Decentralized caching system

• US 9,094,090 B2
• Filed: 03/01/2012
• Issued: 07/28/2015
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Gilat Satellite Networks Limited
• Original Assignee: Gilat Satellite Networks Limited
• Inventors: Markovitz, Oren, Hecht, Yoseph, Argov, Nitay, Kanfi, Zohar
• Primary Examiner(s): Choe, Yong
• Application Number:
  US13/409,705
• Publication Number:
  US 20130080701A1
• Time in Patent Office: 1,244 Days
• Field of Search: 711/137, 711/115, 711/E12.017
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 9/383 Operand prefetching cache prefetching G06F12/0862
• CPC Class Codes: H04B 7/18517 Transmission equipment in earth stations
• CPC Class Codes: H04B 7/18528 Satellite systems for providing two-way communications service to a network of fixed stations, i.e. fixed satellite service or very small aperture terminal [VSAT] system
• CPC Class Codes: H04B 7/18584 Arrangements for data networking, i.e. for data packet routing, for congestion control data switching networks H04L12/00
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04W 28/0289 Congestion control load shedding arrangements in network planning H04W16/08; performing reselection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12

Abstract

In a satellite communication system comprising at least a hub and a plurality of terminals, at least one terminal may include a cache for storing data objects. The cache may be based on a detachable memory device that may be inserted to or removed from the terminal at any given time, including after the terminal is deployed. Aspects are directed to preventing a prefetching of objects already stored in a cache of a remote terminal. In some embodiments, an efficient multicasting of content to terminals over an adaptive link may occur in a manner which may benefit terminals comprising a cache while not affecting or minimally affecting the performance of terminals that may not include a cache.

Claims

1. A method comprising:

receiving, at a terminal of a satellite communication system, a first request from a user device coupled to the terminal;

forwarding the first request to a hub included in the satellite communication system;

determining that a first object associated with the first request is stored in a cache that is detachably inserted into the terminal;

retrieving the first object from the cache;

receiving, at the terminal and over a satellite link, any of a unicast transmission and a multicast transmission each comprising one or more objects associated with the first request, wherein receiving the multicast transmission comprises;

selecting one or more multicast streams associated with one or more multicast groups, wherein a number of the one or more selected multicast streams is less than or equal to a predetermined number which is determined based on any of a storage capacity of the terminal'"'"'s cache, a rate of traffic the terminal is configured to process, a volume of traffic the terminal is configured to process, and a rate of traffic the terminal is configured to receive considering its satellite link conditions; and

listening to the one or more selected multicast streams to receive the multicast transmission;

storing at least one object of the one or more objects received over the satellite link in the cache; and

sending the first object and the one or more objects received over the satellite link to the user device.

2. The method of claim 1, wherein storing the at least one object of the one or more objects received over the satellite link in the cache comprises:

determining whether the at least one object is cacheable; and

storing the at least one object in the cache in response to determining that the at least one object is cacheable.

3. The method of claim 1,

wherein sending the first object and the one or more objects associated with the first request to the user device comprises sending the first object and the one or more objects while enforcing a maximum information rate between the terminal and the user device.

4. The method of claim 1, further comprising:

receiving one or more multicast responses associated with the one or more selected multicast streams;

determining for each of the one or more multicast responses whether it comprises an object of interest; and

merging the object of interest with any objects received from one or more unicast streams.

5. The method of claim 1, further comprising:

determining whether the cache is present in a slot of the terminal,

wherein storing the at least one object of the one or more objects received over the satellite link in the cache is responsive to determining that the cache is present in the slot of the terminal.

6. The method of claim 1, wherein receiving the first request from the user device comprises receiving a first uniform resource locator (URL) requested by the user device.

7. The method of claim 6, further comprising:

receiving, at the terminal and over the satellite link, a reference record corresponding to the first URL, wherein the reference record includes at least a URL identifier corresponding to the first URL and an index for at least one object of the one or more objects received over the satellite link and associated with the first request; and

storing the reference record in the cache.

8. The method of claim 7, further comprising:

receiving, at the terminal, a second request from a user device coupled to the terminal, wherein the second request comprises the first URL;

searching the cache for objects associated with the first URL in accordance with the reference record stored in the cache; and

constructing a request for the first URL and sending it to the hub, wherein the request includes at least a last modification time for at least one object associated with the first URL found in the cache.

9. A method comprising:

receiving, at a terminal of a satellite communication system, a first request from a user device coupled to the terminal;

forwarding the first request to a hub included in the satellite communication system;

determining that a first object associated with the first request is stored in a cache that is detachably inserted into the terminal;

retrieving the first object from the cache;

receiving, at the terminal and over a satellite link, any of a unicast transmission and a multicast transmission each comprising one or more objects associated with the first request;

storing at least one object of the one or more objects received over the satellite link in the cache; and

sending the first object and the one or more objects received over the satellite link to the user device, while enforcing a maximum information rate between the terminal and the user device, wherein the sending comprises;

assigning a priority level to the first object and to the one or more objects received over the satellite link, wherein the priority level assigned to the one or more objects received over the satellite link is higher than the priority level assigned to the first object retrieved from the cache;

determining whether to drop any objects to enforce the maximum information rate; and

dropping lower priority objects before higher priority objects to enforce the maximum information rate.

10. The method of claim 9, wherein the priority level assigned to non-cacheable objects received over the satellite link is higher than the priority level assigned to cacheable objects received over the satellite link.

11. The method of claim 9, wherein storing the at least one object of the one or more objects received over the satellite link in the cache comprises:

determining whether the at least one object is cacheable; and

storing the at least one object in the cache in response to determining that the at least one object is cacheable.

12. The method of claim 9, further comprising:

determining whether the cache is present in a slot of the terminal, wherein storing the at least one object of the one or more objects received over the satellite link in the cache is responsive to determining that the cache is present in the slot of the terminal.

13. A method comprising:

receiving, at a terminal of a satellite communication system, a first request from a user device coupled to the terminal;

forwarding the first request to a hub included in the satellite communication system;

determining that a first object associated with the first request is stored in a cache that is detachably inserted into the terminal;

retrieving the first object from the cache;

receiving, at the terminal and over a satellite link, any of a unicast transmission and a multicast transmission each comprising one or more objects associated with the first request;

storing at least one object of the one or more objects received over the satellite link in the cache;

sending the first object and the one or more objects received over the satellite link to the user device;

determining whether the cache is present in a slot of the terminal;

receiving a multicast frame related to a multicast group the terminal belongs to;

in response to determining that the cache is absent from the slot of the terminal, determining whether the multicast frame includes at least one object requested by the terminal; and

extracting the at least one object from the multicast frame if the at least one object from the multicast frame is requested by the terminal.

14. The method of claim 13, wherein receiving the multicast transmission comprises:

selecting one or more multicast streams associated with one or more multicast groups, wherein a number of the one or more selected multicast streams is less than or equal to a predetermined number which is determined based on at least one of a storage capacity of the cache, a performance characteristic of the terminal, or a maximal data rate of the terminal; and

listening to the one or more selected multicast streams to receive the multicast transmission.

15. The method of claim 13, further comprising applying a filter to locate a terminal identifier at a predetermined offset from a media access control (MAC) address field of the multicast frame.

16. A terminal, comprising:

an indoor unit having a slot configured to receive a detachable cache; and

terminal caching logic configured to;

receive a first request from a user device coupled to the terminal;

forward the first request to a hub;

determine that a first object associated with the first request is stored in the detachable cache;

retrieve the first object from the detachable cache;

receive, over a satellite link, any of a unicast transmission and a multicast transmission each comprising one or more objects associated with the first request, wherein receiving the multicast transmission comprises;

selecting one or more multicast streams associated with one or more multicast groups, wherein a number of the one or more selected multicast streams is less than or equal to a predetermined number which is determined based on any of a storage capacity of the terminal'"'"'s cache, a rate of traffic the terminal is configured to process, a volume of traffic the terminal is configured to process, and a rate of traffic the terminal is configured to receive considering its satellite link conditions; and

listening to the one or more selected multicast streams to receive the multicast transmission;

store at least one object of the one or more objects received over the satellite link in the detachable cache; and

send the first object and the one or more objects received over the satellite link to the user device.

17. The terminal of claim 16, wherein the terminal caching logic is further configured to:

determine whether the detachable cache is present in the slot,

wherein storing the at least one object of the one or more objects received over the satellite link in the detachable cache is responsive to determining that the detachable cache is present in the slot.

18. The terminal of claim 16, wherein the terminal caching logic is further configured to:

receive one or more multicast responses associated with the one or more selected multicast streams;

determine for each of the one or more multicast responses whether it comprises an object of interest; and

merge the object of interest with any objects received from one or more unicast streams.

19. The terminal of claim 16, wherein the slot is accessible from an exterior of the indoor unit and the indoor unit is configured to allow the detachable cache to be inserted or removed from the slot without taking the indoor unit apart or removing any panel or cover of the indoor unit.

20. The terminal of claim 16, wherein the indoor unit and the terminal caching logic allow the detachable cache to be inserted into or removed from the slot while the terminal is operative.