CN104540038B - The seamless system and method that service is provided of mobile video live broadcast vehicle in NDN networks - Google Patents

Abstract

The present invention relates to a kind of seamless system and method for providing service of mobile video live broadcast vehicle in NDN networks.The system includes NDN network controllers, NDN nodes, net cast car, content requestor, access point；The net cast car migration is responsible for receiving Interest bags and sends Data bags, and send the MoveInfo bags for including mobile message to NDN network controllers when switching access point in whole network topology scope；The content requestor sends Interest bags, and receives Data bags；The new NDN nodes that the NDN network controllers are responsible for, when net cast car switches access point, to be connected according to it recalculate the forwarding outlet of each node in network, are coated with the Interest in network and are correctly transmitted to net cast car.The present invention can effectively shorten the round-trip delay of request response, reduce control flow, and improve Consumer's Experience.

Description

The seamless system and method that service is provided of mobile video live broadcast vehicle in NDN networks

Technical field

Present patent application belongs to computer network field, more particularly to shifting in one kind name data network (NDN) The dynamic seamless system and method that service is provided of net cast car.

Background technology

It is mobile with the fast development of the widespread deployment and wireless communication technology of 3G/4G/LTE base stations and hotspot Equipment can be not only connected on internet anywhere or anytime, and is also become increasingly with the communication of other equipment on internet It is convenient.Therefore, mobile device can not only also possess as content provider (Content as the user for obtaining content Provider, CP) ability serviced is provided.Net cast car is a kind of typical mobile CP.

Net cast car can have many problems as CP.For example, due to movement, live broadcast vehicle can be cut in the service of offer WAP is changed, may cause user's request that rule can not have been forwarded to reach live broadcast vehicle by equipment.This problem can trigger Invalid network traffics, network congestion may be caused when serious；The Quality of Service Experience of user can be also reduced simultaneously.

Name data network (NDN) is a kind of critically important design of information centre's network (ICN), and is promised to be not Carry out the architecture of network.In NDN networks, the problem of user (Consumer) mobility is brought, can be by the way that resend please Ask and be resolved；But CP mobility the problem of bringing, still requires study.

At present, for CP mobility problems in NDN networks, most of solutions are using ID/Locator seperators System.For example, Hermans, Ngai and Gunningberg (F.Hermans, E.Ngai and P.Gunningberg, Global Source Mobility in the Content-Centric Networking Architecture,in Proc.of NoM ' 12, pp, 13-18,2012.) CP current location is recorded using home agent.CP switches WAP every time, all Need first to the local agent update current location of oneself.When Consumer wants request content, it can't be direct Send request to CP, but need to send a request to CP home agent first, then from home agent replace Consumer to CP request contents.It is obvious that the forwarding strategy can not only trigger unnecessary network traffics, and content obtaining can be increased and prolonged Late.

Jiang et al. (X.Jiang, J.Bi, Y.Wang, P.Lin and Z.Li, A Content Provider Mobility Solution of Named Data Networking, in Proc.of ICNP ' 12, pp.1-2,2012.) make CP ID and its positional information are mapped with a mapped system.For the needs of realization, author is in Interest The field Locator of a storage location information is with the addition of in bag, and original content name is used as ID.In repeating process, Interest is used when being matched with Content Store (CS) or Pending Interest Table (PIT) Id field, that is, the name of request content；And matched with Forwarding Information Base (FIB) Shi Ze uses the Locator fields in Interest.This design principle is, it is necessary to which mapped system grasps the topology letter of network simultaneously The distribution information of breath and content.

In addition, Luo et al. (Y.Luo, P.N.Tran, C.An, J.Eymann, L.Kreft and A.Timm-Giel, A Novel Handover Prediction Scheme in Content Centric Networking using Nonlinear Autoregressive Exogenous Model,in Proc.of VTC Srping’13,pp.1-5, 2013.) a kind of new switching forecasting mechanism strong and weak based on reception signal is proposed.This mechanism can be predicted effectively due to CP It is mobile and caused by disconnecting problem, while can be prepared for seamless switching.However, this mechanism needs before being predicted Want a complicated learning process, virtually add it deployment and operation difficulty.

Forwarding strategy refers to select a suitable outlet to forward the method for the packet received in each node.Turn The research of hair strategy is a very popular topic.For example, Yi et al. (C.Yi, A.Afanasyev, L.Wang, B.Zhang, L.Zhang,AdaptiveForwarding in Named Data Networking,ACM SIGCOMM ComputerCommunication Review, vol.42, no.3, pp.62-67,2012.) it is that NDN proposes one kind adaptively Forwarding strategy.The strategy establishes intelligence, adaptive data using the state of the data message of NDN routers and put down Face.The program uses the forwarding state each exported on green, yellow, red three kinds of colors record node.Forwarding strategy first look for by Outlet labeled as green is forwarded；If there is no the outlet of green, then may proceed to search the outlet for being marked as yellow Forwarded；But any content forwards all without from the outlet for being marked as red.Author is reached by this mechanism To the purpose that content is obtained using optimal path.But when content source has mobility, this mechanism can not adjust in time to be turned Deliver, content source can be caused to lose.

Qian et al. (H.Qian, R.Ravindran, G.Wang, D.Medhi, Probability-BasedAdaptive Forwarding Strategy in Named Data Networking,IFIP/IEEEInternational Symposium On IM 2013, pp.1094-1101,2013.) propose a kind of adaptive forwarding strategy based on probability.This tactful basis The quality of each outlet is chosen final forwarding according to probability and exported.The quality of each outlet can pass through Interest and Data Weighed.This forwarding strategy does not consider content source mobility, and the forward table renewal of network node equally occurs not In time, content source is caused to lose in a network.

In addition, Silva et al. (F.Silva, D.Dujovne, Predictive mobility applied to Content centricnetworks, 2013 IEEELATINCOM, pp.1-6,2013.) from infrastructure aspect propose one The solution for outwards forwarding Interest of kind selectivity.As a result show that the solution can be effectively reduced delay simultaneously Improve hit rate.The main policies of this mechanism are, when user has mobility, will ask most frequent content or future Most possible requested content is cached in some node on user's request path nearby in a period of time.Work as user When asking corresponding contents, it can obtain nearby.This mechanism is the solution proposed for user mobility, can not be supported interior Rong Yuan mobility.

The content of the invention

The present invention uses control information unnecessary caused by ID/Locator separation mechanisms to reduce, while improves use The Quality of Service Experience at family, propose the seamless system and method that service is provided of mobile video live broadcast vehicle in a kind of NDN networks.

The seamless system for providing service of mobile video live broadcast vehicle, major system components include NDN networks in a kind of NDN networks Controller (NDN Controller, NDNC), NDN nodes (NDN Node, NDNN), net cast car (Television Transmission Vehicles, TTV), content requestor (Content Consumer, CO), WAP (Access Point,AP)；Packet type used in the system includes Interest bags, Data bags, MoveInfo bags.

The TTV is connected with the AP by wireless network, the AP and the NDNN, the CO and the NDNN and Secure connection is established by Internet by NDN network connections, the NDNN and NDNC between the NDNN.It is described TTV mainly includes NDN protocol stacks, and is connected by radio network interface with AP, main to be responsible for receiving Interest bags, send Data bags；When the TTV switches AP, MoveInfo bags can be sent；The TTV random walks are in whole network topology scope.

The CO mainly sends Interest bags, receives Data bags.

The NDNN includes FIB (the Forwarding Information Base of original NDN networks：For recording The forwarding information of Interest bags), PIT (Pending Interest Table：For recording Interest letters to be responded Breath) and CS (Content Store：For caching Data contents) function, according in the logical forwarding network of NDN networks Interest bags and Data bags, possess the network interface being connected with NDNN, AP and the network interface being connected with Internet, and And the MoveInfo bags received from TTV can be transmitted to NDNC.

The NDNC includes the network interface being connected with Internet, is mainly responsible for when TTV switches AP, will according to it The new NDNN of connection recalculates the forwarding outlet of each node in network.The new NDNN is that mobile TTV will be connected and obtained The NDNN that the AP of content is connected.

The Interest bags and Interest the and Data bags that the Data bags are former NDN networks.

The MoveInfo bags mainly include Packet Name, Provider Info and AP-ID fields.Packet Name field is used for the type for indicating this bag；Provider Info fields include the name and TTV for the content that TTV is carried Identity information；AP-ID fields, which include, is used for the identity information for indicating the AP that TTV was connected and will connected originally.

The Interest bags are sent by CO, for TTV request contents；The Data bags are sent by TTV, for CO Feedback content；The MoveInfo bags are sent by TTV, for when TTV switches AP, its mobile message to be reported to NDNC.

After the NDNC receives the mobile message of TTV reports, first have to according to the threshold value N of setting judge to carry out it is global/ Local FIB renewals, and the congestion condition of the regular and each bar link according to SPF, reselect each NDNN and reach New NDNN forwarding outlet.Hop counts of the threshold value N between the NDNN.When the overall situation is updated to the TTV switchings, by The FIB for the NDNN that all forwarding outlets change in the NDNC renewals network.The local updating switches for the TTV When, by all NDNN passed through NDNC renewal TTV current connected AP to the AP that will be connected FIB.

It is described judge the overall situation/local updating process be：The AP being connected by NDNC records with TTV original states is directly closed The NDNN of connection, when TTV switches, calculate the hop count between the NDNN that new NDNN distances are recorded.If jumping figure value is less than N, only Carry out local updating；Otherwise, global renewal is carried out, and the value for the NDNN that NDNC is recorded is updated with new NDNN value.

The NDNC is issued accordingly according to result of calculation (forwarding calculated exports) to the NDNN for needing to update FIB Forwarding rule.If TTV random movements in a network, when not being switched to the new AP reported really, can cause FIB more Kainogenesis mistake, cause CO can not find TTV.In this case, ID/Locator mechanism will be activated；When finding again After TTV, ID/Locator mechanism will close, and restart mechanism proposed by the invention.

The seamless method for providing service of mobile video live broadcast vehicle, comprises the following steps in a kind of NDN networks：

1) CO sends Interest bags, content needed for request；

2) Interest bags are transmitted to TTV by NDNN according to the forwarding information of the FIB Interest bags recorded；

3) TTV switches WAP (i.e. AP) in moving process, and before the handover, TTV is sent comprising movement to NDNC The MoveInfo bags of information；

4) NDNC obtains the NDNN being attached thereto as new NDNN according to new AP-ID in the MoveInfo bags received；

5) NDNC judges that carrying out global/local FIB updates according to new NDNN and threshold value N, and according to SPF Regular and each bar link congestion condition, reselect the forwarding outlet that each NDNN reaches new NDNN；

6) NDNC issues new forwarding rule, more according to result of calculation (forwarding calculated exports) to corresponding NDNN Its new FIB, makes the Interest bags in network to be correctly transmitted to TTV.

If because of TTV random movement, and producing the FIB renewals of mistake, cause CO can not find TTV, then ID/ Locator mechanism will start；After TTV is correctly found again, ID/Locator mechanism will close, and restart we Method.

The congestion shape of each link in access point (AP) information and network that the present invention will access according to net cast car The forwarding-table item of condition, calculating and more new network device, user's request is set quickly to reach the position after the movement of net cast car, Reduce the responsiveness that user obtains the delay of institute's request content and improves user's request.Meanwhile threshold value is set, according to net cast The hop count information of car switching, global/local forward table is selectively carried out to the network equipment and is updated, is effectively reduced in network Control flow.In addition, when forward table renewal makes a mistake, start ID/ as standby mechanism from ID/Locator mechanism Locator mechanism；After treating network recovery normal work, close ID/Locator mechanism and restart proposed by the invention Mechanism.

Compared with other solution methods, this method to NDNC by before TTV switches AP, sending mobile message, in TTV While switching, by NDNC complete forward-path recalculate and corresponding NDNN FIB updates, reach TTV switchings and The purpose that FIB renewals are carried out simultaneously in NDNN, it can effectively shorten the round-trip delay of request response.According to threshold value N, selectivity Progress it is global/local more capable, efficiently reduce control flow.Necessary NDNN FIB is updated by NDNC so that TTV shifting It is dynamic that transparent, raising QoS of customer experience is perceived to user.

Brief description of the drawings

Fig. 1：The structure chart of NDN networks.

Fig. 2：The request response schematic diagram of NDN networks.

Fig. 3：The comparison schematic diagram for the method communication delay that the inventive method separates with traditional ID/Locator.

Fig. 4：The comparison schematic diagram for the method responsiveness that the inventive method separates with traditional ID/Locator.

Fig. 5：The schematic diagram of caused control flow in the case of the inventive method difference translational speed.

Embodiment

In order to facilitate the understanding of the purposes, features and advantages of the present invention, below by specific embodiment and Accompanying drawing, the present invention will be further described.

The purpose of this method is NDNC is calculated the positions to be moved of TTV and update related NDNN fib table in advance, so as to Reach the purpose of TTV seamless switchings.

Fig. 1 describes the primary structure of whole scheme.Wherein 1 is CO, and 2 be NDNN, and 3 be AP, and 4 be TTV, and 5 be NDNC, 6 It is the transmission link of CO and NDNN either between AP and NDNN or NDNN and NDNN, 7 be the Quality Initiative between NDNN and NDNC Road 8 is the wireless transmission link between TTV and NDNN, and 9 be TTV motion track.As illustrated, CO and TTV transmissions is any Information can all first pass around the NDNN each connected, then be forwarded by NDNN.TTV is mobile, and into two AP can be switched in good time according to the AP received signal strength during the region of individual AP alternate coverings.

This method is illustrated with an example below.Between TTV and AP the communication between communication, NDNN, NDNN and AP (or CO the communication between) is based on NDN agreements.In addition, this method utilizes existing OpenFlow agreements, as NDNC and NDNN it Between communication protocol.

Assuming that TTV is just in live auto rally, by being wirelessly connected to the different AP passed through on the way.Some in network CO asks broadcasting at TTV, plays out.With the traveling of vehicle, TTV is constantly cut also by high-speed mobile Change AP.

For working-flow as shown in Fig. 2 wherein 21 be the transmission path of Interest bags, 22 be the transmission road of Data bags Footpath, 23 be the transmission path of MoveInfo bags, and 24 be the transmission path of NDNC control information.Interest bags, Data bags, The internal structure of MoveInfo bags is respectively as shown in table 1 below, table 2, table 3.

Table 1.Interest pack arrangements

Table 2.Data pack arrangements

Table 3.MoveInfo pack arrangements

As shown in Fig. 2 working-flow step is as follows.

1. the content name carried first for each TTV.Because OpenFlow technologies do not support the knowledge of content name at present Not, the system uses special name "/00:00:00:00:00:01 " is named to content.And the specific name of use "/ 127.0.0.1 MoveInfo bags " are indicated.

2.CO sends Interest bags.Interest bags include following field：ContentName represents the name of request content Word；Selector includes some Optional Fields；Nonce is used to detect Routing loops.

3.NDNN receives Interest bags, checks itself CS according to the ContentName fields of Interest bags first, such as Fruit finds the content of matching, then directly returns to corresponding Data bags；Otherwise, i.e., if not finding the content of matching, search PIT, if the claims to corresponding contents in PIT tables be present, the entrance of Interest bags is added in corresponding entry； Otherwise, i.e., FIB is searched if the claims to corresponding contents are not present in PIT tables, if corresponding forward in fib table be present Outlet, then Interest bags are forwarded from corresponding outlet, while new PIT list items are added in PIT tables, recorded The forwarding situation of Interest bags；Otherwise, i.e., export, then lose Interest bags if corresponding forwarding is not present in fib table Abandon.

4. when each NDNN is without the caching of corresponding content on the way, Interest bags eventually reach TTV, by TTV pairs The Interest bags received carry out response and return to Data bags.Data bags include following field：ContentName, which is represented, carries Data Name；Signature carries TTV signature；SignedInfo carries the information relevant with checking signature；Data, which is represented, to be carried Content.

5.Data bags are transmitted along the direction opposite with Interest bags.When NDNN receives Data bags, look into first PIT is looked for, if corresponding list item in PIT tables be present, each outlet that Data bags are recorded from list item forwards, and deletes Except corresponding PIT list items；Otherwise Data bags are abandoned.Data bags eventually arrive at CO.

6.TTV is constantly moved, can be according to the different AP received signal when TTV enters the region of two AP alternate coverings Power, select the AP of connection.When the new AP received signal intensity is more than current connected AP signal intensities, TTV meetings It is switched to new AP.

7. before switching, TTV sends MoveInfo bags；MoveInfo bags reach AP by wireless connection, and AP can be incited somebody to action MoveInfo bags hand to the NDNN being joined directly together, then by NDNN by controlling link that MoveInfo bags are handed into NDNC. MoveInfo bags include following field：PacketName is used to indicate MoveInfo bags；ProviderInfo is used to carry TTV's The name of identity information and the content of carrying；AP-ID is used to carry the AP identity letter that TTV was connected and will connected originally Breath.

After 8.NDNC receives MoveInfo bags, according to the AP that will be connected in MoveInfo bags identity information and network Topology, NDNN that the AP is joined directly together is calculated as new NDNN.

9. after new NDNN is got, NDNC judges to carry out global/local FIB renewals.The method of judgement is：Initial shape Under state, the NDNN for connecting AP direct correlation with TTV of NDNC records at that time information, when TTV switches AP, NDNC calculates new Hop count between NDNN and the NDNN recorded, and compared with threshold value N.When hop count is less than N, then local FIB is carried out more Newly；Otherwise, global FIB renewals, and the information of the NDNN using new NDNN renewal NDNC records are carried out.

10. after NDNC determines to carry out the overall situation/local updating, NDNC is according to SPF, best Link State The principle of next, each NDNN reaches new NDNN forwarding outlet in calculating network.

11.NDNC reaches the NDNN being calculated new NDNN forwarding outlet and it is possible thereby to the content name asked Word is packaged into control information, is handed down to corresponding NDNN in network.

12.NDNN receives the control information that NDNC is sent, and extracts content name therein and is exported with corresponding forwarding, more Original corresponding list item in new fib table.

13. when TTV free random movements in a network, and there is being not attached to the new AP reported situation, it will hair Raw NDNC sends the FIB renewals of mistake.When because TTV is mobile and caused by FIB renewal mistakes, when causing CO can not get content, ID/Locator mechanism will be activated；After CO finds TTV again, ID/Locator mechanism will be closed, and this programme is made It will be restarted with mechanism.

According to abundant experimental results, compared with the method that traditional ID/Locator is separated, the inventive method can be used less Time obtain asked content；The communication delay of two methods is as shown in Figure 3.The inventive method can sent as much In the case of request, more responded, the responsiveness of two methods is as shown in Figure 4.In addition, the inventive method can pass through Threshold value N is set to efficiently reduce control flow, the control flow under different threshold values is as shown in Figure 5.

It will be appreciated by those skilled in the art that：Realizing all or part of the systems and methods embodiment can pass through The related hardware of programmed instruction is completed, and can also be completed by software.Above example is merely to illustrate the technical side of the present invention Case, rather than its limitations.Although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should Understand：It can still modify to the technical scheme described in foregoing embodiments, or to which part technical characteristic Equivalent substitution is carried out, and these are changed or are replaced, and the essence of appropriate technical solution is departed from technical solution of the present invention Spirit and scope, protection scope of the present invention should be to be defined described in claims.

Claims (5)

1. the seamless system that service is provided of mobile video live broadcast vehicle in a kind of NDN networks, it is characterised in that including NDN network controls Device processed, NDN nodes, net cast car, content requestor, access point；Wherein, net cast car passes through wireless network with access point Connection, pass through NDN network connections, NDN sections between access point and NDN nodes, content requestor and NDN nodes and NDN nodes Point establishes secure connection with NDN network controllers by Internet；The net cast car migration is in whole network topology model Enclose, be responsible for receiving Interest bags and send Data bags, and sent when switching access point to NDN network controllers comprising movement The MoveInfo bags of information；The content requestor sends Interest bags, and receives Data bags；The NDN network controllers It is responsible for when net cast car switches access point, the new NDN nodes that will be connected according to it recalculate each node in network Forwarding outlet, it is coated with the Interest in network and is correctly transmitted to net cast car；The NDN network controllers, which receive, to be regarded After the mobile message of frequency live broadcast vehicle report, judge that carrying out global/local FIB updates according to the threshold value N of setting, and according to most short The congestion condition of the regular and each bar link of heat source, reselect each NDN nodes and reach transferring for new NDN nodes Mouthful；Hop counts of the threshold value N between NDN nodes；When the overall situation is updated to the switching of net cast car, controlled by NDN networks The FIB for the NDN nodes that all forwarding outlets change in device renewal network；The local updating switches for net cast car When, the current connected access point of net cast car is updated by NDN network controllers and passed through to the access point that will be connected The FIB for all NDN nodes crossed；Judge that the process that global/local FIB updates is：Recorded by NDN network controllers with regarding The NDN nodes for the access point direct correlation that frequency live broadcast vehicle original state is connected, when net cast car switches, calculate new NDN Hop count between the NDN nodes that nodal distance is recorded；If jumping figure value is less than N, local updating is only carried out；Otherwise, carry out complete Office's renewal, and the value of the NDN nodes recorded with the value renewal NDN network controllers of new NDN nodes.

2. the system as claimed in claim 1, it is characterised in that：The NDN nodes possess FIB, PIT and CS work(of NDN networks Can, according to the Interest bags and Data bags in the logical forwarding network of NDN networks, and will be received from the net cast car MoveInfo bags be transmitted to NDN network controllers.

3. the system as claimed in claim 1, it is characterised in that if producing mistake because of the random movement of net cast car FIB updates, and causes content requestor can not find net cast car, then starts ID/Locator mechanism；When being correctly found again ID/Locator mechanism is closed after net cast car.

4. a kind of seamless method that service is provided of mobile video live broadcast vehicle in NDN networks using system described in claim 1, its Step includes：

1) content requestor sends Interest bags, content needed for request；

2) Interest bags are transmitted to net cast car by NDN nodes according to the routing iinformation of the FIB Interest bags recorded；

3) net cast car switches access point in moving process, and before the handover, net cast car is sent to NDN network controllers MoveInfo bags comprising mobile message；

5) NDN network controllers obtain the NDN node conducts being attached thereto according to new access point ID in the MoveInfo bags received New NDN nodes；

6) NDN network controllers judge that carrying out global/local FIB updates according to new NDN nodes and threshold value N, and according to most short The congestion condition of the regular and each bar link of heat source, reselect each NDN nodes and reach transferring for new NDN nodes Mouthful；Judge that the process that global/local FIB updates is：By NDN network controllers record and net cast car original state institute The NDN nodes of the access point direct correlation of connection, when net cast car switches, calculate the NDN that new NDN nodal distances are recorded Hop count between node；If jumping figure value is less than N, local updating is only carried out；Otherwise, global renewal is carried out, and with new NDN nodes The value of NDN nodes that is recorded of value renewal NDN network controllers；

7) NDN network controllers export according to the forwarding calculated, issue new forwarding rule to corresponding NDN nodes, update it FIB, the Interest bags in network are made correctly to be transmitted to net cast car.

5. method as claimed in claim 4, it is characterised in that：If mistake is produced because of the random movement of net cast car FIB updates, and causes content requestor can not find net cast car, then starts ID/Locator mechanism；When being correctly found again ID/Locator mechanism is closed after net cast car.