KR20000065144A - Integrated telecommunications system architecture for wired and wireless access featuring PACS wireless technology - Google Patents

Abstract

Very cost effective for small scale applications (e.g. up to 80 lines), but field upgrade-scalable via backplane bus 68 for applications with a significant number of additional lines (e.g. 30,000 lines) Telecommunications systems 52-82. The integrated voice / data telecommunications system is flexible enough to handle low frequency (eg 64 kbps mu-law) voice as well as high frequency multimedia data switching. If no suitable wireless network facility is available, as an alternative to PACS infrastructure requirements, the system may be configured as a low cost, standalone PACS system for "village phone" or "PACS-on-POTS" applications.

Description

Integrated telecommunications system architecture for wired and wireless access featuring PAS wireless technology

Several systems have been developed and implemented to meet the explosive demand for high quality wireless communications. In addition, with the increasing use of wide area networks (such as the Internet), there has been a tremendous demand for systems that support data communication.

Personal communication systems (PCS) are still under development to meet this demand. Personal Access Communications Systems (PACS) is a PCS that was developed to support voice, data, and video images for indoor and micro cells. PACS uses digital voice codes and digital modulation and is designed to support low speed, portable use.

As shown in FIG. 1, the PACS architecture includes four main components: a fixed transceiver 4 or a portable transceiver 2, known as a subscriber unit (SU); A fixed base unit 6 known as a radio port (RP); A radio port control unit (RPCU) 8; And access manager (AM) 10. Each fixed RP 6 communicates with multiple SUs 2 and 4 via one interface A (air interface) in such a way that each SU simultaneously allows access to the port based on multiplexing.

In PACS, a low power multiplexing radio link provides a number of independent full duplex request-assigned digital channels between each of the RP and the associated SU. Each RP transmits the bitstream at a predetermined carrier frequency. Next, each SU that accesses the RP responds by sending a burst at a common predetermined carrier frequency. In the case of licensed PACS, most radio frequency (RF) channels are frequency division in a dual communication scheme with 80 MHz spacing. For licensed PCS bands from 1920 MHz to 1930 MHz, several PACS, PACS-UBs have been developed in the United States. PACS-UB uses time division duplexing rather than the frequency division duplexing used in the original PACS standard.

Some of the advantages to PACS come from the reliability of relatively small base stations (RPs). Because of their small size and relatively low cost, RP can be widely used inside and outside utility poles, buildings, tunnels, and rooms, thus providing greater support for wireless access services. Since relatively low power is needed, the RP can be line or battery power.

PACS and PACS-UB allow wire-quality voice and data communication services at a price and capacity close to wired technology. These standards include (1) wireless local loop environments; (2) low mobility / high density public access PCS environment; And (3) it is particularly suitable for use in a number of environments, including in-building (residential or business) telephone and data environments.

For wireless local loop environments and low mobility / high density public access PCS environments, PACS is based on a system architecture based on the Advanced Intelligent Network (AIN) and ISDN wired network principles. AIN allows a user to have a single number for both wired and wireless services and allows smoother handoff when the subscriber moves from one location to another. One AIN architecture consists of three levels: intelligent level; Transport level; And access level. The intelligent level includes a database for storing information about network users. The transport level handles the transfer of information. The access level provides access to users in the network and includes a database that updates the location of each user in the network.

ISDN is a complete network architecture that uses common channel signaling (CCS) and uses digital communication technology to provide simultaneous transmission of user data, signaling data, and other related traffic over the network. ISDN provides a dedicated signaling network to supplement the Public Switched Telephone Network (PSTN). This provides a network for signaling traffic that can be used to provide new data services or route voice traffic on the PSTN between the network node and the terminal user.

While PACS architectures are useful in the environments described above, including AIN and ISDN features, they may not be appropriate for wireless loop or mobile PCS applications where there is no wired AIN or ISDN infrastructure. Moreover, PACS has very limited applicability for wireless systems in buildings, especially for small business settings.

In small work environments, small computer systems architecture (SCSA) may be used. SCSA is an open industry specification for computer-based telephony systems. The SCSA architecture consists of a 32-card node with a local, non-blocking time slot switched SCbus backplane that is hierarchically connected to the 16-node system via SCxbus. Non-blocking SCbus preallocates transmission slots in the system configuration, thus limiting the dynamic configuration of the 16.384 Mbps (4048 octet / frame) SCbus.

In addition to the limited dynamic configuration, node-to-node traffic in an SCSA system requires routing on three buses: two SCbus and two interconnect SCxbus on two nodes. Control messages are routed on independent multi-master contention buses. Therefore, a relatively high degree of switching is required to connect the hardware.

Apart from SCSA systems, other conventional architectures that are often used in small work environments include PBX architectures that are commercially available from several critical systems and telecommunications equipment manufacturers. Critical systems usually provide less than 125 lines; Small PBXs usually provide 125 to 1,000 lines, medium PBXs provide 1,000 to 10,000 lines, and large PBXs provide more than 10,000 lines. Often, different system architectures apply to each of these groups of products. Thus, as the number of users increases, it is very difficult to change the current system to provide additional lines. As a result, the scale is relatively limited for such systems.

In the light of the foregoing, PACS and PACS-UB wireless in “village telephone” environments (ie, characterized by high density of low mobile users) and in-building telephony and data environments (for PACS-UB), especially in low-cost modularity There is a need for an architecture that can provide the benefits of an access phone. In order to avoid any detailed wired infrastructure assumptions, there is a need for an associated requirement for an architecture that can provide "standalone" PACS performance, an architecture that can exist without an existing AIN or ISDN architecture.

The present invention relates to an integrated telecommunications system for providing wired and wireless access, and more particularly, to a system for providing voice and data telecommunications that can be used in a cost-effective, upgradeable, and wired and wireless environment.

1 is a block diagram of a conventional PACS architecture,

2 is a block diagram of a telecommunications system in accordance with an example of the present invention;

3 is a diagram of a backplane frame structure in accordance with the present invention;

4 is a diagram of a control channel according to the invention,

5 is a diagram of an address word bit allocation in accordance with the present invention;

6 is a diagram of an address data word in accordance with the present invention;

7 shows a block diagram illustrating a multi-cage system in accordance with the present invention.

In addressing these needs and others, we have developed a design that recognizes the importance of modularity and the importance of integrated support for a wide range of telecommunication services. For both system cost and system hardware, modularity is an important feature. This is because a village telephone system or an in-building voice and data system can span three orders of magnitude in the number of supported terminals. In addition, in view of the explosive growth in demand for data connections (primarily accelerated by Internet access), systems that can support a range of telecommunication services are desirable. Integrated support for wired access as well as wireless access is highly desirable, and it is possible for PACS wireless technology to provide wired voice terminals in business communication settings or to obtain even higher data communication rates.

Therefore, an object of the present invention is a field upgrade-scalable telecommunications system for applications that are very cost effective for small applications (e.g. up to 80 lines) but with a significant number of additional lines (e.g. 30,000 lines). To provide. It is yet another object of the present invention to provide an integrated voice / data telecommunications system that is flexible enough to handle high band multimedia data switching as well as low band (eg 64 kbps mu-law) voice. It is also an object of the present invention to provide a low cost, standalone PACS system for "village phone" or "PACS-on-POTS" applications, as an alternative to the need for a PACS infrastructure when no suitable wireless network facility is available. It is.

As described in detail below, the present invention provides a fairly high bus band (1.0486 Gbps) that is dynamically allocated, thus allowing the system to utilize usage statistics. In addition, for the present invention, all data and control traffic uses a common 32-bit wide backplane. Small systems can run in one card cage. Larger systems utilize multiple card cages interconnected in a ring arrangement over a single, high-pass, serial fiber link. There is no need for switching on the hardware that connects between cages.

In contrast to prior art critical systems, the present invention scales to systems with 30,000 lines in applications requiring very few lines (eg, 10 or less). As a result, the system backplane has a band large enough to support high-speed wired connections to desktop computing stations. Voiceband-rate voice and data connections are added to desktop and wireless voice and data terminal devices.

Other advantages of the present invention will become apparent to those skilled in the art from the following description.

The following is a description of the preferred examples of the present invention. First, a description of a single-cage embodiment of the present invention is described. As described below, this system is particularly suitable for use in wireless local loop environments, "village phone" environments, and / or in-building environments. Multi-cage examples illustrating the scalability provided by the present invention are also discussed.

2 is a diagram showing an example of a single-cage according to the present invention. The communication system 50 includes a unit 75 that provides voice and data access for various communication devices. As described below, this system provides wired and wireless voice and data communication between different types of terminals deployed in different networks. In this example, the system may include terminals between " stand-alone " terminals and within PSTNs; PACS-based wireless network; Terminals in a wide area network (WAN); And access between terminals in a local area network (LAN).

As shown, trunk line 66 leads to a central office (CO) switch that forms part of the PSTN. Serial interface 64 provides access to PPP server 60, which may be connected to LAN 62. This architecture can support routers (such as Internet Protocol (IP) routers) that link with WANs (such as the global Internet).

One or more standalone terminals, such as desktop personal computer 58, can access system 50 for data (or voice) transmission. Similarly, one or more voice terminals, such as wired station 56, provide wired voice access.

As described, system 50 supports PACS or PACS-UB architecture. One or more RPs 54, each of which can serve multiple terminals, such as portable terminal 52, are connected via unit 75 to the other network and PSTN shown. This architecture is particularly suitable for relatively dense distribution of wireless low mobile users.

The card cage 75 where the interconnection is done in principle comprises a backplane bus 68 connecting the control processor card 72 and several peripheral cards 70, 74, 76, 78, 80, and 82. . The backplane bus 68 provides high speed communication between the network and the various peripheral devices connected to the unit 75. Using the addressing structure to be described in detail below, the backplane bus 68 establishes a message stream or information stream communication path between the two systems under the control of the control processor card 72 (hereinafter referred to as control unit CU). to provide.

In this example, the peripheral card is a PSTN card 70, a number of RPCU cards 1 to N (represented by cards 74 and 80), a wired station control unit card (WSCU) 78, a hub controller card ( 78), feature card 82, and data interworking peripheral card 84. A general description of each of these peripheral cards is now disclosed.

The PSTN interface card 70 serves as the first network interface peripheral to support telephone service. Trunk 66, which can be analog or digital, provides a line interface from the local switched central office. In addition to analog POTS or ISDN interfacing, the PSTN interface card transcodes voice between 32 kb / s ADPCM (used over air and on the backplane) and analog waveforms or 64 kb / s PCM. Several wire drops may interface with the PSTN interface 70. However, if only a 2-wire drop is provided and the 2-to-4 wire hybrid is removed from the plant or from the central office, this peripheral may also be needed to implement the echo control means.

In a single card-cage system (or a chain of card-cage control units used according to the embodiment described below), the first PSTN interface card cuts off the analog POTS lines and replaces them with an external line affix for voice terminals. Make available as a run. The dialing information is communicated from the system control unit card 72 to the PSTN interface card 70 via the backplane virtual control channel. The call progress tone is digitized and sent back to the client voice terminal via one of the in-band allocable backplane time slots.

RPCU cards 76 and 82 provide a centralized architecture to support the radio-specific functionality generally described with respect to FIG. 1. In accordance with the architectural principles of PACS and PACS-UB, each RPCU services multiple RPs 54 that in turn provide wireless access to several SUs 52. As is known, the RP 54 limits functionality to enable high density coverage of the service area at minimal cost. RP 54 provides high performance modem characteristics, converts downlink (RPCU to SU) information streams from baseband to RF, and conversely, error detection of uplink (SU to RPCU) information streams from RF to baseband Convert with As shown, RP 54 is interfaced to the RPCU peripheral (cards 76 and 80 in this example) via standard twisted pair distribution wiring.

The twisted pair interface to the remote wireless port electronics provides full duplex digital link and DC power. In large PACS-UB systems, the remote port electronics can be a considerable distance from the system controller. In order to improve the reliability of the link, it is desirable to minimize the signaling speed between the ends. For example, the air interface speed of 384 kb / s is shared in a time division manner, and each half-duplex management uses a FIFO buffer to speed convert the line interface to 192 kb / s.

RPCU peripherals 76 and 80 define many radio-specific PACS protocols. Each processes SU requests for air interface sources and requests bus and other peripheral sources, such as network interfaces, via elements 64, 60, and 62. In addition, since the RPCU maintains connection status information for all time slots of the RP it is servering, it can provide high level information and commands to the RP so that the RP follows the spectrum usage rules. In this example, a single RPCU peripheral card, such as card 76 or 80, can server two single-carrier RPs or one dual carrier RP for a total of eight full duplex voice quality (32 kb / s) channels.

In addition to including a twisted pair and backplane interface, the RPCU peripheral preferably includes a dedicated microcontroller running on a small real-time kernel. In order to manage and communicate with the server RP, and to define the higher layer protocols used in link maintenance and call control algorithms, the processor provides the intelligent peripherals needed to communicate with the control unit 72.

One or more WSCU cards 78 support the use of a wired station described as a single wired station 56. Although only one such wired station is shown in FIG. 2, each WSCU card 78 can support up to eight stations in a manner similar to the eight full duplex 32 kb / s channels that the RPCU peripheral card can support.

In this example, the wired station transmits phantom power to the wired terminal and time divisions for the in-band high-speed channel (eg, 64 kb / s mu law PCM) and the out-of-band low-speed control channel (key press for call processing). Interferes with the WSCU card 78 via a single twisted pair carrying dual TDD digital data. WSCU card 78 uses a PACS Layer 3 protocol message (type INFO) to communicate keypresses (for direction on uplink) and relay status messages, and (for downlink direction), for example. Control station display and request user signaling or keypad input. The peripheral also utilizes an implementation such as RPCU cards 74 and 80 to convert keypress control channel messages to audio channel DTMF, which is for post-initiation dialing applications such as voicemail system conversations, for example.

The data interworking peripheral 84 also matches the previous architectural sensitivity for data service in the PACS. Functionally, data interworking peripheral 84 is considered as another network interface peripheral similar to line interface peripheral 70, but is used for non-voice service instead of voice service. For example, when a SU signals a RPCU that it is servering to set up a data call, the RPCU requests a backplane source to request service from the data interworking peripheral 84 and the data interworking peripheral ( 84) communicate the information stream to and from. The data interworking peripheral then communicates to a data interworking function (IWF) via a known data-specific protocol. The IWF then handles the specific network interface protocols required by the service. For access to local IP-based enterprise data networks and the global Internet, the IWF must support IP internetworking.

Controller card (78):

The proliferation of powerful desktop computers and the need to connect them has created a significant demand for computer networking hardware. In current business communication systems, efforts to integrate computing and telephony hardware are accelerating, with a primary focus on new functionality (eg, computer / telephone integration). In particular, for small businesses, it may be beneficial to provide voice and basic high speed data connections in the same system architecture, instead of requiring the use of physically separate network hardware for each use. Since the system backplane has such significant capacity, it is possible to provide multiple time slots to support high speed, common-media data connections, and to use the backplane peripherals to coordinate the use of these sources among connected desktop computers. This peripheral functions very similarly to an independent Ethernet lab controller, here the label of FIG.

Feature Card (82):

Additional feature functions are provided as "feature cards" in the system software or hardware. For example, a set of negotiating bridges can be implemented on a peripheral card, creating a backplane interface to low speed three-way and other multi-sided calls.

The fully loaded card cage contains 10 to 16 cards. For example, each card can support eight wired terminals or two PACS-UB BRs. This provides approximately eight (at the same time) line capacity per cage, with some physical card slots assumed to be provided for network interface functions.

Peripherals that server the terminal are supported by the high speed backplane bus 68 and fixed CU 72 described above provided in each unit 75. CU 72 makes voice and data circuit switch connections on a high speed digital backplane bus 68 that uses time slot interchange for data exchange. In this particular example, up to 31 slave peripheral cards can be plugged into a card cage with a fixed CU and a high speed backplane. This architecture provides a low cost system that is particularly useful for relatively small enterprises (using 80 lines or less). At the same time, this architecture allows expansion paths to much larger systems using more than 20,000 lines.

As shown in FIG. 3, the backplane is 32 bits and has 4096 time slots per frame. Each 32-bit time slot is separated into four 8-bit octets, each with four physical channels (0, 1, 2 for 0-7, 8-15, 16-23, and 24-31 bits, respectively). , And 3). The frame repeats every 125 ms, a rate corresponding to 8 ms voice sampling rate. At 1.0486 Gbps, it provides 16,384 (16k) octet slots per frame for data and voice communications, with each octet in the frame providing a 64 kbps unidirectional channel.

In the last 256 time slots of the frame, all four octets (channels 0-3) are provided to the system control data 104; In the first 256 time slots 102, each lower octet (channel 0) is provided to the system control data. As such, more than 15,000 assignable octets are available for circuit switched data. It supports, for example, 7,500 simultaneous simple full duplex voice conversations, which in turn can support 30,000 voice terminals. This assumes an activity factor of 25% or less.

4 shows the control channel provided in the last 256 time slots (indicated by reference numeral 104 of FIG. 3) of each frame. Each of the last 256 time slots of frame N is paired with one of the first 256 time slots of frame N + 2 and provided in one particular card cage. The upper octets (data bits 24-31 and data bits 16-23) are defined as address bytes that select a particular register on a particular card. An array of address bytes is shown in FIG.

The next octet in each time slot (data bits 8-15) consists of data bytes 108 written to the slave card at the CU. The last octet 110 (data bits 0-7) is left for an unclaimed service request from the slave card to the controller CU. In the first 256 time slots of the frame (reference numeral 102 in FIG. 3), only the lowest octets (data bits 0-7) are provided to the control channel. It contains the response data byte (112 in FIG. 4) from the slave card to the system CU. In all, there are five octets provided in each cage for two-way communication with a CU. For example, physical channel 0 (first octet) of time slot 0 and physical channel 0-3 (all 4 octets) of time slot 3840 (slot 0 of last 356 slot block) Is provided in the cage (0). Similarly, physical channels 1 and 3841 are provided in the cage 1. Etc.

As shown in Figure 4, there is a delay of up to one frame from the output of the last cage N (hexadecimal FF) to the input of the cage 0 (hexadecimal 00). This delay is included to compensate for unexpected aggregate delays from the N parallel-serial-parallel conversations (one set of transforms per cascade) that occur. Thus, the maximum configured system has 255 card cages.

In order to address a particular register to a particular card in a particular cage, a combination of control channel slot position and 16 bit address is used. For example, for the first cage (cage 0) of the system, the physical channels 2 and 3 of the time slot 3840 are associated to provide 16 bit addressing for data message communication. Bit 15 (most significant bit) is a read / write bit, and bits 10-14 are used to address one of the 32 possible card locations in the cage. The remaining ten bits (0-9) are available for peripheral card register addressing (see Figure 5).

Each cage has one of the last 256 time slots provided as a control channel from the cage's slave card to the system (CU). The lower octet 110 of the time slot is reserved for the unclaimed service request from the slave card to the call processing CU. This octet is a shared source of cage cards. Wired-AND control lines are provided for self-regulation. Each card is fixed in a specific physical slot. For example, a card in physical cage slot number 3 knows that it is in slot 3 by searching for five hard wired address lines leading to it through the backplane connector.

If a card in slot 1 wishes to access a service request octet, it must someday bring the service request coordination control line low within the first 64 time slots of the frame. If the card in slot 2 requires a service request octet, it first searches the control line to determine whether the card 1 controls the octet, and if not, then it is the second of the frame. Control is set low in 64 slots. This continues for the first 32 groups of time slots, allowing only one card to access the service request octet until the control channel arrives.

With this architecture, the data path from the slave card register to the CU is provided on the physical channel (0) of the time slot (0). Due to the one-frame time delay inherent in the reverse communication from cages 1 to 254 to cage 0, the card present in cage 0 has data for one frame, as described above with reference to FIG. You need to delay the response data for reading. Thus, cage 1 uses time slots 1 and 3841 and cage 2 uses time slots 2 and 3841. Etc.

The propagation channel used in the present invention is important for the function of the higher layer PACS protocol. PACS-UB specifies the common layer 2 and layer 3 protocols with PACS, to improve the interaction between authorized and unlicensed systems. At various times, the fixed system substructure must flow various information through the air to the handheld. This information includes a system information channel having a message for changing an item such as a port ID, a system ID and an access right, a registration area ID, an encryption module, or a portable parameter; And an alert channel through which a warning or " ringing " message is sent to inform the registered inactive handset that an incoming call has been received. Many of these items can be downloaded once from the system controller to the RPCU peripheral at system power-up, and formatting this information with the appropriate message at the appropriate time can be done by the RPCU. However, the controller must intervene in real time to generate an alert message that propagates across the alert area (in this case, the whole system) and to handle incoming call requests. As mentioned above, a method of implementing propagation performance for a system controller is to use a control channel time slot (slot number 255) for all propagation messages (see Figure 4). This can reduce the maximum number of cages supported in large systems by only one cage to 255, but allows a single message to reach all peripheral cards in all cages in the system. Regarding the peripheral backplane interface, the peripheral given in cage 254 must be able to read two consecutive time slots on the backplane. This is because the propagation time slot and control time slot for the cage are adjacent.

One feature of the present invention is that the system is not limited to one single cage architecture. For example, in the example of FIG. 7, the system can support up to 255 cages cascaded into a serial high speed fiber link 150. This provides over 20,000 lines in a fully configured system, while at the same time allowing a minimum system configuration that can support up to eight lines before requiring a second cage and cascading hardware. As system performance requirements increase, additional cages can be cascaded over high speed (1.0486 Gb / s) serial links. Each additional cage is connected in series in a ring.

In a preferred example of a multi-cage system, the cage controller card is present at the card slot address (0) of each cage. It provides a 32,768 MHz and independent frame start pulse on the backplane, allowing the slave card to synchronize to the backplane timing. The frame start line is high during slot 0 of the frame and low in other cases. During slot 0, the cage controller must place the cage number on channel 1 so that it knows which cage the slave card is plugged into and which control channel to monitor. The sync bit pattern lies in channels 2 and 3 of time slot 0, so that the card card can recover frame timing. The cage controller card is a system CU in a cage 0 or a cascade card.

The physical address of the card is hardware encoded with five backplane lines fixed at the appropriate level for each card slot. As such, the card can be plugged in, and within two frame intervals (250 ms) it knows which cage is present and which physical slot is plugged in. As such, the card knows which control channel time slots to monitor and which address range to respond to. Thus, the card can be plugged into the operating system, automatically determine its address in the system, and send the service request to the main unit for configuration.

Short time / channel assignment is communicated as 14 bits contained in two data octets. Two MSBs determine the physical channel, and 12 MSBs determine the time slots (see Figure 4). The 254 cage, with 16 cards each with eight lines per card performance, offers 32,640 lines of performance. A 4096 time slot with four physical channels of less than 256 time slots with five control channels results in a 14,104 single channel or 7,552 dual call. As mentioned above, assuming 25% occupancy, this allows 30,208 lines.

In single-cage systems, slot assignment is done by call processing, so only one device is allowed to write access to a given time / channel octet. However, in a multi-cage system, there is a dispute between the cascading card connected to the previous cage and another slave card present in the same cage. The time / channel octet is allocated by one CU in the cage, but the cascading card randomly repeats the data found on the backplane of the previous cage without knowing the call processing.

In addition, a system with N cages results in multiple delay lines inserted between the output of cage N-1 and the input of cage 0, which is exactly one frame that feeds back into cage 0 where the total number of cages are used. This is a delay. When the loop is closed, it maintains the frame slot structure. It also inserts a delay of one frame relative to the card in cage 1 to N-1, for response data to the data read command. Thus, the cards in cage 0 must recognize their position so that they align with the rest of the system and insert a delay of one frame.

The frame sync word located in the top two octets of the first time slot of the frame provides frame and time slot synchronization. Each cage is based on the timing of the previous cage and has an M time slot delay caused by the parallel-to-serial-to-parallel conversion required in using a 1.0486 Gb / s serial link. For card address decoding, the cage number is displayed in the second octet of the first time slot in each cage, so that cards in cage N-1 are within their local cage timing relative to the cage (0) frame timing of the system (N -1) Allow to recognize M time slot delay. This relative timing information is used by the RPCU card to subtract integer slot time from frame start timing to allow system-wide superframe and hyperframe for all wireless ports as required by the PACS-UB protocol. The resulting time accuracy is within 1 microsecond.

The frame sync word is transmitted without being invertered in the first frame of the superframe of 16 frames. The superframe structure allows for bit scrambling based on 16 frames in the pn sequence in length. This prevents a consistent appearance of frame sync words that can be embedded in user data.

In the cage (N-1 to 1), the high speed serial receiver generates a bus clock signal, and the frame sink draws and copies frame data from the previous cage. Such a receiver is quite simple in that it does not need to maintain knowledge of the call handling state. For example, a four wired-AND control line is used to instruct the receiver card whether it will write to a specific octet in a frame or tri-state to allow one of the local cards to fill a slot. In the time slot prior to the time slot in which the slave card will be written to the backplane, the slave card should pull the appropriate control line low so that it indicates to the receiver card that it tri-states its octet in the next time slot. This resolves the aforementioned potential conflict between the cascading card and another slave card in the same cage.

The above-described CU functions can be executed on call control software operations, for example on commercially available Intel x86 family processors. Of course, other configurations may be used in accordance with the present invention.

Since the backplane switching architecture exchanges groups of one or more 64 kbps data streams, the system is very flexible in terms of the nature of the cards that plug into the cage. For example, a data interworking card can be used to support wireless data in accordance with the PACS data architecture. Additional cards may also be used for voice path bridging (eg, conferences or three-way calls), voice messages, and the like.

An access management card can be added to a large system to free the main CU from such things as key management for access authentication and link encryption. In this regard, the PACS specification describes an AM function that provides multiple services for a wireless system. The basic PACS-UB system performs some of those functions, such as internal components of call control software. These functions include the establishment, maintenance and deletion of SU registration records, and the assignment of associated wireless systems; Authentication and verification of SU registration requests, which may include decryption of SU eligibility; Initiation of a SU alert related to call transfer in response to an incoming call service request from a line interface peripheral; And adjusting the SU call initiation attempt through the registration record. The PACS specification requires RPCU to AM communication over ISDN channels using standard national ISDN-1 messages. In a private access telephone / data system, it may be desirable to provide a local AM function to manage individual user groups.

Other changes to the system are also possible. For example, given a relatively general backplane structure and call processing software functionality, different RPCU peripherals may be specified for different air interface protocols.

In order to achieve the above object of the present invention, a detailed description of the preferred embodiment of the present invention has been described. This description is merely illustrative. Within the spirit and scope of the present invention, those skilled in the art will be able to make many additional modifications or changes.

Claims (9)

In a communication system having a plurality of terminals for exchanging user communication signals, A backplane bus having a plurality of module connection means; A controller connected to said backplane bus via at least one said module connection means; And A plurality of interfaces, each connected to the backplane bus via at least one said module connection means, for supplying said user communication signal over said backplane bus at a format and speed determined by said controller, wherein said format is said A time division format in which user communication signals are divided between a plurality of frames, each frame having a predetermined number of timeslots, the first number of timeslots providing system control data and the second number of timeslots being the user Provide user data corresponding to communication signal, Through this, the device characterized in that for routing the user communication signal between the terminal. The method of claim 1, wherein at least one of the interfaces And a wireless control unit for communicating user communication signals to and from the wireless transceiver in a time division baseband format, the wireless transceiver providing wireless access to one or more wireless terminals. 2. The device of claim 1, wherein the time division baseband format is a format specified by a personal access communication system protocol. 2. The device of claim 1, wherein the portion of the system control data includes addressing data indicating a destination present on one of the plurality of interfaces. The method of claim 1, wherein the addressing data is Card address data indicating the position of the selected module connecting means; And And register address data representing a register address associated with said selected module connection means. The device of claim 1, wherein the backplane, the controller, and the plurality of interfaces are provided in a module card cage assembly. 7. The device of claim 6, wherein the card cage assembly is provided as a slave to the controller up to a predetermined number of the interfaces. 7. The system of claim 6, further comprising a plurality of module card cage assemblies each comprising a backplane bus, a controller, and one or more peripherals, each controller of each module card cage assembly being linked in a daisy chain arrangement by a serial communication interface. Device characterized in that the. 7. The device of claim 6, wherein the serial communication interface transmits data at the same rate at which data is transmitted over the backplane bus.