Terminal roaming method and system in passive optical network system

Abstract

The present invention discloses a terminal roaming method in a passive optical network system: after the terminal successfully connects to the AP of one of the sub-gateways for the first time, the master gateway uniformly allocates non-directed ALLOC ID, non-directed GEMPORT ID, and other network resources under the PON network to this sub-gateway, and associates these resources with this sub-gateway; when the terminal needs to switch the AP due to movement of its location, after receiving the handover instruction, the original AP disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect with the terminal; after receiving the connection message of this terminal, the sub-gateway where the target roaming AP is located associates the non-directed ALLOC ID, non-directed GEMPORT ID, and other network resources with this sub-gateway; after receiving the bandwidth allocation instruction sent by the master gateway, the target roaming AP starts to transmit data frames to the master gateway, and at the same time reports new bandwidth requirement information to the master gateway, and the connection of the terminal to the target roaming AP is immediately restored. The present invention also provides a corresponding terminal roaming system in a passive optical network system.

Description

Technical Field

[0001] The present invention belongs to the technical field of passive optical networks, and more specifically, relates to a terminal roaming method and system in a passive optical network system. Background Art

[0002] Figure 1 It is a general PON (Passive Optical Network) access system architecture. The main gateway is generally a PON OLT (Optical Line Terminal) or FTTR (Fiber to The Room), which is connected to multiple sub-gateways in a P2MP (Point to multi-point) manner through optical fibers. Each sub-gateway is deployed at different locations (such as different rooms), and various mobile terminals (such as mobile phones) access the network through the AP (such as wireless WIFI) of the sub-gateway. When the location of the terminal changes, it is required that the network connection of the terminal can quickly switch (roam) from one sub-gateway AP to another sub-gateway AP, that is, the fast roaming ability. If the roaming time is too long, obvious network lag or interruption will occur, greatly affecting the user experience. This requirement is particularly prominent in the access scenario of all-optical networks (such as FTTR). For example, in the "FTTR Fiber to the Room White Paper", it is clearly required that "for mobile terminal access, support a roaming handover ability of less than 20 ms". However, in the current technology, this roaming handover delay is much greater than 20 ms, and the average delay has exceeded 100 ms.

[0003] The following analyzes the source of the handover delay: Take Figure 1For example, it can be seen that when the terminal roams from AP1 to AP2, the sub-gateway also switches from sub-gateway 1 to sub-gateway 2. Therefore, the handover delay includes two parts: the handover delay of the AP and the handover delay of the sub-gateway. For the problem of the AP handover delay, some related patents have proposed improvement methods. For example, in the patent "A Method for Implementing Home WIFI Roaming" (Patent No. 201711009292.5), a roaming method based on a network architecture of a main AP and extended APs is given. By monitoring the increasing speed of the RSSI of each extended AP, an AP with the highest RSSI value is determined as the target roaming AP. However, there is no relevant literature or patent regarding the handover delay of the sub-gateway. For example, in a PON-based network system, the handover is generally carried out according to the PON standard protocol. Taking GPON as an example, the general handover process is as follows: when the terminal roams from AP1 of sub-gateway 1 to AP2 of sub-gateway 2, sub-gateway 2 needs to apply to the main gateway for a new ALLOC ID (Allocation Identifier) or the main gateway designates an existing ALLOC ID in sub-gateway 2. Then the main gateway allocates a new GEMPORT ID to sub-gateway 2. Sub-gateway 2 creates a WIFI service flow ID and associates the WIFI service flow ID, GEMPORT ID, and ALLOC ID. The main gateway also synchronously associates the GEMPORT ID (GPON Encapsulation Method Port Identifier) and ALLOC ID. The Dynamic Bandwidth Allocation (DBA) module of the main gateway starts to allocate bandwidth for the new ALLOC ID. Since the new ALLOC ID does not have the bandwidth report information of the original ALLOC ID, it is necessary for the DBA module of the main gateway to allocate bandwidth to sub-gateway 2 for several rounds before the accurate bandwidth requirement of the newly added terminal in sub-gateway 2 can be obtained, and then the required bandwidth can be allocated to the newly added terminal in sub-gateway 2. Since the above roaming process is dynamic, software (such as an embedded CPU) needs to manage the WIFI service flow ID, GEMPORT ID, and ALLOC ID in real time, and the time is relatively long (including at least 5 ms from the main gateway allocating a new GEMPORT ID to the main gateway receiving the completion of the association of the GEMPORT ID by the sub-gateway; at least 5 ms for the association of the ALLOC ID and GEMPORT ID and the association of the WIFI service flow ID and GEMPORT ID; at least 10 ms for the newly switched sub-gateway to obtain the accurate bandwidth requirement of the newly added terminal until the bandwidth is fully restored). As a result, the entire handover time of the sub-gateway is close to or even exceeds 20 ms, while the handover delay of a general AP exceeds 80 ms, and the sum of the two exceeds 100 ms.Obviously, the existing technologies can no longer meet the requirements of low-latency roaming handover scenarios in PON networks. Summary of the Invention

[0004] Aiming at the problem of excessive roaming handover delay of sub-gateways in PON networks, the present invention provides a terminal roaming solution in a passive optical network system. After adopting this method, the roaming handover delay of sub-gateways can be greatly reduced and even controlled within 1 ms.

[0005] To achieve the above object, according to one aspect of the present invention, a terminal roaming method in a passive optical network system is provided, including the following steps:

[0006] After the terminal successfully connects to the AP of one of the sub-gateways for the first time, the master gateway uniformly allocates non-directed ALLOC ID, non-directed GEMPORT ID, and other network resources in the PON network to this sub-gateway, and associates these resources with this sub-gateway;

[0007] When the location of this terminal moves and an AP handover is required, after receiving the handover instruction, the original AP disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect to the terminal;

[0008] After receiving the terminal connection message, the sub-gateway where the target roaming AP is located associates the non-directed ALLOC ID, non-directed GEMPORT ID, and other network resources with this sub-gateway;

[0009] After receiving the bandwidth allocation instruction sent by the master gateway, the target roaming AP starts to transmit data frames to the master gateway, and at the same time reports new bandwidth requirement information to the master gateway, and the connection of the terminal to the target roaming AP is immediately restored.

[0010] In an embodiment of the present invention, the situation that when the location of this terminal moves and an AP handover is required specifically includes: when the location of this terminal moves and it appears within the signal coverage ranges of two or more APs, the sub-gateways where these APs are located periodically report the signal quality between the terminal and the AP to the master gateway, and the master gateway judges whether this mobile terminal needs to handover. If the handover condition is met, it notifies the original AP and the target roaming AP to perform the handover of the terminal connection.

[0011] In an embodiment of the present invention, when an AP handover is required, the master gateway selects the sub-gateway with the largest scheduling weight W as the target roaming AP, where the scheduling weight is determined by the following parameters: signal quality S, the sum of the bandwidths allocated for all non-directed ALLOC IDs A, and the sum of the bandwidths requested for all non-directed ALLOC IDs R. The scheduling weight W is calculated according to S, A, and R, and the relationship between W and S, A, and R is as follows: the larger S is, the larger W is; the larger A is, the larger W is; the larger R is, the smaller W is.

[0012] In one embodiment of the present invention, after receiving the handover instruction, the original AP disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect with the terminal, which specifically includes: the sub-gateway where the original AP is located continues to send all frames that the terminal has sent to this sub-gateway to the master gateway, and when sending the last frame or frame fragment, sends a handover completion message to the master gateway at the same time; after receiving the handover completion message of the original AP, the DBA module of the master gateway continues to allocate the bandwidth of this ALLOC ID according to the bandwidth request information of the original AP, and notifies the target roaming AP to receive the bandwidth allocation instruction of this ALLOC ID and transmit data frames to the master gateway.

[0013] In one embodiment of the present invention, the message for the target roaming AP to connect with the terminal is sent from the original AP to the target roaming AP through the sub-gateway; when the PON network does not support the direct intercommunication of information between sub-gateways, it is relayed through the master gateway.

[0014] In one embodiment of the present invention, when the terminal needs to send a long frame in fragments, the original AP can immediately disconnect the connection with the terminal, that is, a part of the fragments of this frame are transmitted through the original AP, and the remaining fragments are transmitted through the target roaming AP. Since the ALLOC ID does not change at the master gateway, the complete frame is restored at the master gateway by recombining each fragment.

[0015] In one embodiment of the present invention, the method further includes: when the mobile terminal is not within the signal coverage range of any AP, the master gateway deletes the uniformly allocated non-directional ALLOC ID, non-directional GEMPORT ID resources and other network resources.

[0016] In one embodiment of the present invention, the other network resources include: IP address, DNS address, subnet mask and default gateway.

[0017] In one embodiment of the present invention, the sub-gateway periodically reports the signal quality between the terminal and the AP to the master gateway, specifically:

[0018] In the PON network, the sub-gateway reports the signal quality of its AP to the master gateway by using a downlink 125us periodic signal.

[0019] According to another aspect of the present invention, there is also provided a terminal roaming system in a passive optical network system, including a master gateway and at least two sub-gateways, and the master gateway, sub-gateways and APs in the sub-gateways execute the terminal roaming method in the passive optical network system as described above, so that the terminals in the passive optical network can achieve fast roaming.

[0020] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

[0021] The present invention performs unified allocation of ALLOC ID, GEM PORT ID and other network resources based on the entire main gateway PON network. When the terminal roams between different APs, there is no need to re-allocate new ALLOC ID, GEM PORT ID and network resources, and the DBA module of the main gateway is also unaware of the roaming of the terminal. After receiving the roaming message from the main gateway, the sub-gateway can immediately switch even in the case of long frame fragmentation. By adopting the method of the present invention, the connection of the mobile terminal can be seamlessly switched from the original AP to the target roaming AP, with good switching reliability, and the switching time can be controlled within 1 ms. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the roaming of a terminal between different APs in a PON network;

[0023] Figure 2 It is a schematic flowchart of the terminal roaming method in the passive optical network system in the embodiment of the present invention;

[0024] Figure 3 It is a flowchart of mobile phone roaming in the FTTR scenario in the embodiment of the present invention. Detailed Embodiments

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] In order to solve the problems existing in the prior art, as Figure 2 shown, the present invention provides a method for realizing fast roaming of a sub-gateway in a PON network, including the following steps:

[0027] Step (1): After the terminal successfully connects to the AP of one of the sub-gateways for the first time, the main gateway uniformly allocates non-directed ALLOC ID, non-directed GEMPORT ID and other network resources (such as IP address, DNS address, subnet mask, default gateway, etc.) under the PON network to this sub-gateway, and associates these resources with this sub-gateway;

[0028] According to the service requirements of the terminal, the number of allocated non-directed ALLOC ID and non-directed GEMPORT ID is one or more;

[0029] Different from the directed ALLOC ID and directed GEMPORT ID in the traditional PON network, the undirected ALLOC ID and undirected GEMPORT ID can be directly shared among multiple sub-gateways without the need for allocation and reallocation processes;

[0030] The undirected ALLOC ID, different from the directed ALLOC ID in the traditional PON network, has its ALLOC ID bound to the sub-gateway. The undirected ALLOC ID means that such an ALLOC ID is not bound to a specific sub-gateway;

[0031] The undirected GEMPORT ID, different from the directed GEMPORT ID in the traditional PON network, has its GEMPORT ID bound to the sub-gateway. The undirected GEMPORT ID means that such a GEMPORT ID is not bound to a specific sub-gateway.

[0032] Step (2): When the terminal needs to perform an AP handover due to a location movement, after receiving the handover instruction, the original AP disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect to the terminal;

[0033] Specifically, when the terminal moves and appears within the signal coverage ranges of two or more APs, the sub-gateways where these APs are located periodically (for example, a 125us cycle signal in the downlink in the PON network) report the signal quality (such as RSSI (Received Signal Strength Indication)) between the terminal and the AP to the master gateway. The master gateway determines whether the mobile terminal needs to perform a handover based on a unified sub-gateway handover algorithm. If the handover condition is met, the master gateway notifies the original AP and the target roaming AP through a downlink broadcast message that the handover of the terminal connection will be performed.

[0034] Specifically, the sub-gateway handover algorithm is as follows: Select the target roaming AP according to the scheduling weight (W). The master gateway selects the sub-gateway with the largest W as the target roaming AP.

[0035] The scheduling weight is determined by the following parameters: signal quality (S), the sum of the bandwidths allocated by all undirected ALLOC IDs (A), and the sum of the bandwidths requested by all undirected ALLOC IDs (R). Calculate the scheduling weight (W) based on S, A, and R. The relationship between W and S, A, and R is as follows: The larger S is, the larger W is; the larger A is, the larger W is; the larger R is, the smaller W is (the larger the requested bandwidth, the more bandwidth is occupied by users of this AP, so W should be smaller, and this AP should be avoided during handover).

[0036] After receiving the handover instruction, the original AP disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect with the terminal; the sub-gateway where the original AP is located continues to send all the frames that the terminal has sent to this sub-gateway to the master gateway. When sending the last frame or frame fragment, a handover completion message is sent to the master gateway at the same time; after receiving the handover completion message from the original AP, the DBA module of the master gateway continues to allocate the bandwidth of this ALLOC ID based on the bandwidth request information of the original AP, and notifies the target roaming AP to receive the bandwidth allocation indication of this ALLOC ID and transmit data frames to the master gateway;

[0037] Specifically, the message for the target roaming AP to connect with the terminal is sent from the original AP to the target roaming AP through the sub-gateway; when the PON network does not support direct information intercommunication between sub-gateways, it is relayed through the master gateway.

[0038] Specifically, when the terminal needs to send a long frame in fragments, the original AP can also immediately disconnect the connection with the terminal, that is, a part of the fragments of this frame are transmitted through the original AP, and the remaining fragments are transmitted through the target roaming AP. At the master gateway, since the ALLOC ID has not changed, the complete frame is restored by recombining each fragment at the master gateway, effectively solving the problem of further increasing latency due to frame retransmission caused by long frame fragmentation in the prior art.

[0039] Step (3): After receiving the terminal connection message (from the original AP or relayed by the master gateway), the sub-gateway where the target roaming AP is located associates the non-directed ALLOC ID, non-directed GEMPORT ID, and other network resources with this sub-gateway.

[0040] Step (4): After receiving the bandwidth allocation indication sent by the master gateway, the target roaming AP starts to transmit data frames to the master gateway, and at the same time reports new bandwidth requirement information to the master gateway, and the connection of the terminal to the target roaming AP is immediately restored.

[0041] Since the bandwidth obtained by the target roaming AP is allocated according to the bandwidth requested by the original AP, the bandwidth obtained by the terminal meets the bandwidth requirements of the original mobile terminal, and both the service flow and the bandwidth are restored.

[0042] Step (5): When the mobile terminal is not within the signal coverage range of any AP, the master gateway deletes the uniformly allocated non-directed ALLOC ID, non-directed GEMPORT ID resources, and other network resources.

[0043] Estimation of handover time:

[0044] In the handover process of the above sub-gateway, the handover time is related to the time of the following processes: the time (t1) for the original AP to notify the target roaming AP to connect to the terminal, the time (t2) for the original AP to transmit the remaining frames of the terminal, and the time (t3) for the main gateway DBA to allocate bandwidth to the target AP. However, the handover time only depends on t1, because when the original AP transmits the remaining frames of the terminal (t2), the target AP is establishing a physical connection with the terminal synchronously, so t2 does not need to be considered separately; and the ALLOC ID of the main gateway DBA bandwidth allocation remains unchanged, and the allocated bandwidth is directly switched from the original AP to the target AP, so the bandwidth allocation time t3 does not need to be considered either. When the PON network does not support direct information exchange between APs, it needs to be relayed through the main gateway. In the PON system, the shortest time interval for information transmission between the sub-gateway and the main gateway is 125 us, and when it supports directly sending messages from the original AP to the target roaming AP, this time is shorter; considering the transmission delay of the optical fiber, t1 can be controlled within 1 ms and can be basically ignored in the whole roaming handover.

[0045] The following gives a specific implementation device and process based on the FTTR scenario, where the terminal is a mobile phone. As Figure 3 shown, the method includes:

[0046] Step 10: After the mobile phone successfully connects to the AP of one of the sub-gateways for the first time, the main gateway uniformly allocates non-directed ALLOC IDs, non-directed GEMPORT IDs, and other network resources (such as IP addresses, DNS, etc.) under the PON network to this sub-gateway, and associates these resources with this sub-gateway;

[0047] Step 20: When the location of the mobile phone moves and it appears within the signal coverage ranges of two or more APs, the sub-gateways where these APs are located continuously report the signal quality (such as RSSI) of their APs to the main gateway. The main gateway determines whether the mobile terminal needs to be handed over according to a unified sub-gateway handover scheduling algorithm. If the handover condition is met, the main gateway notifies the original AP and the target roaming AP through a downlink broadcast PLOAM (Physical Layer Operations Administration and Maintenance) message that the handover of the terminal connection will be carried out.

[0048] Step 30: The main gateway selects the target roaming AP according to the scheduling weight (W) of the sub-gateway, and selects the sub-gateway with the largest W as the target roaming AP.

[0049] The scheduling weight W adopts the following calculation formula, W = S^1.5 * A / R

[0050] Where S is the signal quality, A is the sum of the bandwidths allocated for all non-directed ALLOC IDs, and R is the sum of the bandwidths requested for all non-directed ALLOC IDs. In the above formula, S has an exponential factor of 1.5, which means that the influence of the signal quality S is greater than that of A, that is, the influence of S on the weight is greater than that of A.

[0051] Step 40: After receiving the handover instruction, the original AP disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect to the terminal; the sub-gateway where the original AP is located continues to send all the frames that the terminal has sent to this sub-gateway to the master gateway. When sending the last frame or frame fragment, a handover completion message is sent to the master gateway; after receiving the handover completion message from the original AP, the DBA module of the master gateway continues to allocate the bandwidth for this ALLOC ID based on the bandwidth request information of the original AP, and notifies the target roaming AP to receive the bandwidth allocation indication for this ALLOC ID and transmit data frames to the master gateway.

[0052] Among them, the message of the connection between the target roaming AP and the terminal can be directly sent from the original AP to the target roaming AP.

[0053] Among them, when the terminal needs to send a long frame in fragments, the original AP can immediately disconnect the connection with the terminal, that is, a part of the fragments of the frame are transmitted through the original AP, and the remaining fragments are transmitted through the target roaming AP. At the master gateway, since the ALLOC ID has not changed, the complete frame is restored at the master gateway by recombining each fragment, effectively solving the problem of further increasing the delay due to frame retransmission caused by long frame fragmentation in the prior art.

[0054] Step 50: After receiving the terminal connection message sent by the original AP, the sub-gateway where the target roaming AP is located associates the GEMPORT ID, ALLOC ID, and network resources with this sub-gateway.

[0055] Step 60: After receiving the bandwidth allocation indication sent by the master gateway, the target roaming AP starts to transmit data frames to the master gateway, and at the same time reports new bandwidth demand information to the master gateway. The bandwidth obtained by the target roaming AP is allocated according to the bandwidth requested by the original AP. Therefore, the bandwidth obtained by the terminal meets the bandwidth requirements of the original terminal, and the service flow and bandwidth are both restored.

[0056] Step 70: When the mobile phone is not within the signal coverage range of any AP, the master gateway deletes the uniformly allocated non-directed ALLOC ID, non-directed GEMPORT ID resources, and other network resources.

[0057] Furthermore, the present invention also provides a terminal roaming system in a passive optical network system, which includes a main gateway and at least two sub-gateways. The main gateway, the sub-gateways and the APs in the sub-gateways execute the terminal roaming method in the passive optical network system, so as to enable the terminals in the passive optical network to achieve fast roaming.

[0058] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A terminal roaming method in a passive optical network system, characterized in that, It includes the following steps: After the terminal successfully connects to the AP of one of the sub - gateways for the first time, the master gateway uniformly allocates non - directional ALLOC ID, non - directional GEMPORT ID, and other network resources under the PON network to this sub - gateway, and associates these resources with this sub - gateway; When the terminal needs to switch APs due to a change in its location, after the original AP receives the handover instruction, it disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect to the terminal; specifically including: when the terminal moves and appears within the signal coverage ranges of two or more APs, the sub - gateways where these APs are located periodically report the signal quality between the terminal and the AP to the master gateway. The master gateway determines whether the mobile terminal needs to switch. If the handover conditions are met, it notifies the original AP and the target roaming AP to perform the handover of the terminal connection; when an AP switch is required, the master gateway selects the sub - gateway with the largest scheduling weight W as the target roaming AP, where the scheduling weight is determined by the following parameters: signal quality S, the bandwidth sum A of all non - directional ALLOC ID issued, and the bandwidth sum R of all non - directional ALLOC ID requested. The scheduling weight W is calculated based on S, A, and R, and the relationship between W and S, A, R is as follows: the larger S, the larger W; the larger A, the larger W; the larger R, the smaller W; After the sub - gateway where the target roaming AP is located receives the terminal connection message, it associates the non - directional ALLOC ID, non - directional GEMPORT ID, and other network resources with this sub - gateway; After the target roaming AP receives the bandwidth allocation instruction sent by the master gateway, it starts to transmit data frames to the master gateway, and at the same time reports new bandwidth demand information to the master gateway, and the connection of the terminal to the target roaming AP is immediately restored.

2. The terminal roaming method in the passive optical network system according to claim 1, characterized in that, After the original AP receives the handover instruction, it disconnects the wireless connection with the terminal and notifies the target roaming AP to immediately connect to the terminal, specifically including: The sub - gateway where the original AP is located continues to send all frames that the terminal has sent to this sub - gateway to the master gateway. When the last frame or frame fragment is sent, a handover completion message is sent to the master gateway at the same time; after the master gateway receives the handover completion message from the original AP, the DBA module of the master gateway continues to allocate the bandwidth of this ALLOC ID based on the bandwidth request information of the original AP, and notifies the target roaming AP to receive the bandwidth allocation instruction of this ALLOC ID and transmit data frames to the master gateway.

3. The terminal roaming method in the passive optical network system according to claim 2, characterized in that, The message of the target roaming AP connecting to the terminal is sent from the original AP to the target roaming AP through the sub - gateway; when the PON network does not support direct information inter - communication between sub - gateways, it is relayed through the master gateway.

4. The terminal roaming method in the passive optical network system according to claim 1, wherein, When the terminal needs to send a long frame in fragments, the original AP can immediately disconnect the connection with the terminal, that is, a part of the fragments of the frame are transmitted through the original AP, and the remaining fragments are transmitted through the target roaming AP. Since the ALLOC ID has not changed in the master gateway, the complete frame is restored by recombining each fragment in the master gateway.

5. The terminal roaming method in the passive optical network system according to claim 1, characterized in that The method further includes: When the mobile terminal is not within the signal coverage of any AP, the main gateway deletes the uniformly allocated non-directional ALLOC ID, non-directional GEMPORT ID resources, and other network resources.

6. The terminal roaming method in the passive optical network system according to claim 1, characterized in that, The other network resources include: IP address, DNS address, subnet mask, and default gateway.

7. The method for terminal roaming in the passive optical network system according to claim 1, characterized in that The sub-gateway periodically reports the signal quality between the terminal and the AP to the main gateway, specifically: In the PON network, the sub-gateway uses a 125 us cycle signal in the downstream direction to report the signal quality of its AP to the main gateway.

8. A terminal roaming system in a passive optical network system, characterized in that, It includes a main gateway and at least two sub-gateways. The main gateway, sub-gateways, and the APs in the sub-gateways execute the terminal roaming method in the passive optical network system according to any one of claims 1-7, so as to enable the terminals in the passive optical network to achieve fast roaming.

Images