CN1253021C - Comprehensive switch on business realizing method based on aerial band width resources - Google Patents

Abstract

The present invention relates to a method for implementing an integrated access service based on air bandwidth resources. E1 data uplink transmission and downlink transmission are performed between a terminal and a base station. The E1 data uplink transmission includes the following steps: 1) generating a fixed-period Bandwidth allocation mapping (MAP) figure to determine the transmission time of uplink E1 data; 2) terminal writes the transmission time of E1 data into hardware register according to the MAP figure of described generation; 3) according to the transmission time in the hardware register, Send E1 data; 4) The base station receives the E1 data according to the special identification code. Described E1 data downlink sending comprises the following steps: 5) setting E1 business parameter in hardware register; 6) hardware is set in MPEG frame according to described parameter and is specially used in the area that sends E1 data; 7) E1 data is put into above-mentioned sent in the region. The method of the present invention solves the problem that there is no air protocol suitable for the broadband wireless access system, especially it enables the broadband wireless access system to provide E1 services, improves the application range of the DOCSIS protocol, and increases the number of services provided by the broadband wireless access system. service type.

Description

A Realization Method of Integrated Access Service Based on Air Bandwidth Resource

technical field

The invention relates to a broadband wireless access system in the communication field, in particular to a method for realizing integrated access services based on air bandwidth resources in the broadband wireless access system.

Background technique

The broadband wireless access system adopts the point-to-multipoint wireless transmission mode to realize the fixed wireless integrated service access between the user network and the backbone network.

So far, there is no air protocol suitable for broadband wireless access systems, especially to support real-time circuit services provided by broadband wireless access. The DOCSIS protocol (Data-Over-Cable Service Interface Specifications) is a standard formulated for the two-way data transmission system of the cable TV network, which mainly stipulates the implementation of the physical layer and the MAC layer, and is used for point-to-multipoint integration in the cable TV network. business access.

Contents of the invention

The technical problem to be solved by the present invention is to expand and modify the bandwidth allocation strategy of the DOCSIS protocol in view of the fact that the transmission medium of the broadband wireless access system is different from that of the wired network and supports real-time circuit services, so as to overcome the fact that the DOCSIS protocol does not support broadband wireless To meet the needs of the broadband wireless access system to provide real-time circuit services.

The technical solution of the present invention is to provide a method for implementing integrated access services based on air bandwidth resources, including uplink transmission and downlink transmission of E1 data, characterized in that,

The E1 data uplink transmission comprises the following steps: 1) generating a bandwidth allocation mapping (MAP) map with a fixed period to determine the sending time of the uplink E1 data; 2) the terminal sends the E1 data sending time according to the generated MAP Write into the hardware register; 3) send E1 data according to the sending time in the hardware register; 4) the base station receives the E1 data according to the special identification code,

Described E1 data downlink transmission comprises the following steps: 1) setting E1 service parameter in hardware register; 2) hardware is set in MPEG frame according to described parameter and is specially used in the area that sends E1 data; 3) E1 data is put into above-mentioned sent in the region.

DOCSIS MAC frames are involved in the above steps, which will be briefly introduced below. The DOCSIS protocol is a protocol corresponding to the MAC layer and the PHY layer in the seven-layer protocol of the ISO OSI network. The main content defined by the MAC layer is the bandwidth allocation controlled by the base station and the corresponding QoS guarantee. It also involves variable length, Multiple rates, and support for multiple types of packets in the future.

The basic unit sent between the MAC layer of the base station and the terminal is a MAC frame. The uplink and downlink directions use the same basic frame structure. The length of the MAC frame is variable, and it is divided into four types: the MAC frame of the packet PDU, which supports variable-length Ethernet type packet data PDU; the MAC frame of the ATM cell, indicating that there is an ATM PDU in the frame; for future MAC frame reserved for PDU type; MAC frame for specific MAC control.

Among them, specific MAC frames are used for special functions. These functions can support downlink timing and uplink ranging/power modulation, terminals request bandwidth from base stations, base stations allocate bandwidth to terminals, etc., segmentation and concatenation of multiple MAC frames.

Step 1 in the above-mentioned uplink transmission involves MAP. The following briefly introduces the uplink bandwidth allocation map (MAP) of DOCSIS. The uplink channel is a data stream composed of mini-slots. The base station must be able to generate timing references for identifying these slots. In addition, it must also control the terminal's access to these time slots. For example, it can grant certain consecutive time slots to the terminal for sending data PDUs. The terminal must send data according to the timing requirements to ensure that the base station receives it at the specified time reference.

The system implements uplink channel bandwidth management through allocation mapping (MAP). The MAP is a variable-length MAC management message sent by the base station on the downlink channel, and defines the sending timing of the uplink channel. It contains a fixed-length header and many information elements IE (INTERVAL ELEMENT), each information element defines the range of the allowed mini-slots. A given MAP may designate certain slots as authorizations for specific stations to send data, certain slots for contention requests, and certain slots for opportunities for new stations to join the link.

Step 1 in the above-mentioned uplink transmission involves the bandwidth management of the E1 service uplink channel. For the E1 service, it is a specific real-time service, and adopts the provision of unsolicited bandwidth service (Unsolicited GrantService UGS). The base station must periodically provide a fixed data transmission bandwidth for the service flow, establish a service flow for each terminal's E1 data flow according to the number of E1 service channels opened by the terminal, and specify corresponding parameters. Then activate the service flow and assign a SID.

For the E1 service, in the first MAP diagram, data authorization is performed for each terminal E1 data frame sending opportunity. In the future, the base station will no longer authorize the E1 service in the MAP diagram, but it will not specify this period of time for other purposes (this period of time can be allocated to a SID that is not used by terminals). The terminal saves the sending opportunity and the sending period, and still sends the E1 data frame at the sending opportunity according to a certain period. However, when the sending opportunity needs to be changed (such as a terminal increasing or decreasing the number of N×64K circuits), the MAP map is sent again to authorize the sending opportunity of the E1 service. At the same time, the E1 service can be authorized to send once every certain period (which can be much longer than the MAP period).

In order to realize the E1 business, a certain expansion is made on the basis of the DOCSIS protocol, and an internal frame is used. The definition of each domain in the frame structure is shown in Table 1.

In step 1 of the above-mentioned uplink transmission, the maximum transmission delay of the E1 service in the system is required to be no more than 5ms according to the standard, so multiple data authorizations for the same E1 service need to be performed in each MAP. In this way, the delay of the E1 service will not exceed the standard.

In the first MAP diagram, data authorization is performed for each terminal E1 data frame sending opportunity. In the future, the base station will no longer authorize the E1 service in the MAP map, but this period of time will not be designated for other purposes. The terminal saves the sending opportunity and the sending period, and still sends the E1 data frame at the sending opportunity according to a certain period. When the sending opportunity needs to be changed (for example, a terminal increases or decreases the number of N×64K circuits), the MAP map is sent again to authorize the sending opportunity of the E1 service.

Step 4 of the above-mentioned uplink transmission involves a specific identification code. Referring to the reserved PDU frame header of the DOCSIS MAC frame, the E1 data frame header is set to 0×8C. The principle is that it does not differ from other types of frame headers (mainly management frames and data frames ) repeats.

The purpose of using the above-mentioned special frame header is to use hardware to quickly and conveniently distinguish E1 service frames from IP data frames; the second is to save overhead. For each terminal, the E1 frame length is relatively fixed, without source and destination MAC addresses, so a complete DOCSIS protocol MAC frame header is not required. While E1 frames are sent more frequently, using a shorter internal frame header can save a certain frame header overhead; the third is to distinguish different terminals. A simple terminal number should be included in the internal frame header to distinguish E1 frame headers from different terminals.

Step 2 of the above-mentioned downlink transmission involves MPEG frames, and the bandwidth management of the downlink E1 service is mainly realized by hardware. The bandwidth management of downlink E1 business is actually the distribution of MPEG frame payload. On the base station side, after serial-to-parallel conversion, the E1 data coming in from the two E1 interfaces completes the cross-connection of circuit services according to the queuing control parameters generated by the network management assignment information, and sequentially enters the downlink circuit service flow FIFO. At the same time, the framing, timing control and sending circuits generate a kind of MPEG frame according to the E1 service assigned by the network management.

Among them, the two domains of P circuit service pointer and circuit service payload are optional domains, and their availability and occupied bytes are determined by the configuration of E1 services. In case of a non-full configuration, the remaining bytes of these two fields can be used as data traffic payload.

For the data service, the MPEG frame header, the circuit service pointer field, and the length of the circuit service payload can all be regarded as a part of the physical layer, which is invisible to it. A data frame may be split into several data traffic payload fields for transmission. This also includes specific MAC frames. Note that the SYNC frame is special and cannot be interrupted. It is up to the hardware to ensure that it is transmitted in a data service payload field.

The invention solves the problem that there is no air protocol suitable for the broadband wireless access system, especially it enables the broadband wireless access system to provide E1 services, improves the application range of the DOCSIS protocol, and increases the services provided by the broadband wireless access system type.

Description of drawings

Figure 1 is a general MAC frame structure;

Fig. 2 is a standard MAC frame header format;

Fig. 3 is the extended MAC frame header format used for E1;

Fig. 4 is the DOCSIS MPEG packet format;

Fig. 5 is the expanded MPEG frame structure that can be used for E1;

Fig. 6 is the flowchart of the uplink sending of E1 data among the present invention;

Fig. 7 is a flowchart of downlink transmission of E1 data in the present invention.

Detailed ways

As shown in Figure 6, in the method for realizing integrated access services based on air bandwidth resources in the present invention, the E1 data is sent uplink through the following steps:

1) generating a bandwidth allocation mapping (MAP) diagram with a fixed period to determine the sending time of the uplink E1 data;

2) The terminal writes the sending time of the E1 data into the hardware register according to the generated MAP diagram;

3) sending E1 data according to the sending time in the hardware register;

4) The base station receives the E1 data according to the special identification code.

As shown in Figure 7, in the present invention's method for implementing integrated access services based on air bandwidth resources, E1 data is sent downlink through the following steps:

1) E1 service parameters are set in the hardware register;

2) the hardware sets the area specially for sending E1 data in the MPEG frame according to the parameters;

3) Put the E1 data into the above-mentioned area and send it.

Figure 1 is a general DOCSIS MAC frame structure. As can be seen from Figure 1, there are three domains in the general MAC frame structure: before the MAC frame is a physical medium (PMD) sublayer overhead (uplink) or an MPEG stream header ( downlink); the first part of the MAC frame is the MAC header, which uniquely identifies the content of the MAC frame; after the header is an optional data PDU domain. The format of the data PDU and its presence are defined in the MAC header.

Figure 2 is the general DOCSIS MAC frame header format. The general MAC header should have the general frame header format shown in Figure 2. The fields in the format are shown in Table 1. The frame control (FC) field is the first byte, the only To identify the rest of the content in the MAC header; after the FC field is a 3-byte MAC control field, an optional extended header field (EHDR) and a header check sequence (HCS).

Table 1 MAC header field usage length FC Frame control: Identify the type of MAC header 8 bits MAC_PARM Parameter field, usage depends on FC: if EHDR_ON=1, used for EHDR length (ELEN); used in concatenated frames (see Error! Reference source not found.) used for MAC frame count; or indicates the requested minislot number of (only for request messages) 8 bits LEN(SID) The length of the MAC frame. Defined as the sum of the number of bytes in the extension header and the number of bytes after the HCS field. (For the header of the request message, this field is replaced by the business ID) 16 bits EHDR Extended MAC header (variable length) 0-240 bits HCS MAC header check sequence 2 bytes The length of the MAC header 6 bytes + EHDR

The HCS field is a 16-bit CRC, which is used to ensure the integrity of the MAC header. It shall cover the entire MAC header, starting from the FC field and including all occurrences of the EHDR field. The HCS is calculated using the CRC (x ¹⁶ +x ¹² +x ⁵ +1) defined in ITU-T Recommendation X..25.

Among them, the FC field is divided into FC-TYPE sub-field, FC-PARM sub-field and an EHDR_ON indication flag, and its format is shown in Table 2. Among them, the FC_TYPE subfield is the highest two bits of the FC field. These two bits represent one of the four possible MAC frame formats: the MAC header of the packet PDU; the MAC header of the ATM cell; the MAC header reserved for future PDU types ; or the MAC header for specific MAC control.

Table 2 FC domain usage length FC_TYPE MAC frame control type field 00: MAC header of packet PDU 01: MAC header of ATM PDU 10: MAC header of reserved PDU 11: MAC specific header 2 bits FC_PARM Parameter bits, usage depends on FC TYPE 5 bits EHDR_ON When EHDR_ON=1, it means that there is an EHDR domain (the length of EHDR (ELEN) is determined by the MAC_PARM domain) 1 bit

The 5 bits behind FC_TYPE are FC_PARM subfields. The usage of these bits depends on the type of MAC header; the lowest bit of the FC field is the EHDR_ON indicator. If this bit is 1, it means that there is an extended header (EHDR).

The code type of the filling byte in the transmission convergence sublayer is defined as 0×FE, which means that the combination of FC_TYPE=11 and FC_PARM=11111 should not appear in the FC byte.

According to the FC domain, the MAC_PARM field of the MAC header has multiple purposes. If the EHDR_ON indicator is set to 1, the MAC_PARM field is applied to the extended header length (ELEN), and the EHDR field length can vary between 0 and 240 bytes; if this is A concatenation MAC header, then the MAC_PARM field represents the number of concatenation MAC frames (CNT); if this is a request message MAC header (REQ), then the MAC_PARM field represents the requested bandwidth number. Otherwise, the MAC_PARM field is reserved for future use.

The third field has two possible usages. In most cases, it indicates the length (LEN) of the MAC frame; in a special case, that is, in the request message MAC header, since the MAC header does not follow the PDU, it Used to indicate the CM ID.

The Extended Header (EHDR) field provides extensions to the MAC frame format. It is used for slotted data link security, frame segmentation, and is extensible to support functionality added in future releases. In a primary implementation, this field should be passed to the handler. Later software upgrades can benefit from this capability.

The MAC header can be followed by a data PDU, and the type and format of the data PDU are defined in the frame control field of the MAC header. The FC domain clearly defines the packet data PDU, ATM data PDU, MAC specific frame and a reserved code (for the escape mechanism when it is extended in the future). All CMs shall use the length field in the MAC header to skip all reserved data.

Figure 3 is the MAC frame header format extended by DOCSIS for E1. Referring to the reserved PDU frame header of DOCSIS MAC frame, set the E1 data frame header as 0×8C. The principle is not to overlap with other types of frame headers (mainly management frames and data frames).

The upstream channel is actually a data stream composed of mini-slots, and the CMTS must be able to generate timing references for identifying these slots, and it must also control the CMs to access these slots. For example, it can grant certain consecutive time slots to the CM for sending data PDUs. The CM must send data according to the timing requirements to ensure that the CMTS receives it at the specified time reference. The protocol elements used in requesting, granting and upstream bandwidth allocation are described below. Among them, the bandwidth allocation management mechanism is to allocate MAP.

Assignment MAP is a MAC management message sent by the downlink channel of the CMTS, which describes the time when the uplink mini-slot is sent. A given MAP can designate certain time slots as authorizations for specific stations to send data, some time slots for contention transmissions, and other time slots as opportunities for new stations to join the link.

Figure 4 is the DOCSIS general MPEG format, which includes 4 bytes of MPEG overhead, a pointer field (not present in all packets) and the net load. Wherein the MPEG payload is used to bear the MAC frame.

Fig. 5 is the MPEG form that the present invention expands, and it comprises the MPEG overhead of 4 bytes, a pointer field (not all existing in all packets), net load front part is the circuit service payload, and the rear part is other service payloads.

Compared with the general DOCSIS MPEG format, the present invention increases the payload of the circuit service.

Regarding the delay guarantee of the E1 service, according to the standard, the maximum transmission delay of the E1 service in the system is not more than 5ms, so in each MAP), it is necessary to perform multiple data authorizations for the same E1 service. In this way, the delay of the E1 service will not exceed the standard.

In the first MAP diagram, data authorization is performed for each terminal E1 data frame sending opportunity. In the future, the base station will no longer authorize the E1 service in the MAP map, but this period of time will not be designated for other purposes. The terminal saves the sending opportunity and the sending period, and still sends the E1 data frame at the sending opportunity according to a certain period. When the sending opportunity needs to be changed (for example, a terminal increases or decreases the number of N×64K circuits), the MAP map is sent again to authorize the sending opportunity of the E1 service.

The invention expands and improves the DOCSIS protocol, and the protocol can be applied to the broadband wireless access system, especially after being improved, it can ensure that the broadband wireless access system provides E1 services satisfying a certain maximum delay.

Claims (8)

1. A method for implementing an integrated access service based on air bandwidth resources, performing uplink transmission and downlink transmission of E1 data between a terminal and a base station, characterized in that, The E1 data uplink transmission comprises the following steps: 1) generating a bandwidth allocation mapping map map with a fixed period to determine the sending time of the uplink E1 data; 2) the terminal writes the sending time of the E1 data according to the generated MAP map Hardware register; 3) according to the sending time in the hardware register, send E1 data; 4) base station receives described E1 data according to special identification code, Described E1 data downlink transmission comprises the following steps: 1) setting E1 service parameter in hardware register; 2) hardware is set in MPEG frame according to described parameter and is specially used in the area that sends E1 data; 3) E1 data is put into above-mentioned sent in the region. 2. The method for implementing integrated access services based on air bandwidth resources according to claim 1, characterized in that the sending unit of the MAC layer for uplink and downlink between the base station and the terminal is a variable-length MAC frame, including: support MAC frame of packet data PDU packet of variable length Ethernet type; MAC frame of ATM cell indicating that there is an ATM PDU in the frame; MAC frame reserved for future PDU types; MAC frame for specific MAC control. 3. The method for implementing integrated access services based on air bandwidth resources according to claim 1, characterized in that the uplink channel for E1 data uplink transmission includes data streams composed of mini-slots, and the base station generates and transmits data streams that can identify these The timing of the slots references and controls the access slots of the terminals. 4. The method for realizing integrated access services based on air bandwidth resources according to claim 1, characterized in that it comprises the following steps: for E1 services, in the first MAP diagram, the sending opportunity of each terminal E1 data frame For data authorization, the terminal saves the sending timing and sending cycle, and sends E1 data frames at the sending timing according to a certain period, but sends the MAP map when the sending timing needs to be changed, and authorizes the sending timing of the E1 business, or every certain period , and then perform a sending authorization for the E1 service. 5. The method for implementing integrated access services based on air bandwidth resources according to claim 4, wherein the authorization includes expanding the use of an internal frame on the basis of the DOCSIS protocol, and each MAP requires the same E1 Multiple data authorizations are performed for the business, and in the first MAP diagram, data authorization is performed for each terminal E1 data frame sending opportunity. 6. The method for implementing integrated access services based on air bandwidth resources according to claim 1, wherein the authorization includes that the terminal saves the sending opportunity and the sending cycle, and sends the E1 data frame according to a certain period by the sending opportunity, and when the sending opportunity When the need changes, send the MAP map to authorize the sending timing of the E1 service. 7. The method for realizing integrated access services based on air bandwidth resources according to claim 1, wherein the base station receives the specific identification code in the E1 data according to the special identification code, and refers to the reserved PDU of the DOCSIS MAC frame Frame header, set the E1 data frame header as 0x8C or other numbers that do not overlap with other types of frame headers. 8. The method for realizing integrated access services based on air bandwidth resources according to claim 1, wherein the hardware sets an area specially used for sending E1 data in the MPEG frame according to the parameters, wherein the MPEG frame The two fields of P circuit service pointer and circuit service payload are optional fields. The configuration of E1 services determines whether they exist and the number of occupied bytes. Sections can be used as data traffic payloads.

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