WO2006078173A1

WO2006078173A1 - Wireless signal distribution

Info

Publication number: WO2006078173A1
Application number: PCT/NO2006/000027
Authority: WO
Inventors: Oddvar FLØLO
Original assignee: Local Digital Holding As
Priority date: 2005-01-20
Filing date: 2006-01-20
Publication date: 2006-07-27
Also published as: NO20050325L; NO20050325D0

Abstract

The present invention discloses a system and a method for distribution of radio, television or multimedia traffic, where the system and the method comprise a receiving unit including an antennae (2.2), a dish aerial (1.2) or a input connector, further the system and the method comprises signal processing or components for signal processing of signals within the UHF frequency channel. The signals are forwarded within the UHF channels preferably as QAM modulated signals.

Description

Wireless signal distribution

Technical field

The present invention relates to distribution of signals such as television signals , radio signals , multi-media sig- nals and similar signals . More particularly, the present invention discloses an apparatus and a system comprising at least said apparatus, a method and a use of said apparatus and a system for wireless distribution of said signal types using at least one receiver unit, a transmodulator, a pre- amplifier, an output amplifier and a transmitting antenna .

Background of the invention

It is difficult to achieve a good coverage for distribution of signals , such as television signals , radio signals , multi-media signals and alike in areas with open settlement and difficult topography . The use of conventional wireless signal distribution is not compatible with reasonable cost effectiveness because conventional transmitters for television signals , radio signals , multimedia signals and alike are expensive and complicated. Heavy constructional work will be necessary in order to reach a small number of users . As a consequence of difficult topography, conventional transmitters will have a very limited range . Furthermore, one may get areas without coverage, i . e . shadow, one may get multi path fading of signals , i . e . signals as a conse- quence of the difficult topographical nature will have a number of single paths between the transmitter and the receiver, and one may receive more than one signal . A particular variant of multi path fading is Rayleigh fading . In this case the receiver will not be in line of sight with the transmitted signal . The signal will rather be reflected from hillsides , mountain hills and the like, and the receiver will receive signals from many different indirect choices of path . The received signal will be the sum of many identical signals which only differs in phase and to some extent in amplitude .

One may imagine a solution where "each person has his own dish aerial", but this solution will also be unfavourable in that it is not always possible to place a dish aerial in such a manner that it can obtain optimal receiving conditions . This will in particular be the case with valleys stretching east-west . Furthermore, one will often experience that due to esthetical reasons there will be a re- striction to the use of dish aerials , still further dish aerials are an expensive solution for the end user .

The ideal solution for distribution of television signals is wireless reception with the customer . However, it is almost impossible to build out a wireless terrestrial network for digital television today, which offers the same channel capacity as a dish aerial or a cable television with conventional technology based on COFDM modulation . COFDM based equipment is extremely expensive and the technique of modulation demands amplifying equipment with a good phase line- arity . Furthermore, the use of guard intervals and error correcting programmes consumes a lot of frequency resources . A typical capacity is approximately 22 mbit/sec at 8 MHz bandwidth with room for 4-5 television channels with good quality .

Summary of the invention

It is an obj ect of the present invention to provide an apparatus , a system and a method and the use of said apparatus and system which removes the above mentioned problems . The method, apparatus, system and the use is characterised by the accompanied independent claims . Brief description of the drawings

To ease the readability of the present invention in the following discussion references will be made to the accompanied drawings .

Fig . 1 shows a typical configuration according to the present invention combined with satellite reception of QPSK modulated signals .

Fig . 2 shows another configuration of the present invention combined with wireless reception of QAM modulated signals .

Detailed description of the present invention

The system and method according to the present invention is thoroughly tested on numerous transmitters . The system is characterised by using a completely different transmitting technology than the prior art technology as referenced above . This technology enables the transmission of distributed radio-, television-, or multimedia signals wireless and in a conceptual manner as known from cable television . This is made possible by a combination of transmitting components each being known, partly from digital cable network technology and components known from other technical areas . The system and method performs a unique signal processing and transmits QAM modulated signals within UHF band ( 470- 860 MHz) . Furthermore, the signal is transmitted with weak signal strength, typically approximately 4-8 Watt and hence solves expected problems with selective damping and reflections . The range is typically 12 kilometres at 4-8 Watt ERP . Mathematical models have suggested that it is physically impossible to build such a system with a reasonable transmitter power and still achieve an acceptable range . Systematically development has , however, resulted in a technology for transmission of wireless radio- , television- , or multimedia signals using QAM modulation which is documented to be liable . Because the new technology utilizes QAM modulation not including "guard intervals" or error correction programmes ( FEC) , the bandwidth is utilized in a supreme and efficient way. The channel capacity per 8 MHz bandwidth is according to the present invention approxi- mately 38 mbit/sec against 22 mbit/sec using COFD based transmission . The complexity of building transmitters is also less complex .

It should be noted that signals that are to be forwarded within UHF band can, according to the present invention, in principle be received in any format that is common within wireless or cable transmission of television signals , radio signals or multimedia signals that is a number of frequencies and modulations . The transmodulator ( .3) is in the following description an apparatus adapted to change QPSK signals to QAM signals . One may, however, imagine the use of other transmodulators if signals that are received have another modulation format . Typically one may imagine that one has a number of receiving-transmitting systems interconnected according to the present invention, in which a first receiver-transmitter e . g . receives QPSK signals from a satellite, signals being processed and forwarded within the UHF band advantageously using QAM modulation, a new receiver adapted to receive UHF and QAM modulation receives the signal and forwards this . Between a numbers of re- ceiver-sender units according to the present invention, one may use wireless or cabled transmission dependent on the situation . An essential common feature of the present invention is that the end user receives QAM modulated television-, radio-, or multimedia signals within the UHF band with a high quality .

A first preferred embodiment of the invention

In the following a detailed description of a first preferable embodiment of the invention is disclosed wherein the invention, a receiver-transmitter system is described from satellite reception to UHF forwarding . To increase the readability it is in the following explanation given a description where a particular type of modulated signal is received, QAM modulated and forwarded within the UHF band reference is in particular made to Fig . 1.

QPSK modulated signals are received from a satellite ( 1.1 ) using an aerial dish (1.2 ) . The signal from LNB is received in the aerial dish ( 1.2 ) and is connected to the input on the transmodulator ( 1.3 ) . The input on the transmodulator ( 1.3 ) is a QPSK-receiver with a bandwidth of 950-2150 MHz . From the output of the QPSK receiver the signal is being modulated to QAM modulation . The signal outputted from the QAM modulator is up-converted (transmodulated) to an optional frequency bandwidth from 470-860 MHz .

The QAM modulated signal out from the QAM modulator is fed into a preamplifier ( 1.5 ) via a first selective channel filter ( 1.4 ) . Furthermore, the signal is outputted from the output of the preamplifier ( 1.5) to the output amplifier ( 1.8 ) via a second selective channel filter ( 1.7 ) . The out- put from the other channel filter (1.7 ) can be connected to a third selective filter ( Fig . 2 (2.9) ) which is used so as to limit the bandwidth in a requested signal to for example 8 MHz . The channel is selected by using the filter . From this output the signal is fed to a transmitting antenna ( 1.10 ) with a typical antenna amplification rate of 10-12 dB .

A second preferred embodiment of the invention

In the following it is disclosed a second preferable embodiment according to the invention . In this case, signals are not received at the receiver-transmitter unit via satellite . On the contrary, the QPSK modulator signals are received from a transmitter using a receiver antenna . The signal may pass an LMB mounted within the antenna and being fed to the input on the transmodulator ( 1.3) for transfor- mation to QAM modulated signals . The further signal path follows the path laid out in the first preferable embodiment according to the invention and according to Fig . 1 and

2.

A third preferred embodiment of the invention

In the following a third preferred embodiment is disclosed according to the present invention with reference to Fig . 2. In this case signals are not received by the receiver- transmitter unit from satellite but QAM modulated signals are received from a transmitter utilising a UHF receiving antenna connected (2.2 ) to a receiver (2.3 ) and the regenerated QAM signal that is up-converted to UHF is transmitted to a preamplifier (2.5) via a first selective channel filter . Thereafter the signal follows the same signal path as for the first preferred embodiment from the preamplifier ( 1.4 ) to the transmitting antenna ( 1.10 ) . This configuration will be advantageous where there is a need for amplification of the signal before forwarding. Thus, in this example one will use the transmitter receiver unit as a sig- nal amplifier for forwarding the QAM modulated signal to an end user or an equal configured receiver-transmitter unit within the UHF wave range . This solution is of interest where the range for a single receiver-transmitter unit is not sufficient for an end user in order to receive signals with the desired signal quality . One may in principle image an entire chain of such receivers-transmitter units in which for example a first receiver-transmitter unit is configured according to the first preferred embodiment , whereas the subsequent receiver-sender units are configured according to a third embodiment .

A fourth preferred embodiment of the invention

In the following it is disclosed a fourth preferred embodiment according to the invention . This is a variant of the third embodiment but in this case the QAM modulated signals are received from a transmitter via a cable . Thus , the receiving-transmitting unit which is the sender of this signal will not have a transmitting antenna ( 1.10 ) but be directly connected using a cable . This implies that the re- ceived QAM modulated signal is connected to a preamplifier ( 1.5 ) via the first selected channel filter ( 1.4 ) or directly to a QAM receiver (2.3) . Then, a signal follows the same signal path as described for the other previous embodiments from the preamplifier ( 1.4 ) to the transmitting antenna ( 1.10 ) . This configuration will be preferable where there is a need for an amplification of the signal for forwarding . Hence, in this example one will use the transmitter- receiving- unit as a signal amplifier for forwarding the QAM modulated signal to an end user or an equally con- figured receiving-transmitting unit within the UHF wave range .

This solution is of interest where the range for a single receiver-transmitting unit is not sufficient for an end user to receive signals with a sufficient signal quality. Compared to the solution outlined as the third embodiment , this solution can be of interest where the distance between two receiver-sending units is small, which may be the case where there are particular topographical situations to be considered . One may in principle image a whole chain of such receiving-transmitting units where for instance one first receiving transmitting unit is configured according to the first preferred embodiment, whereas the subsequent receiving-transmitting units are configured according to the third or fourth embodiment .

Conclusion

Above a number of scenarios are outlined according to the present invention, in which the fourth embodiment appears to be a conventional signal amplifier . However, a combination of the fourth embodiment and the other embodiments can be particularly favourable and make a completely new and preferable solution for distribution of signals , such as television signals , radio signals and multimedia signals .

Above the invention is described by means of four different embodiments . However, the invention should also be under- stood as any technical possible combination of these embodiments for an arbitrary number of receiver-transmitting units can be realised according to the present invention . The unique aspect of the invention is among other things the fact that an end user can receive high quality signals o with a wide bandwidth over the UHF, and the range for this is particularly good compared to transmitted power . Additionally, the end user will benefit from the use of particularly compact and reasonably priced receiving antennas with a favourable design.

s Level adjustment of the transmitter :

The output level from the amplifiers can be adjusted so as to minimize the number of bit errors typically > 1-8 and modulation errors typically > 32 dB .

Equipment description

o 1-1 : Satellite adapter for transmission of QPSK modulated signals .

1.2 : Aerial dish with an LMB .

1.3 : QPSK-QAM transmodulator . This is a unit which transforms received QPSK signals to QAM modulated signals . Typi- 5 cally the input on the QPSK-QAM transmodulator is fed from LNB in the aerial dish with a frequency of 950-2150 MHz which is QPSK modulated. The signal from the QPSK receiver is transmodulated to QAM and up-converted to the UHF band with typical signal strength of 100 dBμV . o 1.4 : Selective channel filter is used for the elimination of undesirable frequency components extending beyond the requested channel, such as inter modulation products and wideband noise . 1.5 : Preamplifier fed from the output transmodulator so as to amplify the signal level to the desired level so as to feed the next amplifier stage .

1.6 : Power supply for feeding of amplifiers and other tech- nical equipment with current .

1.7 : Selective channel filter.

1.8 : Output amplifier which is fed from the output of the preamplifier and amplifies the signal to a required level so as to feed the transmitting antenna . 1.10 : Transmitting antenna connected to the output amplifier where the antenna polarization can be vertical or horizontal .

2.2 : Receiving antenna for reception of QAM signals .

2.3 : QAM receiver which generates the QAM signal up- converted to UHF bandwidth .

2.5 : Preamplifier with channel filters or preamplifier and a separate channel filter .

2.9 : Antenna filter for selected channel within the UHF range .

Abbreviations

COFDM Coded Orthogonal Frequency Division Multiplexing

QAM Quadrature Amplitude Modulation, a modulation technique which uses variations within amplitude and phase so as to accepted coded data to be represented as any of 16 or 32 states .

UHF Ultra High Frequency

ERP Effective Radiated Power .

FEC Forward Error Correction Coding, a technique with an error detection and correction in which a transmitting node includes a number of redundant bits in a payload within a block or frame with data . The receiver uses these bits so as to de- tect, isolate and correct any transmission error .

QPSK Quadrature Phase Shift Keying Modulation, a compression technique which is used among others in modem and within wireless networks . A simple implementation of QPSK enables transmission of two bit per symbol in which each symbol constitute a phase area of a sinus wave, hence a 2 : 1 compression is achieved .

LNB Low Noise Block converter,

Claims

Patent Claims

1. A transmitter- receiving- apparatus for distribution of radio, television or multimedia signals where the apparatus at least comprises a receiving unit ( 1.3 , 2.3) , an ampli- fier and a filter unit and a transmitting unit ( 1.10 , 2.10 ) c h a r a c t e r i s e d i n that

the receiving unit at least comprises :

a transmodulator ( 1.3) for reception of QPSK modulated signals , where the receiver is configured to trans- modulate received signals into QAM signals and to up- convert signals to the UHF band, or

a QAM receiver (2.3 ) for reception of QAM modulated signals where the receiver is configured to up-convert signals to the UHF frequency band, and

the amplifier and the filter unit at least comprises one amplifier and at least one filter, and

the transmitting unit at least comprises one transmitting antenna ( 1.10 , 2.10 ) adapted for transmission on the UHF frequency band.

2. Apparatus according to claim 1, c h a r a c t e r i s e d i n that the amplifier and the filter unit at least comprise :

a preamplifier ( 1.5 ) fed from said receiving unit ( 1.3, 2.3) , a first selective channel filter ( 1.4 ) , an output amplifier ( 1.8 ) , a second channel filter ( 1.7 ) , or

a preamplifier (2.5 ) fed from said receiving unit ( 1.3 , 2.3) with a integrated first channel filter, a output amplifier (2.8 ) with an integrated second channel filter .

3. Apparatus according to claim 1 or 2 , c h a r a c t e r i s e d i n that the amplifier and the filter unit is adjusted for use within the UHF frequency band.

4. Apparatus according to any of the previous claims , c h a r a c t e r i s e d i n that the transmitting unit further comprises an antenna filter (2.9) for the UHF band.

5. Apparatus according to any of the previous claims , c h a r a c t e r i s e d i n that the apparatus further comprises a power supply .

6. Apparatus according to any of the previous claims , c h a r a c t e r i s e d i n that the transmitting an- tenna ( 1.10 ) is designed with a typical directivity of 10- 12 dB .

7. Apparatus according to any of the previous claims 1-5 , c h a r a c t e r i s e d i n that the preamplifier ( 1.5 , 2.5 ) and the output amplifier ( 1.8 , 2.8 ) is adjusted for minimum bit and modulation errors, typically >l-8 , respectively and >32 dB .

8. A system for distribution of radio- , television- , or multimedia signals where the system at least comprises an apparatus according to claim 1 , c h a r a c t e r i s e d i n that the receiving unit (1.3 , 2.3) is adapted for interconnection with an antenna (2.2 ) , a aerial dish ( 1.2 ) or a contact .

9. System according to claim 8 , c h a r a c t e r i s e d i n that the system is config- ured for reception of QPSK signals from a satellite ( 1.1) via a satellite receiver ( 1.2 ) and these signals after hav- ing passed a band pass filter, LNB, is further processed by a transmitting receiving apparatus for distribution of the radio-, television- , or multimedia signals where the transmitting- receiving- apparatus at least comprises said re- ceiving unit ( 1.3 ) , amplifier and filter unit and transmitting unit ( 1.10 ) where the receiving unit at least comprises the transmodulator (1.3) for reception of QPSK modulated signals where the receiver further is configured so as to transmodulate received signals to QAM signals and up- convert the signals to UHF frequency band, the amplifier and filter unit is at least comprising one amplifier and at least one of the filters and the transmitting unit at least comprises the transmitting antenna ( 1.10 ) designed for transmission within the UHF frequency band .

10. System according to claim 8 , c h a r a c t e r i s e d i n that the system is adapted for concatenated connection, hence enabling the system for reception of QAM signals within the UHF bandwidth over cable .

11. System according to claim 8 , c h a r a c t e r i s e d i n that the system is adapted for reception of signals within the UHF band from a transmitter over an antenna (2.2 ) and after having passed a band pass filter, LNB, further process the signals in a trans- mitter- receiver- apparatus for distribution of radio-, television-, or multimedia signals where the apparatus at least comprises said receiving unit (2.3 ) , the amplifier and filter unit and the transmitting unit (2.10 ) where the receiver unit at least comprises a QAM receiver (2.3) for reception of QAM modulated signals where the receiver is configured to up-convert signals to UHF frequency band, the amplifier and filter unit is at least comprising one amplifier and at least the one filter and the transmitting unit at least comprises the transmitting antenna ( 2.10 ) designed for transmission within the UHF frequency band .

12. System according to claim 8 or 11 , c h a r a c t e r i s e d i n that the received radio-, television-, or multimedia signals after processing in the transmitting receiving apparatus for the distribution of radio-, television-, or multimedia signals where the apparatus at least comprises said receiving unit ( 1.3 , 2.3 ) , the amplifier and filter unit and transmitting unit ( 1.10 , 2.10 ) where the receiving unit further at least comprises :

said transmodulator ( 1.3 ) for reception of QPSK modu- lated signals , where the receiver is configured for transmodulating received signals to QAM signals and up-converting signals to the UHF frequency band, or

said QAM receiver (2.3 ) for reception of QAM modulated signals where the receiver is configured for up- converting signals to UHF frequency band, and the amplifier and filter unit is at least comprising said amplifier and at least the one filter, and

the transmitting unit at least comprises the transmitting antenna ( 1.10 , 2.10 ) designed for transmission within the UHF frequency band being transmitted over cable connection to a second system adapted for reception of UHF signals over cable for further distribution of radio-, television-, or multimedia signals .

13. System according to claim 10 or 12 , c h a r a c t e r i s e d i n that the second system for further distribution of radio-, television-, or multimedia signals comprises a receiving unit designed as an antenna (2.2 ) , a aerial dish ( 1.2 ) or a contact . The system further comprises a transmitter-receiver apparatus for distribution of radio-, television-, or multimedia signals where the apparatus at least comprises a receiving unit ( 1.3 , 2.3 ) , amplifier and filter unit and transmitting unit ( 1.10 , 2.10 ) where further the receiving unit at least comprises : a transmodulator ( 1.3 ) for reception of QPSK modulated signals where the receiver is configured for trans- modulation of received signals to QAM signals and to up-convert the signals to the UHF bandwidth, or

a QAM receiver (2.3) for reception of QAM modulated signals where the receiver is configured for up- converting signals to the UHF frequency band, and the amplifier and filter unit is at least comprising an amplifier and at least a filter, and the transmitting o unit at least comprises a transmitting antenna ( 1.10 , 2.10) adapted for transmission on the UHF frequency band .

14. A method for distribution of radio-, television-, or multimedia signals where the method comprises reception of s said signals within a receiver unit ( 1.3 , 2.3 ) further the method comprises at least further processing of the signals within an amplifier and filter unit and a transmission unit c h a r a c t e r i s e d i n the steps of :

a) in the receiver unit :

o in a transmodulator (1.3) for reception of QPSK modulated radio-, television-, or multimedia signals to transmodulate the signals to QAM signals and then to uρ-convert the signals to UHF frequency band, or

within a QAM receiver (2.3) reception of QAM modulated 5 radio-, television-, or multimedia signals to up- convert the signals to the UHF frequency band, and

b) amplify and filter the up-converted signals in the UHF band, and

c) transmitting the up-converted signals in the UHF band o using a transmitting antenna ( 1.10 , 2.10 ) .

15. Method according to claim 14 , c h a r a c t e r i s e d i n that step b further comprises the step of amplifying the QAM regenerated signal within a preamplifier (2.5 ) and filtrate the signal within a first channel filter integrated in said preamplifier

(2.5) and further to process the signal in a output amplifier (2.8 ) , and filtrate the signal within a second channel filter integrated in said output amplifier (2.8 ) .

16. Method according to claim 14 , c h a r a c t e r i s e d i n that step b further comprises the processing of the signal in a first selective filter ( 1.4 ) after processing in the receiver (2.3 ) thereafter to amplify the signal in a preamplifier ( 1.5 ) and further to transfer the signal to a second selective chan- nel filter, thereafter to feed out the signal to an output amplifier ( 1.8 ) , favourably and thereafter connect the signal to an antenna filter (2.9) and thereafter feed the signal to a transmitting antenna ( 1.10 ) for wireless signal transmission .

17. Use of an apparatus according to the claims 1-7 for the distribution of radio-, television-, or multimedia signals .

18. Use of a system according to the claim 8-17 for the distribution of radio-, television-, or multimedia signals .