WO2007052180A2

WO2007052180A2 - Wireless interface

Info

Publication number: WO2007052180A2
Application number: PCT/IB2006/053909
Authority: WO
Inventors: Ozcan Mesut; Alexander W. Heerink; Jarno Guidi; Jozef P. Van Gassel
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2005-10-31
Filing date: 2006-10-24
Publication date: 2007-05-10
Also published as: WO2007052180A3

Abstract

The invention relates to a method of processing a data packet within a wireless interface of a device, the method comprising receiving a data packet at the wireless interface, processing the data packet on the basis of a MAC address in order to determine whether the data packet is intended for the device, and if the data packet is intended for the device, then analyzing at least a part of the content of the data packet according to a predetermined condition, and discarding the data packet if the predetermined condition is not met.

Description

A UPnP aware low-powder wireless interface

The present invention relates to a UPnP Aware Low-Power Wireless Interface, and in particular to a wireless interface with filtering capabilities.

A wireless in- home network connects various kinds of entertainment and productivity devices with each other and enables them to share content. Home media centers, televisions, personal audio-video jukeboxes, personal computers, notebooks, Personal Digital Assistants (PDAs), and mobile telephones are examples of such devices. For example, a personal audio-visual juke-box may synchronize with a home media center wirelessly, and a PDA may synchronize in the same way with a personal computer. All devices and their respective services may be displayed, for example, on a touch screen of a remote control. Using such a remote control a user can initiate content exchange between devices or streaming of content from media servers such as a home media center, personal jukebox and personal computer, to media Tenderers such as a television, personal jukebox and audio device.

The current dominant technology for connecting devices in a home network is Universal Plug and Play (UPnP), although other protocols and techniques are available. In a wireless UPnP network, devices are able to join and leave the network dynamically.

In one example, a UPnP network is controlled by a UPnP Control Point. In such a network, the control point searches for devices of interest on the network by sending out search requests in the form of multicast frames. Each device receiving a search request must respond to the search request in order to be found. Responding to a search request is done by the transmission of a unicast message from the device to the control point.

All devices in the network periodically advertise their presence so that the control point becomes, and remains, aware of their presence. This is done by periodic multicasting of discovery messages. The discovery messages contain information specific to the device, and are received by the wireless interface of each of the other devices in the network, as well as by the control point. Search requests from the control point, unicast response messages, and discovery messages are all in the form of data packets.

An example of a known wireless network device 2 is illustrated in Figure 1. The device 2 comprises two main sections; a host system 4 and a wireless interface module 6. The host system 4 may comprise a display unit 8, a data storage unit 10, a host central processing unit (CPU) 12, and a battery 14. Data storage unit 10 may consist of a combination of volatile and non- volatile memory. The host system 4 may comprise only RAM memory, or non- volatile flash memory, or RAM memory in combination with a small HDD, or RAM memory in combination with flash memory. The wireless interface module 6 comprises a central processing unit (CPU) 18, a data storage unit 20, and a radio frequency (RF) transceiver 22. The wireless interface module 6 also comprises a Media Access Control (MAC) layer 21, which may be provided by the CPU 20. Communication between the host system 4 and the wireless interface module 6 takes place via a host interface 16.

Multicast messages from a control point (not shown) of the network (not shown) and/or from other devices of the network are received at the RF transceiver 22 of the wireless interface module 6 via an RF air interface. These messages are in the form of data packets. Received data packets are passed to the Central Processing Unit (CPU) 18 of the wireless interface 6 where the MAC layer 21 processes the data packets according to their MAC address. The MAC address of the data packet indicates the MAC address of the device for which the packet is intended. If the MAC layer 21 determines that the data packet is not intended for the device (for example the data packet relates to a response message intended only for the control point), the data packet is discarded. If the MAC layer 21 determines that the data packet is intended for the device (for example the data packet relates to a discovery message or a search request), then the data packet is passed via the host interface 16 to the host CPU 12. The host CPU 12 is thereby activated and processes the data packet appropriately.

If the received data packet relates to a search request from a control unit, the device must respond. In this case, the host CPU 12 sends a message to the wireless interface module 6 with instruction to transmit a response in the form of a unicast message to the control unit.

If the received data packet relates to a periodic discovery message from another device, the host CPU 12 does nothing with the message, as no response is required. The host CPU can then return to a dormant state, if appropriate. The host CPU 12 of each device 2 is also responsible for multicasting out the periodic discovery messages of the device. This means that the host CPU 12 has to be activated periodically in order to multicast discovery messages.

It will therefore be appreciated that the host CPU 12 is regularly activated from a dormant power-saving state, even if the received data packet is not intended for the device 2. This causes a problem for battery-powered devices, as the host CPU 12 and data storage unit use energy when activated. Accordingly, activation of the host CPU 12 when not required wastes stored battery power unnecessarily.

It is therefore clear that there is a need for methods of receiving and transmitting the necessary messages in a more efficient manner.

According to one aspect of the present invention there is provided a method of processing a data packet within a wireless interface of a device, the method comprising the steps of: receiving a data packet at the wireless interface; processing the data packet on the basis of a MAC address in order to determine whether the data packet is intended for the device, and if the data packet is intended for the device: analyzing at least a part of the content of the data packet according to a predetermined condition; and discarding the data packet if the predetermined condition is not met. According to another aspect of the present invention there is provided a wireless interface module for use in a device, the wireless interface module comprising: a MAC address reader operable to determine whether a received data packet is intended for the device; and a data packet analyzer operable to analyze at least part of the content of a received data packet according to a predetermined condition, and to discard the data packet if the predetermined condition is not met. The wireless interface module may also comprise a data packet generator operable to multicast discovery messages.

According to another aspect of the present invention there is provided a method of multicasting discovery message over a wireless network from a wireless interface module of a device which includes a host system and a wireless interface module, the method comprising the step of multicasting discovery messages from the wireless interface module of the device independently of the host system.

According to another aspect of the present invention there is provided a wireless interface module for use in a device, the wireless interface module comprising a data packet generator operable to multicast discovery messages. Fig. 1 illustrates a standard networked device; Fig. 2 illustrates a first aspect of the present invention; Fig. 3 is a flow chart illustrating the first aspect of the present invention;

Fig. 4 illustrates a second aspect of the present invention; Fig. 5 is a flow chart illustrating the second aspect of the present invention; and

Fig. 6 illustrates a third aspect of the present invention.

A first aspect of the present invention will be described in relation to Figures 2 and 3. As before, a networked device 2 comprises two main sections; a host system 4 and a wireless interface module 30. The host system 4 may comprise a display unit 8, a data storage unit 10, a host central processing unit (CPU) 12, and a battery 14. It will be appreciated that the host system 4 may or may not comprise a display unit 8, as the display unit 8 may be situated elsewhere. The wireless interface module 30 comprises a central processing unit (CPU) 32, a data storage unit 34, a radio frequency (RF) transceiver 36 and a data packet analyzer 38. The wireless interface module 6 also comprises a Media Access Control (MAC) layer 31 , which may be provided by the CPU 32. Communication between the host system 4 and the wireless interface module 30 takes place via a host interface 16. It is to be understood that the units and functionality described here may be provided by separate units, a single overall unit, or any suitable combination of units. The functions may be provided by hardware, firmware, software or an appropriate combination of those elements. Multicast messages from a control point (not shown) of a network (not shown), or from other devices of the network, are received over an RF interface at the RF transceiver 36 of the wireless interface module 30. These messages are in the form of data packets. Received data packets are passed to the CPU 32 of the wireless interface 30 where a MAC layer 31 processes the data packets according to their MAC address. The MAC address of the data packet indicates the MAC address of the device for which the packet is intended. If the MAC layer 31 determines that the data packet is not intended for the device (for example the data packet relates to a response message intended only for the control point), the data packet is discarded. If the MAC layer 31 determines that the data packet is intended for the device (for example the data packet relates to a discovery message or a search request), then the data packet is not discarded, and is passed to the data packet analyzer 38. In one possible alternative, data packets are passed straight to the data packet analyzer 38 without being processed according to their MAC address. Data packet analyzer 38 may be provided by the CPU 32 or may be a separate unit. The data packet analyzer 38 is configured by a configuration command received from the host system 4. The configuration command specifies to the data packet analyzer 38 a predetermined condition which determines which data packets are to be passed to the host CPU 12 and which are to be discarded. This configuration of the data packet analyzer 38 may take place only once, or may take place many times in a dynamic way, depending on the application. The configuration command may specify the type of data packets to be passed or discarded based on the IP address of the data packet, for example unicast, multicast or broadcast. Alternatively, the configuration command may specify the type of data packets to be passed or discarded based on the protocol, for example File Transfer Protocol (FTP), Hyper Text Transfer Protocol (HTTP), Real-time Transport Protocol (RTP) or Universal Plug and Play (UPnP).

Examples of possible configuration commands are as follows:

"discard all multicast messages",

"pass all unicast messages",

"discard all UPnP discovery messages". Alternatively, the host system 4 can pass a pattern 'S' (ASCII, binary, etc) and a byte position 'P' which are used by the data packet analyzer 38 in the wireless interface module 30 to discard or pass frames of which the bytes starting from position 'P' match the pattern 'S'. Additionally, to save overhead, the type of frame, for example unicast or multicast, could also be specified by the host device. The data packet analyzer 38 analyses the content of the data packet in order to determine whether the packet is to be discarded or passed to the host CPU 12. The data packet analyzer 38 can be seen to filter out unwanted data packets in order to prevent these being passed to the host CPU 12 unnecessarily.

As an example of filtering a data packet by having bit-to-bit matching, consider a UPnP device which is not interested in receiving any discovery message except for SSDP searches. As all SSDP searches are encapsulated in a UDP datagram and start with "M-SEARCH * HTTP/1.1" string, the host system 4 of the device 2 passes to the wireless interface module 30 the following parameters:

Pattern="M-SEARCH*HTTP/l .1"

Position=42 byte Note that the position is given by adding up the MAC header (14 bytes), the IPv4 header (20 bytes) and the UDP header (8 bytes). The values of those headers are typically constant, but some of them, for example IPv4, can be bigger due to optional extensions. Therefore, in general, the position of the pattern must be calculated by the application. The application itself could keep track of the average or the most likely IP header size when processing the UPnP messages in active mode. Some other headers are communication medium dependent and can vary due to different communication technologies, for example when running IP over Bluetooth. Again, the application can keep track of the average or the most likely header sizes and pass the information to the wireless module when programming it.

Identifying discovery messages on an Ethernet medium is very straightforward and can take place at a very low level. For discovery purposes, UPnP uses an especially reserved multicast IP address: 239.255.255.250. This translates directly into the following Ethernet MAC address: 01.00.5e.7f.ff.fa as specified by the Internet authorities. This can be easily detected by the address decoding logic of the wireless interface module 30 on a very low level. These Ethernet packets will contain IP packets that contain UDP packets with HTTP headers.

The data packet analyzer 38 can analyze these HTTP messages for specific keywords (such as NOTIFY or M-SEARCH). If the wireless interface module 30 is UPnP aware, it could parse these HTTP headers completely. It could also store the HTTP message as such and compare it to the previously received HTTP message (from the same device / service). In case of changes in successive messages, the host CPU 12 can be signaled. The host CPU 12 could also poll for the latest message at the wireless interface module 30.

Hence the data packet analyzer 30 analyses the content of received data packets according to a configuration command received from the host system 4. Data packets are then either discarded or passed to the host CPU 32 via the host interface 16.

The host CPU 12 is hence activated only when a data packet is received which it has specified it is interested in. Data packets that are not important to the host system 4 are not passed to the host CPU 12, and the host CPU 12 is not activated. The system is hence more efficient than previously.

A second aspect of the present invention will be described in relation to Figures 4 and 5. As before, a networked device 2 comprises two main sections; a host system 4 and a wireless interface module 50. The host system 4 may comprise a display unit 8, a data storage unit 10, a host central processing unit (CPU) 12, and a battery 14. It will be appreciated that the host system 4 may or may not comprise a display unit 8, as the display unit 8 may be situated elsewhere. The wireless interface module 50 comprises a central processing unit (CPU) 52, a data storage unit 54, a radio frequency (RF) transceiver 56 and a data packet generator 58. The wireless interface module 50 also comprises a Media Access Control (MAC) layer 51, which may be provided by the CPU 52. Communication between the host system 4 and the wireless interface module 50 takes place via a host interface 16. It is to be understood that the units and functionality described here may be provided by separate units, a single overall unit, or any suitable combination of units. The functions may be provided by hardware, firmware, software or an appropriate combination of those elements.

As previously described, the device 2 must periodically advertise its presence so that the control point becomes, and remains, aware of their presence. This is done by periodic multicasting of discovery messages. In the second aspect of the present invention, the wireless interface module 50 comprises a data packet generator 58. The host CPU 12 may inform the wireless interface module 58 of the discovery message content and the required advertisement period. Alternatively, the data packet generator 58 may already be aware of the discovery message requirements of the host CPU 12. The data packet generator 58 within the wireless interface module 50 then takes care of multicasting the discovery messages at the period defined by the host CPU 12. The host CPU 12 does not therefore have to be activated periodically to send out discovery messages. This allows the host CPU to enter a dormant state and hence save energy.

A third aspect of the present invention will be described in relation to Figure 6. As before, networked device 2 comprises two main sections; a host system 4 and a wireless interface module 80. The host system 4 may comprise a display unit 8, a data storage unit 10, a host central processing unit (CPU) 12, and a battery 14. It will be appreciated that the host system 4 may or may not comprise a display unit 8, as the display unit 8 may be situated elsewhere. The wireless interface module 80 comprises a central processing unit (CPU) 82, a data storage unit 84, a radio frequency (RF) transceiver 86, a data packet analyzer 88 and a data packet generator 89. The wireless interface module 80 also comprises a Media Access Control (MAC) layer 81, which may be provided by the CPU 82. Communication between the host system 4 and the wireless interface module 80 takes place via a host interface 16. It is to be understood that the units and functionality described here may be provided by separate units, a single overall unit, or any suitable combination of units. The functions may be provided by hardware, firmware, software or an appropriate combination of those elements.

The third aspect of the invention is a combination of the first and second aspects of the invention. Figure 6 therefore illustrates wireless interface module 80 that is able to analyze the content of received data packets, and either discard them, or pass them to the host CPU 12, as is described in relation to Figures 2 and 3. It is also able to generate and multicast discovery messages as is described in relation to Figures 4 and 5.

Applications of the invention include UPnP devices that have wireless networking capabilities. The invention suitable for battery powered audio/video jukeboxes with streaming capabilities over an IEEE 802.11 wireless NIC in an UPnP network, for example.

Furthermore, the entire UPnP discovery process can be taken care of by the wireless interface module 30. In a standby mode, the host CPU 12 can remain switched off while the wireless interface module 30 keeps up to date on devices and services in the network. If internal UPnP devices are present these will be automatically advertised in the network. If changes in the network occur (i.e. devices leave or enter) the host CPU 12 can be signaled, or the host CPU 12 can poll the wireless device for this information.

Even more UPnP awareness can be added to the wireless interface module 30 in case of UPnP eventing. This is the case when a device, for example a control point has subscribed to specific services in the network. The wireless device can receive the events of changes of state variables of services that the control point application has subscribed to and cache these (most recent) values for the host CPU 12.

Claims

CLAIMS:

1. A method of processing a data packet within a wireless interface of a device, the method comprising the steps of: receiving a data packet at the wireless interface; processing the data packet on the basis of a MAC address in order to determine whether the data packet is intended for the device, and if the data packet is intended for the device: analyzing at least a part of the content of the data packet according to a predetermined condition; and discarding the data packet if the predetermined condition is not met.

2. The method as claimed in claim 1, further comprising the step of passing the data packet to a host CPU if the predetermined condition is met.

3. The method as claimed in claims 1 or 2, further comprising the step of receiving a configuration command specifying the predetermined condition.

4. The method as claimed in claim 3, wherein the configuration command specifies a type of data packet not to be discarded.

5. The method as claimed in claim 4, wherein the type of data packet is specified based on an IP address of the data packet.

6. The method as claimed in claim 5, wherein the IP address is unicast, multicast or broadcast.

7. The method as claimed in claim 4, wherein the type of data packet is specified based on the type of protocol of the data packet.

8. The method as claimed in claim 7, wherein the type of protocol of the data packet is FTP, HTTP, RTP or UPnP.

9. The method as claimed in claims 1 or 2, wherein the step of analyzing involves bit-to -bit matching.

10. The method as claimed in claims 1 or 2, wherein the step of analyzing involves analyzing the data packet for a specific keyword.

11. A wireless interface module operable to perform the method of processing a data packet as claimed in any one of claims 1 to 10.

12. A wireless interface module for use in a device, the wireless interface module comprising: a MAC address reader operable to determine whether a received data packet is intended for the device; and a data packet analyzer operable to analyze at least part of the content of a received data packet according to a predetermined condition, and to discard the data packet if the predetermined condition is not met.

13. A wireless interface module as claimed in claim 12, wherein the wireless interface module is operable to pass the data packet to a host CPU if the predetermined condition is met.

14. A wireless interface module as claimed in claims 12 or 13, further comprising a receiving unit operable to receive a configuration command specifying the predetermined condition.

15. A wireless interface module as claimed in claim 14, wherein the configuration command specifies a type of data packet not to be discarded.

16. A wireless interface module as claimed in claim 15, wherein the type of data packet is specified based on an IP address of the data packet.

17. A wireless interface module as claimed in claim 16, wherein the IP address is unicast, multicast or broadcast.

18. A wireless interface module as claimed in claim 15, wherein the type of data packet to be discarded is specified based on the type of protocol of the data packet.

19. The method as claimed in claim 18, wherein the type of protocol of the data packet is FTP, HTTP, RTP or UPnP.

20. A wireless interface module as claimed in claims 12 or 13, wherein the step of analyzing involves bit-to -bit matching.

21. A wireless interface module as claimed in claims 12 or 13, wherein the step of analyzing involves analyzing the data packet for a specific keyword.

22. A wireless interface module as claimed in any of claims 12 to 21, further comprising a data packet generator operable to multicast discovery messages.

23. A method of multicasting discovery message over a wireless network from a wireless interface module of a device which includes a host system and a wireless interface module, the method comprising the step of multicasting discovery messages from the wireless interface module of the device independently of the host system.

24. A wireless interface module for use in a device, the wireless interface module comprising a data packet generator operable to multicast discovery messages.

25. A method of communicating with a wireless network comprising a method as claimed in any of claims 1 to 11, and a method as claimed in claim 23.