GB2521187A - Method and system for transferring Wi-Fi signals - Google Patents

Abstract

There is provided a method and system of transferring Wi-Fi signals within a building (10) by passively transmitting Wi-Fi signals along an elongate coaxial cable (12) having a plurality of access points (14, 16) and extending from a first region having good Wi-Fi reception to a second region having poor Wi-Fi reception. A Wi-Fi antenna (21) is connected to a first access point (14) and a further Wi-Fi antenna (21) is connected to a second access point (16) spaced apart from the first access point. A Wi-Fi router can be connected to the first access point (14) using an amplifier device (44) configured to receive cable television signals and Wi-Fi signals.

Description

Title: Method and System for transferring Wi-H Signals

Field of the invention

This invention relates to a method arid system of transferring Wi-Fi signals, particularly for in-home environments where multiple rooms or floors are to be connected to a single Wi-Fi access point.

Background to the invention

Wi-H is increasingly used within domestic installations such as offices, flats and a homes, to allow ready access to broadband networks regardless of a user's location within a building. Unfortunately, problems are often encountered with sending data wirelessly to and from broadband networks due to lack of bandwidth, often caused by signal loss due to noise effects or obstructions, Wi-H boosters or extenders can be used to increase the Wi-Fi signal but this can cause problems with the radiated power output from the Wi-Fi extenders or boosters causing electromagnetic interference.

Data throughput for the network can also be slowed due to processing required for standard Wi-Fi extenders to receive Wi-Fi signals, process the signals and then re- transmit them. The extender has to switch between receiving the Wi-H and re-transmitting the processed Wi-Fi, so slowing data throughput.

Summary of the invention

In accordance with one aspect of the invention, there is provided a method of transferring Wi-Fi signals comprising transmifting Wi-Fi signals along a coaxial cable extending from a first region having useable, or good, Wi-H reception of at least -65 dBm to a second region having unuseable, or poor, Wi-Fi reception of less than -65 dBm, thereby to provide useable Wi-Fi reception in the second region. By using existing coaxial cables within a building, and in particular a domestic dwelling, Wi-Fi access with adequate data transmission capabilities for video streaming and other activities requiring transfer of large amounts of data can be provided throughout the dwelling from a single Wi-Fi access point located in the first region.

The Wi-UI signals are preferably transmitted passively with no processing or modification of the Wi-Fi signals required for transmission to occur.

The method may thither comprise connecting a first Wi-Fl antenna to the coaxial cable in the first region and connecting a second Wi-Fi antenna at a spaced apart location along the coaxial cable in the second region. The first Wi-Fi antenna may be s connected to the coaxial cable using a splitter device such as a two-way splitter.

Alternatively a Wi-Fi router may be connected to the coaxial cable in the first region using an amplifier device configured to receive cable television signals and Wi-Fi signals, with a Wi-Fl antenna connected at a spaced apart location along the coaxial to cable in the second region.

In accordance with another aspect of the invention, there is also provided a system for transfening Wi-Fi signals comprising coaxial cable with a plurality of access points, wherein a first access point is adapted to receive Wi-Fi signals and a Wi-Fi antenna is is connected to at least one second access point spaced apart from the first access point, the first access point situated in a region having useable, or good, Wi-Fi reception of at least -65 dBm and the second access point situated in a second region having unuseable, or poor, Wi-Fl reception of less than -65 dBm. This enables good Wi-Fi reception to be provided in the second region where previously Wi-Fi reception had been poor and unuseable. As will be appreciated, additional further Wi-Fi antennas may be provided at additional second access points to provide a Wi-Fi signal anywhere in the coaxial network at regions where previously the Wi-Fi signal was unobtainable or too poor quality to be useable.

A further Wi-Fi antenna may be connected to the first access point using a splitter device, such as a 2.4 0Hz microstrip splitter, which is particularly desirable where a wireless router is also used. Thus the coaxial cable will be connected to one port of the splitter, a wireless router connected to a second port of the splitter and typically an antenna element connected to the remaining port of the splitter. Alternatively the o further Wi-Fi antenna may be connected to the first access point using an amplifier device configured to receive cable television si_s and Wi-Fi si_s.

The invention will now be described by way of example, and with reference to, the accompanying drawings in which: Figure 1 shows a schematic drawing of a first embodiment of a system for conveying Wi-Fi signals through a building using coaxial cable; Figure 2 shows a schematic diagram of a second embodiment; Figure 3 shows a schematic diagram of a second embodiment; Figures 4(a) and (b) show a schematic diagram of an experimental set-up to test received power under different conditions; and Figures 5 and 6 are graphs depicting received power under different test conditions.

Detailed description

Figure 1 shows a building tO with coaxial cable 12 running between different rooms and floors. Multiple access points to coaxial cable 2 are provided on different floors, of which two access points 14, 6 are shown by way of example. Wi-Fi router 8 is connected to an external network 19 mn by a communications provider and is able to generate and receive Wi-Fi signals. Panel antenna 21 is connected to access point 14, and so to coaxial cable 12, by an F-connector 23 with panel antenna 21' connected to a distal access point 6 by F-connector 23'. Wi-Fi signals received by antenna 21 in a first region 13 having good Wi-Fi signal of at least -65 dBm are transmitted along coaxial cable 12 to reach antenna 21' at a second region tS being a remote floor or building where the Wi-Fi signal is unuseable and typically less than -65 dBm.

Antenna 2F then radiates these Wi-Fi signals onto this remote floor or building for transmission to, for example, laptop 36. Similarly Wi-Fi signals received by antenna 21' are transmitted along coaxial cable 12 to reach antenna 21 for transmission to router 18.

By connecting antennae 21, 21' directly to coaxial cable 12 using F-connectors, there is a direct wired contact between the antennae for receiving and transmitting Wi-Fi signals and the in-house coaxial cable network. Wi-Fi signal obtained from router 18 by antenna 21 is transmitted through the existing coaxial network 12 to be re-transmitted by antenna 21' at a different location 16 where previously there was poor, or no, Wi-Fi coverage, No connection of router 18 to coaxial network 12 is required.

The arrangement is bi-directional, allowing for downstream transmission of Wi-Fi signals along coaxial cable 12 to antenna 2]' so as to reach a user device, such as laptop 36, and also allowing upstream or return transmission of signals from laptop 36 to antenna 21' and thence via coaxial cable 12 to reach antenna 21.

Wi-Fi and CATV signals use different frequencies (CATV: 5-1006 MHz, Wi-Fi 2400 MHz) and so it is possible to transmit both signals simultaneously along a coaxial cable. Thus Wi-Fi signals can be transmitted passively over a hard-wired coaxial link without the need to use Wi-Fi boosters or extenders. The present arrangement extends the range of the Wi-Fi signal without any signal processing being required a and is thus a full-duplex extension.

Figure 2 shows an alternative embodiment where Wi-Fi router 18 is connected to access point]4, and so to coaxial cable 12, by a splitter 20 having three ports 22, 24, 26. Port 22 is connected to Wi-Fi router 18, antenna 30 is connected to port 26 and access point 14 is connected to port 24. Wi-Fi signals received at splitter 20, typically a 2.4 0Hz microstrip splitter, are transmitted along coaxial cable 12 to reach antenna 32 on a remote floor of building 10. Antenna 32 is connected to coaxial cable]2 by F-connector 34.

By connecting Wi-Fi router t 8 directly to coaxial cable 12 using splitter 20, there is a direct wired contact between the Wi-Fi router and the in-house coaxial cable network, Wi-Fi signal obtained from router] 8 with antenna 30 is transmitted through the existing coaxial network 12 to be re-transmitted by antenna 32 at a different location 16 where previously there was poor, or no, Wi-Fi coverage. The arrangement is bi-directional, allowing for downstream transmission of signals from router 18 along coaxial cable 12 to antenna 32 so as to reach a user device, such as laptop 36, and also allowing upstream or return transmission of signals from laptop 36 to antenna 32 and thence via coaxial cable 12 to reach router 18.

Many different arrangements can be configured to take advantage of passive Wi-Fi transmission along a coaxial cable, see for example Figure 3 where a similar arrangement is used for a user building 10 receiving both CATV input 40 and Wi-Fi input 42. In this embodiment, Wi-Fi router 18' is connected to a CATV amplifier 44 configured to receive both Wi-H input 42 and CATV input 40 and transmit these along coaxial cable 12. In a room with little, or no, Wi-Fi coverage, a diplexer 46 is connected to cable access point 16, with diplexer 46 connected to antenna 32' and television 50. Using the existing coaxial network within building 10 allows Wi-Fi to be provided in regions remote from Wi-Fi router 18' without needing extenders or boosters. Acceptable levels of Wi-Fi signal have been provided to a different region within building 10 which would otherwise have had an inadequate Wi-Fi signal.

Other devices used in this arrangement could include a panel antenna with an F-a connector, a Wi-H splitter with built-in diplexer for Wi-Fi/CATV, wall outlet with built-in diplexer for Wi-Fi/CATV and integrated Wi-Fi antenna, and an in-home amplifier with Wi-Fi input and four combined CATV/Wi-Fi outputs.

Using the existing coaxial cable already placed within a building to convey Wi-Fi to other in-home locations allows Wi-Fi to be transported to other areas without substantial signal loss and ensures there is sufficient data capacity for video streaming and the like to be possible in multiple rooms and on multiple floors even when the building only has a single Wi-Fi generation point connected to an external communications provider.

To confirm that it is possible to transmit \Vi-Fi signals over a coaxial cable within a building having multiple access points to a coaxial cable, which has previously been thought not possible, theoretical calculations and experiments were undertaken to determine the received power levels achievable when passively transmitting Wi-Fi signals over coaxial cable.

Theoretical calculations were undertaken of the received power R at an antenna for a theoretical transmission power TX, such as is emitted by a Wi-Fi transmitter. Power flux density was calculated by: Pt (Vrms/m)2 = 4rrL2 [W/m2] = 120n Equation I where p is power flux density at a distance L from a transmitter generating a transmission power of P1.

Thus for an EIRP (i.e. P) of 17 dBm, at a distance of 5 metres p was calculated as 0.25 VIm, Using an effective antenna aperture Aer as calculated by: Aer = Gri Em2] 4u io Equation 2 at 14 dBi for a signal of frequency 2.4 GHz, Aer was 0.03 1m2.

Received power Pr is given by: P = p.Aer [WI Equation 3 This gave a theoretical calculated received power of -23 dBm at a receiving antenna 2() on the same floor but Sm away from a Wi-Fi transmitter, as in Figure 1. Connecting the receiving antenna to a distal antenna by a lOm length of coaxial cable having a 5dB attenuation produces power at the second distal antenna of -28 dBm with an EIRP of -14 dBm. If this distal antenna transmits to a remote Wi-Fi receiving device Sm away in the same room, such as a laptop, then the received power at the laptop is calculated to be -68 dBm and for a Im distance from the antenna -54 dBm, These calculations indicate that transmission of Wi-Fi signals along a coaxial cable should prove sufficient power for Wi-H signal transmission in a remote room. Equivalent calculations were undertaken for the arrangements shown in Figures 2 and 3.

Thus for Figure 1, with an effective isotropic radiated power (EIRP) at antenna 2 five metres away from router 18, the EIRP produced by antenna 2]' on the upper floor will be -14 dBm, so allowing laptop 36 to receive a power of-68 dBm.

For Figure 2, with an effective isotropic radiated power (EIRP) at the ground floor of +13.5 dBm, the EIRP produced by antenna 32 on the upper floor will be +8.5 dBm, so allowing laptop 36 to receive a power of -47.5 dBm.

In Figure 3, the EIRP at the upper floor, allowing 2 dB for wall outlet 46, will be +2 a dBm with the power received at the laptop 36 being -54 dBm.

Testing of these theoretical findings was then undertaken by the experimental set-up shown in Figures 4(a) and (b).

The experimental set-up consisted of signal generator 60 to act as a Wi-Fi frequency source for antenna 62, these two items effectively acting as equivalents to an in-home single Wi-Fi router connected to an external communications provider and a separate Wi-Fi receiver or antenna within the same room of a building. Second and third antennas 64, 66 were placed within a screened room 70 so as to provide equivalent conditions to a room having no, or poor, Wi-Fi coverage. Antenna 64 is equivalent to a Wi-Fi emitter/receiver and antenna 66 equivalent to a remote user device within the same room, such as a laptop. In Figure 4(a) there is no wired connection between antenna 62 and antenna 64 and when testing with 2442 MHz as the Wi-Fi frequency, setting generator 60 to +]0 dBm (50 Ohm), the received power R at the panel antenna 66, i.e. the antenna mimicking a laptop, was -90.1 dBm, see FigureS. This is not sufficient signal to enable access to the Wi-Fi signal within the screened room.

The experimental set-up was then modified as shown in Figure 4(b) so as to connect antenna 62 to antenna 64 with a length of coaxial cable 72, which was done by directly connecting the two antennae and using an insertion loss of around -8.9 dB to replicate the insertion loss of a 17,Sm coaxial cable, In this arangement, there is a hard-wired link from one region having good Wi-Fi connectivity, i.e. at antenna 62, to another region that previously had no Wi-Fi coverage, i.e. antenna 64. When the received R power at panel antenna 66 (equivalent to a laptop) was measured, the R power was found to be -59.5 dBm when antenna 64 and antenna 66 were separated by a distance of im, see Figure 6. For a spacing of O.5m between antennae 64 and 66, the received power R was -57.3 dBm as shown in Figure 7. This compares with calculated values for the received power R of -57.6 dBm and -51.6 dBm respectively.

When the difference between antennae 64 and 66 was U,Sm, the measured received power was lower than calculated using theoretical models. This is possibly because the coaxial antenna was in a near-field zone rather than in a far-field zone, however even so it was still possible to achieve and utilise the benefits of the Wi-Fi system at a ci distal region by using the hard-wired connection.