CN101754424A - Interaction method of MAC layer and network layer and dual core embedded system - Google Patents

Abstract

The invention provides an interaction method of an MAC layer and a network layer, which comprises a function of completing the network layer on an ARM, a function of completing the MAC layer on a DSP, and realization of message interaction of the network layer and the MAC layer by an interface message sent from the MAC layer to the network layer, an interface message sent from the network layer to the MAC layer, an MAC layer service primitive and a network layer service primitive, wherein the network layer function at least comprises routing and addressing; and the MAC layer function at least comprises access, queue scheduling and time slot reservation. After using a C++ simulation platform developed by Microsoft Visual Studio.Net on a Windows operating platform to test the data sending and receiving processes among nodes, the interaction method connects the DSP and the ARM to carry out combined test on the data interaction of the MAC layer and the network layer. The test result shows that the data interaction is normally completed.

Description

The exchange method and the dual core embedded system of a kind of MAC layer and network layer

Technical field

The invention belongs to the wireless Mesh netword communications field, particularly relating to is a kind of MAC layer and network layer exchange method and a kind of dual core embedded system based on the IEEE802.16d design of protocol.

Background technology

Wireless mesh network, form by mesh routers (router) and mesh clients (client), wherein mesh routers constitutes backbone network, and is connected with wired internet net, and being responsible for mesh clients provides the wireless internet of multi-hop to connect.Wireless Mesh netword (based on wireless mesh network) is also referred to as " multi-hop (multi-hop) " network, and it is a kind of and the diverse novel radio network technology of conventional wireless network.

In wireless Mesh netword, any wireless device node can be simultaneously as AP and router, and each node in the network can send and received signal, and each node can carry out direct communication with one or more peer node.The largest benefit of this structure is: congested if nearest AP causes owing to flow is excessive, data can re-route a less adjacent node of communication flows automatically and transmit so.The rest may be inferred, and packet can also continue to be routed to nearest with it next node and transmit according to the situation of network, till arriving the final destination.

The continuous variation of the time variation of wireless channel environment and network topology in the wireless Mesh netword requires can intercourse information between each layer of network service, makes a response fast to improve network performance.For the information interaction between network layer and the MAC layer, the MAC layer is the classification of awareness network layer data in time, communication mode, information such as transmitted power, and network layer also needs to obtain the state of node such as received power and at net state etc. by the MAC layer, this just need determine a kind of communication process of standard between MAC layer and network layer, to realize the mutual of network layer and MAC layer information.

IEEE 802.16d agreement has been carried out detailed standard to the air interface of wireless metropolitan area network MAC layer and physical layer, but agreement has just provided processing framework and the flow process of data at the MAC layer from the angle of MAC layer, do not proceed from the situation as a whole to consider mutual with network layer, this has stayed the research space just for protocol development person.

In a word, a technical problem that needs those skilled in the art to solve at present is exactly: how can improve IEEE 802.16d mac-layer protocol, provide the implementation of data in the concrete reciprocal process of network layer and MAC layer.

Summary of the invention

Technical problem to be solved by this invention provides a kind of MAC layer and network layer exchange method based on IEEE 802.16d design of protocol, and a kind of dual core embedded system, by design to the hardware interface of MAC layer and network layer communication, and to the design of interlayer interface message, service primitive and reciprocal process thereof, thereby realized data mutual at network layer and MAC layer.

In order to address the above problem, the invention discloses the exchange method of a kind of MAC layer and network layer, comprising: finish the function of network layer on ARM, described Network layer function comprises route, addressing at least; Finish the function of MAC layer on DSP, the function of described MAC layer comprises access, queue scheduling and time slot reservation at least; Between ARM and DSP, by the interface message of MAC layer to network layer, network layer is given the interface message of MAC layer, and MAC layer service primitives and network layer service primitive realization network layer and MAC layer message is mutual; Wherein, interface message is meant that the data with the N+1/N layer send to the N/N+1 layer also for the message of its use, and service primitive is used for N+1/N course N/N+1 layer and sends instruction, realizes the dialogue between the different layers in the protocol stack.

Preferably, when main frame need be communicated by letter with DSP, can send interruption to DSP by writing interrupt bit DSPINT, DSP handles data by dma mode inside; When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame is by the HPI read data.

Preferably, network layer comprises for the interface message of MAC layer: the data type of network layer; The communication mode of network layer data; Network layer is by the maximum transmit power of topology control decision; The classification of network layer IP packet; The length of network layer IP bag; And, next-hop ip address.

Preferably, the MAC layer comprises for the interface message of network layer: radio frequency is given the received power of MAC layer; The MAC layer receives the source IP address of network layer data; The received power value that network layer is given according to the MAC layer routing operations of being correlated with; Network layer is set up reverse route according to source IP address.

Preferably, network layer comprises following two types for the service primitive of MAC layer: IP address notification message and multicast address upgrade primitive.

Preferably, MAC comprises following two types for the service primitive of network layer: network insertion primitive and People Near Me upgrade primitive.

According to another embodiment of the present invention, a kind of be used to realize MAC layer and the mutual dual core embedded system of network layer are also disclosed, comprising:

Arm processor is used to finish the function of network layer, and described Network layer function comprises route, addressing at least;

Dsp processor is used to finish the function of MAC layer, and the function of described MAC layer comprises access, queue scheduling and time slot reservation at least;

Interface unit comprises the bus interface that links to each other with arm processor, and the HPI interface that links to each other with dsp processor communicates by parallel bus between bus interface and the HPI interface; All can visit described HPI interface as the arm processor of main frame and the CPU of DSP;

Between arm processor and dsp processor, by the interface message of MAC layer to network layer, network layer is given the interface message of MAC layer, and MAC layer service primitives and network layer service primitive realization network layer and MAC layer message is mutual; Wherein, interface message is meant that the data with the N+1/N layer send to the N/N+1 layer also for the message of its use, and service primitive is used for N+1/N course N/N+1 layer and sends instruction, realizes the dialogue between the different layers in the protocol stack.

Preferably, in the time need communicating by letter with DSP as the arm processor of main frame, write interrupt bit DSPINT and send interruption by the HPI interface to DSP, DSP handles data by dma mode inside; When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame is by the HPI read data.

Compared with prior art, the present invention has the following advantages:

The present invention has improved IEEE 802.16d mac-layer protocol, provides the implementation of data in the concrete reciprocal process of network layer and MAC layer.The present invention is on hardware is realized, based on the ARM+DSP dual core embedded system, designed the interface of hardware communications between DSP that realizes the MAC layer function and the ARM that realizes Network layer function, promptly MAC layer and the network layer data exchange method between ARM and DSP hardware is to realize by the HPI interface that main frame and DSP CPU can visit.Further, the present invention has provided interface message and service primitive and using method thereof that MAC layer and network layer are used when mutual on software is realized.

Description of drawings

Fig. 1 is a kind of structural representation that is used to realize the dual core embedded system that MAC layer and network layer are mutual of the present invention;

Fig. 2 is the schematic diagram of the interface message frame format in MAC layer of the present invention and the network layer reciprocal process;

Fig. 3 is the frame format schematic diagram of the service primitive in MAC layer of the present invention and the network layer reciprocal process.

Embodiment

For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

Core idea of the present invention is: the inventor of this patent is by analyzing IEEE 802.16d agreement, unspecified MAC layer and network layer communication flow process in the design agreement, from application point of view MAC layer and network layer communication implementation method are proposed, concrete has comprised: the design of MAC layer and network layer hardware interface, the design of software interface message and reciprocal process thereof; The combination of the two is used and has been realized MAC layer and network layer communication flow process.

The C++ emulation platform of the present invention by using Microsoft Visual Studio.Net exploitation at the Windows operating platform to node between data send and receive after flow process tests, connect DSP and ARM and carry out the mutual of joint test MAC layer and network layer data, test result shows that data interaction normally finishes.The present invention has filled up the not blank of the communication mechanism of standard network layer and MAC layer of IEEE 802.16d agreement.

With reference to Fig. 1, show that the present invention is a kind of to be used to realize MAC layer and the mutual dual core embedded system of network layer, comprising:

Arm processor 101 is used to finish the function of network layer, and described Network layer function comprises route, addressing at least;

Dsp processor 102 is used to finish the function of MAC layer, and the function of described MAC layer comprises access, queue scheduling and time slot reservation at least;

Interface unit 103 comprises the bus interface 1031 that links to each other with arm processor, and the HPI interface 1032 that links to each other with dsp processor communicates by parallel bus between bus interface and the HPI interface; All can visit described HPI interface as the arm processor of main frame and the CPU of DSP;

Between arm processor and dsp processor, by the interface message of MAC layer to network layer, network layer is given the interface message of MAC layer, and MAC layer service primitives and network layer service primitive realization network layer and MAC layer message is mutual; Wherein, interface message is meant that the data with the N+1/N layer send to the N/N+1 layer also for the message of its use, and service primitive is used for N+1/N course N/N+1 layer and sends instruction, realizes the dialogue between the different layers in the protocol stack.

HPI (Host-Port Interface) host interface can be used a parallel port that 16bit/32bit is wide usually.Main frame (host) can be realized by the EDMA controller the visit in cpu address space.The visit of HPI interface is general main to be realized by three special registers: HPI control register (HPIC), HPI address register (HPIA) and HPI data register (HPID).

In the time need communicating by letter with DSP as the arm processor of main frame, write interrupt bit DSPINT and send interruption to DSP by the HPI interface, DSP handles data by dma mode inside; When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame is by the HPI read data.

The present invention comprises the design particular content of MAC layer and network layer hardware interface: the access of MAC layer, and scheduling, functions such as time slot allocation are downloaded to DSP and go up realization, and the functional module of network layer then is encapsulated in ARM and goes up realization; Whole system realizes based on the ARM+DSP dual core embedded system.For realizing communicating by letter between ARM and DSP, both hardware interfaces of communication are also designed.

The MAC layer as shown in Figure 1 and the hardware interface of network layer communication, from the angle of MAC layer, the hardware interface that links to each other with it is exactly the HPI interface that main frame and DSP CPU can visit; By the HPI interface, can realize the exchanges data of main frame and DSP.When main frame during to certain address of DSP memory space write data, can send interruption to DSP by writing interrupt bit DSPINT, DSP handles data by dma mode inside.When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame has just been realized the exchanges data of main frame and DSP thus by the HPI read data.

DSPINT is that main frame is sent out interrupt signal and notified pin on its sheet that reads or writes data for the HPI register; HINT then is that DSP sends out interrupt signal to pin on the sheet of its read data of host notification; The HPI register is divided into HPIC (control), and three kinds of HPIA (address) and HPID (data), main frame can visit this three kinds of registers, and DSP CPU can visit HPIC and HPIA register.The realization flow of data between hardware is to specify DSP the preceding paragraph address space storage networking layer to give the data of network layer for MAC layer and MAC layer.Send to the MAC layer when network layer has data, carry out the memory space that the HPI operation writes data to appointment, send interrupt signal notice MAC layer then and fetch data by main frame; When having data, the MAC layer to give network layer, by operating the HPIA register and sending interrupt signal notice main frame from the designated memory space read data.So just realized mutual by hardware of MAC layer and network layer data.

The present invention also provides a kind of MAC layer on the dual core embedded system of ARM and DSP and the mutual implementation of network layer, comprising:

Finish the function of network layer on ARM, described Network layer function comprises route, addressing at least; ,

Finish the function of MAC layer on DSP, the function of described MAC layer comprises access, queue scheduling and time slot reservation at least;

Between ARM and DSP, by the interface message of MAC layer to network layer, network layer is given the interface message of MAC layer, and MAC layer service primitives and network layer service primitive realization network layer and MAC layer message is mutual;

Wherein, interface message is meant that the data with the N+1/N layer send to the N/N+1 layer also for the message of its use, and service primitive is used for N+1/N course N/N+1 layer and sends instruction, realizes the dialogue between the different layers in the protocol stack.

When main frame need be communicated by letter with DSP, can send interruption to DSP by writing interrupt bit DSPINT, DSP handles data by dma mode inside; When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame is by the HPI read data.

The present invention also comprises the design at interface message and interaction flow thereof except the design to the hardware interface of MAC layer and network layer.Concrete, its interaction flow need comprise: the data with the N+1/N layer send to the N/N+1 layer and provide the interface message of subsequent operation desired parameters for it; The interlayer request, reply, the primitive message of indication and response message dialogue.

Described MAC layer and network layer interface message specifically comprise: the interface message that the MAC layer gives MAC layer both direction for network layer and network layer.Similarly, service primitive also is divided into two kinds of MAC layer service primitives and network layer service primitives.

Data are called frame at the form of MAC layer, and the MAC layer is by adding that with its data cell MAC-PDU that transmits message the frame head postamble reaches the purpose of data framing; Frame Check Sequence FCS is used for the control of MAC layer data mistake; CMD then is used to distinguish MAC layer News Category to indicate and to control corresponding flow chart of data processing; LEN then represents to remove the data length of frame head postamble.

The form of interface message and service primitive is different, the interface message frame format as shown in Figure 2, it comprises frame head 201, length is 1 byte, postamble 202, length is 1 byte; Be used to distinguish the CMD203 of News Category, length is 1 byte; Remove the frame length LEN204 of frame head postamble,, length is 2 bytes; Interlayer interface message 205, length are 8 bytes; Frame Check Sequence FCS206, length is 1 byte.MAC-PDU207 is the unit that the MAC layer transmits message, may take 4480 bytes usually.

The frame format of service primitive as shown in Figure 3, it comprises the CMD303 of 302,1 bytes of postamble of 301,1 bytes of frame head of 1 byte, the service primitive information 305 of the FCS304 of 1 byte and 8 bytes.

The difference of interface message and service primitive is that interface message is to send to corresponding protocol layer with sending data, and it provides deal with data required message for corresponding protocol layer.Service primitive belongs to a kind of instruction, and in a single day it be received, and will make respective response, and interface message then need not make an immediate response.

Below each interface message and service primitive are elaborated.

Network layer comprises for the interface message of MAC layer: the data type of network layer; The communication mode of network layer data; Network layer is by the maximum transmit power of topology control decision; The classification of network layer IP packet; The length of network layer IP bag; And, next-hop ip address.

Concrete, network layer is given the interface message form such as the following table 1 of MAC layer,

CMD＝0x80

Parameter	Sign	Placeholder	Describe in detail
				Control/Data Labels	??flag_contrl_data	??2bit	0x1: control; 0x0: data
Broadcasting/clean culture/multicast flags	??flag_brod_muti_uni	??2bits	0x0: broadcasting; 0x1: clean culture; 0x2: multicast
				Maximum transmission power	??tx_power_max	??4bits	The maximum of NET layer notice MAC layer sends merit
			Rate
				The type of service flag bit	??flag_service	??8bits	The type of service of NET layer notice MAC layer data clean culture/multicast
The length of IP bag	??ip_length	??16bits	The maximum length of IP bag is 2 16
				Next-hop MAC ID/ multicast ID address	??next_ip_addr	??32bits	Broadcasting/clean culture/multicast flags position

Wherein, flag_control_data is the Ip packet of 0 expression network layer, and flag_control_data is the control messages such as the Hello message of 1 expression network layer, REQ, RERR, ARP request etc.;

Flag_brod_multi_uni represents the communication mode of network layer data, and flag_brod_multi_uni is 0 expression broadcasting, is 1 expression clean culture, is 2 expression multicasts.

Tx_power_max represents that network layer passes through the maximum transmit power of topology control decision, and IEEE802.16 agreement regulation performance number should increase progressively with 2dBm from 8dBm, as 1111 expression 38dBm.

Flag_service represents the classification of network layer IP packet, and flag_service is that 0x0 represents the UGS business, for 0x1 represents the Rtps business, for 0x2 represents the Nrtps business, for 0x3 represents the BE business.

Ip_length represents the length of network layer IP bag;

Next_ip_addr represents next-hop ip address, if network layer data broadcasting, be that flag_brod_multi_uni is 0, then next_ip_addr is 0xFFFFFFFF, if network layer data clean culture, then next_ip_addr is the next-hop ip address of clean culture, if the network layer data multicast, then next_ip_addr is a multicast ip address.

The MAC layer is according to the data type of the flag_control_data mark position to distinguish network layer in the network layer interface message and handle accordingly, the MAC layer sends at the DSCH sending time slots control messages, will carry out time slot reservation to the IP data before transmission and be connected with request.To broadcasting, handle accordingly by clean culture and multi-case data by flag_brod_multi_uni and next_ip_addr for the MAC layer, and different communication modes is in the corresponding different data pathfinding mode of MAC layer.The MAC layer is classified and list in order of importance and urgency to network layer data by flag_service; Thereby calculate PDU length according to ip_length data are carried out branch package bag.

The MAC layer comprises for the interface message of network layer: radio frequency is given the received power of MAC layer; The MAC layer receives the source IP address of network layer data; The received power value that network layer is given according to the MAC layer routing operations of being correlated with; Network layer is set up reverse route according to source IP address.The MAC layer is given the interface message form such as the following table 2 of network layer,

CMD＝0x00

Parameter	Sign	Placeholder	Describe in detail
				Received power	??recv_power	??8its	From 8dBm, 2dBm increases progressively
Last one hop IP address that receives/multicast ID	??prev_ip_addr	??32bits	This message is carried in Mesh head
				Keep the position	??reserved	??24bits	MAC → NET and NET → MAC interface size is consistent

Wherein, recv_power represents that radio frequency gives the received power of MAC layer, and prev_ip_addr represents that the MAC layer receives the source IP address of network layer data.The recv_power value that network layer is given according to the MAC layer is carried out route maintenance, operations such as location and range finding; Set up reverse route by prev_ip_addr.

Network layer has two kinds for the service primitive of MAC layer: IP address notification message and multicast address upgrade primitive.Wherein,

The form of IP address notification primitive such as following table 3,

CMD＝0x81

Parameter	Sign	Placeholder	Describe in detail
				This node IP address	??device_ip_addr	??32bits	Network layer receives access primitive, sends this message immediately to the MAC layer

If node receives the MAC layer and inserts primitive, just reply IP address notification primitive and give the MAC layer.

Multicast address upgrades the form such as the following table 4 of primitive,

CMD＝0x82

Parameter	Sign	Placeholder	Describe in detail
				Multicast IP upgrades	??next_group_ip	??32bits	The network layer multicast address is upgraded

Find multicast address when network layer and change, just send multicast address and upgrade primitive to the new multicast ip address of MAC layer notice MAC layer.

MAC comprises following two types for the service primitive of network layer: network insertion primitive and People Near Me upgrade primitive.

Wherein, the form of network insertion primitive such as following table 5,

CMD＝0x01

Parameter	Sign	Placeholder	Describe in detail
				Node access network sign	??flag_access	??8bits	0: the node access network

If node access network, it is that 1 service primitive is to network layer that the MAC layer sends flag_access, network layer one receives this message, just gives the MAC layer by network layer IP address notification service primitive recovery of node IP, so that the MAC layer is corresponding one by one with NodeID and IP address.

People Near Me upgrades the form such as the following table 6 of primitive,

CMD＝0x02

Parameter	Sign	Placeholder	Describe in detail
				Flag bit	??flag_type	??8bits	0: invalid neighbours address 1: effective neighbours address
Neighbours IP address	??invalid_node_ip	??32bits	Next hop address

The MAC layer is after receiving network layer interface message, if in the node neighbor list, can not find the next_ip_addr in the interface message, it is that 0 this neighbours address of expression is invalid that the MAC layer is provided with flag_type in the primitive message, by invalid_node_ip invalid IP address notification network layer with the renewal routing table.

More than to the dual core embedded system of a kind of ARM provided by the present invention and DSP, and a kind of MAC layer on its basis and the mutual implementation of network layer, be described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (8)

1. the exchange method of MAC layer and network layer is characterized in that, comprising:

Finish the function of network layer on ARM, described Network layer function comprises route, addressing at least;

Finish the function of MAC layer on DSP, the function of described MAC layer comprises access, queue scheduling and time slot reservation at least;

Between ARM and DSP, by the interface message of MAC layer to network layer, network layer is given the interface message of MAC layer, and MAC layer service primitives and network layer service primitive realization network layer and MAC layer message is mutual;

Wherein, interface message is meant that the data with the N+1/N layer send to the N/N+1 layer also for the message of its use, and service primitive is used for N+1/N course N/N+1 layer and sends instruction, realizes the dialogue between the different layers in the protocol stack.

2. the method for claim 1 is characterized in that:

When main frame need be communicated by letter with DSP, can send interruption to DSP by writing interrupt bit DSPINT, DSP handles data by dma mode inside;

When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame is by the HPI read data.

3. the method for claim 1 is characterized in that, network layer comprises for the interface message of MAC layer:

The data type of network layer; The communication mode of network layer data; Network layer is by the maximum transmit power of topology control decision; The classification of network layer IP packet; The length of network layer IP bag; And, next-hop ip address.

4. the method for claim 1 is characterized in that,

The MAC layer comprises for the interface message of network layer: radio frequency is given the received power of MAC layer; The MAC layer receives the source IP address of network layer data;

The received power value that network layer is given according to the MAC layer routing operations of being correlated with; Network layer is set up reverse route according to source IP address.

5. the method for claim 1 is characterized in that, network layer comprises following two types for the service primitive of MAC layer:

IP address notification message and multicast address upgrade primitive.

6. the method for claim 1 is characterized in that, MAC comprises following two types for the service primitive of network layer:

Network insertion primitive and People Near Me upgrade primitive.

7. one kind is used to realize MAC layer and the mutual dual core embedded system of network layer, it is characterized in that, comprising:

Arm processor is used to finish the function of network layer, and described Network layer function comprises route, addressing at least;

Dsp processor is used to finish the function of MAC layer, and the function of described MAC layer comprises access, queue scheduling and time slot reservation at least;

Interface unit comprises the bus interface that links to each other with arm processor, and the HPI interface that links to each other with dsp processor communicates by parallel bus between bus interface and the HPI interface; All can visit described HPI interface as the arm processor of main frame and the CPU of DSP;

Between arm processor and dsp processor, by the interface message of MAC layer to network layer, network layer is given the interface message of MAC layer, and MAC layer service primitives and network layer service primitive realization network layer and MAC layer message is mutual; Wherein, interface message is meant that the data with the N+1/N layer send to the N/N+1 layer also for the message of its use, and service primitive is used for N+1/N course N/N+1 layer and sends instruction, realizes the dialogue between the different layers in the protocol stack.

8. dual core embedded system as claimed in claim 7 is characterized in that:

In the time need communicating by letter with DSP as the arm processor of main frame, write interrupt bit DSPINT and send interruption to DSP by the HPI interface, DSP handles data by dma mode inside;

When DSP has data will be with main-machine communication the time, send interruption by DSP control HINT position to main frame, the notice main frame is by the HPI read data.

Images