CN100574197C - Distribution method of dynamic bandwidth, system and the device of quick response - Google Patents

Abstract

The invention discloses the distribution method of dynamic bandwidth, system and the device that respond fast in a kind of EPON, this EPON comprises optical line terminal (OLT) and a plurality of optical network unit (ONU), described OLT communicates by any tree-like light distributed network and described a plurality of ONU to multiple spot, descending employing broadcast mode, up employing time division multiplexing mode, described ONU sends report message to described OLT; After receiving described report message, described OLT handles it immediately, and sends corresponding gating message to described ONU immediately.Described ONU comprises: buffer storage is used for the buffer memory business datum; Deriving means is used for obtaining report message from buffer storage; Dispensing device is used to send business datum and report message.Described OLT comprises: receiving and processing device, after being used to receive report message, immediately it is handled; Dispensing device is used for after handling described report message, sends corresponding gating message immediately.

Description

Rapid response dynamic bandwidth allocation method, system and device

technical field

The invention relates to a passive optical network, in particular to a fast-response dynamic bandwidth allocation method, system and device in the passive optical network.

Background technique

Passive Optical Access Network (PON) is a technical solution that utilizes passive optical devices such as optical fibers and optical splitters to form an optical distribution network for broadband access. It is usually composed of optical line terminal (OLT), optical network unit (ONU) and optical distribution network (ODN). Figure 1 shows a typical passive optical access network. It includes OLT 11, splitter 12, point-to-multipoint tree optical distribution network 13 and N ONUs, which are ONU 141, ONU 142...ONU 14N. Wherein, the OLT communicates with multiple ONUs through a point-to-multipoint tree ODN 13. In the communication mode, the downlink adopts the broadcast mode, and the ONU receives its own data packets according to the identification of the data packets. However, the uplink uses time division multiplexing (TDMA) to share the bandwidth, and the ONU can only transmit information to the OLT in the time slot allocated to itself, and can only wait at other times. The uplink transmission time slot of the ONU is allocated by the OLT, and the OLT notifies the ONU when it can start transmitting uplink data and how long it will take by sending a strobe message to the ONU. In this way, the OLT can implement uplink bandwidth allocation among the ONUs. It can be seen that PON is a system based on a point-to-multipoint network structure, and all ONUs share transmission bandwidth through OLT scheduling. Existing PON technologies include APON/BPON based on Asynchronous Transfer Mode (ATM), EPON based on Ethernet and GPON with Gigabit rate.

Since the data traffic carried on the PON is often bursty, if a fixed bandwidth is simply allocated to each ONU, the following situation may occur: some ONUs arrive at a small amount of data, and most of the bandwidth allocated to it is not used. However, the amount of data arriving in some other ONUs is very large, and the bandwidth allocated to it cannot meet the needs at all. In addition, the same ONU may basically have no data arriving in a certain period of time, so there is no data to transmit in the time slot allocated to it; while a large amount of data arrives in another period of time. The above situations will cause a huge waste of the precious uplink bandwidth of the PON system. Therefore, in order to effectively utilize the bandwidth, the PON system often adopts a dynamic bandwidth allocation (DBA) strategy in the upstream direction, that is, the OLT dynamically adjusts the upstream bandwidth allocated to the ONU according to the actual service status of the ONU.

The existing dynamic bandwidth allocation mechanism generally divides the uplink bandwidth (uplink transmission time) into periods of equal or unequal length. All ONUs report their queue status to OLT at a certain period of time in the cycle; OLT collects all the status information of all ONUs and then processes them centrally, thus determining the start time and end time of sending each ONU in the next cycle. Then the OLT notifies the ONU of relevant information through a downlink gating message. Since the OLT needs a certain amount of time to process, the ONU usually reports the service status at the beginning of the cycle to ensure that the strobe message returned by the OLT can reach the ONU before the start of the next cycle. For the convenience of description, a period of long or short continuous uplink transmission time allocated by the OLT to the ONU is collectively referred to as a "time slot" below.

Although the above method can better realize dynamic bandwidth allocation, the OLT needs to centrally perform bandwidth allocation processing after collecting the report messages of all ONUs, and then send a gating message. In this case, in order to support fixed bit rate services, OLT must allocate a dedicated time slot independent of data for each ONU to send report messages. Since the OLT only uses one optical receiver to receive the signals sent by each ONU, in order to synchronize the OLT with the received data as soon as possible, the ONU must send a pilot signal at the beginning of each independent sending time slot. In addition, a certain interval of guard bandwidth should usually be inserted between two independent uplink time slots. Thus, the introduction of dedicated reporting time slots independent of data reduces the bandwidth utilization of the system. In addition, when the above-mentioned traditional method supports a constant bit rate (CBR) service, the OLT generally divides the uplink transmission time into periods of equal length. However, since the data packets transmitted in the PON system can be of unequal length (in the EPON and GPON protocols, the PON system is required to support the transmission of variable-length Ethernet data packets), this will inevitably lead to a part of each cycle Upstream bandwidth cannot be allocated because they cannot accommodate packets of a certain length.

In addition, the traditional method does not provide a solution for the fairness of each ONU's participation in bandwidth allocation, but only gives all the allocation decision-making power to the OLT.

Contents of the invention

Aiming at the above-mentioned shortcomings in the prior art, the technical problem to be solved by the present invention is to provide a dynamic bandwidth allocation method, system and device for rapid response in the passive optical network, so as to support a certain quality of service while improving Improve the bandwidth utilization of the network and reduce the requirements on the equipment.

In order to solve the above problems, according to the present invention, a fast-response dynamic bandwidth allocation method in a passive optical network is provided. The passive optical network includes an optical line terminal and a plurality of optical network units, and the optical line terminal passes through a point The multi-point tree-shaped optical distribution network communicates with the plurality of optical network units, the downlink adopts the broadcast method, and the uplink adopts the time division multiplexing method. The method includes the following steps: the optical network unit sends the optical network unit to the optical line terminal Send a report message; after receiving the report message, the optical line terminal immediately processes it, and immediately sends a corresponding gating message to the optical network unit, and in one cycle of uplink, each optical network A unit has only one time slot for service data transmission.

The present invention also provides a passive optical network, which is suitable for fast-response dynamic bandwidth allocation. The passive optical network includes an optical line terminal and a plurality of optical network units, and the optical line terminal passes through a point-to-multipoint The tree-shaped optical distribution network communicates with the plurality of optical network units, the downlink adopts broadcast mode, and the uplink adopts time division multiplexing mode, and the optical network unit sends a report message to the optical line terminal; after receiving the report message , the optical line terminal immediately processes it, and immediately sends a corresponding gating message to the optical network unit, and in one uplink cycle, each optical network unit has only one time slot for service data transmission.

The present invention also provides an optical network unit in a passive optical network. The passive optical network includes an optical line terminal and a plurality of optical network units. The optical line terminal passes through a point-to-multipoint tree optical The distribution network communicates with the plurality of optical network units, the downlink adopts the broadcast mode, and the uplink adopts the time division multiplexing mode, and it is characterized in that the optical network unit includes: a buffer device for buffering service data; an acquisition device for Obtain the report message from the buffer device; the sending device is used to send the service data from the buffer device and the report message from the obtaining device to the optical line terminal, and in one cycle of the uplink, the optical network unit has only one Time slots are used for business data transmission.

The present invention also provides an optical line terminal in a passive optical network, the passive optical network includes an optical line terminal and a plurality of optical network units, and the optical line terminal passes through a point-to-multipoint tree-shaped optical distribution network To communicate with the multiple optical network units, the downlink adopts the broadcast method, and the uplink adopts the time division multiplexing method. It is characterized in that the optical line terminal includes: a receiving and processing device for receiving the report message from the optical network unit , to process it immediately; the sending device is used to send the corresponding gating message to the optical network unit immediately after the receiving and processing device has processed the report message, and in one cycle of the uplink, only allocate one hour Slots are given to the optical network unit for service data transmission.

Preferably, the report message and service data are sent in the same time slot.

Preferably, the length of the report message is fixed, and includes two status information: the minimum queue status and the maximum queue status, and the two status information are the length status including the complete data packet.

Preferably, the optical line terminal specifies a minimum guaranteed bandwidth for each optical network unit.

Preferably, the minimum guaranteed bandwidth specified for each optical network unit satisfies the following conditions:

NG+(1～3)×(L-G)≤B

Among them, N is the number of optical network units, G is the average minimum guaranteed bandwidth specified by the optical line terminal for each optical network unit, L is the average bandwidth required by the business data arriving from all optical network units within two cycles, and B is the total upload bandwidth in the period.

Preferably, the minimum guaranteed bandwidth is sent to the ONU through a downlink management link.

Preferably, the sum of the minimum queue status and the bandwidth required by the report message is less than or equal to the minimum guaranteed bandwidth.

Preferably, the gating message includes a maximum required bandwidth or a minimum required bandwidth value, wherein the maximum required bandwidth is the sum of the maximum queue status and the bandwidth required by the report message; the minimum required bandwidth is the minimum queue status and the required bandwidth of the report message sum of bandwidth.

Preferably, the optical line terminal first meets the requirements of the report message that arrives earlier in the same period, when the maximum required bandwidth corresponding to the message is the same as the bandwidth reserved for the optical network unit that has sent the report message and the bandwidth that has not yet sent the report message When the sum of the minimum guaranteed bandwidth reserved by the optical network unit is less than the total bandwidth in one cycle, the optical line terminal sends a strobe message including the maximum required bandwidth value to the optical network unit that sends the report message; otherwise, sends a strobe message including the minimum required bandwidth value. Value strobe message.

Preferably, the order in which the optical line terminal processes the report messages of the optical network unit is cyclically shifted.

Preferably, the period of time division multiplexing is not fixed, but varies around a certain standard period value.

Preferably, the length of the cache device is at least three times the average length of service data arriving within two cycles.

After adopting the present invention, the following beneficial effects can be obtained: the bandwidth utilization rate of the network is improved, and the transmission performance of the system is improved; the fast bandwidth allocation method adopted by the present invention is very simple, which is beneficial to hardware implementation; the instant bandwidth allocation strategy makes optical The network unit has enough time to assemble the upstream data flow, which reduces the ONU's requirements for processing speed and saves costs; it can realize fair bandwidth allocation among ONUs on the basis of ensuring a certain bandwidth, and make each ONU have Certain business quality assurance.

Description of drawings

Figure 1 shows a typical passive optical access network;

Figure 2 shows a schematic diagram of a "priority in order" bandwidth allocation method;

Figure 3 shows a schematic diagram of the "quasi-periodic";

Figure 4 shows a schematic diagram of "cyclic shift";

Figure 5 shows a schematic diagram of an optical network unit;

Fig. 6 shows a schematic diagram of an optical line terminal.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As mentioned earlier, Figure 1 shows a typical passive optical access network. It includes OLT11, splitter 12, point-to-multipoint tree optical distribution network 13 and N ONUs, namely ONU 141, ONU 142...ONU 14N. Wherein, the OLT communicates with multiple ONUs through a point-to-multipoint tree ODN 13. In the communication mode, the downlink adopts the broadcast mode, and the ONU receives its own data packets according to the identification of the data packets. Uplink adopts time division multiplexing (TDMA) to share bandwidth, ONU can only transmit information to OLT in the time slot allocated to itself, and can only wait at other times.

In one embodiment of the present invention, the OLT immediately processes the arriving report message and sends the corresponding gating message immediately, instead of the OLT collecting the report messages of all ONUs in the prior art, then centrally performing bandwidth monitoring. Allocate processing, then send a strobe message. In extreme cases, such a situation may occur that the transmission bandwidth required by a certain ONU report message is very large, so that other ONUs will not be able to transmit service data in the next cycle. In order to make each ONU provide a certain quality of service (QoS) guarantee, in one embodiment of the present invention, the OLT specifies a minimum guaranteed bandwidth for each ONU, and notifies the minimum guaranteed bandwidth to ONU. In this way, both the OLT and the corresponding ONU know the minimum guaranteed bandwidth. The minimum guaranteed bandwidth can vary according to the situation, and in extreme cases, it can also be zero. Therefore, even if the OLT does not receive the report message from the ONU, it still knows the total guaranteed bandwidth that should be reserved for each ONU in a specific period.

In one embodiment of the present invention, the report message of each ONU is fixed-length, and includes two pieces of information: the bandwidth required by the minimum queue state and the bandwidth required by the maximum queue state, represented by S _min and S _max respectively .

In one embodiment of the present invention, the report message is sent immediately after the service data, without providing an independent sending time slot for it. Therefore, in addition to the bandwidth required by service data, the OLT must also consider the bandwidth and protection bandwidth required by the report message itself. In the following description, for simplicity, the guard bandwidth is included in the report message. At this time, S _min refers to the bandwidth required by the queue state, which is less than or exactly equal to the value after subtracting the report message bandwidth from the minimum guaranteed bandwidth, and S _max refers to the bandwidth required by the current queue state. When S _max is smaller than the minimum guaranteed bandwidth, S _min =S _max .

Since the occupancy state of the queue changes with the length of the arriving data packet, the length of the arriving data packet is not fixed but changes. In order to simplify the PON system so that it does not need to have complex upper-layer assembly functions and can make full use of bandwidth, in one embodiment of the present invention, the bandwidth information required by the queue status reported by the ONU must enable it to send a certain number of complete data packet, so the above two information must contain the bandwidth information required by the complete data packet.

In one embodiment of the present invention, the fast dynamic bandwidth allocation process is as follows:

(1) OLT only allocates one uplink data transmission time slot for each ONU in one cycle, and the length of the time slot corresponds to the sum of the selected ONU queue status and the bandwidth required by the report message;

(2) The ONU uploads the report message and data to the OLT together in the time slot allocated by the OLT, and the report message is sent immediately after the service data without providing an independent sending time slot;

(3) The OLT immediately processes the arriving report time slot, and immediately sends a corresponding gating message to tell the ONU the uplink transmission time slot of the next cycle;

(4) After receiving the strobe message, the ONU arranges the next round of data upload according to the information therein.

In one embodiment of the present invention, the OLT adopts an "in order first" strategy to process report messages. That is, if possible, the OLT tries to meet the requirements of the report message that arrives earlier in the same cycle, but the OLT must reserve the promised minimum guaranteed bandwidth for other ONUs. In addition, the OLT uses the two values of the maximum required bandwidth and the minimum required bandwidth in bandwidth calculation. The maximum required bandwidth is equal to the sum of the maximum queue state reported by the ONU and the bandwidth required by the report message; the minimum required bandwidth refers to the sum of the minimum queue state reported by the ONU and the bandwidth required by the report message.

Figure 2 shows a symbolic representation of a "priority in order" bandwidth allocation method. As shown in the figure, if the total upload bandwidth in a period is P, and the number of ONUs is N, the guaranteed bandwidth promised by the OLT to each ONU is G ₁ , G ₂ ... G _N , and the bandwidth allocated by each ONU is respectively Expressed by V ₁ , V ₂ , V ₃ . . . V _i-1 . If the maximum required bandwidth of this ONU is Max _i and the minimum required bandwidth is Mini from the queue information reported by the i-th ONU, then the bandwidth V _i allocated to ONU _i by the method of "priority in order _" can be expressed by the following formula:

的值，并在每次分配完成后对它们进行修改。在此实施方式中，每次分配只需要进行5次加法，1次减法和1次判断。其中，求最大要求带宽和最小要求带宽分别各一次加法，求和两次加法，修改

和

的值分别用一次加法和一次减法。此外，在本发明的另一个实施方式中，为了在每个周期开始时不用对进行累加，采用一个特定的变量保存该累加值。In a preferred embodiment of the present invention, for the needs of fast processing, two variables are used to save and

, and modify them after each allocation completes. In this embodiment, only 5 additions, 1 subtraction and 1 decision are required for each allocation. Among them, the maximum required bandwidth and the minimum required bandwidth are respectively added once, summed twice, and modified

and

The values of , respectively, use one addition and one subtraction. In addition, in another embodiment of the present invention, in order not to Accumulate, and use a specific variable to save the accumulated value.

From the previous definition of the minimum required bandwidth, it can be seen that the total minimum guaranteed bandwidth is always greater than or equal to the total minimum required bandwidth. Therefore, the bandwidth reserved by the OLT for subsequent ONUs cannot be fully utilized. Similarly, in other bandwidth allocation methods, there is also the problem that the bandwidth cannot be fully utilized, but it is not as serious as in the aforementioned "priority in order" method. Therefore, in one embodiment of the invention, "quasi-periodic" is used. It means that the length of the period is no longer fixed, but changes dynamically, that is, the remaining bandwidth is included in the next period for allocation according to the actual bandwidth allocation situation. The reason why this embodiment can be realized is that after receiving the report message from the ONU in this cycle, the OLT performs processing to realize the ONU's uplink transmission in the next cycle, so the OLT can adjust the cycle length at any time. Thus, the actual cycle length varies around a standard cycle length. Preferably, in order to better support the traditional voice service with 8KHZ sampling, the length of the standard period is 125 μs. Of course, the present invention is not limited thereto, and the length of the standard cycle can be other values. In the same "quasi-period", all ONUs in the PON system complete a data upload. At the same time, the OLT allocates the next "quasi-period" upload bandwidth to each ONU in sequence according to the order in which the report messages arrive.

Figure 3 shows a schematic diagram of the "quasi-periodic". As shown in the figure, if the bandwidth that can be allocated in the standard cycle of the system is P=P ₀ , the remaining bandwidth after the OLT completes the allocation of the last ONU in the i-th cycle is Δ _i . Then in the next period, the bandwidth that the OLT can allocate becomes P' _i+1 =P ₀ +Δ _i .

In order to prevent Δ _i from increasing infinitely when the load is low, in one embodiment of the present invention, when Δ _i ≥ _{P 0} , P′ _i+1 = Δ _i . In this way, the time for the PON system to complete a round of uploading is relatively short when the load is low; and when the load is heavy, the quality requirements of various services can still be guaranteed. When the OLT allocates a certain amount of bandwidth to each ONU in each cycle, even for real-time constant bit rate (CBR) services like voice services, since the clock on the OLT side is exactly the same as that of the ONU, as long as the clock at the exit is added The business flow can be completely restored by the last buffer mechanism. In addition, this embodiment enables the OLT to discover the newly added ONU as soon as possible. This is because the length of the "quasi-period" is shorter when the load is low. If a new ONU is searched every M (M is a constant) "quasi-period", the new ONU will be very fast when the load is low. can be found. However, when the load is high, although the discovery time is extended, this embodiment can still ensure that a new ONU is discovered in time.

As mentioned earlier, through the "priority in order" bandwidth allocation method and the introduction of "quasi-period", PON has been able to make full use of all bandwidth. Moreover, within a "quasi-period", the ONU that sends the report message first has a certain allocation priority for the bandwidth. However, since the report message of the ONU is sent to the OLT together with the subsequent service data at the beginning of the upload time allocated by the OLT, and the OLT assigns the next "quasi-period" upload to the ONU in sequence according to the order of the report messages arriving. Time, this first-come-first-allocation policy will always make the first ONU that sends a report message in the "quasi-period" the highest priority in bandwidth allocation, resulting in other ONUs not being treated fairly.

Therefore, in one embodiment of the present invention, a "cyclic shift" strategy is adopted to overcome the problem of unfair bandwidth allocation. That is, in each "quasi-period", the OLT does not immediately process the first arriving report message, but stores its information; starting from the second report message, the OLT allocates bandwidth in a "priority in order" method; Until the processing of the last report message in the "quasi-period" is completed, the OLT processes the first arriving report message and allocates bandwidth to the corresponding ONU. In the above situation, the cyclic shift of the ONU upload sequence is actually realized in each "quasi-period", and the shift step of the cyclic shift is 1. Figure 4 shows a schematic diagram of "cyclic shift". However, those skilled in the art should understand that the present invention does not make specific regulations on the manner and step size of the cyclic shift, and only requires that it can realize the traversal of various orders.

Fig. 5 shows a schematic diagram of an optical network unit. As shown in the figure, the ONU 50 includes an acquiring device 51 , a buffering device 52 and a sending device 53 . Wherein the obtaining means 51 obtains the report message including the bandwidth information required by the maximum queue state and the minimum queue state from the buffering means, and sends the report message to the sending means 53 . The cache device is used for buffering the service data of the user, and sending the service data to the sending device 53 at an appropriate time. When it is the time slot of the ONU, the sending device 53 sends the service data and the report message to the OLT.

As mentioned above, in the "circular shift" mode with a step size of 1, the first ONU to send a report is processed only at the end, which doubles the upload interval of this ONU. Therefore, in one embodiment of the present invention, in order to prevent bursty business data from overflowing during this period, the length of the buffer device of each ONU is at least 3 times the average length of the business data arriving in two standard cycles .

In order to ensure that the first ONU that sends the report message in each cycle can basically clear its cache device after uploading data, so as to have more cache space to store the arriving service data, the OLT should make all In addition to meeting the guaranteed bandwidth of all ONUs, the upload bandwidth should also leave a certain amount of free space. In one embodiment of the present invention, when the average bandwidth required by the service data arriving in two standard cycles of all ONUs is L, the average guaranteed bandwidth of each ONU is G, and the bandwidth of this free space should be at least (L-G) 1 to 3 times. In the case of considering the quasi-period, the bandwidth of the free space does not have any impact on the utilization rate of the upload bandwidth.

Fig. 6 shows a schematic diagram of an optical line terminal. As shown in the figure, the optical line terminal 60 includes a receiving processing device 61, which is used to process the service data and report messages sent by the optical network unit in real time. The OLT 60 further includes sending means, configured to send a corresponding gating message to the ONU immediately after the processing means finishes processing the report message.

Many other changes and modifications can be made without departing from the spirit and scope of the present invention. It should be understood that the invention is not limited to the particular embodiments, but that the scope of the invention is defined by the appended claims.

Claims (27)

1. A fast-response dynamic bandwidth allocation method in a passive optical network, said passive optical network comprising an optical line terminal and a plurality of optical network units, said optical line terminal passing through a point-to-multipoint tree-shaped optical distribution network To communicate with the multiple optical network units, the downlink adopts a broadcast method, and the uplink adopts a time division multiplexing method, wherein the method includes the following steps: the optical network unit sends a report message to the optical line terminal; After receiving the report message, the optical line terminal immediately processes it, and immediately sends a corresponding gating message to the optical network unit, And in one uplink cycle, each optical network unit has only one time slot for service data transmission. 2. The method according to claim 1, wherein the report message and service data are sent in the same time slot. 3. The method according to claim 1, wherein the length of the report message is fixed, and includes two status information: minimum queue status and maximum queue status, and these two status information contain complete data packet length state. 4. The method according to claim 3, wherein the optical line terminal specifies a minimum guaranteed bandwidth for each optical network unit. 5. The method according to claim 4, wherein the minimum guaranteed bandwidth specified for each optical network unit satisfies the following conditions: NG+(1～3)×(L-G)≤B Among them, N is the number of optical network units, G is the average minimum guaranteed bandwidth specified by the optical line terminal for each optical network unit, L is the average bandwidth required by the business data arriving from all optical network units within two cycles, and B is the total upload bandwidth in the period. 6. The method according to claim 4, wherein the minimum guaranteed bandwidth is sent to the ONU through a downlink management link. 7. The method according to claim 4, wherein the sum of the minimum queue status and the bandwidth required by the report message is less than or equal to the minimum guaranteed bandwidth. 8. The method according to claim 4, wherein the gating message includes a maximum required bandwidth or a minimum required bandwidth value, wherein the maximum required bandwidth is the sum of the maximum queue state and the required bandwidth of the report message; the minimum The required bandwidth is the sum of the bandwidth required for the minimum queue status and report messages. 9. The method according to claim 8, wherein the optical line terminal first meets the requirements of the report message that arrives earlier in the same period, when the maximum required bandwidth corresponding to the message is the same as that of the optical network that has sent the report message When the sum of the bandwidth reserved by the unit and the minimum guaranteed bandwidth reserved for the optical network unit that has not sent the report message is less than the total bandwidth in one cycle, the optical line terminal sends the report message to the optical network unit including the maximum required bandwidth value Otherwise, send a strobe message including the minimum required bandwidth value. 10. The method according to claim 9, wherein the order in which the optical line terminal processes the report message of the optical network unit is cyclically shifted. 11. The method according to any one of claims 1-10, characterized in that the cycle of time division multiplexing is fixed. 12. The method according to any one of claims 1-10, characterized in that the cycle of time division multiplexing is not fixed. 13. A passive optical network suitable for fast-response dynamic bandwidth allocation, said passive optical network comprising an optical line terminal and a plurality of optical network units, said optical line terminal passing through a point-to-multipoint tree optical The distribution network communicates with the plurality of optical network units, the downlink adopts the broadcast mode, and the uplink adopts the time division multiplexing mode, wherein the optical network units include: a cache device for caching service data; obtaining means, for obtaining the report message from the cache device; sending means, configured to send the service data from the buffering means and the report message from the acquiring means to the optical line terminal, The optical line terminal includes: The receiving processing device is used to process the report message immediately after receiving it from the optical network unit; The sending device is used to send the corresponding gating message to the optical network unit immediately after the receiving and processing device has processed the report message, and in one cycle of uplink, each optical network unit has only one time slot for Business data transfer. 14. The passive optical network according to claim 13, wherein the report message and service data are sent in the same time slot. 15. The passive optical network according to claim 13, characterized in that, the length of the report message is fixed, and includes two state information: minimum queue state and maximum queue state, and these two state information are to include The length status of the complete packet. 16. The passive optical network according to claim 15, wherein the optical line terminal specifies a minimum guaranteed bandwidth for each optical network unit. 17. The passive optical network according to claim 16, wherein the minimum guaranteed bandwidth specified for each optical network unit satisfies the following conditions: NG+(1～3)×(L-G)≤B Among them, N is the number of optical network units, G is the average minimum guaranteed bandwidth specified by the optical line terminal for each optical network unit, L is the average bandwidth required by the business data arriving from all optical network units within two cycles, and B is the total upload bandwidth in the period. 18. The passive optical network according to claim 16, wherein the minimum guaranteed bandwidth is sent to the optical network unit through a downlink management link. 19. The passive optical network according to claim 16, wherein the sum of the minimum queue status and the bandwidth required by the report message is less than or equal to the minimum guaranteed bandwidth. 20. The passive optical network according to claim 16, wherein the gating message includes a maximum required bandwidth or a minimum required bandwidth value, wherein the maximum required bandwidth is between the maximum queue status and the required bandwidth of the report message and; the minimum required bandwidth is the sum of the bandwidth required for the minimum queue status and report messages. 21. The passive optical network according to claim 20, wherein the optical line terminal first meets the requirements of the report message that arrives earlier in the same cycle, when the maximum required bandwidth corresponding to the message is equal to the number of the report message that has been sent When the sum of the bandwidth reserved by the optical network unit and the minimum guaranteed bandwidth reserved for the optical network unit that has not yet sent the report message is less than the total bandwidth in one cycle, the optical line terminal sends the report message to the optical network unit including the maximum A strobe message requiring a bandwidth value, otherwise, a strobe message including a minimum required bandwidth value is sent. 22. The passive optical network according to claim 21, wherein the order in which the optical line terminal processes the report message of the optical network unit is cyclically shifted. 23. The passive optical network according to any one of claims 13-22, characterized in that the cycle of time division multiplexing is fixed. 24. The passive optical network according to any one of claims 13-22, characterized in that the cycle of time division multiplexing is not fixed. 25. An optical network unit in a passive optical network, the passive optical network includes an optical line terminal and a plurality of optical network units, and the optical line terminal is connected to a point-to-multipoint tree-shaped optical distribution network The plurality of optical network units communicate, the downlink adopts a broadcast method, and the uplink adopts a time division multiplexing method, wherein the optical network unit includes: a cache device for caching service data; obtaining means, for obtaining the report message from the cache device; sending means, configured to send the service data from the buffering means and the report message from the acquiring means to the optical line terminal, And in one uplink cycle, the ONU has only one time slot for service data transmission. 26. The optical network unit according to claim 25, wherein the length of the buffer device is at least three times the average length of service data arriving within two cycles. 27. An optical line terminal in a passive optical network, the passive optical network includes an optical line terminal and a plurality of optical network units, and the optical line terminal communicates with the optical line terminal through a point-to-multipoint tree-shaped optical distribution network A plurality of optical network units communicate, the downlink adopts the broadcast mode, and the uplink adopts the time division multiplexing mode, and it is characterized in that the optical line terminal includes: The receiving processing device is used to process the report message immediately after receiving it from the optical network unit; a sending device, configured to send a corresponding gating message to an optical network unit immediately after the receiving and processing device processes the report message, And in one uplink cycle, only one time slot is allocated to each optical network unit for service data transmission.

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