| JP3890715 | SIGNAL PROCESSING UNIT |
| WO/1993/020658 | MULTIRESOLUTION DIGITAL TELEVISION BROADCAST SYSTEM |
| JP06169474 | MUSE SIGNAL TRANSMISSION SYSTEM |
| Claims
What is claimed is:
1. A bi-directional interface system between a wireless system and a cable system, comprising means for operating a mixer as a bi-directional device to concurrently perform upconversion in one direction and downconversion in the other, wherein input signals are applied to the mixer at both its RF and IF ports and output signals are extracted from the same ports, and wherein a signal is also applied to the LO input of the mixer as required in the mixer.
2. The bi-directional interface system according to claim 1, wherein using a high level mixer.
3. The bi-directional interface system according to claim 1, wherein signals to and from the wireless system are connected to the mixer's RF port, and signals to and from the cable system are connected to the mixer's IF port.
k. The bi-directional interface system according to claim 1, further including filter means between the mixer and the wireless system for selecting the desired signals for transmission over wireless.
5. The bi-directional interface system according to claim 1, further including filter means between the mixer and the cable system for selecting the desired signals for transmission over cable.
6. The bi-directional interface system according to claim 1, wherein the wireless system comprises the wireless Internet 802.11 x, in its various forms and implementations.
7. The bi-directional interface system according to claim 1, wherein the cable system comprises CATV.
8. In a wireless LAN system with coverage over a first area, a method for increasing the LAN coverage to a second area, comprising: a. connecting signals from the first area into a cable system using a first bi-directional interface system which concurrently converts between operating frequencies of the wireless system and the cable system, and wherein the first interface system is connected to an outlet of the cable system located in the first area; b. connecting signals from the cable system to a second area using a second bi-directional interface system which concurrently converts between operating frequencies of the wireless system and the cable system, and wherein the second interface system is connected to an outlet of the cable system located in the second area; wherein signals in the cable system propagate concurrently in both directions between the first and second areas, and wherein the interface systems concurrently translate signals from the higher frequency range of the wireless system to the lower frequency range of the cable system in one direction, and from the cable frequency range to the wireless frequency range in the other direction.
9. The method for increasing the LAN coverage according to claim 8 , wherein the first and second bi-directional interface system uses a mixer operating as a bi-directional device to concurrently perform upconversion in one direction and downconversion in the other, wherein input signals are applied to the mixer at both its RF and IF ports and output signals are extracted from the same ports, and wherein a signal is also applied to the LO input of the mixer as required in the mixer.
10. The method for increasing the LAN coverage according to claim 8, wherein using a plurality of bi-directional interface systems to concurrently connect to a plurality of second areas. |
Wireless interface system and method
Cross-Reference to Related Applications
The present application is related to, and claims priority from, the patent application No. GB0617660.6 filed on September 8, 2006 in Great Britain by the present applicant and entitled "Wireless interface system" .
Field of the Invention
The invention relates to a wireless LAN system with means for increasing the LAN coverage, and more particularly to such a system using an existing coaxial cable network and a bidirectional mixer.
Background of the Invention
The wireless Internet 802.11 x, in its various forms and implementations, become an ubiquitous off-the-shelf system. It is used at home, in public places and in various business locations.
The method for laying the network is very simple and user-friendly, even for non-professional users, and the prices are reasonable.
The firms which have developed this technology are now the OEM suppliers, providing the integrated components to tens of firms worldwide which manufacture the end product.
This technology, like other technologies in the past, has advanced in time to answer the need for distributing data at rates of 100 MBit/sec, to various applications including for example video IP.
With the growth of the market and the need to distribute data, it become apparent there is a problem with the limited coverage of the wireless network. It is well known that the coverage of a space depends on various
factors which may be independent of the technology itself, such as the work environment, noise, shielding, building structural characteristics such as walls and their structure, etc.
For example, in an open space the area covered is larger than in a building with walls made of concrete.
Moreover, as the data rate increases, the area covered by the wireless network decreases, for example:
The most up-to-date of the wireless network 802.11 N specifies a data rate of more than 100 MBit/sec, however the open space coverage is up to 20 meters .
Solutions to the problem of limited coverage have been devised, in the form of repeaters which are installed in passages between rooms and between areas which are not covered by the wireless network. A disadvantage of such solutions is their relatively high cost.
Other disadvantages include a more difficult installation including additional antennas, and a higher level of RF radiation, day and night, in the dwelling space of people.
At present, the wireless network only covers a small area. To enhance the coverage, in prior art systems there are dedicated wired links being installed, this requiring new infrastructure with its related high cost, expensive repeaters with expensive installation and complex antenna arrays with high RF level transmission.
There were attempts to transmit the wireless LAN signals over coaxial cable networks, however these attempts were not successful - the wireless LAN signals at 2.4 GHz do not propagate well in cables designed for 900 MHz.
In recent years, wireless networks have become the main channel for distributing IP information over short distances. These networks are widely spread and used at home, in the office, in public places, etc. Therefore, it is important to increase the area of coverage of these networks .
Summary of the Invention
According to the present invention, a new system aims to increase the coverage area of a wireless network, using the existing coaxial cable infrastructure which is installed practically in any house, building or campus . This solution achieves excellent performance at low cost.
It has been found by the present inventor that a mixer may be used as a bi-directional device, to concurrently perform upconversion in one direction, and downconversion in the other. This structure is efficient and economical, using less components.
Thus, the mixer is used in one direction to downconvert wireless signals to a lower frequency range which can propagate over coaxial cables, and at the same time to upconvert signals which propagated over the cable, back to the higher wireless frequency range.
The coaxial cable network has been chosen because of its wide bandwidth, which is larger than that of other networks installed in buildings.
Filters may be used as necessary (band-pass, low-pass, high-pass) to extract from the mixer's output the desired signals.
The new system achieves a larger area of coverage of the wireless network in buildings, house or campus at low cost, while preserving the quality of the wireless network, including the remote management array and while preventing unauthorized access to the network.
An adapter installed near a TV socket achieves a wireless network coverage in the area surrounding that socket.
Thus, the increase in the area covered by the wireless network is achieved by using the existing, already installed coaxial cable network in a building, without the need to perform changes in the wireless network or to lay a new network.
- U -
Using a new wireless to coax adapter means, it is possible to distribute the wireless information, as is, over a coaxial network, to distances of about 1 km. All this is achieved with no increase in the sensitivity to external interference, walls do not limit the network, and no undesirable high RF power transmissions are required. The covered area may include several floors of a building and/or separately located places.
V
This is a significant increase in the coverage area or the wireless network, which in prior art is limited to tens of meters in an open space.
The new system may support both present and future generations of wireless networks, since it comprises an addition to the 802.11 wireless transmission technology. Thus, a long product life may be expected for the present invention.
The problem of transmitting the wireless signals over coax cable is solved using a frequency converter. To use the network signals and protocols as is, without any changes, a new converter has been devised, which is bi-directional - signals entering from the WLAN end are converted from 2.4 GHz to cable frequency (ie 600 to 1,200 MHz) while, concurrently, signals entering from the cable end are converted from cable frequency to WLAN frequency. Two preferred embodiments of the bi-directional frequency converter are detailed.
Brief Description of the Drawings
Fig. 1 illustrates a wireless network enhanced to use existing coaxial cable network
Fig. 2 details another embodiment of a wireless network enhanced to use existing coaxial cable network
Fig. 3 details the frequency converter means
Detailed Description of the Preferred Embodiments
A preferred embodiment of the present invention will now be described by way of example and with reference to the accompanying drawings.
Fig. 1 illustrates a wireless network enhanced to use an existing coaxial cable network for enhanced coverage, for example to include a first room 11 and a second room 12.
In this example, signals from part of the wireless network, with WLAN gateway 43 and antenna there, are converted from about 2.4 GHz to about 600 - 1,200 MHz range in the Yanircom(tm) adapter 3, a bi-directional frequency converter.
The lower frequency signals can pass through the coaxial cable infrastructure, including the splitter 28, combiner 27, cable modem or ADSL 29 and CATV cables 21, 22, 23, 24 which are between various rooms, which form part of the coaxial cable infrastructure in the building or apartment.
Signals passing through cable 24 are converted back to 2.4 GHz in the Yanircom(tm) adapter 3 in room 12. The signals at the wireless network frequency may pass through WLAN gateway 43 to be transmitted in room 12. Thus, an effective communication between rooms 11 and 12 is achieved. The other CATV cables may connect the lower frequency signals to other rooms .
Various equipment may be connected, such as laptop computers 41, 42 using a wired or wireless connection, or an adapter IP STB 44 to a television unit.
Thus, wireless signals from a space or a room may be received in an antenna there, converted to a lower frequency suitable for coax cable, and transferred through the cable to another room or space. There, the signal is converted back to the higher frequency and is transmitted there as a wireless signal.
Each frequency converter 3 is bi-directional, to allow signals passage in two directions at the same time.
Fig. 2 details another embodiment of a wireless network enhanced to use existing coaxial cable network with cable to modem or DSL 49, splitter 28, combiner 27, CATV cables 22, 23 between various rooms, part of the coaxial cable infrastructure in the building or apartment.
The communications infrastructure 2 may include CATV or a coaxial network. This infrastructure allows to transfer the wireless network signals between a first room 11, second room 12, third room 13, etc.
The Yanircom(tm) adapter 3, a bi-directional frequency converter, is used between the above coax cable infrastructure and the wireless network, including for example a WLAN gateway 43, such as per 802.11 G gateway, a laptop computers 41, personal computer 45 (PC), adapter IP STB 44 to a television unit, etc.
The adapter 3 is detailed, to include in one embodiment (in room 11): a local oscillator or frequency synthesizer 32 and a mixer 31. In this embodiment, the mixer is used as a bi-directional device, as detailed with reference to Fig. 3.
The adapter 3 includes in another embodiment (in room 12): a local oscillator or frequency synthesizer 32 and a pair of mixers 31, 33. In this embodiment, each mixer is used as a uni-directional device.
Fig. 3 details the frequency converter means 3, used as adapter, including: a frequency synthesizer 32 at the frequency difference or sum, as known in the art; an RF amplifier 324, optional, if required to operate the mixer 31 at a high level of LO signal.
The mixer 31 is used here as a bi-directional device, that is it can at the same time downconvert signals passing from WLAN side 381 to CATV side 382, and upconvert signals passing from CATV side 382 to WLAN side 381.
The frequency converter means 3 further includes a filter 35 (either a low pass filter or a band pass filter) .
It has been found by the present inventor that a mixer may be used as a bi-directional device, to concurrently perform upconversion in one direction, and downconversion in the other.
Upconversion
This structure is efficient and economical, using less components.
Further, it has been found by the present inventor that high level mixers (using a higher power LO) are better suitable for this function. The mixer may include, for example, model ADE-30W or ADE-30W+ manufactured by Mini Circuits (R).
In a mixer 31, the higher frequency signals is connected to the RF port, the lower frequency signal to the IF port, and the oscillator to the LO port. Upconversion is thus performed from the IF (I) to RF (R) ports and downconversion - from the RF to IF ports.
The interface unit using the bi-directional mixer may be used to connect a plurality of areas, all connected by the cable network. In each area (i.e. each room) , an interface unit converts from the cable frequency range to the wireless and transmits to that area using an antenna; at the same time, wireless signals there are converted back to cable range signals.
It will be recognized that the foregoing is but one example of an apparatus and method within the scope of the present invention and that various modifications will occur to those skilled in the art upon reading the disclosure set forth hereinbefore.