CA2396196A1

CA2396196A1 - Wireless access system

Info

Publication number: CA2396196A1
Application number: CA002396196A
Authority: CA
Inventors: Doron Amir; Ofer Zilberberg; Bezalel Itzhaky
Original assignee: Individual
Current assignee: Teledata Networks Ltd
Priority date: 2000-01-03
Filing date: 2000-12-29
Publication date: 2001-07-12
Also published as: ZA200206036B; AU2698401A; WO2001050778A3; IL150309A0; EP1245122A2; CN1451245A; WO2001050778A2; BR0016896A

Abstract

There is disclosed an access system formed by the coupling of a Wireless Local Loop (WLL) system to a Digital Loop Carrier (DLC) system. This coupling is such that the DLC system supports the WLL system. This coupling is achieved by the provision of a remote unit for the DLC system that includes cards for accommodating voice/data transmissions to/from "wired" subscribers, typically already on the DLC system, as well as cards in accordance with the present invention for accommodating voice/data transmissions to/from "wireless"
subscribers, those on the WLL system. The line cords in accordance with the invention comprise a central processing unit (132), an interface unit, (134), at least one modem section (136), a baseband section (140), a signal combining section (138), a signal splitting section (139) and an intermediate frequency section (142).

Description

WIRELESS ACCESS SYSTEM
FIELD OF THE INVENTION
The present invention is directed to digital loop carrier (DLC) systems and in particular to telephone systems where DLC systems are combined with wireless systems, and apparatus for facilitating this combination.
BACKGROUND OF THE INVENTION
Remote access systems are of increasing importance in providing cost effective and efficient telephone services. Specifically, prior to the development of remote access systems, the end user or subscriber of the telephone services could not be more than 3.5 miles (18,000 feet) from the service provider's central office. This was due to the fact that the connections between the central office and the subscriber were direct, copper wire connections, and were limited to this distance due to attenuation. Moreover, these direct connections were, and remain, costly to install and maintain.
One type of remote access system that has gained favor belongs to a class of systems known as digital loop carrier (DLC) systems. These DLC
systems fall under the general category of carrier systems for subscriber loops, that consolidate traffic from hundreds of subscribers onto a small number of physical lines to the central office, while extending the lengths for the necessary connections beyond the previous 3.5 mile (18,000 feet) limitation. DLC systems are designed for placement within a carrier's local loop infrastructure and serve to provide telephone services, including data and video services, over trunks using various media such as fiber optic and copper cables, between the central office and the residential or business end user (subscriber), typically in urban and suburban locations.
Another type of remote access system that has been used for servicing rural subscribers is a class of systems known as wireless local loop (WLL) systems. In these systems, physical lines from central office are connected to a base unit, typically a radio-frequency transmitter/receiver for wireless communication with remote station terminals (RST). These RSTs are connected, typically by wires, cables or the like, to the respective subscribers.
One WLL system employed for this purpose is the StarAccessTM ERC wireless communication system available from ADC/Teledata Communications Ltd. of Herzlia, Israel.
Fig. 1 details a local exchange, employing a DLC system 1 and a WLL
system 2. In the DLC system 1, subscribers 10a, 10b, typically urban and suburban subscribers, connect to a remote unit 12. This remote unit 12 is typically a neighborhood site where the service is transitioned to lines 13a, 13b, typically copper wires or coaxial cables, for delivery to the respective subscribers 10a, 10b. This service transition is commonly referred to as a local loop. The remote unit 12 connects to a central unit (CU) 14 via trunks (trunk lines) 16. The central unit 14 may be located within a central office 20 of the local exchange, where the actual switching is performed.
In the WLL system, subscribers, typically rural subscribers 10r, communicate via their respective remote station terminal (RST) 22, with a base unit 24, typically over radio frequencies (RF). The base unit 24 connects to a central unit 25, analogous to central unit 14 for the DLC but adapted for the WLL, in the central office 20 via trunks 16.
The DLC system 1 is exemplary of DLC systems in general, and as shown in Fig. 2, typically comprises a central unit 14 and a remote unit 12.
The central unit 14 connects to the central office 20 by lines 32, while connections with the remote unit 12 are made by trunks (trunk lines) 16, as detailed above.
Other exemplary DLC systems are models DCS-20, DCS-30, DCS-40, all commercially available from ADC/Teledata Communications Ltd., Herzlia, Israel Turning also to Fig. 3A, there is detailed the remote unit 12 of the DLC
system 1, exemplary of remote units in general. The remote unit 12 includes trunk cards 34 that connect to an allocation unit 36, that in turn connects to line cards 38. The trunk cards 34 interface the remote unit 12 with the trunk 16, and serve to extract relevant information for the remote unit, such as a voice/data telephone connection information that belongs to a subscriber of that particular remote unit 12. The allocation unit 36 allocates the bandwidth for each subscriber of the particular remote unit. The line cards 38, detailed in Fig.

2 below, interface with the allocation unit 36 and transfer the voice/data connection to the subscribers' individual lines, for example, lines 13a and 13b.
The line cards 38, shown in Fig. 3B, typically include physical interfaces 50, that communicate with subscriber lines, such as subscriber lines 13a, 13b, in communication with a routing unit 52. A DLC interface 54 is in communication with the routing unit 52. The DLC interface 54 and routing unit 52 are controlled by a CPU 56.
Conventional systems, employing DLC systems and WLL systems separately connected to the central office (exchange) in its infrastructure exhibit drawbacks. Specifically, with respect to DLC systems alone, these systems require the running of wires/cables to each subscriber, and thus, the costs of installation and maintenance of these lines remain high. Moreover, these costs are particularly high in remote or sparsely populated areas, thus limiting the numbers of subscribers that DLC systems can accommodate.
Additionally, by employing separate DLC and WLL systems, the service provider must install and maintain components for two completely separate systems, including separate trunk lines and hardware, one for the DLC system and one for the WLL system. This results in increased costs. Moreover, conventional DLC systems provide services, such as Synchronous Digital Hierarchy (SDH) and Asymmetric Digital Subscriber Line (ADSL), that are not available on conventional WLL systems, and as such, WLL subscribers can not receive all of the services that subscribers on the DLC system are able to receive.
SUMMARY OF THE INVENTION
The present invention improves on the conventional art, by combining DLC systems with WLL systems, as integrated into local loops, to improve voice/data transmissions. As a result, a service provider need only install and maintain a single system, the DLC system, as the WLL system connects to it, so that the WLL system is supported by the DLC system. Thus the costs of installation and maintenance of a system for servicing urban, suburban and rural subscribers is reduced substantially, as only a single line system, for the

3 combined system, from the central office to the DLC system, is required, thus eliminating the need for separate line systems for each of the DLC and WLL
systems. Additionally, as the WLL system is connected to the DLC system, the WLL system subscribers can receive all of the services available to subscribers of the DLC system, such as connection to SDH rings and connection to ADSL
lines, and thus, eliminating any additional investment in the WLL system to facilitate these additional services. Moreover, the system will have increased range as its WLL system (components thereof) can be placed farther from the central office, than with the presently employed WLL systems, that are directly connected to the central office (exchange).
Embodiments of the present invention are directed an access system and to a line card apparatus, typically in a remote unit of a DLC system, and methods for their use. These embodiments are such that voice/data transmission services can be supplied to subscribers residing on conventional wired lines, as well as wireless tines.
There is disclosed an access system comprising at least one digital loop carrier (DLC) system and at least one wireless local loop (WLL) system with a coupler for placing the at least one DLC system into operative communication with the WLL system.
There is also disclosed a remote unit for a digital loop carrier (DLC) system comprising at least one first card for supporting wired connections to at least one subscriber and at least one second card for supporting wireless connections to at least one other subscriber. The at least one second card is configured for operatively coupling the DLC system with a wireless local loop (WLL) system, along which the at least one other subscriber is located.
Additionally, there is disclosed a line card for supporting a Wireless Local Loop (WLL) system on a Digital Loop Carrier (DLC) system comprising a central processing unit (CPU), an interface unit for buffering transmissions to and from the line card, this interface unit in operative communication with the CPU.
There is at least one modem section in operative communication with the interface unit, this at least one modem section configured for receiving digital data and converting this digital data into at least one digital signal, and for receiving at

4 least one digital signal and converting it to digital data. There is a base band section in operative communication with the at least one modem section, this base band section including at least a digital to analog converter and an analog to digital converter. Also included are a signal combining (summing) section in operative communication with the at least one modem section and the digital to analog converter, and a signal splitting section in operative communication with the at least one modem section and the at least one analog to digital converter.
There is a intermediate frequency (IF) section in operative communication with the base band section, this intermediate frequency section configured for modulating the at least one analog signal onto a carrier signal and demodulating at least one signal from a carrier signal. The card is arranged such that the CPU
controls operations of the at least one modem section, the base band section and the intermediate frequency section.
It is preferred that there be a plurality of modem sections, preferably twelve, with each modem section typically including a modem, a digital signal processor (DSP) and at least one memory unit operably coupled thereto, with the modem in operative communication with the digital signal processor.
There are also disclosed methods for transmitting voice/data to a WLL
system subscriber over a DLC system and from this WLL system subscriber to the DLC system and thereover. This method includes providing a digital loop carrier (DLC) system, providing a wireless local loop (WLL) system, coupling the DLC and WLL systems, and converting digital data from the DLC system into at least one analog signal adapted for transmission over said WLL system. When voice/data is transmitted from the WLL subscriber to the DLC system and thereover (the reverse of the aforementioned transmission), at least one carrier signal from the WLL system, that includes the subscriber transmission, is converted into digital data for transmission over the DLC system.
BRIEF DESCRIPTION OF THE DRAWINGS
Attention is now directed to the attached drawings, wherein like reference numeral or characters indicate corresponding or like components. In the drawings:

5 Fig. 1 is a diagram of a conventional telephony system that utilizes separate DLC and WLL systems;
Fig. 2 is a diagram of a conventional DLC system in a conventional telephony system;
Fig. 3A is a diagram of a remote unit of the conventional telephony system of Fig. 2;
Fig. 3B is a diagram of a line card used with the remote unit of Fig. 3A;
Fig. 4 is a diagram of a telephony system of an embodiment of the present invention;
Fig, 5A is a diagram of a remote unit of one embodiment of the present invention;
Fig. 5B is diagram of a portion of the remote unit of Fig. 5A;
Fig. 6 is a line card of one embodiment of the present invention; and Fig. 7 is a diagram of a telephony system of an alternate embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Fig. 4, details the system 100 of the present invention where a DLC
system connects to a WLL system (forming a portion of the system 100), via a remote unit 102, in accordance with the present invention. Subscribers 103a (here urban but could also be suburban), receive service over the DLC system, as they are directly connected thereto by physical lines 104, while other subscribers 103b-103d, in urban 103b, suburban 103c and rural 103d, locations, receive service by wireless communications (arrows 105) over the WLL portion of the system 100. In this system 100, connections are such that all of the components are arranged to define both transmitting (Tx) and receiving (Rx) paths for data.
The DLC system is formed by the central unit (CU) 14, internal or external to the central office 20 or exchange (connected by lines if the central unit 14 is external to the central office 20), that in turn, connects to the remote unit 102 via trunks) 109. The trunks) 109 could be wired or wireless, and if wireless could be a satellite system or the like.

6 The WLL portion of the system 100 is formed of at least one base unit 110, for example, a base radio frequency (BRF) unit, and remote station terminals (RSTs) 112. The RSTs 112 connect to the respective subscribers 103b-103d by conventional lines. The WLL portion of the system 100 connects to the DLC system at the remote unit 102 via a line card 126 (the remote unit 102 and line card 126 are shown in detail in Figs. 5A, 5B and 6 and described below). The base unit 110 is preferably a radio frequency (RF) unit, that transmits and receives signals, preferably RF signals, although other transceiving units are also permissible. The base unit 110, is in communication with the remote unit 102 via conventional line connections (detailed below).
In one embodiment of the WLL portion, the components for the wireless transmitting and receiving, including the RSTs, are provided by components from the StarAccessTM ERC system, commercially available from ADC/Teledata Communications Ltd. of Herzlia, Israel. In other embodiments, CDMA, TDMA, analog CMA or other wireless technology are used.
The system 100 forms a transmitting (Tx) path as the data is received at the central office 20 and is sent to the central unit 14. The central office includes a switch in communication with the central unit 14, that multiplexes the transmission (signal) on the trunks) 109, preferably a digital line(s), to the remote unit 102. This digital data is then modulated on analog signals for transmission to the base RF units 110 and to directly connected subscribers 103a. From the base RF unit(s) 110, RF transmissions are received by the respective RSTs 112 (these RSTs configured with hardware and software for accommodating RF transmissions) and passed to the corresponding subscribers 103b-103d.
In a receiving (Rx) path for the system 100, directly connected subscribers 103a, transmit their calls (voice/data) to the remote unit 102 over physical lines 104. Subscribers 103b-103d along the WLL portion employ the RF transmitter or the like, for sending their calls to the base RF unit 110, with the call then sent to the remote unit 102. In the remote unit 102, the modulated analog signal is converted into a digital signal and sent over trunks) 109 to the

7

8 PCT/IB00/02042 central unit 14 and past the switch in the central office 20 and outward in accordance with conventional telephony.
Fig. 5A shows the internal logical connectivity between components in the remote unit 102 of the present invention. The remote unit 102 includes trunk cards 120 (for example, Part No. 712-y1803B from ADC/Teledata Communications Ltd., Herzlia, Israel), that connect to an allocation unit 122, that in turn connects to line cards 124a, 124b and a WLL line card 126, the WLL
line card 126 in accordance with an embodiment of the present invention. Line cards 124a, 124b are adapted for physical wired links, and for example, can be Part No. 712-419100 from ADC/Teledata Communications Ltd., Herzlia, Israel, while the WLL line card 126 is adapted for wireless links. While two trunk cards 120, two "wired" line cards 124a, 124b and one WLL or "wireless" line card 126 are shown, this is exemplary only as any number of these trunk and line cards can be used, provided there is at least one "wireless" line card, in accordance with the desired embodiment of the present invention.
In Fig. 5B, there are detailed physical connections in the remote unit 102 that form the DLC bus 127 of allocation unit 122 and line cards 124a, 124b and 126 (as shown enclosed by the broken lines in Fig. 5A, for illustration purposes only). Data from and to the allocation unit 122 travels to and from the line cards 124a, 124b, 126 over a series of Point-To-Point connections (PTPs) 128a, 128b and buses 129a, 129b.
Each PTP 128a, 128b is a special path between the allocation unit 122 and each line card. Each PTP 128a, 128b has N or greater than N connections with the allocation unit 122, N corresponding to the total number of line cards in the remote unit 102. Each specific connection of the N connections then extends from the respective PTP 128a, 128b, to the respective line card. While line cards shown here are line cards 124a, 124b, 126, this is exemplary only, as the system is suited for N number of "wired" 124a, 124b and "wireless" 126 line cards. Typically, one PTP, such as PTP 128a is CELL oriented while the other PTP 128b would be TDM oriented. Moreover, in a system typical to that shown in this embodiment, PTP 128a may be approximately 155M, while PTP 128b may be approximately 8MBPs on each PTP Branch.

The busses 129a, 129b typically employ single connections to the allocation unit 122 and N line cards, here, for example, line cards 124a, 124b, 126. Typically, one bus 129a is SDH oriented and can, for example, be approximately 155-622M, while the other bus 129b would be TDM oriented, and can, for example, be approximately 266M.
In this remote unit 102, connections are such that the components are arranged to define both transmitting (Tx) and receiving (Rx) paths for data.
In the transmitting path, digital data, typically a digital signal, from the respective trunk 109 (Fig. 4) is received by a corresponding trunk card 120, and passed to the allocation unit 122, where the data signal is directed and routed to the proper line card 124a, 124b, 126 over the internal DLC bus 127. Should the data be directed to a conventionally connected subscribers, such as the DLC system subscribers 103a (Fig. 4), the digital data is sent to, for example, line cards 124a, 124b. Should the data be allocated to a WLL subscriber 103b-103d (Fig.
4), WLL line card 126 is employed. Here, the digital signal/data is converted to an analog signal/data for transmission to the base RF unit 110 (Fig. 4), this base RF unit 110 including a converter for converting the received signal into an RF
signal(s), for transmission to the WLL subscribers 103b-103d as detailed above.
In the receiving path (Rx), analog signals from the subscribers 103a and base RF (BRF) unit 110 enter the line cards 124a, 124b, 126, where they are converted to digital data. This digital data is then passed through the allocation unit 122, where it is directed, and then through the respective trunk cards 120, to the respective trunks 109, for transmission to the central unit 14 (Fig. 4).
Fig. 6 details the WLL ("wireless") line card 126 of an embodiment of the present invention. Although only a single WLL line card is shown, this is exemplary only, as multiple WLL line cards may be used with the present invention. The components of the WLL line card are arranged so as to provide both transmitting (Tx) and receiving (Rx) paths.
Card 126 is capable of handling several subscribers, with some subscribers able to be served simultaneously, whereby each card preferably includes multiple modems. The combined information of all subscribers in the card 126 is transmitted, preferably via radio frequency, to the subscribers.
The

9 card 126 serves to transform DLC traffic into a radio frequency (RF) data stream that is sent from the base unit 110. The line card 126 includes a CPU 132 in communication with a DLC Interface 134, single or plural, modem sections) 136, of which there are preferably twelve, logic sections 138 (Tx section), (Rx section), employing technologies such as FPGA or ASIC, a base band section (BB) 140, and an Intermediate Frequency (IF) section 142.
The DLC interface 134 connects to the DLC bus 127 and serves as a buffer between the DLC bus 127 and the modem sections) 136. The CPU 132 interacts with DLC interface 134 by providing it with allocation information, for example, information as to destination, source, rate, signaling, etc., for the entering data/transmission. Moreover, the DLC interface 134 signals one of the preferred twelve modem sections 136, that a transmission is entering.
Each modem section 136 preferably modulates the information of each radio channel on a carrier frequency and vice versa. Each radio channel can be for single or multiple subscribers. Each modem section 136 includes a modem 150, in communication with a digital signal processor (DSP) 152, preferably coupled with a memory unit 154. The DSP 152 processes data associated with data received over the DLC bus 127, controlled by commands received from the CPU 132, and creates a digital representation of an analog signal, that comes from the DLC bus 127, preferably with error correction signals. This digital representation of an analog signal is a digital signal formed of analog samples of digital signals) coming from the DLC bus 127, filtered and corrected for phase errors (this filtering and correcting performed in the respective modem section 136).
This digital signal is sent to the modem 150. Each modem section 136 is available as a single unit and for example can be Teledata Part No. 712-71101 D, from ADC/Teledata Communications Ltd., Herzlia, Israel.
The Tx section 138 processes the digital signals) by algorithms, such as Fast Fourier Transforms (FFT) with filtering or weighting, in order to combine (sum) the digital signals as received from each modem section 136 and produce a combined (summed) digital signal. This Tx section 138 is adapted for functioning along the transmitting (Tx) path for the WLL line card 126. This Tx section is available as Teledata Part No. 752-71200B, from ADC/Teledata Communications Ltd. Herzlia Israel.
The Rx section 139 is adapted for functioning along the receiving path for the WLL line card. This Rx section 139 employs Inverse Fast Fourier Transforms (IFFT) with filtering or weighting, in order to analyze the signal from the base band section 140 and split the signal to each modem 150 (of the preferred 12 modems). This Rx section is available as Teledata Part No. 752-710000, from ADC/Teledata Communications Ltd., Herzlia, Israel.
The base band section (BB) 140, includes signal converters. This section includes a digital to analog converter and filter 156, in communication with the Tx section 138, and an analog to digital converter and filter 157 in communication with the Rx section 139, for converting the signals received in this section 140 accordingly.
The IF section 142 includes a modulator as well as a demodulator. When in the transmitting (Tx) path, the modulator functions such that the analog signal, as received from the base band unit 140 is modulated on a carrier signal and sent to a base unit 106, typically by coaxial cable or other conventional carrier.
When in the receiving (Rx) path, the demodulator functions to extract the analog signal from the coaxial cable or other conventional carrier and send it to the base band section 140.
In the transmitting (Tx) path, the DLC interface 134 receives the transmission, typically a digital signal(s), from the DLC bus 127. The signals) is then taken according to the allocation information from the CPU 132 and coupled to the respective modem 150 (in the respective modem section 136). In the respective modem section 136, the signal moves from the modem 150 to a DSP 152, where it is processed, in accordance with the allocation information provided from the CPU 132. This digital signal is then passed through the respective modem 150 to the Tx section 138, where it is processed by algorithms such that it is combined (summed) with other similar digital signals as received from the other modem sections (as processed in a manner identical to that described above).

The signal is now sent to the base band section 140, where it is converted to an analog signal by being passed through the digital to analog converter and filter 156 of this section 140. The analog signal is sent to the IF
section 142, where it is modulated onto a carrier signal and sent to the base unit 110, typically by coaxial cable of other conventional carrier.
In the receiving (Rx) path, the analog signal is demodulated from the signal received from the base unit 110, in the IF section 142. The analog signal is then sent to the base band section 140, where it is converted into a digital signal upon its being passed through an analog to digital converter and filter in the base band section 140. The digital signal is sent to the Rx section 139, where it is analyzed (split) to extract modem signals, preferably twelve modem signals corresponding to the preferred twelve modems, with each extracted signal sent to the respective selected modem section 136. In each modem section 136, the digital signal is converted to DLC bus digital data. The modem 150 then sends this data to the DLC interface 134, where it enters the DLC bus 127, for transmission to the central office 20 (Fig. 4).
Turning now to Fig. 7, there is a second system 200 in accordance with the present invention. This system includes a modified DLC with wireless local loop capabilities. This system enables the service provider to enlarge coverage of the system to sites where conventional lines can not be deployed or would be cost prohibitive.
In this system 200, the central unit (CU) 14, in communication with the central office 20 (exchange) (via lines 32), connects to a remote unit 202, in accordance with the remote unit 102 above, in a manner where all exchange traffic is multiplexed into a high speed physical trunk. Here, the trunk is a synchronous digital hierarchy (SDH) protected ring 208.
The remote unit 202 extracts the relevant telephony information form the SDH ring 208 and directs it to a local subscriber line 213, to a directly connected subscriber 213a, by a conventional line card, as detailed above, or over conventional lines or the like. While only a single remote unit 202 is shown, multiple remote units along the SDH ring 208 are also permissible. The remote unit 202 also employs WLL line cards of the present invention (not shown in this figure but shown as line card 126 above and described above), that connect via lines 214 (as detailed above) to a base RF (BRF) Units 218a-218c, similar to the BRF unit 110 detailed above.
The base units 218a-218c communicate with the remote station terminals (RSTs) 220a, 220b, 221 a, 221 b, 221 c (in accordance with those detailed above), by wireless links (arrows 224) and form the WLL portion of the system 200. These RSTs 220a-220b and 221 a-221 c connect to subscribers, both voice 226 and data 228, by conventional connections, typically wired, as detailed above. With respect to base RF units 218b and 218c, base unit 218c is preferably an alternate RF unit for wireless transmissions to the remote station terminals 221 a-221 c.
The SDH ring 208 is controllable by a computer 240, and can be interfaced with an ATM network 242 or the like. It is preferred that the computer 240 and ATM network interface at the central unit 14.
While preferred embodiments of the present invention have been described, so as to enable one of skill in the art to practice the present invention, the preceding description is intended to be exemplary only. It should not be used to limit the scope of the invention, which should be determined by reference to the following claims.

Claims

What is claimed is:

1. A line card for supporting a Wireless Local Loop (WLL) system on a Digital Loop Carrier (DLC) system comprising:
a central processing unit (CPU);
an interface unit for buffering transmissions to and from said line card, said interface unit in operative communication with said CPU;
at least one modem section in operative communication with said interface unit, said at least one modem section configured for receiving digital data and converting said digital data into at least one digital signal, and for receiving at least one digital signal and converting it to digital data;
a base band section in operative communication with said at least one modem section, said base band section including a digital to analog converter and an analog to digital converter;
a signal combining section in operative communication with said at least one modem section and said digital to analog converter;
a signal splitting section in operative communication with said at least one modem section and said at least one analog to digital converter;
an intermediate frequency section in operative communication with said base band section, said intermediate frequency section configured for modulating said at least one analog signal onto a carrier signal and demodulating at least one signal from a carrier signal; and wherein said CPU controls operations of said at least one modem section, said base band section and said intermediate frequency section.

2. The line card of claim 1, wherein said at least one modem section includes a plurality of modem sections.

3. The line card of claim 2, wherein each modem section comprises:
a modem;
a digital signal processor and at least one memory unit operably coupled thereto; and said modem in operative communication with said digital signal processor.

4. The line card of claim 1, wherein said at least one digital to analog converter additionally comprises at least one filter.

5. The line card of claim 1, wherein said at least one analog to digital converter additionally comprises at least one filter.

6. An access system comprising:
at least one digital loop carrier (DLC) system;
at least one wireless local loop (WLL) system; and a coupler for placing said at least one WLL system onto said DLC system, such that said WLL system is supported by said DLC system.

7. The access system of claim 6, wherein said coupler includes a remote unit having at least one card configured for:
converting digital data from said DLC system into at least one analog signal and modulating said at least one analog signal onto a carrier signal for transmission over the WLL system; and demodulating at least one analog signal from a carrier signal from said WLL system and converting said demodulated signal into digital data, for transmission through the DLC system.

8. The access system of claim 7, wherein said card comprises:
a central processing unit (CPU);
an interface unit for buffering transmissions to and from said line card, said interface unit in operative communication with said CPU;
at least one modem section in operative communication with said interface unit, said at least one modem section configured for receiving digital data and converting said digital data into at least one digital signal, and for receiving at least one digital signal and converting it to digital data;

a base band section in operative communication with said at least one modem section, said base band section including a digital to analog converter and an analog to digital converter;
a signal combining section in operative communication with said at least one modem section and said digital to analog converter;
a signal splitting section in operative communication with said at least one modem section and said at least one analog to digital converter;
an intermediate frequency section in operative communication with said base band section, said intermediate frequency section configured for modulating said at least one analog signal onto a carrier signal and demodulating at least one signal from a carrier signal; and wherein said CPU controls operations of said at least one modem section, said base band section and said intermediate frequency section.

9. The access system of claim 8, wherein said at least one modem section includes a plurality of modem sections.

10. The access system of claim 9, wherein each modem section comprises:
a modem;
a digital signal processor and at least one memory unit operably coupled thereto; and said modem in operative communication with said digital signal processor.

11. The access system of claim 8, wherein said at least one digital to analog converter additionally comprises at least one filter.

12. The access system of claim 8, wherein said at least one analog to digital converter additionally comprises at least one filter.

13. A remote unit for a digital loop carrier (DLC) system comprising:

at least one first card for supporting wired connections to at least one subscriber; and at least one second card for supporting wireless connections to at least one other subscriber.

14. The remote unit of claim 13, wherein said at least one second card is configured for operatively coupling said DLC system with a wireless local loop (WLL) system.

15. The remote unit of claim 14, wherein said second card comprises:
a central processing unit (CPU);
an interface unit for receiving transmissions external to said line card, said interface unit in operative communication with said CPU;
at least one modem section in operative communication with said interface unit, said at least one modem section configured for receiving digital data and converting said digital data into at least one digital signal;
a base band section in operative communication with said at least one modem section, said base band section adapted to convert said at least one digital signal into at least one analog signal;
an intermediate frequency section in operative communication with said base band section, said intermediate frequency section configured for modulating said at least one analog signal onto a carrier signal; and wherein said CPU controls operations of said at least one modem section, said base band section and said intermediate frequency section.

16. The remote unit of claim 15, wherein said at least one modem section includes a plurality of modem sections.

17. The remote unit of claim 16, wherein each modem section comprises:
a modem;
a digital signal processor and at least one memory unit operably coupled thereto; and said modem in operative communication with said digital signal processor.

18. An apparatus for coupling a digital loop carrier (DLC) system with a wireless local loop (WLL) system comprising:

first means for receiving digital data from said DLC and converting said digital data into at least one signal adapted for transmission over said WLL;
and second means for receiving at least one signal from said WLL and converting said at least one signal into digital data for transmission over said DLC system.

19. The apparatus of claim 18, wherein said first means additionally comprises:
means for converting said digital data into at least one analog signal and modulating said at least one analog signal onto a carrier signal for transmission via a base unit of said WLL system.

20. The apparatus of claim 19, wherein said base unit includes means for receiving said modulated analog signal and converting said modulated analog signal into a signal at a radio frequency.

21. The apparatus of claim 19, wherein said second means additionally comprises:
means for demodulating a carrier signal from said WLL system and obtaining at least one analog signal therefrom and means for converting said at least one analog signal into digital data for transmission over said DLC
system.