GB2325381A

GB2325381A - Dual Speed Communications Apparatus

Info

Publication number: GB2325381A
Application number: GB9709978A
Authority: GB
Inventors: William Neil Robinson
Original assignee: Motorola Ltd
Current assignee: Motorola Solutions UK Ltd
Priority date: 1997-05-17
Filing date: 1997-05-17
Publication date: 1998-11-18
Also published as: GB9709978D0; WO1998053627A1

Abstract

A communications apparatus (100) for a network comprises a 64 kbit/s pulse code modulator (112) and a low rate vocoder (110) operably connected between a network interface (108) and a radio transceiver (114). The (112) operates at a greater data rate than the vocoder (110). A controller (116) is arranged to select the pulse code modulater (112) or the vocoder (110) in response to at least one predetermined criteria relating to a performance requirement.

Description

A COMMUNICATIONS APPARATUS AND A METHOD THEREFOR Field of the Invention The present invention relates to a communications apparatus, for example of the type used in a wireless local loop (WiLL) system. The invention also relates to a method of communicating for the above communications apparatus.

Background of the Invention It is known that WiLL technology can be used to deliver telecommunications services to a home or an office. However, it is important that the quality of service delivered by the WiLL technology is perceived by an end user to be comparable with alternative technologies, for example, twisted copper pair, hybrid fibre and coaxial cable. Additionally, it is desirable that the WiLL technology uses the radio spectrum efficiently.

One solution is to use low rate vocoder technology, which is known in the art.

Such technology is capable of providing speech of a quality comparable to that provided by a higher data rate coding technique, for example, 64 kbit/s pulse code modulation (PCM) technology, but achieved by transmitting at a lower data rate, for example, in the order of about 8 to 13 kbit/s. However, this increased efficiency is at the cost of delay; the transmission and reception of a signal can take many milliseconds of time due to the processing time, channel coding and decoding time, and propagation time.

Additionally, if a Time Division Multiple Access (TDMA) principle is employed, further delays can be incurred due to the need to synchronise data for transmission with the availability of a time slot.

An alternative to the use of the vocoder technology is to transmit across a radio interface at 64 kbitls. However, such a solution is costly in terms of capacity and spectral efficiency.

It is therefore an object of the present invention to provide a communications apparatus and a method therefor so as to obviate or mitigate the above described problems.

Summarv of the Invention According to a first aspect of the present invention, there is provided a communications apparatus for a network comprising a first information converter means and a second information converter means operably connected between an interface means and a communicating means, the first information converter means having a greater data rate than the second information converter means, and a controller means arranged to select the first information converter means or the second information converter means in response to at least one predetermined criteria relating to a performance requirement.

According to a second aspect of the present invention, there is provided a method of communicating using a communications apparatus for a network, the apparatus including a first information converter means and a second information converter means operably connected between an interface means and a communicating means, the first information converter means having a greater data rate than the second information converter means, and a controller means, the method comprising the step of selecting the first information converter means or the second information converter means in response to at least one predetermined criteria relating to a performance requirement.

According to a third aspect of the present invention, there is provided a communications apparatus for a network comprising a pulse code modulator and a vocoder operably connected between an interface and a transmitter, the pulse code modulator having a greater data rate than the vocoder, and a controller arranged to select the pulse code modulator or the vocoder in response to at least one predetermined criteria relating to a performance requirement.

According to a fourth aspect of the present invention, there is provided a communications apparatus for a network comprising a pulse code modulator and a vocoder operably connected between an interface and a receiver, the pulse code modulator having a greater data rate than the vocoder, and a controller arranged to select the pulse code modulator or the vocoder in response to at least one predetermined criteria relating to a performance requirement.

Other, preferred, features and advantages are set forth in and will become apparent from appended dependent claims 2 to 16, 19 to 33 and the following description.

Brief Descnption of the Drawings The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a schematic diagram of an apparatus constituting an embodiment of the invention, FIG. 2 is a schematic diagram of an apparatus constituting another embodiment of the invention, FIG. 3 is a flow diagram of a first method for use with the apparatus of FIGs.

1 and 2, and FIG. 4 is a flow diagram of a second method for use with the apparatus of FIGs. 1 and 2.

Description of a Preferred Embodiment Referring to FIG. 1, a communications system 100 comprises a local network 101 having a network unit 102 capable of communicating with a user unit 104 via a radio interface 106. The user unit 104 can be located within a telephone apparatus, for example, a terminal or a mobile telephone handset 105. Alternatively, the user unit 104 can be remotely located from the telephone apparatus, for example, within a housing 107, within a domestic residence or an office 109, for interfacing with a fixed line telephone apparatus 111.

The network unit 102 has a network interface 108 (FIG. 2) connected to a transit network 113 (FIG. 1), the network interface 108 also being connected to a low rate network vocoder 110 and a network pulse code modulator (PCM) 112 , the network vocoder 110 providing speech or data at a first rate having an associated first delay, and the network PCM 112 operating at 64 kbit/s and providing speech or data at a second, higher, rate having a second, associated, lower delay than the network vocoder 110. The network vocoder 110 and the network PCM 112 are connected in parallel to a radio frequency network transceiver 114. The network interface 108, the network vocoder 110, the network PCM 112 and the network transceiver 114 are each connected to a first controller 116.

The user unit 104 comprises a user equipment interface 118 connected to circuitry within the telephone apparatus 105 or within the housing 107 remotely located from the telephone apparatus 111, for example, in the office 109, as described above. The user equipment interface 118 is also connected to a low rate user vocoder 120 and a user PCM 122, the vocoder user 120 providing speech or data at the first rate having the first associated delay, and the user PCM 122 operating at 64 kbit/s and providing speech or data at the second, higher, rate having the second, lower, associated delay than the vocoder user 120. The user vocoder 120 and the user PCM 122 are connected in parallel to a radio frequency user transceiver 124. The user equipment interface 118, the user vocoder 120, the user PCM 122 and the user transceiver 124 are each connected to a second controller 126.

Although use of the low rate vocoders 110, 120 and the PCMs 112, 122 have been described above, it is not intended to limit the present invention to the methods of coding information, including voice and/or data, associated with the vocoders 110, 120 and the PCMs 112, 122. Other apparatus can be substituted for the vocoders 110, 120 and/or the PCMs 112, 122 employing different and/or multiple coding techniques. Furthermore, it is not intended to limit the present invention to the specific data rates described above.

During normal operation (FIG. 3), an outgoing call is established by a user or a subscriber. Upon establishment of the call, the network unit 102 determines whether a service which requires support at the higher rate of 64 kbit/s has been explicitly requested (step 300) by the user, for example, for private encryption. If such a service has been requested, the network unit 102 proceeds to determine whether there is capacity to support the call (step 302) at the higher rate of 64 kbit/s. If support at 64 kbit/s is available, the first controller 116 selects the 64 kbit/s network PCM 112 instead of the network vocoder 110 (step 304). The call then continues according to any technique know in the art, using the network PCM 112 to code/decode the user's speech. If, however, no capacity to support the call at the higher rate of 64 kbit/s is available, the user is advised that it is not currently possible to support the call (step 306).

If, however, support at the higher rate of 64 kbit/s has not been requested, the network unit 102 determines whether the call is a local call (step 308), for example, by analysing a number dialled by the user, or by ascertaining whether any network gateways to other networks are to be used for the call.

In the event that the call that has been established is a local call, the network unit 102 determines (step 318) whether the WiLL system has the capacity to support the call at the lower rate provided by the network vocoder 110. If the WiLL system does not have the capacity available to support the lower rate, the user is advised that it is not currently possible to support the call (step 320), otherwise the first controller 116 selects the network vocoder 110 and communicates with the network unit 102 to instruct the second controller 126 to select the user vocoder 120 as well; the call then continues according to any technique known in the art.

If the call is not a local call (step 308), for example, an international call involving a geostationary satellite, or the call is to a second generation cellular telephone, the network unit 102 determines whether an end-to-end delay associated with the call will be less than a predetermined value, D1 (step 310) if support is provided by the network vocoder 110 at the lower rate. D1 is the end-to-end delay below which the quality of the call is not regarded as degraded from the perspective of the user and so is acceptable.

D1 can vary between different subscribers depending upon the subscriber's subscription arrangement. Typically, the end-to-end delay is acceptable if it is less than 300 ms.

The end-to-end delay can be determined or anticipated in a number of ways.

Firstly, the delay can be anticipated by examining the number dialled by the user in order to establish the call. Secondly, a calling party identity corresponding to the established call can be examined. Alternatively or additionally, an end-to-end test can be carried out, according to any method known in the art in order to determine the end-to-end delay, for example, by use of intelligent network technology by which service control points exchange time stamped signals in order to obtain an estimate of likely delay.

The time stamped signals are transported using the same transport pathway as the user's information, for example, voice traffic. Lastly, information messages obtained from the transit network can be examined in order to anticipate the delay.

Once the end-to-end delay has been anticipated, if it is determined that the anticipated delay is less that D1 (step 310), the network unit 102 determines (step 318) whether the WiLL system has the capacity to support the lower rate provided by the network vocoder 110 and acts accordingly (step 320 or step 322) as described above. If however, the network unit 102 decides (step 310) that the anticipated delay exceeds D1, the network unit 102 then determines (step 312) whether any charging constraints are still being met, for example, whether or not the user is willing to pay for the call to be supported by the 64 kbit/s network PCM 112 so as to reduce delay. This information would typically be obtained from the subscriber's subscription information, which could be accessed from a database of subscriber information (not shown).

If the charging constraints are not being met, the network unit 102 determines (step 318) whether the WiLL system has the capacity to support the call at the lower rate provided by the network vocoder 110 and acts accordingly (step 320 or step 322) as described above.

If, however, the charging constraints are being met, the network unit 102 determines (step 314) whether the WiLL system has the capacity to support the call at the higher rate of 64 kbit/s. If support at 64 kbit/s is available, the first controller 116 selects the 64 kbit/s network PCM 112 instead of the vocoder 110 (step 304). The call then continues according to any technique know in the art, using the network PCM 112 to code/decode the user's speech.

If, however, there is no capacity to support the call at the higher rate of 64 kbit/s, the network unit 102 determines (step 316) whether use of the network vocoder 110 is acceptable to the user by, for example, analysing the subscription of the user or real-time enquiry of the user. If use of the network vocoder 110 is acceptable, then the network unit 102 determines (step 318) whether the WiLL has the capacity to support the lower rate provided by the network vocoder 110 and acts accordingly (step 320 or step 322). Otherwise, if use of the network vocoder 110 is not acceptable, the user is advised that it is not currently possible to support the call (step 320).

Thus, for example, when the local call is established, the first controller 116 of the network unit 102 selects the network vocoder 110, since the end-to-end delays of the transit network are negligible. If, however, an international call is established involving the geostationary satellite (which adds approximately 260 ms delay alone), the first controller 116 selects the network PCM 112 for transmitting the voice of the user, subject to the above mentioned criteria relating to performance requirements being met.

Referring to FIG. 4, the user unit 104 monitors the radio interface 106 in order to detect an incoming call (step 400). If the incoming call is not detected, the user unit 104 monitors for a request from the user to establish a call (step 402). If the request to establish the call is not detected, the user unit 104 reverts to monitoring for the incoming call (step 400). This cycle continues until call establishment is desired or a call is received.

When the existence of an incoming call is detected, the user unit 104 awaits a control message (not shown) from the network unit 102 via the radio interface 106 and the transceivers 114, 124 (step 406). Similarly, in the case of the request to establish the call from the user unit 104, the call is established by the telephone apparatus 105, 111 (step 404) and the control message is awaited (step 406) as described above.

Once the control message is received, the user unit 104 determines whether the network unit 102 has selected the 64 kbit/s network PCM 112 or the low rate network vocoder 110 for speech encoding/decoding (step 408). If the network unit 102 has selected the higher rate 64 kbit/s PCM, the second controller 126 of the user unit 104 selects the user PCM 122 (step 410), otherwise the user vocoder 120 is selected (step 312).

Although the above invention has been described in the context of a radio frequency system, it is not intended that the invention be limited to such a system and the implementation using other media, for example, fixed cable, such as fibre optic cable or twisted pair, is envisaged.

Additionally, although the above examples relate to coding of the user's speech, it is intended that the invention also be used for encoding other data, for example, image data or packet mode data.

Claims

1. A communications apparatus for a network comprising a first information converter means and a second information converter means operably connected between an interface means and a communicating means, the first information converter means having a greater data rate than the second information converter means, and a controller means arranged to select the first information converter means or the second information converter means in response to at least one predetermined criteria relating to a performance requirement.

2. An apparatus as claimed in Claim 1, wherein the first information converter means is a pulse code modulator.

3. An apparatus as claimed in Claim 1 or Claim 2, wherein the second information converter means is a low rate vocoder.

4. An apparatus as claimed in any one of the preceding claims, wherein the interface means is a network interface.

5. An apparatus as claimed in any one of the preceding claims, wherein the interface means is a user equipment interface.

6. An apparatus as claimed in any one of the preceding claims, wherein the communicating means is a transmitter.

7. An apparatus as claimed in any one of the preceding claims, wherein the communicating means is a receiver.

8. An apparatus as claimed in any one of the preceding claims, wherein the criteria relating to the performance requirement is the choice of a user.

9. An apparatus as claimed in any one of the preceding claims, wherein the criteria relating to the performance requirement is capacity.

10. An apparatus as claimed in any one of the preceding claims, wherein the criteria relating to the performance requirement is the cost of the performance requirement.

11. An apparatus as claimed in any one of the preceding claims, wherein the criteria relating to the performance requirement is an end-to-end-delay corresponding to the second converter means being less than a predetermined value.

12. An apparatus as claimed in Claim 11, wherein the predetermined value is 300 ms.

13. An apparatus as claimed in Claim 11, wherein the end-to-end delay is determined by examination of a number dialled.

14. An apparatus as claimed in Claim 11, wherein the end-to-end delay is determined by examination of a calling party identity.

15. An apparatus as claimed in Claim 11, wherein the end-to-end delay is determined by an end-to-end test.

16. An apparatus as claimed in Claim 11, wherein the end-to-end delay is determined by an information message from a transit network.

17. A communications apparatus substantially as hereinbefore described with reference to FIGs. 1 and 2.

18. A method of communicating using a communications apparatus for a network, the apparatus including a first information converter means and a second information converter means operably connected between an interface means and a communicating means, the first information converter means having a greater data rate than the second information converter means, and a controller means, the method comprising the step of selecting the first information converter means or the second information converter means in response to at least one predetermined criteria relating to a performance requirement.

19. An method as claimed in Claim 18, wherein the first information converter means is a pulse code modulator.

20. An method as claimed in Claim 18 or Claim 19, wherein the second information converter means is a vocoder.

21. An method as claimed in any one of Claims 18 to 20, wherein the interface means is a network interface.

22. An method as claimed in any one of Claims 18 to 21, wherein the interface means is a user equipment interface.

23. An method as claimed in any one of Claims 18 to 22, wherein the communicating means is a transmitter.

24. An method as claimed in any one of Claims 18 to 23, wherein the communicating means is a receiver.

25. An method as claimed in any one of Claims 18 to 24, wherein the criteria relating to the performance requirement is the choice of a user.

26. An method as claimed in any one of Claims 18 to 25, wherein the criteria relating to the performance requirement is the capacity of the network.

27. An method as claimed in any one of Claims 18 to 26, wherein the criteria relating to the performance requirement is the cost of the performance requirement.

28. An method as claimed in any one of Claims 18 to 27, wherein the criteria relating to the performance requirement is an end-to-end-delay corresponding to the second converter means being less than a predetermined value.

29. An method as claimed in Claim 28, wherein the predetermined value is 300 ms.

30. An method as claimed in Claim 28, further comprising the step of determining the end-to-end delay by examining a number dialled.

31. An method as claimed in Claim 28, further comprising the step of determining the end-to-end delay by examining a calling party identity.

32. An method as claimed in Claim 28, further comprising the step of determining the end-to-end delay by conducting an end-to-end test.

33. An method as claimed in Claim 28, further comprising the step of determining the end-to-end delay by examining an information message from a transit network.

34. A method of communicating substantially as hereinbefore described with reference to FIGs. 3 and 4.

35. A communications apparatus for a network comprising a pulse code modulator and a vocoder operably connected between an interface and a transmitter, the pulse code modulator having a greater data rate than the vocoder, and a controller arranged to select the pulse code modulator or the vocoder in response to at least one predetermined criteria relating to a performance requirement.

36. A communications apparatus for a network comprising a pulse code modulator and a vocoder operably connected between an interface and a receiver, the pulse code modulator having a greater data rate than the vocoder, and a controller arranged to select the pulse code modulator or the vocoder in response to at least one predetermined criteria relating to a performance requirement.