WIRELESS COMMUNICATION SYSTEM FOR MOVING VEHICLES, SUCH AS TRAINS, WITH IMPROVED PRIORITIZATION

Abstract

A method and system for wireless communication between a router in a moving vehicle, such as a train, and a stationary communication server outside the moving vehicle through at least one external mobile network on at least one link are disclosed. The method comprises: providing a first output buffer and a second output buffer, and determining whether said data stream is of a data type belonging to a set of prioritized data types. In case the data stream is of a data type belonging to the set of prioritized data types, the first output buffer is selected, and in case the data is of a data type not belonging to the set of prioritized data types, the second output buffer is selected.

Claims

1. A method for wireless communication between a router in a moving vehicle and a stationary communication server outside the moving vehicle through at least one external mobile network on at least one link, the method, performed in at least one of the stationary communication server and the router, comprising: providing a first output buffer and a second output buffer; receiving data packets of a data stream to be transferred on said at least one link; determining whether said data stream is of a data type belonging to a set of prioritized data types; selecting, in case it has been determined that the data stream is of a data type belonging to the set of prioritized data types, the first output buffer for said data packets; selecting, in case it has been determined that the data is of a data type not belonging to the set of prioritized data types, the second output buffer for said data packets; and transferring the data packets to the selected output buffer, for subsequent transmission of the data packets on said at least one link.

2. The method of claim 1, wherein at least one of the first and second buffer functions as a queue, wherein data packets placed first in the queue will be transmitted first, in accordance with a first in, first out (FIFO) principle.

3. The method of claim 1, wherein the data types of the prioritized data types are further assigned a priority value, and wherein the first buffer is operated as a priority queue in which data packets of a data type with higher priority rank are served prior to data packets of a data type of a lower priority rank.

4. The method of claim 1, wherein at least two links are provided, wherein data packets from the first and second buffers are transmitted on different links.

5. The method of claim 1, wherein the determining if the data stream has a data type belonging to the set of prioritized data types comprises determining at least one of a destination, a size and a pattern of the data stream, and using this for identification of a data type.

6. The method of claim 1, wherein the set of prioritized data types does not include video data streams

7. The method of claim 1, wherein the set of prioritized data types includes at least one of a voice-over-IP (VOIP) data stream, a transaction data stream, an authentication data stream and a VPN data stream.

8. The method of claim 1, wherein data packets are transmitted from the first and second output buffers with essentially the same output rate.

9. The method of claim 1, wherein the bandwidth for each data stream being sent through the second buffer is restricted to a maximum bandwidth value.

10. The method of claim 1, wherein the stationary communication server is an aggregation server, arranged to aggregate data packets of a stream transmitted on different links, and wherein at least one of the first and second buffer is arranged to transmit data packets on at least two simultaneously useable links.

11. The method of claim 1, wherein data streams of data types belonging to the set of prioritized data types have lower amounts of data, and requires lower bandwidth, compared to data streams of data types not belonging to the set of prioritized data types.

12. The method of claim 1, wherein the moving vehicle is a train and wherein the wireless communication system is a train wireless communication system.

13. A wireless communication system for a moving vehicle comprising: at least one router in the moving vehicle, said router being configured for receiving and transmitting wireless data communication to and from a stationary communication server outside said moving vehicle through at least one external mobile network on at least one link via at least one antenna, wherein at least one of the stationary communication server and the router, comprises: a first output buffer and a second output buffer; a traffic classifier arranged to analyze received data packets of a data stream to be transferred on said at least one link, and to determine whether said data stream is of a data type belonging to a set of prioritized data types; and a controller arranged to select, in case it has been determined that the data stream is of a data type belonging to the set of prioritized data types, the first output buffer for said data packets, and to select, in case it has been determined that the data is of a data type not belonging to the set of prioritized data types, the second output buffer for said data packets.

14. The wireless communication system of claim 13, wherein the moving vehicle is a train and wherein the wireless communication system is a train wireless communication system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

[0067] FIG. 1 is a schematic illustration of a train having a wireless communication system in accordance with an embodiment of the present invention;

[0068] FIG. 2 is a schematic illustration of the forwarding of packets in the system of FIG. 1 in a prioritized and non-prioritized channel, in accordance with an embodiment of the present invention; and

[0069] FIG. 3 is a schematic illustration of the traffic prioritization obtained by the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0070] In the following detailed description, preferred embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention. In the detailed embodiments described in the following are related to trains. However, it is to be acknowledged by the skilled reader that the method and system are correspondingly useable on other moving vehicles, such as buses, ferries, airplanes and the like.

[0071] In FIG. 1 a schematic illustration of a vehicle 1, such as a train, having a communication system is provided. The communication system comprises a data communication router, a mobile router 2 for receiving and transmitting data between an internal local area network (LAN) 3, and one or several external wide area networks (WANs) 4a, 4b, 4c. Communication to and from the WANs is provided through one or several antennas 5 a-n arranged on the train, the antennas may be arranged on the roof of the train, on window panes of the train, etc. Two or more data links are available, either between the train and one of the WANs, and/or by using several WANs simultaneously.

[0072] The LAN is preferably a wireless network, using one or several internal antennas to communicate with terminal units 6 within the vehicle. It is also possible to use a wired network within the vehicle. The LAN may be set-up as wireless access point(s). The client(s) 6 may be computing devices such as laptops, mobiles telephones, PDAs, tablets and so on.

[0073] The data communication router comprises a plurality of modems 21 a-n. Assignment of data streams to different WANs and/or to different data links on one WAN is controlled by a controller 23. The controller is preferably realized as a software controlled processor. However, the controller may alternatively be realized wholly or partly in hardware.

[0074] The system may also comprise a receiver for receiving GNSS (Global Navigation Satellite System) signals, such as a global positioning system (GPS) receiver 7 for receiving GPS signals, indicative of the current position of the vehicle.

[0075] The data communication router may also be denominated MAR (Mobile Access Router) or MAAR (Mobile Access and Applications Router).

[0076] The external wide area network(s) (WAN) may include a plurality of trackside base stations, such as trackside access points, distributed along a vehicle path of travel, i.e. the rail, for communication in compliance with a Wireless Local Area Network (WLAN) standard, such as an 802.11 standard, is illustrated in more detail. Such base stations/access points may be connected to a controller via a wired or wireless connection, such as via a fiber connection. The coverage areas may be overlapping, allowing the mobile router of the vehicle to access several access points simultaneously, and thereby distribute the communication between several data links.

[0077] The mobile router may also be connected to other external networks, and may consequently simultaneously distribute the communication also over these networks, e.g., via GSM, Satellite, DVB-T, HSPA, EDGE, 1×RTT, EVDO, LTE, Wi-Fi and WiMAX.

[0078] In terms of general operation of the communication system, the router and the stationary (remote) communication server are preferably connected through a plurality of exterior mobile/cellular networks (provided by the base stations), which are simultaneously useable. Also, the router is preferably arranged to communicate with the stationary communication server on at least two different data links (communication routes) having different characteristics (e.g., on different frequency bands), and then to automatically separate the data traffic between the data links based on an evaluation of link quality. The evaluation of link quality may for example be executed as disclosed in WO 2015/169917, by the same applicant, said document incorporated herein by reference. The data streams are then forwarded on one or several links to and from a dedicated external server, which may be referred to as an aggregation server or gateway. The different links thereby form a single virtual link between the router and the gateway.

[0079] The router 2 is arranged to communicate on several different communication routes (data links) having different characteristics, such as different communication routes to and from the exterior mobile network 4, e.g., owned by different network operators or by the same network operator. The various data streams can be transferred and distributed among the plurality of routers on the different data links, based on e.g., available bandwidth, or other performance parameters, as discussed in the foregoing, and as per se disclosed in EP 2 943 011 by the same applicant, said document hereby incorporated by reference.

[0080] The system further allows certain packet data streams of certain data types to be prioritized over other packet data streams of other data types. This will now be discussed in more detail with reference to FIG. 2.

[0081] The prioritization of the data transfer may be performed in the mobile router 2, for prioritization of the data streams going from the train to the stationary server. Additionally, or alternatively, the prioritization of the data transfer may be performed in a stationary server 9, such as in an aggregation server, for prioritization of the data streams going from the stationary server to the train. In the illustrative example of FIG. 2, prioritization is performed in both directions, i.e. both in the mobile router 2 and in the stationary server 9.

[0082] To this end the mobile router 2 is arranged to determine whether the data stream is of a data type belonging to at least one set of prioritized data types. In the illustrative example, only on set of prioritized data types is used. However, it is also feasible to have e.g., a set of most prioritized data types, and a different set of somewhat less prioritized data types. More sets of differently prioritized data types may also be provided.

[0083] The determination of the data type of a data type, and the determination of whether the determined data type belongs to one of the one or more sets of prioritized data types can e.g., be based on a destination and/or a size and a pattern of the data stream. Most preferably, the size and pattern of the data stream is used to determine the data type. The size and pattern provide a silhouette of the traffic, which can be used to distinguish between data types. However, other ways of distinguishing between different data types are also feasible.

[0084] The determination of whether the data type belongs to one of the one or more sets of data types is here made in a traffic classifier 25. The traffic classifier may be a separate component in the router 2, or be an integrated part in the controller 23.

[0085] The router 2 further comprises a first output buffer 26a and a second output buffer 26b. However, more than two buffers may also be used, such as three or four buffers.

[0086] When a data stream is received by the router, it is determined by the traffic classifier 25 whether the data stream is of a data type belonging to a set of prioritized data types. Based on this, the traffic classifier determines whether to forward the data stream to the first or second buffer. If it has been determined that the data stream is of a data type belonging to the set of prioritized data types, the first output buffer is selected for the data stream. If it has been determined that the data is of a data type not belonging to the set of prioritized data types, the second output buffer is selected for the data stream. The data stream is then transferred to the selected output buffer, for subsequent transmission of the data packets on the at least one link.

[0087] Hereby, the first buffer operates as a fast lane, or priority traffic queue, handling only the prioritized data traffic, which is consequently sent out at a fast rate. The second buffer operates as an ordinary lane, or bulk traffic queue, handling more data packets, and where data packets are sent out at a slower rate.

[0088] The prioritized data types may e.g., be voice over IP (VoIP), gaming communication, transaction data, such as payments, Remote Authentication Dial-In User Service (RADIUS), etc. The prioritized data types will typically contain relatively small amounts of data, which is bursty or has low-throughput data, thus requiring low bandwidth, but with a need for low latency. The non-prioritized data types may e.g., be high volume streaming data, such as video.

[0089] Similarly, the stationary server 9, such as an aggregation server or other gateway, may be arranged to determine whether the data stream is of a data type belonging to at least one set of prioritized data types. In the illustrative example, only on set of prioritized data types is again used. However, it is also feasible to have e.g., a set of most prioritized data types, and a different set of somewhat less prioritized data types. More sets of differently prioritized data types may also be provided.

[0090] The determination of the data type of a data type, and the determination of whether the determined data type belongs to one of the one or more sets of prioritized data types can here be made in the same way as in the mobile router 2.

[0091] The determination of whether the data type belongs to one of the one or more sets of data types is here made in a traffic classifier 95. The traffic classifier may be a separate component in the server 9, or be an integrated part of a main controller in the server.

[0092] The server 9 further comprises a first output buffer 96a and a second output buffer 96b. However, more than two buffers may also be used, such as three or four buffers.

[0093] When a data stream is received by the server/gateway 9, it is determined by the traffic classifier 95 whether the data stream is of a data type belonging to a set of prioritized data types. Based on this, the traffic classifier determines whether to forward the data stream to the first or second buffer, in the same way as in the mobile router 2.

[0094] The buffers may buffer may function as a queue, wherein data packets placed first in the queue will be transmitted first, in accordance with a first in, first out (FIFO) principle. However, one or more of the buffers may also be operated as a priority queue. To this end, the data types of the prioritized data types may further be assigned a priority value, and wherein the first buffer may be operated as a priority queue in which data packets of a data type with higher priority rank are served prior to data packets of a data type of a lower priority rank.

[0095] It is also possible to provide further restrictions on the non-prioritized data sent through the second buffer, such as restricting the bandwidth for each data stream being sent through the second buffer to a maximum bandwidth value. Hereby, all high bandwidth streams could be limited to a certain, maximum, bandwidth, such as to 2 Mbit/s. The maximum bandwidth could also be dynamically adjusted, in accordance with e.g., the total bandwidth that is accessible at any time.

[0096] It is also feasible to use more than two separate buffers, such as three, four or five different buffers. Hereby, different data types may, in case three buffers are used, be assigned to the first, second or third buffer, depending on their prioritization. Thus, the one or several data types of highest priority may be assigned to the first buffer, the one or several data types of somewhat lower priority may be assigned to the second buffer, and data types of lowest priority may be assigned to the third buffer. In such embodiments, the method may further comprise the step of determining whether said data stream is of a data type belonging to a second set of prioritized data types, and selecting, in case it has been determined that the data stream is of a data type belonging to the second set of prioritized data types, a third output buffer for said data packets. In an embodiment with three buffers, and again having data types assigned a priority from 1-5, where 1 is the highest priority and 5 the lowest priority, the data types with priority 1 may e.g., be sent to a buffer A, the data types with priority 2 or 3 may be sent to a buffer B, and the data types with priority 4 or 5 may be sent to buffer C.

[0097] In one embodiment, the data packets are transmitted from the first and second output buffers with essentially the same output rate. Thus, each of the buffers may have the same capacity and be assigned the same bandwidth. The same output rate may also be provided for any third or subsequent buffer. In order to make some buffers, such as the first buffer, faster than others, only a limited number of data types are preferably included in the set(s) of prioritized data types, thereby limiting the traffic through these buffer(s).

[0098] However, other ways of making the prioritized buffer(s) faster may also be used, as have been discussed in the foregoing, such as by assigning different links to the buffers, re-allocating the buffers to new links in different order, etc.

[0099] FIG. 3 illustrates a simplified schematic traffic shaping process, so to provide a basic conceptual understanding. In the exemplary embodiment illustrated in FIG. 3, there are three flows/streams of data packets 103, 105, 107 entering a network edge device 110, such as the router 2 or the gateway 9. In this particular exemplary embodiment, data stream 103 is a High Definition video stream, data stream 105 is a business application stream, such as VPN communication, and 107 is a VoIP stream. Upon reaching the network edge device 110, an internal control unit (such as e.g., 25 or 95 in FIG. 2), determines if the data stream belongs to a set of prioritized data types, and allocates the data stream to one of the buffers based on this. As illustrated by arrows 113, 115, 117 the incoming data packets/data streams, 103, 105, 107 have been differently prioritized, and assigned different buffers. The data stream representing an HD-video stream has a significantly reduced throughput, in favor of the business application, which enjoys the most throughput. The VoIP outgoing data stream 117 may be prioritized in the same way as the business application data, or be assigned to a separate buffer. Preferably applications like VoIP, requiring a certain bandwidth and/or priority to ensure a minimum quality is allocated with at least that minimum bandwidth, but if more bandwidth is available more bandwidth is allocated for the VoIP. By configuring the predefined packet streams, and associating them with a Quality of Service (QoS) measure, the traffic control can be very efficient.

[0100] Furthermore, the sets of prioritized data types, and/or the prioritization within the queues in the buffers, may be dynamic, and may e.g., be configured to depend on time of day, day of the week, number of clients connected, total available bandwidth, etc. Therefore, the bandwidth allocation and/or prioritization for specific software applications may be very dynamic.

[0101] By means of the above-discussed method and system, the end result will be throttling of certain bandwidth-heavy applications such as high definition media streaming, which may not be of high priority, whereas less bandwidth demanding applications are promoted. Thus, more passengers/clients may utilize the network, provided within the train, much more efficiently.

[0102] Additionally, by only analyzing packet sizes and packet patterns of packet streams received by the router, the data stream type can be determined even for encrypted data. Thus, passengers connected via a Virtual Private Network (VPN) tunnel will not impose a problem for the analysis. Moreover, the privacy of the passengers remains uncompromised. Thus, contrary to conventional deep packet inspection, it is here only a need to determine a packet type or type of data stream, whereas the actual content is of no interest. This makes it possible to make the determination easier, faster and more cost-efficient.

[0103] It is thus possible to prioritize data streams efficiently and dynamically. However, even static prioritization provides a very efficient measure to improve the quality of service experienced on the train.

[0104] Some exemplary different data types may e.g., be prioritized as discussed in the following, and as shown in the following table.

TABLE-US-00001 TABLE Example of data stream type characteristics and prioritization BW at Data Quan- BW at BW at very stream Acceptable tity high low low Prior- type latency of data capacity capacity capacity ity Voice A few ms Low High High High High (VoIP) Video >10 s High Medium Low None Low http and >5 s Low- High Medium None Medium https high Payment ~2-5 s Low High High High High

[0105] Voice data streams, such as VoIP calls, are very sensitive to latency. A latency of only a few milliseconds will be experienced as very annoying for users. At the same time, the data streams are typically very long in time, but the data quantity is relatively low. Thus, voice may be highly prioritized, and allocated the first (fast) buffer at all times, regardless of whether the total available capacity is high, low or even extremely low.

[0106] In the same way data streams related to payment services may be highly prioritized, and allocated to the first (fast) buffer. Payment data streams are typically having low quantities of data. Payment services, such as paying for services, ordering tickets, etc, are often aborted relatively quickly. Thus, the latency should not be more than 2-5 seconds, depending on the service providers.

[0107] Video data streams are often large, having high quantities of data. On the other hand, since the receiver normally buffers data, quite long latency times are acceptable. Also, providers of video data streams normally adjust the resolution and quality of the video data stream in accordance with the transmission capacity. Thus, if high bandwidth is available, data streams of high definition may be sent, whereas if moderate or low bandwidth is available, data streams of lower definition will be used. Video data streams will typically have low priority, and normally be assigned to the second (ordinary) buffer, but may also be entirely stopped when the bandwidth capacity is low. Further, the bandwidth capacity may be further restricted, also at times when the bandwidth capacity is high, since this will make the data stream provider transmitting the data stream with lower definition. This is beneficial when the available bandwidth varies greatly over time, which is typically the case at e.g., trains, but also lowers the overall data quantities sent to and from the train, thereby lowering the strains on the communication system and saves costs.

[0108] Other type of http and https data, such as reading newspapers on-line, sending e-mails, etc, are also relatively insensitive to latency, and the data streams are often relatively short and with relatively low quantities of data. For example a newspaper is typically forwarded as a plurality of separate data streams. Preferably, such data streams are allocated to the second buffer.

[0109] The present invention has here been disclosed in relation to trains, where it is considered to be particularly advantageous. However, it may also be implemented and used on other moving vehicles, and in particular vehicles intended for passenger traffic, such as buses, ferries, airplanes, etc.

[0110] The invention has been described with reference to specific embodiments. However, several variations of the communication system are feasible. For example, more than two buffers may be used, and more than one set of prioritized data types may be used. Further, the set(s) of data types may be static, but may also be dynamically altered over time. Further, in addition to the use of different buffers, additional measures, such as restriction of bandwidth for certain data types, prioritization in the queues of the buffer(s) in dependence of the prioritization, etc, may also be used. Further, data types may be identified in many different ways, as already exemplified. Such and other obvious modifications must be considered to be within the scope of the present invention, as it is defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word “comprising” does not exclude the presence of other elements or steps than those listed in the claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.