Method for bidirectional data transfer in narrowband systems

Abstract

A method for bidirectional data transmission, preferably in narrowband systems, between a base station and a terminal device includes providing the terminal device and the base station with frequency reference units and transmitting data between the base station and the terminal device over different frequencies. A basic transmit frequency is defined for transmitting data from terminal device to base station, the terminal device defines a terminal device transmit frequency on the terminal device side for transmitting data from terminal device to base station, a frequency offset Δf.sub.offset exists between the basic transmit frequency and the terminal device transmit frequency, the terminal device opens a receive window for data from the base station, and the frequency offset Δf.sub.offset is taken into account for opening the window. Base station determines the terminal device transmit frequency and base station transmits data to terminal device based on the determined terminal device transmit frequency.

Claims

1. A method for bidirectional frequency-precise data return transmission in a system or narrowband system between a base station and at least one terminal device, the method comprising the following steps: providing each of the at least one terminal device and the base station with their own frequency reference unit; transmitting the data between the base station and the at least one terminal device over different frequencies; defining a basic transmit frequency for transmitting data from the at least one terminal device to the base station; using the at least one terminal device to define a terminal device transmit frequency on a terminal device side for transmitting data from the at least one terminal device to the base station, and providing a frequency offset Δf.sub.offset between the basic transmit frequency and the terminal device transmit frequency; using the at least one terminal device to open a receive window to receive data originating from the base station, and taking the frequency offset Δf.sub.offset into account for opening the receive window; using the base station to determine the terminal device transmit frequency; using the base station to transmit data back to the at least one terminal device with frequency precision based on the determined terminal device transmit frequency; and wherein the terminal device actively sets the frequency offset Δf.sub.offset in order to define the terminal device transmit frequency.

2. A method for bidirectional frequency-precise data return transmission in a system or narrowband system between a base station and at least one terminal device, the method comprising the following steps: providing each of the at least one terminal device and the base station with their own frequency reference unit; transmitting the data between the base station and the at least one terminal device over different frequencies; using the at least one terminal device to open a receive window to receive data originating from the base station, and providing the window with a frequency offset Δf.sub.up/down in relation to the terminal device transmit frequency; using the at least one terminal device to take Δf.sub.up/down into account for opening the receive window; using the base station to determine the terminal device transmit frequency of the data transmitted by the at least one terminal device; using the base station to transmit data back to the at least one terminal device with frequency precision based on the determined terminal device transmit frequency of the at least one terminal device and incorporating Δf.sub.up/down; and wherein the frequency offset Δf.sub.up/down is a fixed value defined in advance.

3. The method according to claim 2, which further comprises: using the at least one terminal device to define a further terminal device transmit frequency on the terminal device side to transmit data from the at least one terminal device to the base station, and providing a further frequency offset Δf′.sub.offset between the basic transmit frequency and the further terminal device transmit frequency; using the at least one terminal device to take Δf′.sub.offset into account for opening the receive window of the further terminal device transmit frequency; and using the base station to determine the terminal device transmit frequency of the data transmitted by the at least one terminal device at the further terminal device transmit frequency.

4. A method for bidirectional data transmission in a system or narrowband system between a base station and at least one terminal device, the method comprising the following steps: providing each of the at least one terminal device and the base station with their own frequency reference unit; providing each of the at least one terminal device and the base station with at least one radio chip; connecting the frequency reference units to the radio chips; transmitting the data between the base station and the at least one terminal device over different frequencies; using the at least one terminal device to open a receive window to receive data originating from the base station, and taking a frequency offset Δf.sub.chip into account for opening the receive window; the frequency offset Δf.sub.chip being dependent on the radio chips in the at least one terminal device; and wherein the frequency offset Δf.sub.chip is at least one of: determined by measuring frequency-influencing effects of the radio chips; or emanating from the architecture of the radio chips.

5. The method according to claim 4, which further comprises fixing and defining the basic transmit frequency in advance.

6. The method according to claim 4, which further comprises providing the frequency offset Δf.sub.up/down as a fixed value defined in advance.

7. The method according to claim 4, which further comprises making the frequency offset Δf.sub.up/down known to the base station and to the at least one terminal device.

8. The method according to claim 4, which further comprises using the at least one terminal device to define the terminal device transmit frequency for avoiding at least one of interference-affected frequencies or interference-affected frequency ranges.

9. The method according to claim 4, which further comprises using the at least one terminal device to measure at least one of its own transmit power or an external power and to define the terminal device transmit frequency based on the measuring step.

10. A method for bidirectional data transmission in a system or narrowband system between a base station and at least one terminal device, the method comprising the following steps: providing each of the at least one terminal device and the base station with their own frequency reference unit; transmitting the data between the base station and the at least one terminal device over different frequencies; carrying out the data transmission from the at least one terminal device to the base station at frequencies of an uplink band; carrying out the data transmission from the base station to a terminal device at frequencies of a downlink band; using the base station to transmit data to the at least one terminal device based on the determined terminal device transmit frequency and taking a width of the downlink band into account; using the at least one terminal device to take the width of the downlink band into account for opening the receive window; and at least one of: using the base station to transmit data to the at least one terminal device incorporating the frequency offset Δf.sub.wrap; or using the at least one terminal device to take into account the frequency offset Δf.sub.wrap for opening the receive window; or choosing the frequency offset Δf.sub.wrap for locating the resulting transmit frequency of the base station within the downlink band.

11. The method according to claim 10, which further comprises making the uplink band wider than the downlink band.

12. The method according to claim 10, which further comprises making the position of the uplink band and the position of the downlink band known to the base station and to the at least one terminal device.

13. The method according to claim 10, which further comprises providing channels of the bidirectional data transmission in the system or narrowband system with a channel bandwidth range selected from the group consisting of: from 1 kHz to 25 kHz, or from 2 kHz to 6 kHz, or from 3 kHz to 5 kHz.

14. The method according to claim 10, which further comprises providing channels of the bidirectional data transmission in the system or narrowband system with a symbol rate range selected from the group consisting of: from 0.5 kbaud to 20 kbaud, or from 0.5 kbaud to 6 kbaud.

15. The method according to claim 13, which further comprises selecting a frequency tolerance Δf.sub.T of the at least one terminal device to be greater than a bandwidth of the channels.

16. The method according to claim 15, which further comprises selecting the frequency tolerance Δf.sub.T of the at least one terminal device to lie within a range selected from the group consisting of: from 1 ppm to 100 ppm, or from 3 ppm to 50 ppm, or from 5 ppm to 30 ppm.

17. The method according to claim 10, which further comprises using the base station to transmit the data to the respective terminal device incorporating a maximum frequency tolerance Δf.sub.T,max of the at least one terminal device.

18. The method according to claim 10, which further comprises using the at least one terminal device to take into account a maximum frequency tolerance Δf.sub.T,max for opening the receive window.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a highly simplified block diagram of the apparatuses of the base station and the apparatuses of the terminal devices;

(2) FIGS. 2A-2B are highly simplified diagrams of the uplink and the downlink between the base station and the terminal device with the frequency offsets Δf.sub.up/down and Δf.sub.offset;

(3) FIG. 3 is a highly simplified diagram of the uplink and the downlink between the base station and the terminal device for three channels;

(4) FIG. 4 is a highly simplified diagram of the uplink and the downlink between the base station and the terminal device with the frequency offset Δf.sub.chip; and

(5) FIGS. 5A-5B are highly simplified diagrams of the uplink and the downlink with the band limits and the frequency range.

DETAILED DESCRIPTION OF THE INVENTION

(6) Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, it is seen that reference number 101 denotes a base station with an apparatus 103 for receiving a signal transmitted by a terminal device 102 in an uplink 207 at a terminal device transmit frequency 202 which has a frequency offset Δf.sub.offset in relation to a basic transmit frequency 201. The base station 101 further has an apparatus 104 for determining the terminal device transmit frequency 202. An apparatus 105 for transmitting a signal to a terminal device 102 in a downlink 208 similarly forms part of the base station 101. The signals to a terminal device 102 are transmitted at a base station transmit frequency 203 in the downlink 208. In this case, the base station transmit frequency is the determined terminal device transmit frequency 202 which has been supplemented by the frequency offset Δf.sub.up/down. The three apparatuses 103, 104 and 105 of the base station 101 are internally connected.

(7) The three terminal devices 102 shown in each case include an apparatus 107 for transmitting a signal at the terminal device transmit frequency 202 and an apparatus 106 for receiving a signal transmitted by the base station 101 at the base station transmit frequency 203. The signals in the uplink 207, shown by the three arrows pointing from the apparatus 107 of a terminal device 102 for transmission to the apparatus 103 of the base station 101 for reception, are transmitted at the corresponding terminal device transmit frequency 202. The signals in the downlink 208 from the apparatus 105 of the base station 101 for transmission to the apparatuses 106 of the terminal devices 102 for reception are transmitted at the base station transmit frequency 203. The terminal device transmit frequency 202 and the corresponding base station transmit frequency 203 may differ for each individual terminal device 102. Particularly in the case of a plurality of terminal devices 102, it is particularly advantageous if the terminal device transmit frequencies 202 of the individual terminal devices 102 differ from one another so that they do not interfere with one another during the transmission. The corresponding base station transmit frequencies 203 similarly differ from one another. The different terminal device transmit frequencies 202 are preferably located in an uplink band 209 and the corresponding base station transmit frequencies 203 in a downlink band 210.

(8) FIGS. 2A and 2B show the uplink 207 and the downlink 208 between the base station 101 and the terminal device 102 with different frequency offsets Δf.sub.up/down, Δf.sub.offset and Δf.sub.T.

(9) FIG. 2A shows the basic transmit frequency 201 and the terminal device transmit frequency 202 in the uplink 207. The terminal device transmit frequency 202 has a frequency offset Δf.sub.offset. The frequency offset Δf.sub.offset can be defined by the terminal device 102 by changing the terminal device transmit frequency 202. One reason for changing the terminal device transmit frequency 202 may, for example, be a different interferer which the terminal device 102 has identified, for example by using a hidden node detection. A change in the terminal device transmit frequency 202 may furthermore occur, for example, alternatively or additionally on the basis of the measurement of the actual transmit power of the terminal device 102. The base station transmit frequency 203 is shown in the downlink 208. On the basis of the terminal device transmit frequency 201, the base station transmit frequency 203 is shifted by the frequency offset Δf.sub.up/down.

(10) In an alternative configuration or development of the invention, the terminal device 102 takes into account the system tolerances or the stored maximum possible frequency tolerance Δf.sub.T,max. In FIG. 2B, the first frequency offset 211 is shown as the range of the frequency tolerance Δf.sub.T around the basic transmit frequency 201. The frequency tolerance Δf.sub.T is also taken into account in the uplink 207 and in the base station transmit frequency 203 in the downlink 208. The maximum frequency tolerance Δf.sub.T can appropriately be known to the terminal device 102 and to the base station 101. The frequency tolerance Δf.sub.T is furthermore greater in this case than the bandwidth 206 of a channel in the narrowband system.

(11) FIG. 3 shows the uplink 207 and the downlink 208 between the base station 101 and the terminal device 102 by way of example for three channels 1, 2, 3 and 1′, 2′, 3′. The terminal device 102 transmits by default in the uplink 207 in only one channel 1, at the basic transmit frequency 201. If the terminal device 102 wishes to transmit on a different channel, e.g. on channel 2, the terminal device 102 assumes the basic transmit frequency 201 which is supplemented with a corresponding frequency offset Δf.sub.offset. For channel 1, the frequency offset Δf.sub.offset corresponds in this example to 0 Hz. In this case, the terminal device transmit frequency 202 is therefore equal to the basic transmit frequency 201. For channel 2, the frequency offset Δf.sub.offset is unequal to 0 Hz and the terminal device transmit frequency 202 is therefore unequal to the basic transmit frequency 201. For a further channel, in this case, for example channel 3, the frequency offset is Δf′.sub.offset. The frequency offset Δf.sub.offset may be unequal to the frequency offset Δf′.sub.offset. The base station 101 receives the signal from the terminal device 102 and determines the terminal device transmit frequency 202. The channel in which the terminal device has transmitted or had intended to transmit is thus irrelevant to the base station 101. In the downlink 208, the base station 101 transmits a signal back to the terminal device 102 at a base station transmit frequency 203 which has the frequency offset Δf.sub.up/down in relation to the determined terminal device transmit frequency 201. The frequency offset Δf.sub.up/down may describe, for example, the frequency offset from the uplink band 209 to the downlink band 210. The frequency offset Δf.sub.up/down has, for example, been defined in advance and is known to the base station 101 and to the terminal device 102. The terminal device 102 in turn opens its receive window at a frequency which it receives through the supplementing of its basic transmit frequency 201 with the frequency offsets Δf.sub.offset or Δf′.sub.offset and Δf.sub.up/down.

(12) In one specific example, the terminal device 102 transmits in the uplink 208 in channel 1 at a frequency of 868.17 MHz. Assuming that no frequency offset occurs due to external influences such as temperature, i.e. no frequency tolerance Δf.sub.T is to be taken into account, the terminal device 102 transmits at a real frequency of 868.17 MHz. In this example, the basic transmit frequency 201 is 868.17 MHz, and for this reason the frequency offset Δf.sub.offset in this case is 0 Hz. The base station 101 receives the signal and determines the terminal device transmit frequency 202 as 868.17 MHz. On the basis of the terminal device transmit frequency, the base station 101 adds the frequency offset Δf.sub.up/down which, in this example, is 1.4 MHz. The base station 101 thus transmits back to the terminal device 102 at a base station transmit frequency 203 of 869.57 MHz in the downlink 208, corresponding, for example, to the return channel 1′. This terminal device 102 has similarly added the frequency offset Δf.sub.up/down to its terminal device transmit frequency 202 and has correspondingly opened a receive window at 869.57 MHz. The terminal device 102 can thus receive the signal of the base station 101 in the downlink 208.

(13) In a further example, this terminal device 102 intends to transmit in channel 2, for example at a frequency of 868.21 MHz. Under the same assumption that no frequency offset occurs due to external influences, the terminal device 102 transmits at a real frequency of 868.21 MHz. Since the basic transmit frequency 201 in this example is 868.17 MHz, the frequency offset Δf.sub.offset is therefore 40 kHz. The terminal device 102 adds the frequency offset Δf.sub.up/down of 1.4 MHz to the terminal device transmit frequency 202 of 868.21 MHz which is derived from the sum of the basic transmit frequency 201 of 868.17 MHz and the frequency offset Δf.sub.offset of 40 kHz, and opens a receive window at 869.61 MHz, denoted in this case as the return channel 2′. The base station 101 receives the signal from the terminal device 102 and determines the terminal device transmit frequency 202 as 868.21 MHz. The base station 101 correspondingly transmits at a base station transmit frequency 203 of 869.61 MHz. The terminal device 102 can thus receive the signal of the base station 101 in the return channel 2′ in the downlink 208.

(14) In this example, the channels have a spacing of 40 kHz from one another. The bandwidth 206 of the channels can appropriately lie within the range from 1 kHz to 20 kHz, preferably from 2 kHz to 6 kHz, preferably from 3 kHz to 5 kHz.

(15) FIG. 4 shows the basic transmit frequency 201 and the terminal device transmit frequency 202 in the uplink 207. The terminal device transmit frequency 202 has a frequency offset Δf.sub.offset in relation to the basic transmit frequency 201. A frequency offset Δf.sub.chip furthermore occurs due to frequency-influencing effects of the radio chip. The frequency offset Δf.sub.chip can be taken into account in the base station or in the terminal device, so that Δf.sub.chip is taken into account unilaterally. In the present example, Δf.sub.chip RX is taken into account in the terminal device. In this case, Δf.sub.chip, TX denotes the frequency error due to the radio chip of the terminal device during transmission and Δf.sub.chip, RX denotes the frequency error due to the radio chip of the terminal device during reception. The terminal device therefore transmits at a terminal device transmit frequency 202b without compensation of Δf.sub.chip, TX. The base station transmit frequency 203 is shown in the downlink 208. On the basis of the terminal device transmit frequency 202b without compensation of Δf.sub.chip, TX, the base station transmit frequency 203 is shifted by the frequency offset Δf.sub.up/down. A base station transmit frequency 203 of 868 MHz, for example, is intended to be set in the terminal device. However, the determined frequency offset Δf.sub.chip is, for example, 0.000300 MHz, so that the terminal device would open its receive window at a base station transmit frequency 203b of 868.000300 MHz without compensation of Δf.sub.chip. If the terminal device, when opening its receive window, takes into account the frequency offset Δf.sub.chip for the opening of the receive window, the terminal device will open its receive window at the base station transmit frequency 203a of 868.000000 MHz with compensation of Δf.sub.chip. It is possible to take into account the frequency offset Δf.sub.chip alone or in combination with the frequency offset Δf.sub.offset and/or the frequency offset Δf.sub.up/down.

(16) FIGS. 5A and 5B show the uplink 207 and the downlink 208 with an indication of the band limits 205 and a frequency range 204. The uplink band 209 is, for example, wider in this case than the downlink band 210. A frequency tolerance Δf.sub.T which occurs, for example due to external influences such as temperature, is assumed for each channel. The narrower downlink band 210 thus produces a frequency range 204a, the limits of which have a distance from the band limits 205 of the downlink band 210 amounting to half of the frequency tolerance Δf.sub.T,max/2. The frequency range 204b in the uplink band 209 is shifted from the frequency range 204a of the downlink band 210 by the frequency offset Δf.sub.up/down.

(17) FIG. 5A shows two channels (channel 1, 2) in the uplink 207 and their corresponding return channels (channel 1′, 2′) in the downlink 208. Both channels are indicated with corresponding frequency tolerances Δf.sub.T. If the frequencies of the channels in the uplink 207 lie within the frequency range 204b, the corresponding frequencies of the return channels (channel 1′, 2′) shifted by the frequency offset Δf.sub.up/down can be used within the frequency range 204a. The base station 101 and the terminal device 102 know the position of the band limits 205 in the uplink 207 and the downlink 208. In addition, the possible frequency tolerance Δf.sub.T may be known or may have been estimated as the maximum possible frequency tolerance Δf.sub.T,max. The position of the frequency range 204a or 204b in the downlink 208 or uplink 207 is thus also known to the base station 101 and to the terminal device 102. The frequency range 204a or 204b lies within the band limits 205 of the downlink band 210 or the uplink band 209.

(18) In one specific example, the downlink band 210 has a width of 250 kHz with the band limits at 869.4 MHz and 869.65 MHz which the base station 101 and the terminal device 102 know. The uplink band 209 has its band limits, for example, at 868.0 MHz and 868.6 MHz and, with a width of 600 kHz, is wider than the downlink band 210. The possible frequency tolerance Δf.sub.T is furthermore known or has been estimated as a maximum value of ±30 kHz. The limits of the frequency range 204a in the downlink band 210 are therefore at 869.43 MHz and 869.62 MHz. The frequency offset Δf.sub.up/down is 1.4 MHz. The terminal device 102 transmits, for example, on channel 1 at a terminal device transmit frequency 202 of 868.19 MHz. This corresponds to a base station transmit frequency 203 of 869.59 MHz shifted by the frequency offset Δf.sub.up/down and therefore lying within the frequency range 204a. The terminal device 102 recognizes this and sees no need to supplement the base station transmit frequency 203 with an additional frequency offset, for example the frequency offset Δf.sub.wrap. The terminal device 102 consequently opens its receive window at the base station transmit frequency 203 of 869.59 MHz. The base station 101 recognizes in the same way that the base station transmit frequency 203 does not have to be supplemented by an additional frequency offset in order to lie within the frequency range 204a. The base station 101 transmits back to the terminal device 102 at the base station transmit frequency 203 of 869.59 MHz (channel 1′).

(19) Channel 3 in FIG. 5B lies outside the frequency range 204b of the uplink band 209. The corresponding return channel (channel 3′) having the base station transmit frequency 203, incorporating the frequency tolerance Δf.sub.T, may thus lie outside the downlink band 210. In order to avoid this, the base station transmit frequency 203 is supplemented with a frequency offset Δf.sub.wrap in such a way that the resulting base station transmit frequency 203 (channel 3″) lies within the frequency range 204a and therefore, taking into account the frequency tolerance Δf.sub.T, within the downlink band 210. The frequency offset Δf.sub.wrap can appropriately correspond to the width of the frequency range 204. If a frequency offset Δf.sub.wrap is required, the base station 101 transmits at a base station transmit frequency 203 which has been supplemented on the basis of the determined terminal device transmit frequency 202 with the frequency offset Δf.sub.up/down and the additional frequency offset Δf.sub.wrap. The terminal device 102 similarly opens its receive window at a base station transmit frequency 203 with an additional frequency offset Δf.sub.wrap.

(20) The terminal device 102 transmits, for example, on channel 3 at a terminal device transmit frequency 202 of 868.24 MHz. The corresponding base station transmit frequency 203 of 869.64 MHz (return channel 3′) shifted by the frequency offset Δf.sub.up/down would therefore still lie below the upper band limit 205 of the downlink band 210 of 869.65 MHz. However, the real terminal device transmit frequency 202 and the corresponding base station transmit frequency 203 could be up to 30 kHz higher due to the frequency tolerance Δf.sub.T. The real base station transmit frequency 203 with a value of up to 869.67 MHz could therefore lie outside the downlink band 210. Every base station transmit frequency 203 greater than or greater than or equal to 869.62 MHz is correspondingly supplemented with an additional frequency offset Δf.sub.wrap. The frequency offset Δf.sub.wrap corresponds in this case, for example, to the width of the frequency range 204. The frequency range 204 has, for example, a width of 190 kHz, corresponding to the width of the downlink band 210 von 250 kHz minus the frequency tolerance Δf.sub.T of 60 kHz. The resulting base station transmit frequency 203 is therefore 869.45 MHz (return channel 3″). The base station 101 consequently transmits the signal at a base station transmit frequency 203 of 869.45 MHz and the terminal device 102 opens its receive window similarly at the base station transmit frequency 203 of 869.45 MHz.

REFERENCE NUMBER LIST

(21) 1 Channel 1 1′ Return channel to channel 1 2 Channel 2 2′ Return channel to channel 2 3 Channel 3 3′,3″ Return channel to channel 3 101 Base station 102 Terminal device 103 Apparatus of the base station for reception 104 Apparatus of the base station for determination 105 Apparatus of the base station for transmission 106 Apparatus of the terminal device for reception 107 Apparatus of the terminal device for transmission 201 Basic transmit frequency 202 Terminal device transmit frequency 202a Further terminal device transmit frequency 202b Terminal device transmit frequency without compensation of Δf.sub.chip, TX 203 Base station transmit frequency 203a Base station transmit frequency, terminal device receive window with compensation of Δf.sub.chip 203b Base station transmit frequency, terminal device receive window without compensation of Δf.sub.chip 204 Frequency range 205 Band limit 206 Bandwidth 207 Uplink 208 Downlink 209 Uplink band 210 Downlink band