JP4082580B2 - Wireless communication control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless communication control apparatus that centrally manages communication in a wireless LAN system, and relates to a technique that is useful when applied to a wireless LAN system that performs polling control for a plurality of terminals.
[0002]
[Prior art]
In a wireless LAN (Local Area Network) system, for example, a centralized control type that centrally manages communication of each terminal such as a notebook computer or a PDA equipped with a wireless LAN adapter by a base station called a so-called access point, and a terminal without a base station There is a distributed control type in which mutual communication is performed directly.
[0003]
In a LAN, in order to avoid a communication collision between a plurality of terminals, medium access control that restricts access to the communication medium by each terminal is necessary. In a centralized management type wireless LAN, as such access control, a polling method in which a base station sequentially inquires about communication requests of terminals and permits access to the wireless LAN, and each terminal reserves packet transmission according to instructions from the base station. And a random reservation method for accessing the wireless LAN.
[0004]
The access control of the polling method requires a base station to permit access to each terminal in the order of registration to a plurality of terminals registered in the polling list together with data transmission to the requested terminal, and the control procedure is somewhat complicated. Therefore, in a conventional wireless LAN system that performs polling-type access control, most of the control is realized by software processing using a dedicated CPU (Central Processing Unit).
[0005]
[Problems to be solved by the invention]
Software processing requires extra processing such as instruction code reading compared to hardware processing, so to achieve the same amount of processing, the operating frequency must be higher than hardware processing. It is more disadvantageous than hardware processing in terms of manufacturing cost.
[0006]
An object of the present invention is to realize polling-type access control by direct data transfer from a memory by a DMA (Direct Memory Access) controller to a MAC (Media Access control) layer controller.
[0007]
Another object of the present invention is to realize access control performed by switching between a polling system and a random reservation system by direct data transfer by a DMA controller.
[0008]
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0009]
[Means for Solving the Problems]
Outlines of representative ones of the inventions disclosed in the present application will be described as follows.
[0010]
That is, a polling communication index (for example, CFP queue 12) indicating a memory access destination at the time of polling communication, a reserved communication index (for example, CP queue 11) indicating a memory access destination at the time of communication in the reserved communication method, and transmission reservation are made. A transmission information list (for example, descriptor lists 13A0 to 13AN) for each terminal in which transmission information for transmitting the received data to the corresponding terminal is stored, and transmission information for polling control for sequentially inquiring each terminal for communication requests are stored. Storage means having a polling transmission information list (for example, descriptor list 13B) to be used, and the data transfer control device (for example, DMA controller 19) switches between the polling communication index and the reserved communication index depending on the period. , The transmission information list for each terminal or the point indicated by each index It reads the transmission information from the ring transmission information list, which is constituted so as to transfer the transmission frame on the basis of the transmission information to the access control device (e.g., MAC layer controller 20). Also, if there is data reserved for transmission during polling communication, the frame change circuit of the MAC layer controller changes this transmission frame for polling communication and transmits it.
[0011]
By such means, it is possible to execute both the polling access control and the communication reservation access control by transferring the transmission frame from the DMA controller to the MAC layer controller by channel control of a simple procedure using a queue. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
[0013]
FIG. 1 is a block diagram showing a configuration related to access control on the wireless LAN side in the wireless LAN control device according to the embodiment of the present invention.
[0014]
The wireless LAN control device 9 of this embodiment is a control device of a base station called a so-called access point that centrally manages communication of a plurality of terminals registered in advance as devices in the same network, and is a physical layer that transmits and receives wireless signals. A processing circuit 21, a MAC layer controller 20 for controlling access to the wireless LAN, a semiconductor memory 10 such as a DRAM (Dynamic Random Access Memory), and the like are provided. The physical layer processing circuit 21 and the MAC layer controller 20 perform transmission / reception of radio signals and access control according to, for example, the IEEE 802.11 standard.
[0015]
Although not shown, the wireless LAN control device 9 includes a CPU that controls the entire device, a nonvolatile memory that stores the control program, and a wired LAN that is connected to the wired LAN and performs access control to the wired LAN. An interface is provided.
[0016]
The semiconductor memory 10 includes a CP queue 11 in which the order information of the data transmission processing that is waiting in the order during the reservation communication period in which the access control of the reservation communication method (for example, so-called random reservation method) is performed is registered. Necessary for data transmission in correspondence with each of a plurality of terminals and the CFP queue 12 in which the order information of the data transmission processing waiting for the order in the polling communication period in which polling access control is performed is registered A plurality of descriptor lists 13A0 to 13AN (in FIG. 1, the descriptor list corresponding to the n-th terminal is described as the STA number n descriptor list) in which polling communication is performed. The transmission information necessary for inquiring communication requests to multiple terminals is registered for multiple terminals. Descriptor list 13B for CF-Poll, a plurality of transmission frames 14-0 to 14-N reserved for transmission to the corresponding terminal, and polling transmitted to inquire communication requests to each terminal by polling control Control transmission frames 15 are stored respectively.
[0017]
2 shows a detailed data chart of the CP queue 11, and FIG. 3 shows a detailed data chart of the CFP queue 12.
[0018]
The CP queue 11 is a pointer-type data array in which information of memory access destinations of the DMA controller 19 at the time of reserved communication is shown in order. One data block which is one element of the data array is shown in FIG. As shown, valid bits indicating validity or invalidity of the block and terminal identification information (referred to as STA number) indicating which terminal to access the descriptor list 13A0 to 13AN are registered. Data registration in the CP queue 11 is performed by the CPU of the wireless LAN control device 9 when a data transmission request is generated based on, for example, reception data on the wired LAN side or communication reservation of each terminal.
[0019]
Data of each block of the CP queue 11 is sequentially read out by the DMA controller 19, and a CP pointer 22 in which information on a reading position of the DMA controller 19 is written is attached to the CP queue 11. The CP pointer 22 is updated by one every time information is read from the CP queue 11 by the DMA controller 19.
[0020]
The CFP queue 12 is a data array in which information of memory access destinations of the DMA controller 19 at the time of polling communication is shown in order, and a valid bit is included in one data block which is one factor of the data array as shown in FIG. And the STA number of the terminal are registered. In polling control, transmission is performed sequentially to a plurality of terminals, so that the STA numbers of a plurality of terminals registered by the CPU of the wireless LAN control device 9 are registered in order in the CFP queue 12 in a loop. Is done. A CFP pointer 24 similar to the CP pointer 22 is also attached to the CFP queue 12.
[0021]
FIG. 4 shows a detailed data chart of the descriptor lists 13A0 to 13AN and 13B.
[0022]
The descriptor lists 13A0 to 13AN for each terminal and the descriptor list 13B for polling are distinguished from each other in registered data, but have the same data structure.
[0023]
These descriptor lists 13A0 to 13AN and 13B are a series of data arrays in which transmission information (also referred to as descriptors) for one time necessary for data transmission is registered in order as described above, and one element of the data array The transmission information of one block includes valid bits indicating validity / invalidity of the block, communication control information such as a transmission rate, additional communication information such as a network ID, and corresponding transmission frames 14-0 to 14-14. The address of the semiconductor memory 10 storing -N, 15 and the frame length of the transmission frame are registered.
[0024]
The descriptor lists 13A0 to 13AN for each terminal are registered in the order in which transmission information of data transmission to the corresponding terminal is generated. For example, the data to the corresponding terminal based on the reception data on the wired LAN side or the communication reservation of each terminal. When a transmission request is generated, the CPU of the wireless LAN control device 9 registers data accordingly.
[0025]
In the polling descriptor list 13B, transmission information necessary for inquiring a communication request to each terminal by polling control is registered for a plurality of terminals. For example, the terminal is registered in the wireless LAN control device 9. At this time, it is generated in advance by the CPU of the wireless LAN controller 9. The polling descriptor list 13B registers polling control transmission information for a plurality of terminals so as to form a loop in the order of STA numbers.
[0026]
These descriptor lists 13A0 to 13AN and 13B are accompanied by descriptor pointers 27 and 27 'indicating the next reading positions, respectively. Similar to the CP pointer 22 of the CP queue 11, the descriptor pointer 27 attached to the descriptor list 13A0 to 13AN for each terminal is updated by one every time the descriptor list is accessed. The descriptor pointer 27 ′ associated with the polling descriptor list 13B is updated by one under the same conditions as the updating condition of the pointer 24 of the CFP queue 12, that is, there is no access to the polling descriptor list 13B. Each time one transmission is completed in the polling communication period, one is updated.
[0027]
The DMA controller 19 directly reads data from the CP queue 11 and CFP queue 12 without using the CPU, accesses the descriptor lists 13A0 to 13AN, 13B according to the read data, and further according to the read data. It includes a control circuit for simple channel control that automatically accesses other memory addresses. The procedure for accessing the semiconductor memory 10 will be described in detail in the operation description.
[0028]
FIG. 5 is an explanatory diagram of a configuration related to switching control between the polling period and the reserved communication period in the wireless LAN control device 9 described above.
[0029]
The wireless LAN control device 9 of this embodiment is configured to alternately switch between a polling method and a reserved communication method at a predetermined cycle by an internal timer. Therefore, the MAC layer controller 20 is provided with a period determination circuit 32 that determines whether it is a polling period or a reserved communication period based on a timer value. Further, the DMA controller 19 is provided with a queue selection circuit 30 for selecting a queue to be used according to a period, either the CP queue 11 or the CFP queue 12, and the period determination circuit 32 determines from what period the present period is. A determination signal 31 indicating this is input to the queue selection circuit 30. The queue selection circuit 30 outputs a selection signal 29 for selecting a queue corresponding to the determination signal 31 to the semiconductor memory 10 so that a queue to be used is selected. Even if the CP queue 11 and the CFP queue 12 are switched and used, the CP pointer 22 and the CFP pointer 24 remember the return destinations, so that the previous order can be taken over at the time of switching to return to normal.
[0030]
FIG. 7 shows an explanatory diagram of a configuration related to polling access control in the wireless LAN control device 9.
[0031]
In the wireless LAN control device 9 of the embodiment, the MAC layer controller 20 is provided with a frame type change circuit 38 that changes the transmission frame read by the DMA controller 19 to a transmission frame for polling communication. Details of the change processing will be described in detail later in the explanation of the operation. The frame type change circuit 38 is operated only in the polling communication period based on the determination signal 31 from the period determination circuit 32.
[0032]
Next, the operation of the wireless LAN control device 9 according to the embodiment will be described.
[0033]
FIG. 6 is a diagram for explaining the operation of the wireless LAN control device during the reserved communication period.
[0034]
When the timer value indicates the reserved communication period, the DMA controller 19 uses the CP queue 11 to perform direct memory access to the semiconductor memory 10. In the CP queue 11, the STA numbers of the respective terminals are registered in the order of transmission reservation, and the STA number indicated by the CP pointer 22 is read into the DMA controller 19.
[0035]
When the STA number is read, the DMA controller 19 accesses the descriptor list 13A0 to 13A2 for each terminal corresponding to the STA number, and reads the transmission information of the block indicated by the descriptor pointer 27. Further, when the valid bit of the transmission information is valid, the transmission frames (DATA) 14-0 to 14-2 are transferred from the semiconductor memory 10 based on the storage address and frame length information of the transmission frame in the transmission information. Read and transfer to the MAC layer controller 20. Note that control information and additional information included in the transmission information of the descriptor lists 13A0 to 13A2 are also transferred to the MAC layer controller 20 together with the transmission frame.
[0036]
The MAC layer controller 20 sends the transmission frame transferred from the DMA controller 19 to the physical layer processing circuit 21 while controlling access to the wireless LAN, and transmits the transmission frame to the corresponding terminal. When the transmission frame is correctly transmitted, the MAC layer controller 20 notifies the DMA controller 19 of the completion of transmission. Based on the notification, the DMA controller 19 transmits the transmission information of the descriptor list and the valid bits of the data block of the CP queue 11 that have completed the transmission process. , And further advances the descriptor list and the pointers 22 and 27 of the CP queue 11 by one, and proceeds to the next transmission process.
[0037]
On the other hand, if the valid block of the transmission information in the block of the CP queue 11 or the descriptor list 13A0 to 13A2 that the DMA controller 19 has accessed earlier indicates invalidity, the reading is interrupted and the CP queue 11 or descriptor list 13A0. The pointers 22 and 27 of .about.13A2 are advanced by 1, and the next transmission processing is started.
[0038]
Then, by repeating the processing as described above, as shown in the transfer data 37 of FIG. 6, the transmission frame “in which the valid bits of the transmission information are valid in the order of the STA numbers registered in the CP queue 11. Data (STA0) to Data (STA2) "are transmitted to the MAC layer controller 20 and transmitted to the corresponding terminal. In the case of FIG. 6, since the transmission information indicated by the pointer 27 of the descriptor list 13A1 with the STA number “1” is invalidated, the transmission frame “Data (STA1)” is omitted and transferred. In FIG. 6, the valid bits of all the blocks in the descriptor list 13A1 are described as invalid. However, the valid bits can be set to invalid and valid independently for each block. The same applies to the case of FIG. 8 described later.
[0039]
FIG. 8 is a diagram for explaining the operation of the wireless LAN control device during the polling period.
[0040]
When the timer value indicates the polling communication period, the DMA controller 19 uses the CFP queue 12 to perform direct memory access to the semiconductor memory 10. In the CFP queue 12, STA numbers of a plurality of registered terminals are registered in order, and the STA numbers indicated by the CFP pointer 24 in order are read into the DMA controller 19.
[0041]
When the STA number is read, the DMA controller 19 accesses the descriptor list 13A0 to 13A2 for each terminal corresponding to the STA number, and reads the transmission information of the block indicated by the descriptor pointer 27. When the valid bit is valid, the transmission frames 14-0 to 14-2 are read from the semiconductor memory 10 and output to the MAC layer controller 20 based on the storage address and frame length information of the transmission frame in the transmission information. To do. This transmission frame is the transmission frame “Data” of the reserved communication system as it is.
[0042]
On the other hand, when the valid bit of the transmission information read from the descriptor list 13A0 to 13A2 for each terminal by the DMA controller 19 is invalid, the DMA controller 19 discards the transmission information and newly creates a descriptor list for polling. 13B is accessed and the transmission information of the block indicated by the descriptor pointer 27 ′ is read. Based on the storage address and frame length information of the polling control transmission frame 15 in the transmission information, the transmission frame 15 is read from the semiconductor memory 10 and output to the MAC layer controller 20. The transmission frame “CF-Poll” read here makes an inquiry for a communication request to the terminal having the STA number indicated by the CFP queue 12.
[0043]
In the case of FIG. 8, when the STA numbers “0 → 1 → 2 → 0 → 1 → 2” are sequentially read from the CFP queue 12 to the DMA controller 19, and the STA numbers 0 and 2 are read. The transmission frames “Data (STA0), Data (STA2)” for reserved communication are transferred in order from the descriptor lists 13A0 and 13A2 of the terminals No. 0 and No. 2. On the other hand, when the first STA number is read, since the valid bit of the corresponding block in the descriptor list 13A1 of the first terminal is invalid, the transmission information is discarded, and instead from the polling descriptor list 13B. The polling transmission frame “CF-Poll (STA1)” has been read. Since the pointer 27 ′ of the descriptor list 13 B for polling is updated in synchronization with the pointer 24 of the CFP queue 12, the polling transmission frame “CF-Poll (STA1)” read here is indicated by the CFP queue 12. Corresponding to the STA number “1”.
[0044]
As described above, when the DMA controller 19 sequentially transfers the transmission frames one by one to the MAC layer controller 20 (a collection of the transmission frames is shown in the transfer data 39 in FIG. 7), the transmission frame is transferred to the MAC layer controller. One by one is input to the frame type change circuit 38 incorporated in the circuit 20. The frame type change circuit 38 determines whether the input transmission frame is of the polling method or the communication reservation method, and if it is a transmission frame “Data” of the communication reservation method, inquires of a communication request for polling communication. Is changed to a polling transmission frame “Data + CF-Poll” by changing the data arrangement. On the other hand, when the polling transmission frame “CF-Poll” is input, no change is made.
[0045]
Then, the MAC layer controller 20 performs the transmission frame reprocessed by the frame type change circuit 38 while performing access control to the wireless LAN (a collection of the transmission frames is shown in the transfer data 40 in FIGS. 7 and 8). One transmission process is sent to the physical layer processing circuit 21 one by one, and this transmission frame is transmitted to the corresponding terminal. When the transmission frame is correctly transmitted, the MAC layer controller 20 notifies the DMA controller 19 of the completion of transmission. Based on the notification, the DMA controller 19 accesses the transmission information in the descriptor list and the end of the CFP queue 12 that have completed the transmission process. The valid bit of the block is invalidated, and the pointers 24, 27, and 27 ′ of the descriptor list, the CFP queue 12, and the descriptor list 13B for polling are advanced by one, and the process proceeds to the next transmission process.
[0046]
Then, by repeating the above processing, if there is valid transmission information reserved for transmission in the order of the STA numbers indicated by the CFP queue 12, as shown in the transfer data 40 of FIG. Transmission frames “Data + CF-Poll (STA0)” and “Data + CF-Poll (STA2)” obtained by converting a transmission frame for communication into a polling type are transmitted from the MAC layer controller 20 to the physical layer processing circuit 21. If there is no valid transmission information reserved for transmission in the descriptor list of the terminal having the STA number indicated by the CFP queue 12, a transmission frame that inquires the terminal for a communication request for polling control. “CF-Poll (STA1)” is transmitted from the MAC layer controller 20 to the physical layer processing circuit 21 and transmitted to the corresponding terminal.
[0047]
As described above, according to the wireless LAN control device 9 of this embodiment, transmission is performed by simple channel control of the DMA controller 19 using the CFP queue 12, the descriptor lists 13A0 to 13AN for each terminal, and the descriptor list 13B for polling. The frame can be directly transferred from the semiconductor memory 10 to the MAC layer controller 20, thereby performing polling communication control. By such hardware processing, power consumption and cost can be reduced as compared with those in which communication control is performed by software processing using a CPU.
[0048]
Further, by alternately switching the CP queue 11 and the CFP queue 12 and using them, both the polling method and the reservation communication method can be controlled by hardware processing of the DMA controller 19 and the MAC layer controller 20.
[0049]
The invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Nor.
[0050]
For example, in the embodiment, it has been described that both types of access control are performed by switching between the CP queue and the CFP queue, but it is also possible to perform polling-type access control using only the CFP queue.
[0051]
Further, the data structure of the CP queue and the CFP queue is not limited to that of the embodiment. For example, the information for identifying each terminal included in each queue is not limited to the STA number. For example, the information is added to the descriptor list for each terminal. An ID number or a memory address associated with each descriptor list may be used. The data structure of the transmission information included in the descriptor list is not limited to that shown in the embodiment, and can be changed as appropriate as long as the transmission frame can be read and transmitted.
[0052]
In the above description, the wireless LAN control device called an access point, which is a field of use behind the invention made by the present inventor, has been described. However, the present invention is not limited to this, and for example, a communication terminal and an access It can be widely used for a wireless LAN device having a configuration that also has a point, a communication module that is mounted on a device that centrally manages wireless communication, and that only performs control on the wireless LAN side.
[0053]
【The invention's effect】
The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
[0054]
In other words, according to the present invention, it is possible to perform transmission control of the polling method by directly transferring transmission information from the storage means by simple channel control of the data transfer control device, and such hardware processing reduces power consumption and costs. There is an effect that it can be reduced.
[0055]
In addition, by switching between the polling communication index and the reserved communication index, both the polling method and the reservation communication method can be realized by hardware processing by the data transfer control device and the access control device. .
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration related to access control on a wireless LAN side in a wireless LAN device according to an embodiment of the present invention.
FIG. 2 is a data chart showing details of the CP queue of FIG. 1;
FIG. 3 is a data chart showing details of the CFP queue of FIG. 1;
4 is a data chart showing details of the descriptor list of FIG. 1. FIG.
FIG. 5 is a diagram illustrating a configuration related to switching control between a polling period and a reserved communication period in the wireless LAN device according to the embodiment.
FIG. 6 is a diagram for explaining an access control operation in a reserved communication method.
FIG. 7 is a diagram illustrating a configuration related to polling access control in the wireless LAN apparatus according to the embodiment.
FIG. 8 is a diagram for explaining a polling access control operation;
[Explanation of symbols]
9 Wireless LAN control device (wireless communication control device)
10 Semiconductor memory (memory means)
11 CP queue (index for reservation communication)
12 CFP queue (index for polling communication)
13A0-13AN descriptor list (transmission information list for each terminal)
13B descriptor list (polling transmission information list)
14-0 to 14-N Transmission reserved transmission frame 15 Transmission frame of polling method 19 DMA controller (data transfer control device)
20 MAC layer controller (access control device)
21 Physical Layer Processing Circuit 22 CP Pointer 24 CFP Pointer 27 Descriptor Pointer 30 Queue Selection Circuit 32 Period Determination Circuit 38 Frame Type Change Circuit (Frame Change Circuit)

Claims (3)

A wireless communication control device that manages wireless communication between a plurality of terminals,
Physical layer processing circuit for transmitting and receiving wireless signals, access control device for controlling access to wireless LAN, and storage means storing transmission information for performing polling control data transmission for sequentially inquiring each terminal for communication requests Bei example and a data transfer control device for transferring to the access control device polling control of the transmission frame by performing reading and writing in a particular access order with respect to,
In the storage means, identification information of each terminal is stored in the order of terminals, and an index for polling communication indicating an access destination at the time of polling communication and identification information of each terminal are stored in the order of reservation of transmission frames to each terminal. Reservation communication index indicating the access destination at the time of communication, transmission information list for each terminal storing transmission information for transmitting transmission reserved data to the corresponding terminal, and communication request to each terminal by polling control A polling transmission information list in which transmission information for sequentially inquiring is stored, and
The data transfer control device
At the time of polling communication, access is made to the transmission information list for each terminal in the order indicated by the information for the index for polling communication, the transmission frames reserved for transmission are transferred in the order of the terminals, and each terminal whose transmission information is invalidated If there is a transmission information list, the polling transmission information frame is accessed to transfer the polling transmission frame, and the storage means is accessed according to the information of the reserved communication indicator during communication in the reservation communication method. radio communication control apparatus characterized by being. The data transfer control device is configured to transfer the transmission frame reserved for transmission by accessing the transmission information list for each terminal indicated in the information of the reserved communication index during the communication of the reserved communication method. The wireless communication control device according to claim 1 . The access control device is provided with a frame change circuit for adding a transmission frame for inquiring a communication request to a transmission frame reserved for transmission transferred by the data transfer control device during polling communication. The wireless communication control device according to claim 2 .

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