave unit fails to receive the fragment i of the sequence j, transmits a content ACK describing the state of the received fragment table, and the master unit updates the transmission fragment table to update the fragment i. FIG. 6 shows an example of the operation for retransmitting the fragment i with no transmission. An example of the transmission fragment table of the parent device and the reception fragment table of the child device in this time chart is shown in FIG.

  In the first embodiment, when the parent device confirms that all fragments of the sequence j have been “transmitted” but the content ACK from the child device has not been received and the time Tack has elapsed, the transmission of the parent device FIG. 8 shows an operation example in which the fragment table is reset, all fragments are not transmitted, and all fragments in sequence j are retransmitted.

  Further, in the first embodiment, if the reception of all fragments of sequence j is not completed even when the number of content ACK transmissions Ns of the slave unit reaches the specified value S, the slave unit connects without transmitting the content ACK. An example of the operation for transmitting the request signal is shown in FIG.

  Further, in the first embodiment, when the number of sequence transmissions Np of the sequence j reaches the specified value P including retransmission, the master unit disconnects the connection with the slave unit and returns to beacon transmission. 10 shows.

  Depending on the magnitude relationship between the specified value P for limiting the number of retransmissions from the parent device and the specified value S for limiting the number of retransmissions from the child device, the parent device issues a beacon first or the child device first issues a connection request signal. It is decided whether to put out. In any case, when one of the parent device or the child device is in such a state, the other device is also in that state, so there is no problem. For example, when the slave unit first issues a connection request signal, the master unit does not receive the content ACK, and therefore repeats retransmission of all fragments of sequence j, while the sequence transmission count Np eventually becomes the specified value P. Issue a beacon. At this time, since the slave unit has already issued the connection request signal, when the master unit receives the connection request signal, the connection operation is started. In this way, instead of returning from S49 to S31 connection waiting (beacon waiting) in FIG. 2, by returning to S32 connection operation (connection request signal transmission), the master unit outputs a beacon with Np = P. When this is done, there is an advantage that reconnection can be made quickly without interrupting other slave units.

  On the other hand, if the master unit first sends out a beacon, the slave unit does not receive the fragment, and thus repeats the transmission of the content ACK requesting the unreceived fragment, while the content ACK transmission count Ns eventually becomes the specified value S. The connection request signal is issued. At this time, since the parent device has already issued a beacon, the connection operation is started when the connection request signal transmitted from the child device is received. FIG. 10 also shows an operation example at this time.

  Further, when the parent device issues a beacon first, another child device transmits a connection request signal for the beacon, and this child device can be interrupted. An example of the operation at this time is shown in FIG. In this case, when the first slave unit transmits a connection request signal, the other slave unit interrupts, and the master unit does not return a connection response signal, so the connection request signal transmission and the response wait are repeated a certain number of times. Thereafter, the process returns to the connection waiting operation of S31 (omitted in FIGS. 2 and 11).

  By the way, when the parent device and the child device do not complete transmission / reception of all fragments of the sequence j and the number of retransmissions exceeds a specified value, reconnection processing is performed between the parent device and the child device. At this time, even if transmission / reception of all the fragments of sequences 1 to (j-1) is completed, the processing is resumed from sequence 1. Here, when all the fragments up to sequence (j-1) have been received by the slave unit, the initial setting of the sequence number of S33 of the slave unit is j, and the connection request signal transmitted by the slave unit is set as j. By entering the information, the base unit uses the fragment divided in the previous process S3 and sets the initial setting of the sequence number to j. This allows retransmission from sequence j fragments.

(Second Embodiment)
FIG. 12 is a flowchart showing the processing procedure of the master unit in the second embodiment of the present invention. The processing procedure of the slave unit corresponding to the master unit of the present embodiment can be handled by that of the first embodiment shown in FIG.

  In the first embodiment, the number of sequence transmissions Np counted every time the master unit transmits all fragments of one sequence is monitored, and it is set not to repeat retransmissions exceeding a specified value.

  By the way, when the base unit performs retransmission, when a part or all of the fragments in one sequence are not received by the slave unit, it is performed based on the information of the received fragment table notified from the slave unit by the content ACK. There are cases (S19, S22, S6˜, FIG. 6, FIG. 9, FIG. 10) and cases where the content ACK from the child device does not reach the parent device (S17, S5, S6˜, FIG. 8). In the former case, which is a normal retransmission process, the number of sequence transmissions Np rarely exceeds the specified value. However, if the slave unit goes out of the radio area (out of service area), even if the content ACK is transmitted, the master unit The master unit repeats retransmission of all fragments of the sequence and exceeds the specified value. The present embodiment shows another processing procedure corresponding to this latter case.

  In FIG. 12, instead of the control based on the sequence transmission number Np performed in S6 and S15 in FIG. 1, control based on the content ACK reception failure number Nack is performed. That is, when all the fragments of the sequence j are set in the signal processing hardware unit in S4, the content ACK reception failure number Nack is reset (Nack = 0). Then, although all fragments of sequence j have been transmitted in S17, content ACK reception failure count Nack is counted when time Tack has been exceeded without receiving content ACK from the slave unit. Then, until the content ACK reception failure count Nack reaches the specified value A, the transmission fragment table is reset and all fragments of the sequence j are retransmitted (S23, S24, S5). If the number of content ACK reception failures Nack reaches the specified value A, the process returns from S23 to S1, transmits a beacon, and waits for connection. An example of the operation at this time is shown in FIG.

(Third embodiment)
FIG. 14 is a flowchart showing a processing procedure of the parent device in the third embodiment of the present invention. The processing procedure of the slave unit corresponding to the master unit of the present embodiment can be handled by that of the first embodiment shown in FIG.

  The feature of this embodiment is that both the sequence transmission number Np of the first embodiment shown in FIG. 1 and the content ACK reception failure number Nack of the second embodiment shown in FIG. 12 are counted and retransmitted more than necessary. Avoid processing. The relationship between the prescribed value P of the sequence transmission number Np and the prescribed value A of the content ACK reception failure number Nack is P ≧ A.

(Fourth embodiment)
FIG. 15 is a flowchart showing a processing procedure of the slave unit in the fourth embodiment of the present invention. FIG. 16 is a flowchart showing the processing procedure of the master unit in the fourth embodiment of the present invention. The processing procedure of the master unit in this embodiment is applied to the processing procedure of the master unit in the third embodiment. Similarly, the processing of the master unit in the first embodiment or the second embodiment is the same. It is also applicable to procedures.

  This embodiment corresponds to the case where the slave unit has received all the fragments of sequence j and has transmitted a content ACK to that effect, but the content ACK has not arrived at the master unit. The processing procedure of the slave unit is basically the same as that of the first embodiment shown in FIG.

  In FIG. 15, when all the fragments of sequence j are received, the slave unit transmits a content ACK for which all fragments have been received, and resets the received fragment table in preparation for the reception of the fragment of sequence j (= j + 1) ( S41 to S45, S46, S47, S34). On the other hand, as shown in the first to third embodiments, when the content ACK does not arrive, the base unit repeats retransmission of all the fragments of sequence j, and when the sequence transmission count Np reaches a specified value P Alternatively, the retransmission process is stopped when the content ACK reception failure count Nack reaches the specified value A. That is, all the fragments of the sequence j retransmitted from the parent device are repeatedly received by the child device, and the child device waiting for the reception of the fragment of the sequence j (= j + 1) receives the fragment of the previous sequence. Since it cannot be received, the content ACK (all fragments not received) continues to be transmitted. For this reason, the content ACK reception count Ns of the slave unit becomes the specified value S, and it takes time until the retransmission request by the content ACK is stopped.

  Therefore, in the present embodiment, in S38 for confirming the received fragment, the sequence number other than the sequence number of the received fragment is confirmed, and when the received fragment is correctly received, the sequence number is set to the sequence j set in the slave unit. On the other hand, it is determined whether or not it is the previous sequence (j-1) (S51). That is, even though all the fragments of sequence (j-1) have been notified to the parent device by content ACK, the fragment of sequence (j-1) has been transmitted again because the content ACK has not arrived. Determine if it is a thing. If the received fragment is a sequence (j-1), a content ACK for receiving all fragments is again generated and transmitted to the master unit (S51, S52, S44). However, since the received fragment table is set to the sequence j, “No” is determined in S45, and reception of the next sequence j fragment transmitted from the parent device is started (S45, S35).

  In FIG. 16, since the content ACK for sequence j does not arrive, the base unit retransmits all fragments (S5 to S11, S12, S13, S6 to), but while retransmitting fragments 1, 2,. That is, when a content ACK is received during the time Ta after transmitting one fragment, the content of the content ACK is confirmed (S12, S13, S25, S19). If the content ACK indicates reception of all fragments of sequence j, transmission of the next sequence j (= j + 1) fragment starts (S19, S20, S21, S4). Other operations are the same as those in the first to third embodiments. An operation example of this embodiment is shown in FIG.

(Fifth embodiment)
FIG. 18 is a flowchart showing a processing procedure of the parent device in the fifth embodiment of the present invention. The processing procedure of the master unit in this embodiment is applied to the processing procedure of the master unit in the third embodiment. Similarly, the processing of the master unit in the first embodiment or the second embodiment is the same. It is also applicable to procedures. Further, the processing procedure of the slave unit corresponding to the master unit of the present embodiment can be handled by that of the first embodiment shown in FIG. Furthermore, the present invention is also applicable to the processing procedure of the master unit and the slave unit in the fourth embodiment.

  In the slave unit of the first embodiment or the fourth embodiment, when the content ACK transmission count Ns indicating that there is an unreceived fragment reaches a specified value S, the connection with the master unit is canceled. Send a request signal. On the other hand, the master unit counts the number of sequence transmissions Np and / or the number of content ACK reception failures Nack to avoid unnecessary retransmission processing, but detects a connection request signal transmitted from the slave unit. It becomes possible to respond immediately.

  In FIG. 18, it is monitored whether or not a connection request signal is received while receiving a fragment of sequence j or when waiting for reception of a content ACK from a slave unit after transmission of all fragments (S12, (S13, S61, S17, S62, S18) When the connection request signal is received, the connection of the slave unit is disconnected and the beacon signal is returned (S61, S62, S1). Note that if the master unit does not reach the master unit even if a connection request signal is issued, such as when the slave unit goes out of service area, the master unit transmits a beacon based on the sequence transmission count Np and / or the content ACK reception failure count Nack. Will return.

(Sixth embodiment)
FIG. 19 is a flowchart showing the processing procedure of the slave unit in the sixth embodiment of the present invention. The processing procedure of the slave unit in this embodiment is applied to the processing procedure of the slave unit in the first embodiment shown in FIG. Further, the processing procedure of the master unit corresponding to the slave unit of this embodiment corresponds to that of the fifth embodiment that monitors the connection request signal.

  The slave unit normally receives N fragments of the sequence j in order after connecting to the master unit. However, if the slave unit goes out of service or the communication environment deteriorates, even if the time Tad elapses from the beginning or midway. Occasionally a fragment is not received. In such a case, the slave unit in the first embodiment repeats transmission of a content ACK indicating that there is an unreceived fragment until the content ACK transmission count Ns reaches a specified value S. The present embodiment is characterized in that, when no fragment is received from the beginning, the connection with the parent device is immediately canceled without waiting for the count of the content ACK transmission count Ns.

  In FIG. 19, when the time Tad is over without being able to receive a fragment, the received fragment table is checked to determine whether there is a received fragment (S36, S63). That is, it is determined whether the state in which no fragment is received is from the beginning or the middle. If there is a fragment received in the received fragment table, it is a case where the fragment is not received from the middle or after the master unit has finished transmitting all the fragments of sequence j, and a normal content ACK is sent as in the above embodiment. Transmit (S63, S49, S50, S43, S44). On the other hand, if there is no received fragment in the received fragment table, it means that no fragment has been received from the beginning, and the connection request signal is transmitted by disconnecting the connection with the master unit (S63, S32). Even in the parent device, the connection of the child device can be immediately restarted by detecting the connection request signal. An example of the operation of this embodiment is shown in FIG.

(Seventh embodiment)
FIG. 21 is a flowchart showing the processing procedure of the slave unit in the seventh embodiment of the present invention. FIG. 22 is a flowchart showing the processing procedure of the parent device in the seventh embodiment of the present invention. The processing procedure of the slave unit in this embodiment is applied to the processing procedure of the slave unit in the fourth embodiment shown in FIG. Further, the processing procedure of the parent device corresponding to the child device of this embodiment is applied to the processing procedure of the parent device in the fifth embodiment shown in FIG. That is, the child device and the parent device of the present embodiment include the functions of all the above embodiments.

(Configuration example of main unit)
FIG. 23 shows a configuration example of the base unit. In the figure, the master unit includes a wireless transmission / reception unit 11, a signal processing hardware unit 12, a signal processing software unit 13, a memory unit 14, a display unit 15, and an operation unit 16.

  The wireless transmission / reception unit 11 receives a radio wave, converts it into a received radio signal, and outputs it to the signal processing hardware unit 12. The wireless transmission / reception unit 11 converts a transmission wireless signal input from the signal processing hardware unit 12 into a wireless radio wave and transmits the wireless radio wave.

  The signal processing hardware unit 12 performs the control processing of the master unit shown in each of the above embodiments, and outputs a transmission radio control signal such as a generated beacon and connection response signal to the radio transmission / reception unit 11. In addition, radio control signal processing is performed on the connection request signal and the content ACK among the received radio signals input from the radio transceiver unit. Further, the wireless data signal processing is performed on the transmission data to the connected slave unit input from the signal processing software unit 13 and output to the wireless transmission / reception unit 11 as a transmission wireless signal.

  The signal processing software unit 13 divides the content data input from the memory unit 14 into a plurality of fragments, and outputs them to the signal processing hardware unit 12 as transmission data. In addition, various application functions are realized.

  The memory unit 14 holds one or more content data, a parent device ID, a connectable child device ID, and the like. Further, when a link is established with the slave unit, the content data requested by the slave unit among the stored content data is output to the signal processing software unit 13.

  The display unit 15 is a display or the like used when the user performs setting or operation of the device. The operation unit 16 is a keyboard or the like used when the user performs setting and operation of the apparatus.

(Example configuration of slave unit)
FIG. 24 shows a configuration example of the slave unit. In the figure, the slave unit includes a wireless transmission / reception unit 21, a signal processing hardware unit 22, a signal processing software unit 23, a memory unit 24, a display unit 25, and an operation unit 26.

  The wireless transmission / reception unit 21 receives a radio wave, converts it into a received radio signal, and outputs it to the signal processing hardware unit 22. Further, the wireless transmission / reception unit 21 converts a transmission wireless signal input from the signal processing hardware unit 22 into a radio wave and transmits it.

  The signal processing hardware unit 22 performs control processing of the slave units described in the above embodiments, and processes received radio control signals such as beacons and connection response signals input from the radio transmission / reception unit 21. In addition, a connection request signal and content ACK transmitted from the wireless transmission / reception unit 21 are generated and output to the wireless transmission / reception unit 21. In addition, among the received radio signals input from the radio transmitting / receiving unit 21, radio data signal processing is performed on the received data signal, and the received data is output to the signal processing software unit 23.

  The signal processing software unit 23 reconstructs the received fragment input from the signal processing hardware unit 22 and outputs it to the memory unit 24 as received content data. In addition, various application functions are realized.

  The memory unit 24 stores received content data input from the signal processing software unit 23. Further, it holds a slave unit ID, a connectable master unit ID, and the like.

  The display unit 25 is a display or the like used when the user performs setting or operation of the device. The operation unit 26 is a keyboard or the like used when the user performs setting and operation of the apparatus.

  Since the basic device configuration of the parent device and the child device is the same, it can be used as a parent device or a child device by setting in a common device configuration.

The flowchart which shows the process sequence of the main | base station in the 1st Embodiment of this invention. The flowchart which shows the process sequence of the subunit | mobile_unit in the 1st Embodiment of this invention. The figure explaining the relationship between the fragment | piece and sequence in the division | segmentation of a mass content data. The time chart which shows the operation example when there is no resending in 1st Embodiment. The figure which shows the fragment table in case there is no resending in 1st Embodiment. The time chart which shows the operation example when there exists resending in 1st Embodiment. The figure which shows the fragment table in case there exists resending in 1st Embodiment. The time chart which shows the operation example when the content ACK in 1st Embodiment does not reach a main | base station. The time chart which shows the operation example in case the subunit | mobile_unit in 1st Embodiment transmits a connection request signal. The time chart which shows the operation example in case the main | base station in 1st Embodiment transmits a beacon. The time chart which shows the operation example in case the main | base station in 1st Embodiment transmits a beacon. The flowchart which shows the process sequence of the main | base station in the 2nd Embodiment of this invention. The time chart which shows the operation example when the content ACK in 2nd Embodiment does not reach a main | base station. The flowchart which shows the process sequence of the main | base station in the 3rd Embodiment of this invention. The flowchart which shows the process sequence of the subunit | mobile_unit in the 4th Embodiment of this invention. The flowchart which shows the process sequence of the main | base station in the 4th Embodiment of this invention. The time chart which shows the operation example when the content ACK in 4th Embodiment does not reach | attain to a main | base station. The flowchart which shows the process sequence of the main | base station in the 5th Embodiment of this invention. The flowchart which shows the process sequence of the subunit | mobile_unit in the 6th Embodiment of this invention. The time chart which shows the operation example of 6th Embodiment. The flowchart which shows the process sequence of the subunit | mobile_unit in the 7th Embodiment of this invention. The flowchart which shows the process sequence of the main | base station in the 7th Embodiment of this invention. The figure which shows the structural example of a main | base station. The figure which shows the structural example of a subunit | mobile_unit. The figure explaining block ACK.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Wireless transmission / reception part 12 Signal processing hardware part 13 Signal processing software part 14 Memory part 15 Display part 16 Operation part 21 Wireless transmission / reception part 22 Signal processing hardware part 23 Signal processing software part 24 Memory part 25 Display part 26 Operation part

Claims (16)

A wireless communication system that establishes a link between a parent device and a child device, and divides and downloads large-capacity content data requested by the child device into a plurality of fragments from the large-capacity content data held by the parent device In
The master unit has a transmission fragment table that records the transmission results of N fragments (N is an integer of 2 or more), and the slave unit has a reception fragment table that records the reception results of N fragments. The fragment size D and the fragment number N in the fragment table are exchanged between the master unit and the slave unit when the link is established.
The base unit is
Means for dividing the large-capacity content data into fragments of the size D, collecting the N fragments as a sequence in order from the top, and forming M (M is an integer of 1 or more) sequence;
Means for continuously transmitting N fragments of one sequence and recording each fragment in the transmission fragment table as transmitted;
Within a predetermined time Tack after transmission of all the fragments of the one sequence, a content ACK having received or unreceived information of N fragments notified from the slave unit is received, and there is an unreceived fragment. For example, the transmission fragment table is updated based on the information of the content ACK, the unreceived fragment is reset to the non-transmission and retransmitted, and recorded as transmitted in the transmission fragment table, and N fragments are received. Means for resetting the transmission fragment table when receiving the content ACK, and sequentially transmitting the M sequences of fragments,
The slave is
Means for recording a fragment received normally while receiving each fragment of one sequence as received, in a received fragment table, and transmitting the reception result of all fragments of one sequence received within a predetermined time as the content ACK; ,
Until all the fragments recorded in the received fragment table have been received, the base unit is instructed to retransmit using the content ACK, and when all the fragments of one sequence have been received, the received fragment table And a means for sequentially receiving the fragments of the M sequences. The wireless communication system according to claim 1, wherein
The base unit includes means for resetting the transmission fragment table and retransmitting all fragments of the sequence when the content ACK is not received within a predetermined time Tack after transmission of all fragments of the sequence. A wireless communication system. The wireless communication system according to claim 1, wherein
The slave unit counts the number of times of content ACK transmission Ns including information on unreceived fragments, and does not transmit the content ACK when Ns reaches a specified value, and reconnects to the base unit. Means for transmitting a connection request signal for the wireless communication system. The wireless communication system according to claim 1, wherein
The base unit counts the number of times of sequence transmission Np at which all fragments have been transmitted, including retransmission, and does not retransmit the fragment when Np reaches a specified value, and reconnects to the slave unit. A wireless communication system comprising means for transmitting a beacon. The wireless communication system according to claim 2,
When the master unit does not receive the content ACK within a predetermined time Tack after transmission of all fragments of one sequence, the master unit counts the number of times the content ACK has failed to receive Nack, and if Nack reaches a specified value, A wireless communication system comprising means for transmitting a beacon for reconnection with the slave unit without retransmitting the fragment. The wireless communication system according to claim 2,
The slave transmits a content ACK including received information of all fragments of the sequence (j-1) (j is an integer of 2 to M), and when waiting for reception of the next sequence j fragment, When the base unit has retransmitted all fragments of the sequence (j-1) because the content ACK is not received by the base unit, the content ACK includes means for retransmitting the content ACK of the sequence (j-1),
The base unit monitors whether or not the content ACK is received when retransmitting all fragments, receives the content ACK, and the content has been received for all the fragments of the sequence (j-1). A radio communication system comprising means for stopping retransmission of a fragment when the information is included and shifting to transmission of the next sequence. The wireless communication system according to claim 1, wherein
The slave unit includes means for transmitting a connection request signal for reconnection with the master unit when no fragment is received within a predetermined time after the reception of one sequence of fragments is started. A wireless communication system. The wireless communication system according to claim 3 or 7,
The master unit monitors a connection request signal transmitted by the slave unit during transmission or retransmission of N fragments of one sequence, or within a predetermined time Tack after transmission of all fragments of one sequence, A wireless communication system comprising means for transmitting a beacon for reconnection with the slave unit when the connection request signal is received. A wireless communication method for establishing a link between a parent device and a child device and dividing the large-capacity content data requested by the child device from a large amount of content data held by the parent device into a plurality of fragments In
The master unit has a transmission fragment table that records the transmission results of N fragments (N is an integer of 2 or more), and the slave unit has a reception fragment table that records the reception results of N fragments. When the link is established, the fragment size D and the fragment number N in the fragment table are exchanged between the parent device and the child device,
The base unit is
Dividing the large-capacity content data into fragments of the size D, collecting the N fragments as a sequence in order from the top, and forming M (M is an integer of 1 or more) sequence;
Continuously transmitting N fragments of one sequence and recording each fragment in the transmission fragment table as transmitted;
Within a predetermined time Tack after transmission of all the fragments of the one sequence, a content ACK having received or unreceived information of N fragments notified from the slave unit is received, and there is an unreceived fragment. For example, the transmission fragment table is updated based on the information of the content ACK, the unreceived fragment is reset to the non-transmission and retransmitted, and recorded as transmitted in the transmission fragment table, and N fragments are received. Resetting the transmission fragment table when receiving the content ACK, and sequentially transmitting the M sequences of fragments,
The slave is
Recording a fragment received normally while receiving each fragment of one sequence as received in the received fragment table, and transmitting reception results of all fragments of one sequence received within a predetermined time as the content ACK; ,
Until all the fragments recorded in the received fragment table have been received, the base unit is instructed to retransmit using the content ACK, and when all the fragments of one sequence have been received, the received fragment table And sequentially receiving the M sequence fragments. A wireless communication method, comprising: The wireless communication method according to claim 9, wherein
The base unit includes a step of resetting the transmission fragment table and retransmitting all fragments of the sequence when the content ACK is not received within a predetermined time Tack after transmission of all fragments of the sequence. A wireless communication method. The wireless communication method according to claim 9, wherein
The slave unit counts the number of times of content ACK transmission Ns including information on unreceived fragments, and does not transmit the content ACK when Ns reaches a specified value, and reconnects to the base unit. A wireless communication method comprising: transmitting a connection request signal for the communication. The wireless communication method according to claim 9, wherein
The base unit counts the number of times of sequence transmission Np at which all fragments have been transmitted, including retransmission, and does not retransmit the fragment when Np reaches a specified value, and reconnects to the slave unit. Transmitting a beacon of The wireless communication method according to claim 10, wherein
When the master unit does not receive the content ACK within a predetermined time Tack after transmission of all fragments of one sequence, the master unit counts the number of times the content ACK has failed to receive Nack, and if Nack reaches a specified value, A wireless communication method comprising: transmitting a beacon for reconnection with the slave unit without retransmitting the fragment. The wireless communication method according to claim 10, wherein
The slave transmits a content ACK including received information of all fragments of the sequence (j-1) (j is an integer of 2 to M), and when waiting for reception of the next sequence j fragment, When the parent device has retransmitted all fragments of the sequence (j-1) because the content ACK is not received by the parent device, the method includes a step of transmitting the content ACK of the sequence (j-1) again,
The base unit monitors whether or not the content ACK is received when retransmitting all fragments, receives the content ACK, and the content has been received for all the fragments of the sequence (j-1). If the information is included, the wireless communication method includes a step of stopping retransmission of the fragment and shifting to transmission of the next sequence. The wireless communication method according to claim 9, wherein
The slave unit includes a step of transmitting a connection request signal for reconnection with the master unit when one fragment is not received within a predetermined time after starting reception of one sequence of fragments. A wireless communication method. The radio communication method according to claim 11 or 15,
The master unit monitors a connection request signal transmitted by the slave unit during transmission or retransmission of N fragments of one sequence, or within a predetermined time Tack after transmission of all fragments of one sequence, A wireless communication method comprising a step of transmitting a beacon for reconnection with the slave unit when the connection request signal is received.

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