WO1999009685A2

WO1999009685A2 - Wireless telecommunications system

Info

Publication number: WO1999009685A2
Application number: PCT/IL1998/000385
Authority: WO
Inventors: Doron Koren; Sergey Toujikov; Lior Nabat
Original assignee: Telescicom Ltd.
Priority date: 1997-08-14
Filing date: 1998-08-13
Publication date: 1999-02-25
Also published as: AU8746498A; IL121548A0; WO1999009685A3

Abstract

A wireless access system including a plurality of user stations, and at least one base station (50) coupled by RF transceiving apparatus to each of the user stations, the base station including a commutator (20) for switching between a plurality of inputs/outputs at one side and at least one output/input at the other side, and including a Medium Access Controller (base MAC) (18), at least one User WAN/LAN interface (52), and an interface converter (56) coupled between each User WAN/LAN interface and the commutator. Preferably, the commutator includes a base MAC including a MAC register and MAC logic, a spooling and transmit state machine (30), and a transmitter buffer (32), the spooling and transmit state machine and the transmitter buffer being coupled to an RF module (34).

Description

WIRELESS TELECOMMUNICATIONS SYSTEM FIELD OF THE INVENTION

The present invention relates to wireless access systems in general and, in particular, to wireless access systems and wireless local loop systems having substantially increased data rates.

BACKGROUND OF THE INVENTION

A number of communication systems are known in the art. The earliest systems were wired systems, such as the Plain Old Telephone System (POTS) , wherein data are transferred over copper wires from a central switching office to the homes of individual users . Such systems typically are capable of transferring 33 KBit/sec over a 4 Khz bandwidth. An alternative system is the so-called wireless local loop, wherein data are transmitted by a wireless transmitter from a central switching office and received by a receiver at the home of the user. These systems provide good speech quality comparable to the POTS system, with the increased flexibility and lower cost of being wireless. These systems typically are capable of transferring 33Kbit/sec over a conventional telephone channel, similar to the wired systems.

Recent innovations in wired communication technology have led to tremendous increases in the rate of transfer of information over these systems. First came the ISDN, a digital line to the user, which transfers data over multiple channels at a rate of 64 KBit/sec. Then, high speed internet and other Digital Subscriber Lines were developed, which are capable of transferring 2Mbit/sec to the house of a subscriber, over copper wires. However, these systems are all limited by the fact that the data must travel over wires. An additional limitation of these systems is that transmission and reception are symmetrical. In other words, even if there is no data to transmit, the time slot and code are reserved for an uplink or downlink communication, and empty bits (null bits) are transmitted in both directions.

Other wireless access systems are also known in the art. These systems are also limited in their performance capabilities.

Accordingly, it would be very desirable to have a wireless access system which is capable of transmitting data at a significantly faster rate than conventional wireless systems, so as to compete effectively with wired systems, and to benefit from the advantages of a wireless system.

There are also known in the art computer networks wherein a plurality of computers are coupled to one another for transmission of data. These local area networks (LAN) generally include a HUB to which each computer is connected such that any computer can send or receive data from any other computer through the HUB.

When it is desired to provide selective transmission and access to data information from a computer on one LAN network to a computer on another LAN network, a pair of interface converters is provided coupled between the networks. The interface converter adds identification data to each packet of data being transferred which indicates both the source address and the destination address. In this way, the bridge directs each data packet to the proper destination.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a base station for use in a wireless access system, the base station including a commutator including a base MAC (medium access control) , at least one User WAN/LAN interface, and an interface converter coupled between each User WAN/LAN interface and the commutator.

There is also provided in accordance with the present invention a wireless access system including a plurality of user stations, and at least one base station coupled by RF transceiving apparatus to each of the user stations, the base station including a commutator including a base MAC (medium access control) , at least one User WAN/LAN interface, and an interface converter coupled between each User WAN/LAN interface and the commutator.

According to a preferred embodiment of the invention each user station includes a User WAN/LAN interface, a user MAC, a interface converter coupling the user MAC to the User WAN/LAN interface and to the base MAC, a radio transmitter, a radio receiver, and a data filter coupled between the receiver and the interface converter.

There is further provided in accordance with the present invention a method for wireless downlink communication over a wireless access system including at least one base station and a plurality of user stations, the method including the steps of sequentially looking at each of a plurality of interface converters in the base station to see whether they are empty; if an interface converter is not empty, sending a signal to a commutator in the base station requesting allocation of resources; indicating to the interface converter when resources have been allocated; transferring a data packet from the interface converter to a transmitter buffer in the base station; when transmitting resources are available, transmitting a data packet from the transmitter buffer to receivers in the user stations. There is still further provided in accordance with the present invention a method for wireless uplink communication over a wireless access system including at least one base station and a plurality of user stations, the method including the steps of providing a signal from a user MAC in a user station to a commutator in the base station indicating that an interface converter in the user station is not empty and requesting allocation of resources; allocating resources by the commutator; indicating to the interface converter when resources have been allocated; transferring a data packet from the interface converter to a receiver in the base station .

There is also provided in accordance with the invention an add-on system for permitting data transmission in a wireless access system including a plurality of user stations each having a radio receiver and a radio transmitter, the add-on system including: a base station including: a commutator including a Medium Access Control (base MAC) ; at least one User WAN/LAN interface; and an interface converter coupled between each User WAN/LAN interface and the commutator; and a user station addition including: a User WAN/LAN interface; a user MAC; a interface converter coupling the user MAC to the User WAN/LAN interface and to the commutator in the base station; a data filter coupled between the radio receiver and the interface converter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which: Fig. 1 is a schematic illustration of a wireless access system constructed and operative in accordance with one embodiment of the present invention for downlink communication;

Fig. 2 is a schematic electric circuit diagram of a commutator for the system of Fig. 1;

Fig. 3 is a schematic illustration of a wireless local loop system constructed and operative in accordance with one embodiment of the present invention for downlink communication; Fig. 4 is a flow chart of the operation of the commutator of the invention for a downlink communication; and

Fig. 5 is a flow chart of the operation of the commutator of the invention for an uplink communication.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to wireless access systems, for example, wireless local loop (WLL) systems, having a significantly increased data rate. In particular, it relates to an add-on system for conventional WLL telephony systems and other access systems. The system is based on inserting a data base station into a wireless access system, thereby permitting data transfer, as well as telephony transmission. The system provides data traffic flow according to the available data load, without transmitting empty bits. This is accomplished by adding a commutator and a plurality of interface converters between each base station and its plurality of user stations. According to one embodiment, for example, the end user station is coupled to a device which acts like a conventional local area network (LAN) as far as its interactions with the user station are concerned, but which serves as a part of the wireless access system as far as data transmission and reception is concerned. When a data packet is to be sent, an interface converter sends a signal to the commutator that it has a data frame to send. The commutator determines when the transmission resources are available, and then transfers the data frame from the interface converter of the source to the interface converter of the destination.

Referring now to Fig. 1, there is shown a schematic illustration of a wireless access system constructed and operative in accordance with one embodiment of the present invention. The system includes a wireless access base station 50 including at least one User WAN/LAN interface 52 for receiving communications from a communication system 54. A interface converter 56 is coupled to each User WAN/LAN interface 52 for interfacing between the communication system 54 and a plurality of users. User WAN/LAN interface 52 can be any conventional User WAN/LAN interface, for physically coupling a communication system to the wireless access system. Interface converters 56 can be any conventional interface converters, which can convert the data from the communication system to a form which can be understood by the wireless system.

A commutator 20, including a Medium Access Control (MAC) 18, is provided to control the data flow throughout the base station and to allocate resources. Commutator 20 is a device including a number of inputs/outputs at one side, and at least one output/input at the other side. In other words, the commutator is bi-directional, depending on the direction of data flow. For example, when data is sent from the base station to a user station, the commutator includes many inputs and at least one output. However, if data is flowing from a user station to the base station, the commutator functions with at least one input and a plurality of outputs. The commutator 20 provides switching between the inputs and outputs according to a predefined switching pattern, which can be set by the base MAC, a user defined pattern, or any other conventional switching pattern. For example, the commutator can poll the inputs, one after another. Alternatively, it can perform statistical polling according to statistics input to the base MAC, or the commutator can operate according to any other pre-selected switching pattern. Commutator 20 is coupled to interface converters 56, a transmitter 22, and a receiver 24. With reference to Fig. 2, there is shown a schematic electronic circuit of the commutator 20. Commutator 20 is coupled to interface converters 56 by an address and data bus 26 and a control bus 28. Commutator 20 includes a spooling and transmit state machine 30 and a transmitter buffer 32, which are both coupled to control an RF module 34. Spooling and transmit state machine 30 determines which interface converters 56 have a data packet to transmit and which have no data packet. It sends signals to each User WAN/LAN interface which has a data packet, in turn, to transmit its data packet to commutator 20. The data packet is stored in a transmitter buffer 32, generally FIFO, until a signal is received from RF module 34 that transmission resources are available. The wireless access system further includes a plurality of user stations belonging to individual users. Each user station includes a User WAN/LAN interface 36 coupled to a user MAC 37 and to a interface converter 38 which, in turn, is coupled to a transmitter 44 and, through a data filter 40, to a receiver 42.

One system for which the invention is particularly suited is a wireless local loop (WLL) system. It will be appreciated, however, that the invention is not limited to a WLL system, but rather can be effectively utilized in any wireless access system. With reference to Fig. 3, there is shown a schematic illustration of a wireless local loop system constructed and operative in accordance with one embodiment of the present invention. The system includes a wireless local loop data base station 10 including a HUB 12, or any other device with an interface to Ethernet, such as a Router, LAN switch, Switched HUB, bridge, etc., for receiving communications from a communications system 14. A plurality of remote bridges 16 are coupled to HUB 12 for interfacing between the communication system 14 and a plurality of users. HUB 12 can be any conventional HUB, such as the Unmanaged HUB Model DFE- 812TX+, manufactured by D-Link Corporation, CA, USA. Remote bridges 16 can be any conventional remote bridges, such as Remote Bridge Model Dl-1140, of D-Link Corporation. A commutator 20' , including a Medium Access Control (MAC) 18', is provided to control the data flow throughout the base station and to allocate resources, substantially as described above. Commutator 20' is coupled to remote bridges 16, a transmitter 22', and a receiver 24'. The WLL system further includes a plurality of user stations belonging to individual users, substantially as described above.

Operation of this system for a downlink communication is as follows. A data packet to be transmitted to the User WAN/LAN interface 36' of a first user station is received at User WAN/LAN interface 52 in the base station from the communication system 54. User WAN/LAN interface 52 passes the data packet to an interface converter 56' associated with first User WAN/LAN interface 36' , together with packet identification data including source and destination of the packet. User WAN/LAN interface 36' sends a signal to commutator 20 that it has a data frame to send to the first user station. When the data transmission resources are available, commutator 20 transfers the data packet from User WAN/LAN interface 36' to transmitter 22 for transmission, as described above with reference to Fig. 2. It will be appreciated that each of User WAN/LAN interfaces 36 has a FIFO memory and can store data frames until they can be sent to commutator 20.

A flow chart of the operation of the commutator in a downlink communication from the base station to a user station is set forth in Fig. 4. Commutator 20 starts with the first interface converter (RBi) and looks to see if it is empty. If yes, the commutator looks at the second interface converter (RB₂) to see if it is empty. If yes, it continues to look at each interface converter, in turn, until it looks at the last interface converter (RB_n) , at which point it starts again at RBi.

If a interface converter is not empty, and if downlink resources are available, the commutator sends a signal to the interface converter to transfer its data packet to the transmitter buffer. The commutator then continues to the next interface converter. When it finds another interface converter which is not empty, it sends a signal to the interface converter to transfer its data packet to the transmitter buffer. In this way, only interface converters which are not empty are allocated resources, thereby substantially reducing the quantity of null bits transmitted. The data packet in the transmitter buffer is transmitted when downlink resources are available, in accordance with a transmit signal received from RF card 70. As in conventional wireless access systems, specific resources are allocated in advance for downlink communication.

The transmitted signals are received at the user stations by receiver 42 through data filter 40, which filters out those signals which are not addressed to User WAN/LAN interface 36' , and transmits those signals which are addressed to User WAN/LAN interface 36' via interface converter receiver 38' to User WAN/LAN interface 36' . It will be appreciated that each user 36 sees an increased data rate, since few empty bits are transmitted between the base station and user stations.

Operation of the system for uplink communication is as follows. When a User WAN/LAN interface 36' wishes to send a message to the base station, it passes the data packet to interface converter 38' together with packet identification data. Interface converter 38' indicates to user MAC 37' that its buffer is not empty. User MAC 37' asks base MAC 18 for allocation of resources. When receiver 24 is available, commutator 20 indicates, in turn, to each interface converter 38 which has a data packet to transmit, to transmit its data packet. The data packet is transferred from interface converter 38 to receiver 24, and the data packet is stored in transmitter buffer 32 of commutator 20. According to the destination address on each data packet, the commutator transmits the data packet to the appropriate interface converter.

A flow chart of the operation of commutator 20 in an uplink communication from a user station to the base station is set forth in Fig. 5. The user MAC in a first user station looks to see if its interface converter URBi is empty. If yes, the first user MAC waits a predetermined delay time, and looks again. When URBi indicates that it is not empty, the user MAC of the first user signals the commutator in the base station that it requests resource allocation. If uplink resources are available, commutator 20 sends a signal to URBi to transmit its data packet. As in conventional wireless access systems, specific resources are allocated in advance for uplink communication. In this manner, commutator 20 signals, in turn, to each URB which is not empty to transmit its data packet to the base station. Thus, only interface converters which are not empty are allocated resources, thereby substantially reducing the quantity of null bits transmitted. The transmitted signals are received at the commutator which divides the transmitted signals according to their destinations, and transfers each transmission to the appropriate interface converter. It is a particular feature of the present invention in both uplink and downlink communications that, when commutator 20 allocates resources, an empty interface converter will not be allocated any resources. In other words, commutator 20 will skip over the empty interface converter until it is no longer empty. In this way, transmissions of empty data frames are substantially reduced.

It is a further particular feature of the present invention that it can be implemented as an add-on system which can be added to a conventional wireless access system to add data transmission capability at a relatively high data rate and communication efficiency. The add-on system consists of two parts, an additional base station including at least one User WAN/LAN interface, an interface converter coupled to each User WAN/LAN interface, and a commutator, and an addition to each user system including a interface converter, a user MAC, and a data filter.

It will be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims which follow.

Claims

1. A wireless access system including a plurality of user stations, and at least one base station coupled by RF transceiving apparatus to each of the user stations, the base station comprising: a commutator for switching between a plurality of inputs/outputs at one side and at least one output/input at the other side, and including a Medium Access Control (base MAC) ; at least one User WAN/LAN interface; and an interface converter coupled between each said User WAN/LAN interface and said commutator.

2. The system according to claim 1, wherein each said user station comprises: a User WAN/LAN interface; a user MAC; a interface converter coupling said user MAC to said User WAN/LAN interface and to said commutator; a user radio transmitter; a user radio receiver; and a data filter coupled between said receiver and said interface converter.

3. The system of claim 1 or 2, wherein said base station further includes a base radio transmitter and a base radio receiver .

4. For use in a wireless local loop system, a base station comprising: a commutator for switching between a plurality of inputs/outputs at one side and at least one output/input at the other side, and including a medium access control (base MAC) ; at least one User WAN/LAN interface; and an interface converter coupled between each said User WAN/LAN interface and said commutator.

5. The base station of claim 4, wherein said base station further includes a radio transmitter and a radio receiver.

6. The base station of any of claims 4-5, wherein said commutator includes: a base MAC including: a MAC register; and MAC logic; a spooling and transmit state machine; and a transmitter buffer; said spooling and transmit state machine and said transmitter buffer being coupled to an RF module.

7. A method for wireless downlink communication over a wireless access system including at least one base station and a plurality of user stations, the method comprising the steps of: a) sequentially looking at each of a plurality of interface converters in the base station to see whether they are empty; b) if an interface converter is not empty, sending a signal to a commutator in the base station requesting allocation of resources; d) indicating to said interface converter when resources have been allocated; e) transferring a data packet from said interface converter to a transmitter buffer in the base station; f) when transmitting resources are available, transmitting a data packet from said transmitter buffer to receivers in the user stations.

8. The method of claim 7, wherein said step of sequentially looking at each of a plurality of interface converters includes : a) looking at a first interface converter to see whether it is empty; b) if it is empty, looking at the next interface converter; c) if it is not empty, sending a signal to a commutator in the base station requesting allocation of resources; d) after transfer of a data packet from said first interface converter, looking at said second interface converter to see whether it is empty; e) if it is empty, looking at the next interface converter; f) if it is not empty, sending a signal to a commutator in the base station requesting allocation of resources; g) after transfer of a data packet from said second interface converter, continuing said steps of looking through said steps of transferring sequentially through all of said interface converters.

9. The method of claim 7 or 8, further comprising the steps of: receiving said data packet in each user station; filtering address and destination information in said data packet in each user station to determine to which user station it is addressed; transferring said data packet to a User WAN/LAN interface in the appropriate user station while rejecting the data packet in all the other user stations.

10. A method for wireless uplink communication over a wireless access system including at least one base station and a plurality of user stations, the method including the steps of: a) providing a signal from a user MAC in a user station to a commutator in the base station indicating that an interface converter in said user station is not empty and requesting allocation of resources; b) allocating resources by said commutator; c) indicating to said interface converter when resources have been allocated; d) transferring a data packet from said interface converter to a receiver in the base station.

11. The method of claim 10, further comprising: receiving said data packet in the base station; filtering address and destination information in said data packet in the base station to determine to which interface converter coupled to the base station it is addressed; and transferring said data packet to the appropriate interface converter.

12. An add-on system for permitting data transmission in a wireless access system including a plurality of user stations each having a radio receiver and a radio transmitter, the add-on system comprising: a) a base station including: a commutator for switching between a plurality of inputs/outputs at one side and at least one output/input at the other side, and including a Medium Access Controller (base MAC) ; at least one User WAN/LAN interface; and an interface converter coupled between each said User WAN/LAN interface and said commutator; and b) a user station addition including: a User WAN/LAN interface; a user MAC; a interface converter coupling said user MAC to said User WAN/LAN interface and to said commutator; a data filter coupled between the radio receiver and said interface converter.