WO1997037442A1

WO1997037442A1 - Method for providing a plurality of services in a communication system

Info

Publication number: WO1997037442A1
Application number: PCT/US1997/005209
Authority: WO
Inventors: Albert Chen; Simon Shen
Original assignee: Motorola Inc.
Priority date: 1996-03-29
Filing date: 1997-03-27
Publication date: 1997-10-09
Also published as: AU2598297A

Abstract

A method for use in a communication system (100) which allows communication channels (318) to be flexibly aggregated together in order to meet the particular demands of a particular service. Moreover, a single subscriber (134-140) can concurrently employ several services. Also, additional calls are set up without interruption of services in progress. Additionally, communication channels/resources (318) of differing quality are economically assigned based on the channel quality demands of the service being facilitated.

Description

METHOD FOR PROVIDING A PLURALITY OF SERVICES IN A COMMUNICAΗON SYSTEM

Background

The present invention relates generally to communication systems, and more particularly to providing a plurality of different services in communication systems. There are a number of services available over telecommunication networks. The different types of data services on these networks require different data rates, also viewed as bandwidth in some communication networks. Examples of data services that can be offered are Plain Old Telephone Service (POTS), computer data transmission, and video conferencing services. The data rate and bandwidth required for POTS is less than the bandwidth for high speed computer data or video conferencing.

Traditional communications systems are relatively inflexible with respect to providing a variety of different types of services. For example, on standard twisted pair land line POTS systems, services are limited to regular voice communications and only those data services which can be supported by the maximum data rate available from an analog modem (typically a mere 28.8 thousand bits per second (Kbps)). Moreover, providing more than one service concurrently to a particular subscriber becomes very cumbersome if not impossible because the limited bandwidth of the twisted pair must be shared by more than one service, and there is no convenient way to set up a call for a second service once a first service is in progress.

Integrated Services Digital Network (ISDN) systems are a slight improvement over standard POTS systems. ISDN Basic Rate Interface (BRI) typically offers a choice of 64Kbps or 128Kbps, with the 128Kbps being particularly cumbersome to set up. A network that is engineered for ISDN BRI has three possible channels (two "B" channels, one "D" channel). Two of the "B" channels are fixed at 64Kbps, while the third "D" is used for signaling. If a service needs more than 64Kbps (but limited to 128Kbps), a complex method of call setup such as "bonding" or Multiple Link Point to Point Protocol (MLPPP) occurs to ensure independent B channels are "bound" together. Furthermore, these channels may be routed through different switches in the public switch telephone network (PSTN). If greater than 128Kbps data rate is needed, ISDN cannot support the service without using data compression. Consequently, even ISDN is relatively inflexible and inelegant for providing a variety of different services. Furthermore, there is no convenient method for providing concurrent services, for example of voice, video and data all at once.

A further limitation of the conventional systems described above is that they cannot flexibly assign different quality resources (channels) to different services depending on the services' quality demand. For example, a computer data communication may require less channel quality than a voice call or video call, because computer data schemes typically provide for error correction and retransmission. Nevertheless, an ISDN service provides the same relatively expensive channel resources for both types of services. Consequently, what is desirable is a method for providing a plurality of different services on the same communication system. It is desirable to have a method that is not limited to a single service at any one time to a particular subscriber, that does not require cumbersome call set up to offer flexible bandwidth, and does not necessarily allocate the same expensive quality channels/resources to all services irrespective of their requirements.

Brief Description of the Drawings FIG. 1 illustrates a cable phone system comprising the Public Switch Telephone Network, Phone Switch, Cable Headend, Subscriber Units, and Homes with different communication services; FIG. 2 illustrates a video call being setup with a ladder diagram of messages being sent between the cable Headend and Subscriber Unit;

FIG. 3 is a diagram illustrating how the system uses the radio frequency spectrum for communication; FIG. 4 illustrates two carriers of different quality and the different types of calls that may be placed; and

FIG. 5 is a flow chart for determining if a communication service needs to be transferred to an alternate carrier in order to setup a new call.

Detailed Description of the Drawings

Generally, one preferred communication system which uses the method of the present invention allows communication channels (also referred to as divisions or resources) to be flexibly aggregated together in order to meet the particular demands of a particular service. Moreover, a single subscriber can concurrently employ several services. Also, additional calls are set up without interruption of services in progress. Additionally, communication channels/resources of differing quality are economically assigned based on the channel quality demands of the service being facilitated.

The preferred system which uses the method and apparatus of the present invention comprises and Hybrid

Fiber Coax (HFC) broadband communication system where a variety of services are available such as POTS, video conferencing, and bandwidth on demand data services. Additionally, the preferred system includes servicing subscriber premises with multiple and varied services. For example, some subscriber premises will be single family homes which tend to require POTS, and data services, while other premises may require POTS, and video conferencing. Additionally, the preferred communication system utilizes a predetermined number of radio frequency (RF) carriers for transmitting digital information which facilitates the various communication services. In the preferred system the predetermined number of radio frequency carriers each comprise eight Time Division Multiple Access (TDMA) channels. Consequently, the resources available for transmitting data which facilitates the provision of the various services constitute eight TDMA channels multiplied by the predetermined number of RF carriers available.

Additionally, a preferred communication system includes multiple transceivers which make up a cable control unit

(CCU) at the cable company's headend and single transceiver at each of the respective subscriber's premises. It will be recognized, therefore, that a subscriber's premises can receive information associated with the various communication services on a single RF carrier and transmit information associated with the various communication services on only that single RF carrier. Consequently, it is advantageous for the communication system to be able to allocate and transfer active data services among the RF carriers and TDMA channels. For example, it would be relatively ineffective for the communication system to reject a data call that requires multiple TDMA channels because additional channels on the same RF carrier are not available. It is preferable for a call to be transferred between one carrier to another carrier, thus freeing the required TDMA channels on the first carrier.

Turning to FIG. 1, FIG. 1 is a schematic diagram providing an overview of the preferred communication system which uses communication resource assigning methods according to the present invention. More specifically, FIG. 1 shows a communication system 100. Communication system 100 is an HFC based broadband communication system. Communication system 100 includes a headend 102. As illustrated, headend 102 is a cable company headend facility. At headend 102 is infrastructure equipment 104.

Infrastructure equipment 104 is a rack of equipment which facilitates providing telephony services over the cable company's HFC network. The telephony services include, but are not limited to POTS, video conferencing as well as bandwidth on demand data.

Infrastructure equipment 104 includes Cable Control Unit (CCU), also referred to as control unit, 106. Control unit 106 converts the data from the HFC network into a form of telephone services that a phone switch, 107 understands. Generally the CCU 106 comprises software and hardware including transceivers, to facilitate the telephony services over the HFC network. Also at headend 102 is combiner 108. Combiner 108 serves to combine the telephony related signals from infrastructure equipment 104 with video programming signals captured by satellite dish antenna 1 10.

Combiner 108 thereby outputs the broadband signal to be distributed throughout the HFC network.

Infrastructure equipment 104 is coupled to a phone switch 107. The phone switch 107 is part of the Public Switched Telephone Network (PSTN) 112. PSTN 112 couples to the rest of the telephony world where two different service originating/terminating terminals 116 and 118 are coupled to the PSTN 112. Originating terminals 116 and 118 represent two of the vast number of service originating/terminating terminals associated with the extending PSTN network 112. Originating/terminating terminal 116 comprises POTS, while originating/terminating terminal 118 comprises a video conference terminal. A fiber 120 extends toward the cable company's HFC service areas. In connection with a particular neighborhood, fiber 120 terminates at fiber node 122. Fiber node 122 converts optical signals carried by optical fiber 120 to electrical signals which are then distributed via coax cables 124 to the individual home 126, 128, 130, 132. The signal is received at the homes 126, 128, 130, 132 by subscriber units 134, 136, 138, 140. The subscriber units 134, 136, 138, 140 convert the RF signals from the CCU 106 to an interface that data services recognize. Example of different types of interfaces that a subscriber unit 134, 136, 138, 140 can have are, but not limited to ISDN, RJ-45, RS-232.

Each subscriber unit 134, 136, 138, 140 can be attached to a multiple of different types of telecommunication devices. Subscriber unit 134 has a Television (TV) 142 and telephone 144 connected to it. Subscriber unit 136 is connected to a TV 146, video camera 148, and telephone 150. Subscriber unit

138 is connected to a TV 152, personal computer (PC) with modem 154, and telephone 156. Subscriber unit 140 is connected two telephones 158, 156. A video camera 148 can originate a video call from the home 128 with subscriber unit 136 to a terminal 118 located in the PSTN 112. FIG. 2 illustrates the video call being setup.

FIG. 2 is the setup of a video call in a HFC network 100. The camera 200 is attached to a dialer 202. Dialer 202 allows the caller to enter the digits and upon pressing a button the dialer goes off-hook and starts the messaging to establish the call. When the dialer 202 goes off-hook and initiates a call, the subscriber unit 204 notifies that CCU 206 at the headend 208 a call is being initiated. The Initiate Call Message 210 is sent to the CCU 206 and contains information about the data rate 212, dialed digit 214 and type of service requested 215. The type of data service being request 215 is video telephony. Further detail on a suitable signally schemes, including the use of system broadcast channels and system access channels is described in co-pending United States Patent Application, serial number 08/564,837, entitled Method and Apparatus for Multiple Access Over Randomized Slots with Collision Detection in a Cable Telephony System, filed on November 29, 1995, which is incorporated herein by this reference. The different types of data services require different quality of RF connections. Furthermore, the quality of the different RF carriers are tracked by the system. The transmission of data and video require higher quality RF connections than POTS and the system uses the carrier quality in determining what carrier is chosen for the call.

The system determines the service type and then assigns an RF carrier of required quality to the call. Accordingly, the service type information 215 can also be viewed as service quality requirement information. The CCU 206 identifies the quality of connection that is required for the requested data service. The CCU 206 allocates a circuit 218 to a phone switch 216 for the call to be routed to the PSTN 220. Connections between the phone switch 216 and the CCU 206 are not dedicated to a subscriber unit 204. A circuit 218 is selected for the subscriber unit 204 when the call is setup. When the CCU 206 has allocated the bandwidth requested and a circuit 218 to the phone switch 216, a call setup message 224 is returned to the subscriber unit 204. The allocation of bandwidth is explained in the later figures.

Turning now to FIG. 3, FIG. 3 illustrates how the communication system shown in FIG. 1 utilizes the RF spectrum for communications. More specifically, portion of the RF spectrum 300 is used for downlink, that is for communications originating at the cable company's headend

102 and terminating at a subscriber premises. RF spectrum portion 300 extends from 50MHz to 750MHz as shown.

Additionally, communication system 100 utilizes an RF spectrum portion 302 for uplink communications, uplink being communications originating from subscriber's premises and terminating at headend 102. RF spectrum portion 302 extends from 5MHz to 42MHz.

With respect to downlink RF spectrum portion 300, the preferred communication system typically utilizes only a portion 304 of that spectrum for its telephony and data communication services. Spectrum portion 306 is an exploded view of a portion of spectrum 304. Spectrum portion 306 illustrates the individual RF carriers 308 used by communication system 100. RF carriers 308 are typically spaced 600KHz apart. Similarly, communication systems 100 typically uses only a portion 310 of RF spectrum 302 for uplink communications. Spectrum portion 312 is an exploded view of a portion of spectrum portion 310. Like spectrum portion 306 in connection with the downlink, spectrum portion 312 illustrates individual RF carriers 314 used in the uplink. It will be relevant to further discussion below, to note that communication system 100 tracks the relative quality of RF carriers 308 and 314, the carrier quality value being used in various methods for assigning communication resources. In this description of the present invention, the word "high" or "highest" in connection with carrier quality indicates a better/more desirable carrier, and correspondingly "lower" refers to a less desirable/clean RF carrier. A series of effective methods for tracking carrier quality in such a system are presented in copending U.S.

Patent Application 08/589,842, entitled Channel Quality Management in a Cable Telephony System, filed on January 22, 1996, which is incorporated herein by this reference. RF carriers 308, 314 can each be illustrated as TDMA channel sequence 316. More specifically, representative RF carrier 316 comprises 8 TDMA divisions 318. As will be recognized by those skilled in the art, each TDMA division or channel 318 can facilitate a separate communication, such as a telephone call. Additionally, in accordance with the present invention, two or more TDMA channels 318 may be combined when a communication service requires more than the bandwidth available in a single TDMA channel. For example, a simple voice telephone call may require only the bandwidth available in single TDMA channel 318, while a video conference may require 6 TDMA channels 318 combined. This is because much less data would be transmitted for voice only as compared to the video and voice required for video conferencing. As used in this description and discussion, the phrase "communication resource" refers to any portion or combination of the bandwidth available on such an RF carrier 316. For example, communication resource in some cases means a single TDMA channel 318, or combinations of multiple channels 318. FIG. 4 illustrates how the system in accordance with the present invention actively and flexibly allocates communication resources. FIG. 4 shows RF carrier 400 with a quality level of four 402 and RF carrier 404 with a quality level of two 406 at time unit zero 408. Each carrier is divided into eight 64Kbps TDMA time slots. At time unit one 412, RF carrier 400 has a telephone voice call on time slot three 414 from subscriber unit 134 and a data call 416 from subscriber unit 138. RF carrier 404 has a telephone voice call on time slot three 418 from subscriber unit 136, telephone voice call on time slot five 420 from subscriber unit 140, and telephone voice call on time slot number seven

422 on a second line from subscriber unit 140.

When subscriber unit 138 has a video call initiated, an Initiate Call Message 210 is sent to the CCU 206. The CCU 206 determines that a link transfer must occur. A link transfer is the movement of a active call (POTS or data service) from a

RF carrier to a different RF carrier. Figure 5 explains how to determine if a link transfer is needed. The CCU locates RF carrier 404 and transfers the telephone voice call on carrier 400 time slot three 414 to carrier 404 time slot two 424 at time unit two 426. The call setup then proceeds and the video call 428 is setup on carrier 400 time slot two, three, and four 430.

FIG. 5 shows the method of allocating the requested bandwidth and determining if a link transfer is needed at the CCU. The CCU receives the Initiate Call Message 502 and based on the service type 215 contained in the message 210, the bandwidth required is requested 504 from the system. The system will verify if enough bandwidth is available 506 for the data rate 212 required by the service that is being requested. If the bandwidth is not available, the call is blocked 508. If the bandwidth is available 510, the system must verify that enough channels on a single RF carrier are available, since a subscriber unit can receive only one RF carrier. If not enough channels are available on a single RF carrier, the system attempts to locate a RF carrier that meets the RF carrier quality requirement of the services requested 514 in the Initiate Call Message 210. The method then performs a link transfer to free up the required channels 516. The link transfer will move a data service that is active to another RF carrier without losing the connection. If the required bandwidth or channels are available 510 on a RF carrier or a link transfer has made them available 516 a RF carrier, the system proceeds with the call setup 512.

Although, as shown in FIGs. 4 and 5, the system shown utilizes a TDMA scheme, and flexibly aggregating TDMA channels/resources, it will be recognized that other resource division schemes, such as Coded Division Multiple Access (CDMA) may be used consistent with the method of the present invention. Consequently, what has been described is a communication system which uses the method of the present invention to allow communication channels (also referred to as divisions or resources) to be flexibly aggregated together in order to meet the particular demands of a particular service. Moreover, a single subscriber can concurrently employ several services. Also, additional calls are set up without interruption of services in progress. Additionally, communication channels/resources of differing quality are economically assigned based on the channel quality demands of the service being facilitated.

Claims

1. In a communication system capable of dedicating a first one or more of a plurality of communication divisions to a first subscriber unit and simultaneously dedicating a second one or more of the plurality of communication divisions to a second subscriber unit, and which provides substantially a constant bit rate for a duration of a communication, a method for providing a plurality of services in the communication system comprising the steps of: receiving a first radio frequency carrier comprising a plurality of the communication divisions; extracting and combining a first number of the communication divisions to facilitate a first type of communication service; and extracting and combining a second number of communication divisions different from the first number, to facilitate a second type of communication service.

2. The method of Claim 1, further comprising the step of responding to a determination that the first radio frequency carrier has less than the first number of communication divisions available by receiving a second radio frequency carrier having at least the first number of communication divisions available.

3. The method of Claim 1, wherein the first type of communication service is data and the second type of communication service is Plain Old Telephone Service (POTS).

4. The method of Claim 1 , wherein the steps of extracting and combining the first number and extracting and combining the second number occur concurrently.

5. The method of Claim 1, wherein the communication divisions comprise Time Division Multiple Access (TDMA) time slots.

6. The method of Claim 1, wherein the communication divisions comprise time multiplexed divisions.

7. The method of Claim 1, wherein the communication divisions comprise Code Division Multiple Access (CDMA) divisions.

8. In a communication system capable of dedicating a first one or more of a plurality of communication divisions to a first subscriber unit and simultaneously dedicating a second one or more of the plurality of communication divisions to a second subscriber unit, and which provides substantially a constant bit rate for a duration of a communication, a method for providing a plurality of services in the communication system comprising the steps of: providing a plurality of radio frequency carriers each comprising a plurality of the communication divisions; aggregating a first number of the communication divisions to carry out a first communication; and aggregating a second number of the communication divisions different from the first number of communication divisions to carry out a second communication.

9. The method of Claim 8, wherein the first communication comprises video and the second communication consists of an audio communication.

10. The method of Claim 8, wherein the steps of aggregating a first number and aggregating a second number occur concurrently.

1 1. The method of Claim 8, wherein each of the communication divisions comprises a Time Division Multiple Access (TDMA) time slot.

12. The method of Claim 8, wherein each of the communication divisions comprises a Code Division Multiple Access (CDMA) division.

13. The method of Claim 8, further comprising the step of receiving a message comprising information indicative of a communication destination and information indicative of a number of communication divisions required.

14. In a communication system capable of dedicating a first one or more of a plurality of communication divisions to a first subscriber unit and simultaneously dedicating a second one or more of the plurality of communication divisions to a second subscriber unit, and which provides substantially a constant bit rate for a duration of a communication, a method for providing a plurality of services in the communication system comprising the steps of: providing a first radio frequency carrier including a plurality of the communication divisions; transmitting a first message including information indicative of a first number of communication divisions required for a first communication, the first communication having a first duration, and; dedicating the first number of communication divisions to the first communication for substantially the first duration.

15. The method of Claim 14, further comprising the step of determining that less than the first number of communication divisions are available on the first radio frequency carrier, and in response selecting a second radio frequency carrier having at least the first number of communication divisions available.

16. The method of Claim 14, further including the step of transmitting a second message including information indicative of a second number of communication divisions required for a second communication having a second duration, the second number being different from the first number; and dedicating the second number of communication divisions to the second communication for substantially the second duration.

17. The method of Claim 16, wherein the first message and the second message each further include a same information indicative of a destination of the first communication and the second communication.

18. The method of Claim 14, wherein the first message further includes information indicative of a channel quality requirement.

19. The method of Claim 14, further including the step of dedicating a second number of communication divisions different from the first number of communication divisions to a second communication concurrently with the step of dedicating the first number of communication divisions.

20. The method of Claim 14, wherein the communication divisions comprise Time Division Multiple Access (TDMA) time slots.

21 . The method of Claim 14, wherein the communication divisions comprise Code Divisions Multiple Access (CDMA) divisions.