Patent Application
20050037795
The invention relates generally to a method and an arrangement for power consumption and an arrangement for RF transmission and RF receiver. Particularly the invention relates to controlling and reducing power consumption in a radio receiver.
In the following, DVB (Digital Video Broadcasting) system and DVB receivers are described as examples, but the use of the invention is not restricted only to the DVB system. Digital video broadcasting has been under development, and it is seen to gradually replace the analog broadcasting systems. This is because of its ability to offer new types of services, digital communication and better quality of service. Digital Video Broadcasting has been under standardisation by European Broadcasting Union (EBU) and European Telecommunications Standards Institute (ETSI) that have created, for example, DVB standard ETS 300 800. Moreover, the DVB standardisation pool includes other standard where digital broadcasting touched. In the digital broadcasting system data is transferred in transport, stream(s). In particular, data can be transferred as MPEG-TS based IP data. The modulation is e.g. Orthogonal Frequency Division Multiplex (OFDM) modulation.
With digital video broadcasting it is possible to achieve a good quality data transfer even if the receiver is mobile. The mobility provides user with the convenience of the flexibility of the reception. Therefore, the mobile applications of terrestrial DVB (DVB-T) will be important. However, the mobile DVB receivers should be small-sized and lightweight with small-sized batteries. Also, the available time of operation between charging the batteries should be long. In achieving this, the power consumption of mobile DVB receivers may become a problem.
A typical DVB receiver comprises tuner integrated circuits (IC's) and discrete amplifiers. Most of the present tuner IC's are operated with +5 V power supply, and if a low voltage battery is used there must be a step up converter for providing the +5 V voltage. However, the voltage of the battery may vary. For example, Li-Io battery providing +3,6 V voltage can also be applied in the present tuner IC. While the transmission of data consists of bursts, it would be possible to turn off the receiver or some parts of the receiver for a period of time between the bursts. That kind of solutions are described in patent documents U.S. Pat. No. 5,878,336 and U.S. Pat. No. 5,515,364.
However, there are certain problems related with applying these solutions in a DVB receiver. Firstly, the break between the data bursts has to be sufficiently long to overcome step-up converters and RF circuits settling time requirements. For example, turning on current, demodulators take approximately 100 symbols corresponding about 150 TS packets. In addition, video content according to the prior art solutions is in nature variable bit rate so it is difficult to predict when particular packet of video data will arrive and thus it is also difficult to predict when the current should be turned on.
A further problem is that in some cases the step up converters output voltage is not entirely dropped down, even if the step up converter is switched off. Therefore, the step up converter leftover voltage appears also in the RF circuits power supply, and RF circuits may not be entirely switched off.
It is an objective of this invention to provide a receiving method and a receiver that offers solutions to the prior art problems. Especially, it is an object of this invention to provide a solution for reducing a power consumption of the receiver, and still to maintain stable receiving conditions and fast tuner lock-in time. In addition one of the object of the invention is to provide a method for controlling power consumption with packet level resolution.
The objects of the invention considering the power saving are fulfilled by turning a receiver at least partly off during the interval of a data reception. In addition, according to the invention, transport stream packets transferred are generated on transport stream generator for providing the predetermined period of the transport stream packets and symbols, whereupon the receiver can be informed about the periodicity of transport stream packets or symbols beforehand if necessary.
An embodiment of the invention is based on switching off the RF circuits connected to the step up converters, and still maintaining power in phase locked loop circuit or in at least a part of the phase locked loop. This is because tuner recovery from power-down to ready-to-receive-data time is mainly originated by the PLL control and lock-in time. According to the embodiment, during the time between the selected data stream packets the power is maintained in at least in some parts of the phase locked loop, while one or several other parts of the receiver are turned off for a certain time period. If there are no selected data to be received for a longer time, then even the phase locked loop is advantageously turned off.
With an embodiment of the invention transferred transport stream packets can be generated so that selected transport stream packet, such as for example PID 1 transport stream packet, is sent periodically, for example, so that every 10th packet is selected transport stream packet, whereupon the receiver is arranged to be on only during to receiving these desired packets. In that situation the receiver can be informed about the periodicity beforehand, advantageously once if the periodicity does not change. That kind of packet level power scheme could be utilized after RF and other OFDM modulator parts of the receiver. At other times particular parts of the receiver can be turned off for saving power. With another embodiment of the invention the selected transport stream packets can be sent also in other predetermined order, such as time based order or order based on data content.
According to the embodiment of the invention the receiver is informed about the periodicity or about the other predetermined order of delivered transport stream packet for example by related data in service information (SI). Another way according to the embodiment of the invention is that the receiver finds or detects the periodicity automatically, such as using an intelligent algorithm. When the receiver detects the periodicity or it is informed about the periodicity, the receiver is able to lock-in to the periodicity. In addition the period of the transport stream packets and/or symbols, where certain information is located, can also be communicated to the receiver by other datagrams or on interaction channel. However, the periodicity is advantageously communicated once to the receiver at the beginning of the data transferring process and then only if the periodicity will change.
In the implementation the phase locked loop circuit can be powered directly from the stabilised low voltage battery. The demodulator may also use this voltage. RF circuits supply voltage is provided by the step up converter and can therefore be switched off during the break between the selected data stream packets. During the step up converter switch off, the phase locked loop circuit maintains the power from the battery. The demodulator may also be switched off during the period by e.g. controlling an internal switch off function. Voltage controlled oscillator tuning voltage is created by using another step up converter. Tuning voltage may also be switched off during the break, if the settling time is sufficiently short.
It is characteristic to a method according to the invention for controlling power consumption in a radio receiver for receiving transport stream packets, wherein selected transport stream packets are transferred to said receiver in predetermined order, that
The invention also applies to an arrangement for controlling power consumption in a radio, receiver for receiving transport stream packets, wherein the arrangement comprises radio transmitting arrangement and radio receiver and means for transferring selected transport stream packets to said radio receiver in predetermined order, which is characterised in that the arrangement comprises
The invention also applies to a radio transmission arrangement for generating transport stream packets and transferring them to a receiver, wherein a radio transmission arrangement comprises means transferring for selected transport stream packets to said receiver in predetermined order, which is characterised in that the radio transmission arrangement comprises
In addition the invention also applies to a radio receiver for receiving transport stream packets, wherein said radio receiver is arranged to receive selected transport stream packets in predetermined order, which is characterized in that the radio receiver comprises
In accordance with another aspect of the invention there is provided a computer program product for controlling power consumption in a radio receiver for receiving transport stream packets, wherein selected transport stream packets are transferred to said receiver in predetermined order, comprising:
Advantageously, the computer program code can be a hardware (Digital Signal Processing), firmware or software implemented in the receiver or in the receiver arrangement.
The one preferred embodiment of the invention is considered to be a use of transport stream generation providing the predetermined period of the selected transport stream packets and symbols and informing the receiver about the periodicity by service information, whereupon at least one or several other parts of the receiver are turned off for a certain time period between the selected data stream packets.
Other preferred embodiments of the invention are presented in dependent claims.
The term “phase locked loop” (PLL) is often understood to include the controlled oscillator for producing the output signal. However, in this context, a “phase locked loop” is considered to include the control parts, and the controllable oscillator is not considered be included in the term. This definition is due to the fact that the oscillator is advantageously located in an integrated circuit together with the mixer, while the control parts are located in a separate integrated circuit.
Some embodiments of the invention are described in the dependent claims.
Next the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which:
The step 206 in the data transferring process is optional and it is performed, for example, once or when it is necessary. The step 206 may be performed in situations, for example, when the periodicity will change. However, in step 206 the radio transmission arrangement may communicate the order or period of selected symbols and/or transport stream packets, where certain information is located, to the receiver. With an embodiment of the invention the order or periodicity may be communicated to the receiver by sending a datagram where the predetermined order or periodicity is disclosed. The order or periodicity may also be communicated to the receiver by related data in service information (SI) or sending data concerning the order or periodicity through an interaction channel. However, the communicating the order or periodicity of the transferred symbols and/or transport stream packets is optional and the periodicity is preferably communicated to the receiver only once at the beginning of the data transfer process. Advantageously the periodicity may be communicated to the receiver also at other times, for example, if the periodicity will change. However it has to be noticed that according to the one embodiment of the invention it is not necessary to communicate the periodicity to the receiver at all because the receiver may also find or detect the periodicity by using an intelligent algorithm.
The radio transmission arrangement transfers the transport stream packets and/or symbols in step 208. According to the invention the radio transmission arrangement can be arranged to operate in a mode, where it transfers the selected symbols and/or transport stream packets in predetermined order or period in order that the receiver can be at least in partly turned off during the interval between to receiving the selected symbols and/or transport stream packets.
When the receiver is locked-in to the periodicity in step 312, or the periodicity is known from earlier steps, at least part of the receiver may be switched off in step 314, after which the receiver can wait predetermined time or signal in step 316. After predetermined time at least part of the receiver is turned on in step 318 for receiving next transport stream packet in step 304. Also receiving a certain signal may cause a turning on process performed in step 318. However, in this situation there must be powered part in the receiver for receiving the certain signal causing a turning on process of the receiver.
It has to be noticed that the steps 306-312 is optional so if there is no information about the new periodicity in step 305 the receiver may next perform the step 314 after the step 305 and switch off at least part of the receiver. Advantageously the receiver performs one of the steps 306, 308 or 312 only once at the beginning of the data receiving process 300 and after logging-in to the periodicity in step 312 the receiver performs only the steps 304, 314, 316 and 318. It is also possible in accordance with one embodiment of the invention that if the receiver is informed about the change of the periodicity in step 305, for example by related data in service information (SI), the receiver may perform the step 306 and/or 308 for finding out the new periodicity and logging-in to this new periodicity.
Also it has to be noticed that at least part of the steps 304-318 in the flow diagram illustrated in
In addition the radio transmitter 400 also comprises means 408 for informing the receiver about the predetermined order or the periodicity of the selected and transferred transport stream packets and/or symbols by related data in service information (SI). The radio transmitter 400 can also comprise means 410 and/or means 412 for informing the receiver about the predetermine order or the periodicity by datagram or interaction channel, respectively. According to the invention the generation of transport stream packets and/or symbols is advantageously managed on a particular transport stream generator 414 on the radio transmitter.
With an embodiment of the invention, the RF signal is received from the radio interface with an antenna, and the received signal is amplified in an RF amplifier. The signal is then filtered with a controllable-frequency pass-band filter, and again amplified in a controllable-gain an AGC (Automatic Gain Control) amplifier. After filtering with pass-band filters the signal is led to a mixer. A voltage controlled oscillator provides a local oscillator signal to the second input of the mixer. An intermediate frequency signal from the mixer output can be amplified and filtered with a narrow-band pass-band filter. The filtered signal can be amplified with an IF amplifier, which gives a feedback control signal for the AGC amplifier. The amplified IF signal can be led to a demodulator that demodulates the intermediate frequency signal into a transport bit stream corresponding to the information that has been modulated into the RF signal. The demodulator may include several functional blocks, such as an Analog-to-Digital converter AD, a Fast Fourier Transformer FFT, Forward Error Correction unit FEC, a channel correlation unit CH. COR., a channel estimator CH. EST., an AGC unit, an interface for a I2C bus, and an output buffer for the transport stream TS OUT.
The synthesizer of the receiver comprises a PLL (Phase Locked Loop), which controls the VCO (Voltage Controlled Oscillator), the output signal of which is amplified by the amplifier in order to generate the output signal for the PLL.
The radio receiver 500 according to the invention comprises means 502 for receiving transport stream packets and/or symbols and means 504 for receiving information concerning the order of the selected transport stream packets and/or symbols. The radio receiver 500 may also comprise means 506 for sending possible query or the like to the radio transmitter for sending a desired or selected data to the receiver. The radio receiver 500 comprises also means 508 for receiving information about the predetermined order or the periodicity of the selected and transferred transport stream packets and/or symbols by related data in service information (SI). The radio receiver 500 can also comprise means 510 and/or means 512 for receiving information about the predetermined order or the periodicity by datagram or interaction channel, respectively.
In addition with an embodiment of the invention the radio receiver 500 comprises means 514 for controlling power of at least part of the receiver, such as for example RF controller 522, digital parts of the front-end 524, demultiplexer controller 526, microprocessor 528, media decoder 530, display 532 or other peripherals. The power controlling means 514 can comprise means 516 for turning on/off power of said part of the receiver or the means 514 are alternatively arranged to operate with means 516. The radio receiver comprises also a power supply 600.
Further the radio receiver 500 according to the present invention advantageously comprises means 518 for detecting the periodicity of the transport stream packets and/or symbols to be received automatically. The radio receiver 500 can be arranged to use for example an intelligent algorithm for detecting the periodicity. Typically the radio receiver 500 comprises also means 520 for locking-in to the periodicity.
The power controlling means 514 may be implemented for example by a computer program product comprising computer program code for turning off power of at least part of the receiver for a period during the time between at least two transport stream packets. The computer program product may comprise also computer program code for informing said receiver when to receive at least one of the following selected transport stream packets. Advantageously, the computer program code can be a hardware (Digital Signal Processing), firmware or software implemented.
It has to be noticed that the means and/or components described above, such as for example an RF amplifier, AGC and filters, may also be a part of a power supply arrangement of the radio receiver illustrated in
The low power integrated circuit (IC) 618 comprising the phase locked loop is connected directly to the stabilised low voltage battery 602, as well as the step up converters 604 and 608, and the demodulator 606. Other RF circuits and IC's are connected to the RF circuit supply voltage, generated in the RF circuit power supply step up converter 604 and the tuning voltage converter 608. During a data transmission break the DC step up converters 604 and 608 and the demodulator IC 606 are switched down from a separate power down pin in the IC's. All the devices connected to the RF circuit power supply, such as an RF amplifier 610, a controllable-gain AGC (Automatic Gain Control) amplifier 612, a mixer/oscillator IC 614 and an IF amplifier IC 616, are therefore switched off. The IC for the phase locked loop being connected directly to the battery power supply 602 remains ready to lock-in, in the transmission channel frequency. The demodulator retains all the previously used parameters such as the code rate, constellation, guard interval and channel estimation during the data transmission break.
The two step-up converters 604 and 608 can be controlled separately, so that either only the RF circuit power supply or both the RF circuit power supply and the tuning voltage power supply can be turned off during the data receive break. The phase locked loop integrated circuit can also be turned down (if this feature supported) from power down switch (IC pin) or via I2c-bus (software) during a longer transmission break. The step up converters can be switched from the demodulator IC, by using I/O-port. Step up converters can be controlled from a separate (power) controller or logic. However, the power may alternatively be switched from the demodulator IC, by e.g. using an I/O-port. The battery supply voltage as well as the demodulator input voltage is preferably low.
With an embodiment of the invention the arrangement 700 comprises means 702 for turning off power of at least part of the receiver for a period during the time between at least two selected transport stream packets, and means 704 for informing said receiver about when to receive at least one of the following selected transport stream packets. The arrangement 700 comprises also means 706 for transferring the transport stream packets to the receiver periodically. This can be achieved for example by a timing unit 706. In addition the arrangement 700 comprises transport stream packet generator or the like for generating selected transport stream packets and providing predetermined period of the transport stream packets or symbols.
In addition the arrangement 700 according to the invention comprises means 708, 710 for communicating the order or periodicity of the selected and transferred transport stream packets to the receiver. This can be performed for example by transferring related data in service information (SI) message or communicating the periodicity to the receiver on interaction channel 710. Alternatively the arrangement may comprise means 712 for detecting the periodicity automatically by the receiver using an intelligent algorithm. The arrangement comprises also means 714 for locking said receiver in to periodicity.
The construction of the control unit of the receiver is not described in a greater detail. In general, the functions in a telecommunication receiver are controlled by a controller including processing capacity in the form of microprocessor(s) and memory in the form of memory circuits. Such arrangements are known as such from the technology of the art. To convert a known telecommunication receiver into a telecommunication device according to the invention, it may be necessary in addition to the hardware changes described above, to store into the memory means a set of machine-readable instructions that instruct the microprocessor(s) of the receiver controller to perform the control operations described above. Composing and storing into memory of such instructions involves known technology which, when combined with the teachings of this patent application, is within the capabilities of a person skilled in the art.
Above, an example embodiment of the solution according to the invention has been described. The principle according to the invention can naturally be modified within the frame of the scope defined by the claims, for example, by modification of the details of the implementation and ranges of use.
Above, DVB-T receiver is used as an example. However, the present invention can naturally be applied, in receivers of any communications system where transmission is not continuous. One example of such a system is Digital Audio Broadcasting (DAB) and mobile telecommunications systems that use Time Division Multiple Access (TDMA) technology.
Above, some examples of values for parameters such as voltages are given. However, other alternative values depending on the circuit design can naturally be applied.
The invention has been explained above with reference to the aforementioned embodiments, and several advantages of the invention have been demonstrated. It is clear that the invention is not only restricted to these embodiments, but comprises all possible embodiments within the scope of the inventive and the following patent claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FI01/00996 | 11/16/2001 | WO |
