Signal Structure for Ground Timing and Positioning Systems

Abstract

Embodiments herein provide a low frequency (LF) broadcast system that improves upon the LORAN-C system to help optimize the use of available spectrum while modernizing the signal structure of the broadcast signal. In particular, embodiments may utilize an orthogonal frequency division multiplexing (OFDM) signal structure to broadcast timing and data signals in consecutive symbols of an OFDM resource block. The signals may include, for example, a comb 1, comb 2, or comb 3 signal structure. Other signal aspects, such as muting scheme, modulation, frequency offset, etc., may vary depending on the desired functionality.

Description

Technical Field

[0001]

[0001] The present invention generally relates to the field of terrestrial positioning, and more particularly to the use of wireless signals broadcast from terrestrial transmitters to determine the location of a receiver.

Background Art

[0002]

[0002] LORAN-C is a type of LORAN (LOng-RAnge Navigation) system that has been used in many countries over the past few decades to provide ground-based hyperbolic radio navigation for aviation and marine navigation. Mariners and pilots can use timing reference signals broadcast from various transmitters to determine their location within a few hundred feet of accuracy. With the emergence of global navigation satellite systems (GNSS) such as the Global Positioning System (GPS), LORAN-C has finally become obsolete. Many countries, including the United States, have recently discontinued their LORAN-C systems.

Summary of the Invention

[0003]

[0003] Embodiments herein provide a low frequency (LF) broadcast system that improves the LORAN-C system to modernize the signal structure of the timing reference signal, enable data communication, and help optimize the use of the available spectrum. In particular, embodiments can utilize an OFDM signal structure to broadcast the timing reference signal and data signals in consecutive symbols of an orthogonal frequency division multiplexing (OFDM) resource block. The signal can include, for example, a COCOM 1, COCOM 2, or COCOM 3 signal structure. Other signal aspects such as muting schemes, modulation, frequency offset, etc. can vary according to the desired functionality. Such a modernized broadcast system can provide timing and navigation in the event of a GNSS system failure.

[0004]

[0004] An exemplary method of transmitting a wireless RF timing reference signal from a broadcast station according to the present disclosure includes transmitting a timing reference signal using one or more sub-carriers during a period of one or more symbols of a first set of OFDM resource blocks generated in a first sub-frame, where each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent sub-carriers and a series of consecutive symbols. The method further includes transmitting data in at least one of one or more sub-carriers in a symbol following each symbol in which the timing reference signal is transmitted, for each symbol of the one or more symbols in which the timing reference signal is transmitted.

[0005]

[0005] An exemplary method of using a wireless RF timing reference signal in a receiver according to the present disclosure includes receiving a timing reference signal and data transmitted from one or more broadcast stations, where for each of the one or more broadcast stations, each respective timing reference signal is received during a period of one or more symbols of a respective set of OFDM resource blocks, where each OFDM resource block of each respective set of OFDM resource blocks comprises a respective set of adjacent sub-carriers and a respective series of consecutive symbols, and each respective data is received in a symbol following each symbol in which the respective timing reference signal is transmitted. The method further includes obtaining information regarding each of the one or more broadcast stations based on each respective timing reference signal or each respective data transmitted by each broadcast station, and performing one or both of the following operations: (i) determining a clock offset of the receiver based at least in part on each respective timing reference signal and the obtained information regarding at least one of the one or more broadcast stations, or (ii) determining a location of the receiver based at least in part on each respective timing reference signal and the obtained information regarding each of the one or more broadcast stations.

[0006]

[0006] An exemplary broadcast station for transmitting a wireless RF timing reference signal according to the present disclosure includes a wireless communication interface, a memory, and one or more processing units communicatively coupled to the wireless communication interface and the memory. The one or more processing units are configured to perform a function including transmitting a timing reference signal via the wireless communication interface using one or more subcarriers during a period of one or more symbols of a first set of OFDM resource blocks occurring in a first subframe, wherein each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols. The one or more processing units are also configured to transmit data via the wireless communication interface in at least one of one or more subcarriers in a symbol following each symbol in which the timing reference signal is transmitted, for each symbol of the one or more symbols in which the timing reference signal is transmitted.

[0007]

[0007] An exemplary receiver configured to use a wireless RF timing reference signal according to the present disclosure includes a wireless communication interface, a memory, and one or more processing units communicatively coupled to the wireless communication interface and the memory. The one or more processing units are configured to perform a function that includes receiving, via the wireless communication interface, a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations, each respective timing reference signal is received during a period of one or more symbols of each respective set of OFDM resource blocks, wherein each OFDM resource block of each respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols, and each respective data is received in a symbol following each symbol of the one or more symbols during which each respective timing reference signal is transmitted. The one or more processing units are further configured to perform a function that includes obtaining information regarding each of the one or more broadcast stations based on each respective timing reference signal or each respective data transmitted by each broadcast station, and performing either or both of the following operations: (i) determining a clock offset of the receiver based at least in part on each respective timing reference signal and the obtained information regarding at least one of the one or more broadcast stations, or (ii) determining a location of the receiver based at least in part on each respective timing reference signal and the obtained information regarding each of the one or more broadcast stations.

Brief Description of the Drawings

[0008]

Figure 1

[0008] Diagram of a broadcast system according to one embodiment.

Figure 2

[0009] Diagram showing the envelope shape of LORAN-C pulses that can be used in the LORAN-C timing reference signal.

Figure 3

[0010] A graph showing the skywave delay over the downrange distance for different ionospheric heights, applicable to LORAN-C signals and / or other signals transmitted using the broadcast system of FIG. 1.

Figure 4

[0011] A graph showing an OFDM signal structure scheme that can be used to transmit a timing reference signal according to some embodiments.

Figure 5

[0012] An explanatory diagram of two signal structure options for various embodiments.

Figure 6

[0013] An explanatory diagram of what a signal structure using Comb 1, Comb 2, and Comb 3 might look like according to some embodiments.

Figure 7

Figure 8

[0014] An explanatory diagram of how some embodiments can employ v-shift hopping.

Figure 9

[0015] A table showing how a broadcast system according to one embodiment can implement v-shift hopping.

Figure 10

[0016] A block diagram of one embodiment of a receiver that can be utilized as described herein.

Figure 11

[0017] A block diagram of one embodiment of a computer system that can be utilized by a broadcast station to cause the broadcast station to execute the techniques described herein.

Figure 12

[0018] A flowchart of a method for transmitting a wireless RF timing reference signal from a broadcast station according to one embodiment.

Figure 13

[0019] A flowchart of a method for using a wireless radio frequency (RF) timing reference signal in a receiver to determine the location of the receiver according to one embodiment.

Best Mode for Carrying Out the Invention

[0009]

[0020] In accordance with some exemplary implementations, like reference symbols in the various drawings indicate like elements. Further, multiple instances of an element can be indicated by following the first number for the element with a letter, or a hyphen and a second number. For example, multiple instances of element 110 can be indicated as 110-1, 110-2, 110-3, etc., or as 110a, 110b, 110c, etc. When referring to such an element using only the first number, any instance of the element is to be understood (e.g., element 110 in the previous example refers to elements 110-1, 110-2, and 110-3, or to elements 110a, 110b, and 110c).

[0010]

[0021] Next, some exemplary embodiments with respect to the accompanying drawings, which form a part of this application, will be described. While specific embodiments in which one or more aspects of the present disclosure can be implemented are described below, other embodiments can be used and various changes can be made without departing from the scope of the present disclosure or the spirit of the appended claims.

[0011]

[0022] The terms "location" and "position" as used herein are used synonymously. Further, the terms "location estimate", "estimated location", "location", "position", "position estimate", "position fix", "estimated position", "location fix", or "fix" may be used to describe a determined or estimated location of a receiver. This determination may comprise an absolute location (e.g., latitude and longitude, and optionally altitude) or a relative location (e.g., a location expressed as a distance north or south, east or west, and optionally as a distance above or below some other known fixed location, or some other location such as the location of the receiver at some known previous time). A location may also be specified as a geodetic location (e.g., latitude and longitude). A location may further include an uncertainty indication or error indication, such as a horizontal distance and optionally a vertical distance by which the location is expected to be incorrect, or an indication of an area or volume (e.g., a circle or ellipse) within which the receiver is expected to be located at a certain level of confidence (e.g., 95% confidence).

[0012]

[0023] Steps have been made to provide backup location and timing services for GNSS, including modernizing existing LORAN-C broadcast systems. For example, the National Timing Resilience and Security Act establishes requirements for backup location and timing systems that distribute an accurate high-power 100 kHz signal (previously used by LORAN-C) and use the LORAN infrastructure and spectrum. Such systems can help ensure that critical infrastructure continues to operate reliably in the event of an outage or disruption to GNSS. Positioning and other timing-related functions may be performed using such systems. FIG. 1 shows how positioning may be determined in such a system.

[0013]

[0024] FIG. 1 is a diagram of one embodiment of a broadcast system 100 that can be used in a LORAN-C or other LORAN system and can be used to broadcast a modernized signal structure, shown in more detail below, in an embodiment, as an addition or alternative. The broadcast system 100 includes a plurality of broadcast stations 110-1, 110-2, and 110-3 (collectively and generically referred to herein as broadcast stations 110) that broadcast radio frequency (RF) signals at precise times relative to each other. These RF signals are referred to herein as "timing reference signals." The receiver 120 can determine its location upon receipt of these timing reference signals by identifying the broadcast stations 110 that transmit each timing reference signal and using the known locations of the broadcast stations 110 to determine the location of the receiver 120. (For simplicity, the receiver 120 is shown in FIG. 1 as a ship, but it will be understood that the receiver 120 can be located on a ship, vehicle, airplane, or other vessel and can comprise an electronic device or a group of devices. Exemplary components of the receiver 120 are shown in FIG. 10, which is described in more detail below.)

[0025] Positioning can generally proceed as follows. The first broadcasting station 110-1 can transmit a first timing reference signal that travels a distance 130-1 and is received by the receiver 120. The second broadcasting station 110-2 and the third broadcasting station 110-3, which can be located hundreds of kilometers or more away from the first broadcasting station 110-1, can similarly transmit their respective second and third timing reference signals, which travel distances 130-2 and 130-3 respectively. The first, second, and third timing reference signals are unique to the broadcasting stations and enable the receiver 120 to identify the respective broadcasting stations 110 that transmit each timing reference signal. Also, the timing reference signals are transmitted at known times relative to each other. (For example, the third broadcasting station 110-3 broadcasts the third timing reference signal 1 ms after the second timing reference signal broadcast by the second broadcasting station 110-2, which is 1 ms after the first timing reference signal.) Using the time difference at which the timing reference signals are received (e.g., the time difference of arrival (TDOA)) and the known relative time difference at which the timing reference signals are broadcast, the receiver can calculate the difference in the distances 130 between pairs of the broadcasting stations 110.

[0014]

[0026] For example, using the first and second timing reference signals received by the first broadcasting station 110-1 and the second broadcasting station 110-2 (along with known information regarding the locations of these broadcasting stations 110-1, 110-2 and the respective timings of the first and second timing reference signals), the receiver 120 can calculate the difference between the first distance 130-1 following the first hyperbola 140-1 and the second distance 130-2. Similarly, the second and third timing reference signals can be used to determine the hyperbola 140-2 (by following the difference between the distances 130-2 and 130-3), and the first and third timing reference signals can be used to determine the hyperbola 140-3 (by following the difference between the distances 130-1 and 130-3). The estimated location of the receiver can include the location where the hyperbolas 140 intersect. Alternatively, fewer hyperbolas 140 (e.g., two) may be used, and ambiguity resolution (e.g., between two possible locations) can be performed using data from other forms of navigation such as dead reckoning.

[0015]

[0027] Under LORAN-C, the broadcast system 100 can provide a series of pulses where each pulse has a duration of approximately 200 μs, the pulses are separated by approximately 1 - 2 ms, and each series of pulses is separated by 60 - 100 ms. The pulses can use a center frequency of 100 kHz (resulting in a wavelength of 3 km) with a bandwidth of approximately 20 kHz. The identification information of the broadcasting station 110 transmitting the timing reference signal can be determined based on a series of pulses having a unique pattern or frequency, and the location of the broadcasting station can be determined by using a look-up table (e.g., an index or an almanac) to link a unique series of pulses to the location. At a typical transmission power of approximately 1 MW, the baseline (e.g., distance 130) can reach over 1000 km.

[0016]

[0028] The propagation of LORAN-C signals can introduce additional complexity to broadcast system 100. For example, the "sky wave", which is a reflection of the timing reference signal from the ionosphere, can travel an additional 50 - 1000 km (and thus be significantly delayed), and is often found to be a major source of error in the timing reference signal received by receiver 120. Lightning is also a source of interference. In addition, the "ground wave", which is the direct path signal used to determine the location of receiver 120, can be affected by seasonal changes in the conductivity, moisture, and other properties of the ground.

[0017]

[0029] Figure 2 shows the envelope shape of LORAN-C pulse 210 that can be used in the timing reference signal in the LORAN-C system by the method described previously. In the case of LORAN-C positioning, receiver 120 can estimate the envelope 220 of pulse 210 to determine the rough time of arrival (ToA) of pulse 210, and ultimately determine the location of receiver 120 by the method described previously. In addition, receiver 120 can search for the zero crossings 230 of the carrier wave 240 of pulse 210 for a more precise estimate of ToA. For example, in some applications, the third zero crossing has a relatively favorable signal-to-noise ratio (SNR) within pulse 210, but is used based on a balance of being located towards the start of the signal to help reduce multipath interference (described in more detail with respect to Figure 3). As an example, the LORAN-C broadcast system uses a 100 kHz carrier wave 240, which is a 3 km wavelength system. The third zero crossing appears approximately 9 km from the start of the pulse. When analyzing multipath from the sky wave, the delay of the multipath signal can be compared to this 9 km zero crossing occurrence to determine when multipath can be a problem. That is, when receiver 120 observes the ground wave signal to determine the third zero crossing with a 9 km delay, the receiver may be subject to multipath interference from the sky wave that occurs when the delay from the sky wave is less than 9 km.

[0018]

[0030] Figure 3 is a graph plotting the skywave delay over the downrange distance for a signal transmitted at 100 kHz. The different curves on the plot represent different ionospheric heights in the range from 100 km to 1000 km (the curve representing the delay from a skywave reflection at 100 km has the lowest delay in the plot, while the curve representing the delay from a skywave reflection at 1000 km has the highest delay in the plot). As can be seen, the skywave delay from a higher ionospheric reflection (e.g., 1000 km) is much longer than the skywave delay from a lower ionospheric reflection (e.g., 100 km), and thus is much less likely to cause multipath interference. However, as shown in the graph, the skywave delay from a 100 km ionospheric reflection can be less than 9 km at longer distances (starting at approximately 900 km), and thus can cause multipath interference with the ground wave at these longer distances.

[0019]

[0031] To provide a modernized broadcast system that can provide sufficient backup timing and location in the event of GNSS outages, the embodiments provided herein can provide various improvements over previous LORAN-C systems to help optimize the use of this available spectrum while modernizing the signal structure itself. As will be described in more detail below, the embodiments can enable a 100 kHz broadcast system that not only provides a timing reference signal for location determination (also referred to herein and in the figures as a "reference signal", "RS", or "timing RS"), but can also enable data communication via a dedicated communication channel (e.g., downlink communication from a broadcast station 110 to a receiver 120). Additionally, the modernized signal structure can have a significantly reduced peak-to-average ratio relative to the transmitted power, which can reduce the output requirements for the power amplifier and as a result, reduce the equipment cost.

[0020]

[0032] FIG. 4 is a graph showing an OFDM signal structure scheme that can be used to transmit a timing reference signal according to some embodiments. The various blocks shown in FIG. 4 represent resources in both the time domain and the frequency domain that are separated into various blocks as shown, mimicking the OFDM scheme used in modern telecommunications such as Long Term Evolution (LTE®). As with the other figures, it will be understood that FIG. 4 is provided as a non-limiting example. Alternative embodiments may divide time resources and / or frequency resources in different ways. For example, an OFDM scheme with a different number of slots and / or symbols may be used, similar to the scheme currently used in 5th Generation New Radio (5G NR, or simply "NR").

[0021]

[0033] With respect to time, time can be divided into a series of consecutive radio frames, each having a duration of T F . The radio frame can be divided into subframes, each having a duration of T SF . The subframe can be divided into slots and symbols as shown. (For example, each subframe can comprise two slots out of twelve symbols. In some embodiments, the slots may not be used.)

[0034] With respect to frequency, the available frequency spectrum can be divided into a plurality of subcarriers. In this scheme, a subcarrier can comprise a basic unit of frequency. In an embodiment where the carrier frequency is centered at 100 kHz and has a bandwidth of 20 kHz, a subcarrier can thus be a divided portion of the frequency ranging from 90 kHz to 110 kHz.

[0022]

[0035] As shown, the basic unit of the OFDM scheme shown in FIG. 4 can comprise a resource element spanning a single subcarrier and a single symbol. A resource block is formed from a group of adjacent resource elements in both time and frequency and can be used to transmit a timing reference signal and other signals.

[0023]

[0036] Returning to the example with a carrier frequency centered at 100 kHz and having a bandwidth of 20 kHz, the OFDM system adopts a version of the LTE system scaled by 1000 times with respect to the sub-carrier spacing. Therefore, the OFDM system can use 15 Hz sub-carriers instead of 15 kHz sub-carriers. As a result, the radio frame can have a duration T of 10 seconds. F Each of the 10 sub-frames can have a duration T of 1 second. SF The minimum time unit T in this system S is calculated by multiplying the reciprocal of the sub-carrier spacing by the number of effective bits per symbol (subtracting the cyclic prefix from the bits). That is, T S = 1 / (15×2048) = 32.55 ms. Multiplying this by the speed of light gives a length of approximately 9.75 km per bit. In some embodiments, a series frame number (SFN) of 10,240 seconds can be used for frame tracking (similarly, a scaled version of the 10.24 second SFN used in LTE).

[0024]

[0037] According to an embodiment, the positioning of the receiver 120 can be based on receiving a timing reference signal transmitted using one or more resource blocks (as described in more detail below) and determining the time at which the timing reference signal was received. Thus, an embodiment can use a correlation sequence such as a Gold code sequence. Using the scaled values of the exemplary 100 kHz system described in the previous paragraph, the correlation peak between nulls is approximately 33 km, which is higher than the 9 km accuracy for multipath separation in a conventional LORAN-C system (using the third zero crossing as described previously). However, an embodiment can utilize multiple samples of the correlation peak, each separated by a fraction of 33 km. For example, by having a sampling rate of 1 / 4 of the correlation peak null-to-null width, the resulting resolution is slightly over 8 km, which has higher accuracy than a conventional LORAN-C system.

[0025]

[0038] As described above, a modernized broadcast system can transmit data communication in addition to a timing reference signal. Thus, some embodiments may use a cyclic prefix that can be used to mitigate inter-symbol interference. When determining an appropriate cyclic prefix, the inherent interference problem at a low frequency (e.g., 100 kHz) previously described with respect to FIG. 3 can be considered. For example, in some embodiments, an extended cyclic prefix (ECP) rather than a normal cyclic prefix (NCP) may be used, because the length of the ECP (512xT S ) is approximately 5000 km, exceeding the maximum skywave delay interference. (As shown in FIG. 3, the maximum skywave delay interference from an ionospheric height of 1000 km is less than 2000 km.) On the other hand, the length of the NCP (144xT S ) results in a length of approximately 1400 km, which can be subject to skywave delay interference.

[0026]

[0039] As described above, embodiments may use a Gold code sequence for the timing reference signal. Thus, a Gold code sequence generator using other technologies (e.g., NR) may be used. Further, as will be described in more detail below, the entire frequency spectrum can be used for each resource block (e.g., each resource block may include data transmission using all subcarrier frequencies). This can result in no ambiguity or cross terms in the corresponding time-domain correlation peak when the correlation peak is aggregated from the reference signal elements of the entire subframe (e.g., comprising a group of 6 out of 12 symbols in the subframe of the COMB6 signal).

[0027]

[0040] In the case of data communication, the data rate can vary based on the amount of resource elements used per resource block and the modulation. As will be described in more detail below, embodiments may transmit data using the COFDM 6, COFDM 3, COFDM 2, or COFDM 1 scheme. Additionally, different forms of modulation including QPSK, 16QAM, and 64QAM may be used. As an example, an embodiment using COFDM 6 can communicate 12 resource elements per resource block. With a bandwidth of 20 kHz, the broadcast station 110 may be able to transmit 100 resource blocks per second. This results in 1200 resource blocks per second. QPSK modulation can provide 2 bits per resource element, thereby providing 2400 baud per broadcast station 110. The broadcast station 110 can transmit different data, thereby increasing the total capacity of the broadcast system 100 for broadcasting data.

[0028]

[0041] Embodiments may also employ muting according to the desired function. That is, different broadcast stations 110 may refrain from transmitting the timing reference signal and possibly also the data signal for a certain time period in order to enable the receiver to receive signals from other broadcast stations without interference. Additional details regarding how embodiments may employ muting are provided herein below. Muting may be effected, for example, at the symbol level, subframe level, or frame level.

[0029]

[0042] Embodiments of the modernized broadcast system described herein may enable one-way communication (as opposed to two-way communication used in modern telecommunications), so the issues related to uplink communication may not need to be considered. Thus, embodiments may exclude the use of random access channels, other (non-positioning) reference signals, etc., that are used in wireless two-way communication. Even so, in some embodiments where two-way communication is desired, such considerations may be made.

[0030]

[0043] FIG. 5 is a diagram of two signal structure options for various embodiments shown in resource blocks 500-1 and 500-2 (collectively and generically referred to herein as resource block 500). As described in the above example, each resource block 500 can have an extended length of a second, and each subcarrier can be 15 Hz, but the symbol length and subcarrier frequency can vary according to the desired function, as well as the number of symbols. As will be appreciated by those skilled in the art, there can be many resource blocks per subframe. (As described above, there can be 100 resource blocks per subframe located at different frequencies and having different subcarriers to utilize more of the available 20 kHz bandwidth.) As shown by the difference in signal structure between the first resource block 500-1 and the second resource block 500-2, the reference signal and data can be transmitted using multiple resource elements from multiple resource blocks. As can be seen, an embodiment can adopt a signal structure in which the resource elements used to transmit data follow the resource elements used to transmit the timing reference signal.

[0031]

[0044] With regard to subcarrier usage, an embodiment can transmit a timing reference signal and data on each subcarrier of a resource block. As shown in FIG. 5, for example, each subcarrier is used once within a resource block to transmit a timing reference signal. Further, this pattern can be repeated for all resource blocks across the carrier bandwidth. Thus, when performing coherent integration of the timing reference signal over one second (the length of the resource block), the resulting frequency domain pulse response is over the entire bandwidth. This can help prevent ambiguity in correlation and the resulting location determination.

[0032]

[0045] Depending on the desired function, different signal structures may be employed to provide a more robust broadcast in the event of a symbol outage. For example, the structure of the second signal structure 500-2, like the first signal structure 500-1, provides the full bandwidth frequency domain response described above by using each subcarrier. However, since the second signal structure 500-2 moves to adjacent subcarriers after transmitting the timing reference signal and data, this structure may be more vulnerable to consecutive symbol outages. This is because this structure makes it relatively difficult to resolve ambiguities (resulting from interference terms due to holes in the frequency domain response). On the other hand, the first signal structure 500-1 helps to avoid this problem by moving to non-adjacent subcarriers (subcarriers that are not directly adjacent) after each transmission of the timing reference signal and data. Any resulting frequency holes due to symbol outages are more "spread out" in the spectrum, and thus the resulting ambiguities are easier to resolve. As will be appreciated, alternative embodiments may employ a wide variety of alternative signal structures using similar mechanisms.

[0033]

[0046] As described above, the use of all sub - carriers on a resource block used to transmit a timing reference signal in a given sub - frame can provide a full - spectrum signal when coherent integration is performed over the sub - frame, thereby reducing the ambiguity terms that can arise from partial - spectrum use. However, embodiments need not be so limited. For example, in some embodiments, coherent integration can be performed over a portion of the resource block, enabling faster integration when the ambiguity can be resolved. For example, resolving the ambiguity can be facilitated by using a tracking technique that includes an initial integration over the entire sub - frame (e.g., 1 second) to resolve any ambiguity, and then subsequent integrations over only a portion of the sub - frame (e.g., if coherent integration is performed symbol - by - symbol, it can be over only 1 / 12 second, for example). The ambiguity obtained in these subsequent integrations can then be resolved by leveraging the previous information obtained from the initial integration. Additional or alternative information sources can make it possible to resolve the ambiguity arising from partial - spectrum use.

[0034]

[0047] Since the resource element for transmitting data can come immediately after the resource element used to transmit the timing reference signal, the demodulation of the obtained data can be easier at the receiver 120. That is, the receiver 120 can use the signal used to transmit the timing reference signal as a phase reference in the demodulation of subsequent data. For example, when the signal is modulated using a QPSK modulation scheme (having four phases), since the phases used in the modulation of the timing reference signal are known, these phases can be used as a phase reference for the demodulation of subsequent data.

[0035]

[0048] The embodiment shown in FIG. 5 utilizes the COMB 6 structure, but it should be noted that alternative embodiments are not so limited. As will be appreciated by those skilled in the art, COMB 6 is a structure in which data is broadcast for every sixth subcarrier, enabling an effective increase in the transmission power by the broadcasting station. However, alternative embodiments may utilize the COMB 1, COMB 2, or COMB 3 structure, depending on the desired function.

[0036]

[0049] For example, FIG. 6 shows how an embodiment utilizing the COMB 1, COMB 2, and COMB 3 signal structures might look. The illustrated example starts transmitting the timing reference signal and the data signal in the third and fourth symbols of each resource block, but the embodiment is not so limited. Different embodiments may start transmitting at different times, utilize different patterns, and / or utilize different numbers of resource elements. Regarding the use of resource elements, the example shown in FIG. 6 uses the same number of resource elements as the example in FIG. 5, two resource elements (one for the timing reference signal and one for the data). However, again, the embodiment is not so limited. For example, FIG. 7 shows how an embodiment utilizing the COMB 1, COMB 2, and COMB 3 signal structures might look if transmission occurs during all symbols of the resource block. Other embodiments may vary.

[0037]

[0050] Some embodiments may utilize a code space to identify different broadcast stations 110, where each station may have a unique ID / code. However, to help make the system more efficient (by preventing searches across a large code space), the number of codes can be reduced to the amount of stations that can be detected at a given receiver. Thus, embodiments can organize broadcast stations 110 into orthogonal groups and utilize the “soft requirement” that the resulting broadcast station ID space size be divisible by the number of codes. For example, if ten groups are used for a code-6 signal structure, the resulting broadcast station ID space size is 60. Assuming the number of LORAN-C stations in North America is 28, this space size may be sufficient. In fact, alternative embodiments can use a smaller space size, but using a code space size of 60 can help prevent the design from becoming obsolete if additional broadcast stations 110 are used in the future.

[0038]

[0051] Codes can be generated using a code sequence generator (e.g., a Gold code sequence generator). In some embodiments, the code sequence generator can generate a unique sequence as a function of symbols and subframes or slots in a manner similar to NR / LTE. Generating a unique code based on symbols and subframe / slot numbers in this way can increase the code space by a factor of ten. Continuing with the example where the station ID space is 60, this can result in 600 searchable codes. However, embodiments need not be so limited. In some embodiments, for example, the code can be, additionally or alternatively, a function of the number of frames, which can increase the code size by a factor of 1024.

[0039]

[0052] Some embodiments may employ v-shift “hopping” to account for the possibility that timing reference signals from different broadcast stations 110 may collide. In v-shift hopping, a group of broadcast stations can shift subcarrier usage as a function of subframes and / or slots, thereby enabling signals that may collide in one subframe to avoid collisions in another subframe.

[0040]

[0053] FIG. 8 provides an explanatory diagram of v-shift hopping. The first resource block 800-1 shows a pattern of a timing reference signal and data signals without a shift. This may be regarded as a basic pattern or a standard pattern from which a v-shift offset can be created. The second resource block 800-2 shows an example of how the pattern of resource elements used in the first resource block 800-1 can be offset by one subcarrier to help prevent collisions between broadcast stations 110. For the case of the comb6 pattern in a resource block 800 having 12 subcarriers, the pattern can be offset by up to 5 subcarriers before the pattern repeats. Thus, including a shift of 0, there are six available v-shift offsets. (Similarly, there are three available V-shift offsets for a comb3 signal structure and two available V-shift offsets for a comb2 signal structure.) The broadcast stations 110 can enter v-shift hopping by applying different V-shift offsets at different times and thereby using different subcarriers to transmit different timing reference and data signals. An example of how this can be implemented is shown in FIG. 9.

[0041]

[0054] FIG. 9 is a table showing how the broadcast system 100 according to one embodiment can implement v-shift hopping. This table shows the offsets employed by different groups of the broadcast station 110 for different subframes. The first column shows the IDs of the broadcast stations 100, which are divided into six groups. The remaining columns show the v-shift offsets employed by each group for a given subframe. (The offset here represents the coom 6 signal structure in a resource block similar to that shown in FIG. 8, which has 12 subcarriers. As described above, since the signal is broadcast on two subcarriers of the resource block at a time, there are six available offsets 0 to 5.) In subframe 0, none of the groups use an offset. In the next subframe, half of the groups use an offset of 1. Additional groups of the broadcast station 110 employ additional offsets in subsequent subframes. Finally, the various groups of broadcast stations cycle through the offsets so that each group avoids colliding with every other group for at least one subframe. It will be appreciated that the table shown in FIG. 9 provides only an example of how v-shift hopping can be implemented. Alternative embodiments can utilize additional or alternative v-shift hopping patterns.

[0042]

[0055] Additionally or alternatively, as described above, embodiments may employ muting in a similar manner such that different groups of broadcast stations refrain from broadcasting signals as a function of subframes to help prevent signal collisions. More specifically, broadcast station 110 may transmit a timing reference signal and data signals at a predetermined schedule or period. Muting occurs when broadcast station 110 refrains from broadcasting the timing reference signal, and optionally the data signal, at a given scheduled periodic instance. Similar to FIG. 9, broadcast station 110 may be divided into different groups, where each group uses a different muting pattern to help reduce signal collisions between groups. For example, every 10 subframes, a first group may mute on subframes 0, 2, 4, 6, and 8, a second group may mute on subframes 0, 1, 2, 3, and 4, a third group may mute on subframes 0, 3, 6, and 9, and so on.

[0043]

[0056] Some embodiments may include techniques for mitigating inter-symbol interference and inter-carrier interference. As described above, for example, embodiments may utilize an ECP having a length greater than the maximum ionospheric delay to help reduce inter-symbol interference. Additionally or alternatively, embodiments may account for inter-carrier interference resulting from different broadcast stations with inconsistent frequencies. For example, the Doppler-induced frequency change at Mach 1 is 0.1133 Hz, which is much smaller than the 15 Hz sub-carrier spacing that may be used in some embodiments. Thus, the clock accuracy target may be determined from the sub-carrier spacing and Doppler requirements. An example of a target having a maximum of 0.15 Hz (greater than the frequency offset at Mach 1) results in a 1.5 parts per million (PPM) offset. Having such a quality clock enables the receiver to avoid frequency search and move directly to performing time search for the broadcast signal.

[0044]

[0057] As described above, the data signal can be accompanied by a timing reference signal and provides a downlink data channel from the broadcasting station 110 to the receiver 120. However, in some cases, such data may not be required. Therefore, some embodiments may be involved in data slotting such that data is transmitted only in a portion of a subframe. For example, data can be communicated once every 10 subframes, resulting in a baud rate of 1 / 10. If necessary, a greater or lesser number of subframes can be used for the data. According to some embodiments, this can be dynamically set and communicated to the receiver 120 to accommodate an increase or decrease in data requirements.

[0045]

[0058] Additionally or alternatively, embodiments may utilize data repetition to ensure that data is sufficiently communicated to the receiver. In some embodiments, for example, the data can simply be repeated across different resource blocks in frequency and / or time. This can help ensure effective data communication in the event that one or more subcarriers experience outages.

[0046]

[0059] In some embodiments, the data can be encoded with a Zadoff Chu code, which can provide a correlation gain. For example, in an implementation of COMA 6 with a bandwidth of 20 kHz and a subcarrier spacing of 15 Hz, there can be 200 resource elements per symbol. Since the Zadoff Chu code uses a prime length sequence, a Zadoff Chu code of length 199 (which is prime) can be used. The differential Zadoff Chu code can be assigned as data. Since there are 198 sequences with a length of 199, a series of bits can be assigned to each of the 198 sequences, resulting in approximately 7.5 bits per symbol, i.e., a capacity of 45 bauds.

[0047]

[0060] In some embodiments, π / 2 - BPSK modulation (rather than, for example, QPSK or other modulation schemes) may be used. Similar to Zadoff Chu codes, this type of modulation can result in a reduction of the peak - to - average ratio of the signal, which can lead to an increase in the signal level. This may reduce the data capacity, but it can be particularly beneficial in providing a larger range for broadcast signals without saturating the power amplifier of the transmitter at the broadcast station. Similarly, embodiments may use Alamouti coding to extend the reception range.

[0048]

[0061] FIG. 10 shows one embodiment of a receiver 120 that may be utilized as described above herein. Note that FIG. 10 is only intended to give a generalized view of various components, and it should be noted that any or all of those components may be utilized as appropriate. In some cases, the components shown by FIG. 10 may be localized in a single physical device and / or may be distributed among various networked devices disposed at different physical locations. For example, the receiver 120 may be incorporated in and / or utilized by an airplane, a ship, or other vehicle and may include various components disposed at different locations on the vehicle.

[0049]

[0062] Receiver 120 is shown that includes hardware elements that can be electrically coupled via bus 1005 (or, optionally, may communicate in other ways). The hardware elements can include, without limitation, one or more general-purpose processors, one or more dedicated processors (such as digital signal processing (DSP) chips, graphics acceleration processors, application specific integrated circuits (ASICs), etc.), and / or other processing structures or means, and can include (one or more) processing units 1010. As shown in FIG. 10, some embodiments can have a separate digital signal processor (DSP) 1020 depending on the desired functionality. Location determination and / or other determinations based on wireless communication can be provided at processing unit 1010 and / or communication interface 1030 (described below). Receiver 120 can also include one or more input devices 1070 that can include, without limitation, a keyboard, touch screen, touch pad, microphone, buttons, dials, switches, etc., and one or more output devices 1015 that can include, without limitation, a display, light emitting diodes (LEDs), speakers, etc.

[0050]

[0063] The receiver 120 may also include a communication interface 1030, which may comprise, but is not limited to, a modem, network card, infrared communication device, wired communication device, wireless communication device, and / or chipset, etc., that may enable the receiver 120 to transmit and / or receive data communications via wired and / or wireless means. This can include, in addition to or as an alternative to wireline communications using optical fiber, coaxial cable, twisted pair, and / or similar wired means, wireless communications such as cellular, Wi-Fi®, Bluetooth®, conventional maritime and / or aeronautical radio frequency (RF) communications, etc. Such wired communications may be performed via a wired communication interface 1031, which may be a sub-component of the communication interface 1030 as shown. In an alternative embodiment, the wired communication interface 1031 may be separate from the communication interface 1030. Thus, the communication interface 1030 may enable data and signaling to be communicated (e.g., transmitted and received) with a network and / or network components, computer systems, and / or any other electronic device.

[0051]

[0064] In particular, depending on the desired functionality, the communication interface 1030 may include a separate transceiver for wireless communication with a base station and other terrestrial transceivers such as wireless devices and access points. The receiver 120 may communicate with different data networks that may include various network types. For example, a wireless wide area network (WWAN) may be a code division multiple access (CDMA) network, a time division multiple access (TDMA) network, a frequency division multiple access (FDMA) network, an orthogonal frequency division multiple access (OFDMA) network, a single carrier frequency division multiple access (SC-FDMA) network, a WiMax (registered trademark) (IEEE 802.16) network, etc. The CDMA network may implement one or more radio access technologies (RATs) such as CDMA2000, wideband CDMA (WCDMA (registered trademark)), etc. CDMA2000 includes the IS-95 standard, the IS-2000 standard, and / or the IS-856 standard. The TDMA network may implement the Global System for Mobile Communications (GSM (registered trademark)), the Digital Advanced Mobile Phone System (D-AMPS), or some other RAT. The OFDMA network may adopt LTE, LTE Advanced, 5G NR, etc. 5G NR, LTE, LTE Advanced, GSM, and WCDMA are described in documents from the "Third Generation Partnership Project" (3GPP (registered trademark): Third Generation Partnership Project). CDMA2000 is described in documents from a group called the "Third Generation Partnership Project 2" ("3GPP2": 3rd Generation Partnership Project 2). The documents of 3GPP and 3GPP2 are publicly available.A wireless local area network (WLAN) may also be an IEEE 802.11x network, and a wireless personal area network (WPAN) may be a Bluetooth network, an IEEE 802.15x network, or some other type of network. Also, the techniques described herein may be used for any combination of WWAN, WLAN, and / or WPAN. Communication may be performed via one or more wireless communication antennas 1032 that transmit and / or receive wireless signals 1034. The communication interface 1030 and / or the processing unit 1010 may perform demodulation, correlation, integration, and / or other processing of timing reference signals and / or data signals as described herein.

[0052]

[0065] The receiver 120 may further include a sensor 1040. The sensor 1040 may include, without limitation, one or more inertial sensors and / or other sensors (e.g., accelerometers, gyroscopes, cameras, magnetometers, altimeters, microphones, proximity sensors, optical sensors, barometers, etc.), some of which may be used in some instances to complement and / or facilitate the positioning described herein. As described above, for example, the receiver 120 may use dead reckoning to resolve ambiguities in positioning. The sensor 1040 may include one or more motion sensors that may be used to perform dead reckoning.

[0053]

[0066] Embodiments of the receiver 120 may also include a low-frequency receiver 1080 capable of receiving signals broadcast by a broadcast station in the manner shown in the embodiments described previously. Generally, a low-frequency receiver may receive RF signals in the low-frequency (LF) band (30 kHz to 300 kHz). More specifically, the low-frequency receiver 1080 may be tuned to receive signals within a frequency band centered substantially at 100 kHz, as described herein. In some embodiments, the low-frequency receiver 1080 may be part of a low-frequency transceiver used in marine radio, marine navigation, and / or other applications.

[0054]

[0067] Some embodiments of the receiver 120 may also include a GNSS receiver (not shown), such as a GPS receiver, that may sometimes be used when GNSS outages do not occur. The GNSS receiver may be capable of receiving signals 1084 from one or more GNSS satellites using an antenna 1082 (which may be the same as antenna 1032). Positioning based on GNSS signal measurements may be utilized to complement and / or incorporate the techniques described herein. The GNSS receiver may use conventional techniques to extract the position of the receiver 120 from GNSS satellites such as GNSS systems, GPS, Galileo, Glonass, the Quasi-Zenith Satellite System (QZSS) over Japan, the Indian Regional Navigation Satellite System (IRNSS) over India, and the BeiDou Navigation Satellite System (BDS) over China. Additionally, the GNSS receiver may be associated with, or in some cases used with, various augmentation systems (e.g., satellite-based augmentation systems (SBAS)) such as the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), the Multi-functional Satellite Augmentation System (MSAS), and the GPS Aided Geo Augmented Navigation System (GAGAN), one or more global navigation satellite systems and / or regional navigation satellite systems.

[0055]

[0068] The receiver 120 may further include and / or communicate with a memory 1060. The memory 1060 can include, but is not limited to, local storage and / or network-accessible storage, a disk drive, an array of drives, an optical storage device, and solid-state memory devices such as random access memory (RAM) and / or read-only memory (ROM) that can be programmable, flash-updatable, etc. Such storage devices can be configured to implement any suitable data store, including, but not limited to, various file systems, database structures, etc.

[0056]

[0069] The memory 1060 of the receiver 120 can also include software elements (not shown in FIG. 10) including an operating system, device drivers, executable libraries, and / or other code such as one or more application programs. The one or more application programs can comprise computer programs provided by various embodiments and / or be designed to implement and / or configure a system according to other methods provided by other embodiments as described herein. By way of example only, one or more of the procedures described above with respect to the methods can be implemented as code and / or instructions in the memory 1060 executable by the receiver 120 (and / or the processing unit 1010 or DSP 1020 within the receiver 120). In one aspect, such code and / or instructions can then be used to configure and / or adapt a general-purpose computer (or other device) to perform one or more operations according to the described methods.

[0057]

[0070] FIG. 11 shows an embodiment of a computer system 1100 that can be used in and / or incorporated into one or more components of a broadcast station 110 as described herein. FIG. 11 provides a schematic diagram of an embodiment of a computer system 1100 that can implement methods provided by various other embodiments. Note that FIG. 11 only gives a generalized view of various components, and any or all of those components can be used as appropriate. Thus, FIG. 11 roughly shows how individual system elements can be implemented, either relatively separated or relatively more integrated. Additionally, note that the components shown by FIG. 11 can be localized in a single device and / or distributed among various networked devices. As shown in the previously described embodiments, the location of the broadcast station 110 (or more specifically, a transmitter of the broadcast station 110 that is part of the wireless communication interface 1133 of FIG. 11 and can be described hereinafter herein) is known and can be used for the positioning of one or more receivers 120. The known location of the broadcast station 110 can be maintained in a lookup table (e.g., a database or an almanac) of one or more receivers 120.

[0058]

[0071] A computer system 1100 is shown that includes hardware elements that can be electrically coupled via a bus 1105 (or, optionally, may communicate otherwise as appropriate). The hardware elements may include, without limitation, one or more general-purpose processors, one or more dedicated processors (such as digital signal processing chips, graphics acceleration processors, etc.), and / or a processing unit 1110 that can include other processing structures configured to implement one or more of the methods described herein, including the method described with respect to FIG. 11. The computer system 1100 may also include one or more input devices 1115 that can include, without limitation, a mouse, keyboard, camera, microphone, etc., and one or more output devices 1120 that can include, without limitation, a display device, printer, etc.

[0059]

[0072] The computer system 1100 may further include (and / or may be in communication with) one or more non-transitory storage devices 1125 that may include, without limitation, local and / or network-accessible storage, and / or may include solid-state storage devices such as RAM and / or ROM that may be, without limitation, a disk drive, drive array, optical storage device, programmable, flash-updateable, etc. Such storage devices may be configured to implement any suitable data store that includes, without limitation, various file systems, database structures, etc.

[0060]

[0073] Computer system 1100 may also include a communication subsystem 1130 that can include support for wireline communication technologies and / or wireless communication technologies managed and controlled by a wireless communication interface 1133. The wireless communication interface 1133 can also be used to transmit the broadcast signals described herein. Accordingly, the wireless communication interface 1133 and / or the processing unit 1110 can be used to create, modulate, and transmit the broadcast signals described herein that can be transmitted using the transmitter of the wireless communication interface 1133. The communication subsystem 1130 can include, for example, a modem, a network card (wireless or wired), an infrared communication device, a wireless communication device, and / or a chipset. The communication subsystem 1130 can include one or more input and / or output communication interfaces, such as the wireless communication interface 1133, to enable data and signaling to be exchanged with a network, a remote device, other computer systems, and / or any other electronic devices described herein. Data broadcast by a broadcast station 110 using the data signals described herein can be received, for example, from one or more remote devices via the communication subsystem 1130. Additionally or alternatively, the data can be transmitted from the broadcast station 110 itself.

[0061]

[0074] In many embodiments, computer system 1100 may further include a working memory 1135 that can include RAM and / or ROM devices. Software elements shown as being located within working memory 1135 may comprise computer programs provided by various embodiments, and / or, as described herein, other code such as an operating system 1140, device drivers, executable libraries, and / or applications 1145 that can be designed to implement a method and / or configure a system provided by other embodiments. By way of mere example, one or more procedures described with respect to the methods described above may be stored (e.g., temporarily) in working memory 1135 and implemented as code and / or instructions executable by a computer (and / or a processing unit within a computer such as processing unit 1110), and then, in one aspect, such code and / or instructions may be used to configure and / or adapt a general-purpose computer (or other device) to perform one or more operations in accordance with the described methods.

[0062]

[0075] These sets of instructions and / or code can be stored on a non-transitory computer-readable storage medium such as the storage device 1125 described above. In some cases, the storage medium can be incorporated within a computer system such as the computer system 1100. In other embodiments, the storage medium can be separate from the computer system (e.g., a removable medium such as an optical disk), and / or the storage medium can be provided as an installation package such that it can be used to program, configure, and / or adapt a general-purpose computer with the instructions / code stored thereon. These instructions can take the form of executable code that is executable by the computer system 1100, and / or can take the form of source code and / or installable code that takes the form of executable code when compiled and / or installed on the computer system 1100 (e.g., using any of various generally available compilers, installation programs, compression / decompression utilities, etc.).

[0063]

[0076] FIG. 12 is a flowchart of a method 1200 for transmitting a wireless RF timing reference signal from a broadcast station according to one embodiment. Similar to the other figures in this specification, FIG. 12 is provided as a non-limiting example. Alternative embodiments can include additional or alternative functions to those shown in the blocks shown in FIG. 12. The means for performing the functions of the blocks can include the hardware components and / or software components of the computer system shown and previously described in FIG. 11 that can be incorporated within the broadcast station 110.

[0064]

[0077] The function in block 1210 comprises transmitting a timing reference signal using one or more sub - carriers during the period of one or more symbols of a first set of OFDM resource blocks that occur in a first sub - frame, where each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent sub - carriers and a series of consecutive symbols. As described above with respect to the resource blocks in the embodiments described, a resource block can include any number of adjacent sub - carriers and symbols. The means for performing the function in block 1210 can include the processing unit 1110, the bus 1105, the working memory 1135, the communication subsystem 1130, the wireless communication interface 1133, and / or other components of a computer system such as the computer system 1100 shown in FIG. 11 and described above that can be incorporated into the broadcast station 110.

[0065]

[0078] The function in block 1220 comprises transmitting data in at least one of one or more sub - carriers among one or more symbols following each of the one or more symbols in which the timing reference signal is transmitted. As described above, transmitting data in the symbol immediately following the symbol used for the timing reference signal can be efficient because the receiver 120 can use the timing reference signal as a phase reference for demodulating the data. The means for performing the function in block 1220 can include the processing unit 1110, the bus 1105, the working memory 1135, the communication subsystem 1130, the wireless communication interface 1133, and / or other components of a computer system such as the computer system 1100 shown in FIG. 11 and described above that can be incorporated into the broadcast station 110.

[0066]

[0079] As detailed in the embodiments described previously, embodiments may include additional features according to desired functionality. According to some embodiments, the timing reference signal and data are transmitted using a frequency band centered substantially at 100 kHz. Additionally or alternatively, the timing reference signal and data are transmitted using a COFDM 6, COFDM 3, COFDM 2, or COFDM 1 signal structure. As shown with respect to FIG. 5, the timing reference signal and data signal may be transmitted using a pair of subcarriers to transmit the signal on consecutive symbols. Thus, an alternative embodiment of method 1200 may include transmitting the timing reference signal and data such that for each resource block of a first set of OFDM resource blocks, a first pair of one or more subcarriers is used for a first plurality of consecutive symbols of each respective OFDM resource block, and a second pair of one or more subcarriers is used for a second plurality of consecutive symbols of each respective OFDM resource block immediately following the first plurality of consecutive symbols. Further, as shown in FIG. 5, the signal structure may be such that non-adjacent subcarriers are used in consecutive symbols to reduce the impact of subcarrier outage. Thus, according to some embodiments, none of the subcarriers in the second pair of subcarriers are directly adjacent to any of the subcarriers in the first pair of subcarriers.

[0067]

[0080] Embodiments may include, additionally or alternatively, muting patterns and / or hopping patterns according to desired functions. According to some embodiments, for example, method 1200 further comprises transmitting additional timing reference signals and a portion of data in a plurality of subsequent sets of OFDM resource blocks so that a muting pattern is executed to omit transmission of the additional timing reference signals and a portion of the data during at least one set of the OFDM resource blocks among the plurality of subsequent sets of OFDM resource blocks, thereby implementing muting. To implement frequency hopping, some embodiments may further comprise transmitting additional timing reference signals and data in a plurality of subsequent sets of OFDM resource blocks such that a frequency offset is implemented to offset the frequency of transmission of at least a portion of the additional timing reference signals and data during at least one set of the OFDM resource blocks among the plurality of subsequent sets of OFDM resource blocks.

[0068]

[0081] The timing reference signals and data transmitted in method 1200 may also vary in other respects according to desired functions. For example, the timing reference signals and data are transmitted using pi / 2 binary phase shift keying (BPSK), 4-phase shift keying (QPSK), 8-phase shift keying (8-PSK), 16 quadrature amplitude modulation (16QAM), or 64QAM modulation, or any combination thereof. In some cases, the timing reference signals and data are transmitted such that all subcarriers of each respective OFDM resource block are used for each resource block of the first set of OFDM resource blocks. In some embodiments, the timing reference signal is transmitted using a code unique to the broadcast station within the code space for the broadcast station. This may include, for example, a Gold code. Additionally or alternatively, the data may be transmitted using a Zadoff Chu code.

[0069]

[0082] Depending on the desired functionality, the broadcast station can further include one or more types of information in the data. For example, according to some embodiments, method 1200 can further comprise including in the data information indicating the identification information of the broadcast station, the location of the broadcast station, or the system time of the broadcast station, or any combination thereof. The receiver can then use this information together with the timing reference signal to determine its location and / or determine the clock offset of the receiver from the system time of the broadcast station.

[0070]

[0083] FIG. 13 is a flowchart of a method 1300 of using a wireless radio frequency (RF) timing reference signal in a receiver according to one embodiment. As shown in the previously described embodiments, these signals can be used to determine the location of the receiver and / or determine the clock offset of the receiver. FIG. 13 is provided as a non-limiting example. Alternative embodiments can include additional or alternative functionality to that shown in the blocks of FIG. 13. The means for performing the functions of the blocks can comprise hardware components and / or software components of the receiver 120, including the components of the computer system shown in FIG. 11 and described previously.

[0071]

[0084] The function in block 1310 comprises receiving a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations, (i) each respective timing reference signal is received during the period of one or more symbols of each respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block of each respective set of OFDM resource blocks comprises each respective set of adjacent subcarriers and each respective series of consecutive symbols, and (ii) each respective data is received in a symbol following each symbol of the one or more symbols during which the respective timing reference signal is transmitted. Examples of the timing reference signal and each respective data are described above and shown in FIGS. 5 - 8. Also, according to some embodiments, the timing reference signal and data are transmitted using a frequency band in the LF spectrum. This can include, for example, a frequency band centered substantially at 100 kHz. The means for performing the function in block 1310 can include the processing unit 1010, the bus 1005, the memory 1060, the low frequency receiver 1080, and / or other components of the receiver 120, such as the components shown in FIG. 10 and described above.

[0072]

[0085] The function in block 1320 comprises obtaining information regarding each of one or more broadcast stations based on each timing reference signal or each data transmitted by each broadcast station. As described above, a broadcast station may transmit a timing reference signal using a code unique to each broadcast station within the code space for the broadcast station, thereby enabling the receiver 120 to identify the broadcast station. In some embodiments, a Gold code may be used. Similarly, embodiments may use a code to convey information bits in the data. As described, according to some embodiments, the data may be encoded using a Zadoff Chu code. Additionally or alternatively, data provided by a broadcast station may be able to convey identification information and / or location information regarding the broadcast station. For example, according to some embodiments, for each of one or more broadcast stations, the obtained information may comprise information indicating the identification information of each broadcast station, the location of each broadcast station, or the system time of each broadcast station, or any combination thereof. Means for performing the function in block 1320 may include the processing unit 1010, the bus 1005, the memory 1060, and / or other components of the receiver 120, such as the components shown in FIG. 10 and described above.

[0073]

[0086] The functions in block 1330 include performing either or both of the following operations: (i) determining the receiver's clock offset based at least in part on each timing reference signal and the acquired information regarding at least one of one or more broadcast stations; or (ii) determining the receiver's location based at least in part on each timing reference signal and the acquired information regarding each of one or more broadcast stations. For example, as described with respect to FIG. 1, when multiple (e.g., three or more) timing reference signals are received from broadcast stations, the positioning of receiver 120 can be determined using the known difference in the timing of the timing reference signals transmitted by pairs of broadcast stations 110, the difference in the times at which the timing reference signals are received, the known positions of the broadcast stations 110 from which the distances to receiver 120 are determined, and the hyperbolas 140 that can be used to ultimately determine the location of receiver 120. The known positions of broadcast stations 110 and the known differences in the timing of the timing reference signals transmitted by broadcast stations 110 can be stored in the memory of receiver 120, e.g., in a database, a lookup table, etc. Alternative embodiments may use the timing reference signals to determine the location of receiver 120 using different positioning methods. For example, if the timing of the reference signals broadcast by different broadcast stations 110 is known and receiver 120 is synchronized with broadcast stations 110, the distance 130 between receiver 120 and broadcast stations 110 can be directly determined from the time at which receiver 120 receives the timing reference signal. In some embodiments, additional inputs (e.g., sensor inputs) may be used to resolve the ambiguity in the position of receiver 120 determined from the timing reference signal. The receiver can also determine its clock offset using the timing reference signal from a single broadcast station if its location is known (or acquired using the timing reference signals from multiple broadcast stations).The means for performing the functions in block 1330 may include the processing unit 1010, the bus 1005, the memory 1060, and / or other components of the receiver 120, such as the components shown in FIG. 10 and described above.

[0074]

[0087] It will be apparent to those skilled in the art that substantial variations may be made in accordance with specific requirements. For example, customized hardware may also be used, and / or certain elements may be implemented in hardware, software (including portable software such as applets), or both. Further, connections to other computing devices, such as network input / output devices, may be utilized.

[0075]

[0088] Referring to the accompanying figures, components that can include a memory can include a non-transitory machine-readable medium. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any storage medium involved in providing data that causes a machine to operate in a specific manner. In the embodiments given above, various machine-readable media may be involved in providing instructions / codes to the processing unit and / or other devices for execution. Additionally, or alternatively, the machine-readable medium may be used to store and / or carry such instructions / codes. In many implementations, the computer-readable medium is a physical and / or tangible storage medium. Such media can take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Common forms of computer-readable media include, for example, magnetic and / or optical media, any other physical media with a pattern of holes, RAM, programmable ROM (PROM), erasable PROM (EPROM), FLASH®-EPROM, any other memory chip or cartridge, the carrier wave described below, or any other medium that a computer can read instructions and / or codes from.

[0076]

[0089] The methods, systems, and devices described herein are examples. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For example, the features described for some embodiments may be combined in various other embodiments. Different aspects and elements of the embodiments may be combined in a similar manner. The various components in the figures provided herein may be implemented in hardware and / or software. Also, technology evolves, and thus, many of the elements are examples and those examples do not limit the scope of the disclosure to those specific examples.

[0077]

[0090] For mainly reasons of general usage, it has been found convenient at times to refer to such signals as bits, information, values, elements, symbols, characters, variables, terms, numbers, digits, etc. However, it should be understood that all of these or similar terms should be associated with appropriate physical quantities and are merely convenient labels. Unless otherwise specified, as is apparent from the above description, throughout this specification, descriptions using terms such as "process," "calculate," "compute," "determine," "confirm," "identify," "associate," "measure," "execute," etc., refer to the operations or processes of a specific apparatus, such as a dedicated computer or a similar dedicated electronic computing device. Thus, in the context of this specification, a dedicated computer or a similar dedicated electronic computing device can operate or transform signals generally represented as electronic, electrical, or magnetic physical quantities within the memory, registers, or other information storage devices, transmission devices, or display devices of the dedicated computer or similar dedicated electronic computing device.

[0078]

[0091] As used herein, the terms "and" and "or" may include various meanings that are also expected to depend at least in part on the context in which such terms are used. Generally, when "or" is used to associate a listing such as A, B, or C, it is meant to mean A, B, and C as used herein in an inclusive sense, as well as A, B, or C as used herein in an exclusive sense. Further, the term "one or more" as used herein may be used to describe any singular feature, structure, or property, or may be used to describe some combination of features, structures, or properties. It should be noted, however, that this is merely an exemplary example and the claimed subject matter is not limited to this example. Further, the term "at least one of" when used to associate a listing such as A, B, or C may be construed to mean any combination of A, B, and / or C, such as A, AB, AA, AAB, AABBCCC, etc.

[0079]

[0092] Although some embodiments have been described, various modifications, alternative configurations, and equivalents may be used without departing from the spirit of the disclosure. For example, the above elements may merely be components of a larger system, and other rules may take precedence over or otherwise modify the application examples of the various embodiments. Also, multiple steps may be initiated before, during, or after the above elements are considered. Accordingly, the above description does not limit the scope of the disclosure.

[0080]

[0093] In view of this description, embodiments may include different combinations of features. Implementation examples are described in the clauses numbered below.

[0081] Clause 1: A method of transmitting a wireless radio frequency (RF) timing reference signal from a broadcast station, comprising: Transmitting a timing reference signal using one or more subcarriers during the period of one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring in a first subframe, where each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols. For each symbol of the one or more symbols during which the timing reference signal is transmitted, transmitting data on at least one of the one or more subcarriers in a symbol following each symbol during which the timing reference signal is transmitted. A method comprising the above.

[0082] Clause 2: The method according to clause 1, wherein the timing reference signal and the data are transmitted using a frequency band centered substantially at 100 kHz.

[0083] Clause 3: The method according to clause 1 or 2, wherein the timing reference signal and the data are transmitted using a COMe6 signal structure.

[0084] Clause 4: For each resource block of the first set of OFDM resource blocks, the timing reference signal and the data are transmitted such that a first pair of one or more subcarriers is used for a first plurality of consecutive symbols of each OFDM resource block, and a second pair of one or more subcarriers is used for a second plurality of consecutive symbols of each OFDM resource block immediately following the first plurality of consecutive symbols. The method according to any one of clauses 1 to 3.

[0085] Clause 5: The method according to clause 4, wherein no subcarrier in the second pair of one or more subcarriers is directly adjacent to any subcarrier in the first pair of one or more subcarriers.

[0086] Clause 6: The timing reference signal and data are transmitted using a COFDM 1 signal structure, a COFDM 2 signal structure, or a COFDM 3 signal structure, in accordance with the method described in any of Clauses 1 to 5.

[0087] Clause 7: The method according to any of Clauses 1 to 6, further comprising transmitting additional timing reference signals and a portion of the data during a period of at least one set of OFDM resource blocks among a plurality of subsequent sets of OFDM resource blocks, such that a muting pattern is executed to omit transmission of the additional timing reference signals and a portion of the data during the period of the at least one set of OFDM resource blocks.

[0088] Clause 8: The method according to any of Clauses 1 to 7, further comprising transmitting additional timing reference signals and data during a plurality of subsequent sets of OFDM resource blocks, such that a frequency offset is implemented to offset the frequency of transmission of at least a portion of the additional timing reference signals and data during a period of at least one set of OFDM resource blocks among the plurality of subsequent sets of OFDM resource blocks.

[0089] Clause 9: The timing reference signal and data are transmitted using pi / 2 BPSK, QPSK, 8-PSK, 16-QAM, or 64-QAM modulation, or any combination thereof, in accordance with the method described in any of Clauses 1 to 8.

[0090] Clause 10: For each resource block of a first set of OFDM resource blocks, the timing reference signal and data are transmitted such that all subcarriers of each OFDM resource block are used, in accordance with the method described in any of Clauses 1 to 9.

[0091] Clause 11: The timing reference signal is transmitted using a code specific to the broadcasting station within the code space for the broadcasting station, in accordance with the method described in any of Clauses 1 to 10.

[0092] Clause 12: In the data, identification information of the broadcasting station, the location of a broadcasting station, or the system time of a broadcasting station, or any combination thereof The method according to any one of clauses 1 to 11, further comprising information indicating the same.

[0093] Clause 13: A method of using a wireless radio frequency (RF) timing reference signal in a receiver, comprising: receiving a timing reference signal and data transmitted from one or more broadcasting stations, wherein for each of the one or more broadcasting stations, each respective timing reference signal is received during the period of one or more symbols of each respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, where each OFDM resource block of each respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective sequence of consecutive symbols; each respective data is received in a symbol following each symbol in which each respective timing reference signal is transmitted; obtaining information regarding each of the one or more broadcasting stations based on each respective timing reference signal or each respective data transmitted by each broadcasting station; performing one of the following operations, namely (i) determining a clock offset of the receiver based at least in part on each respective timing reference signal and the obtained information regarding at least one of the one or more broadcasting stations, or (ii) determining a location of the receiver based at least in part on each respective timing reference signal and the obtained information regarding each of the one or more broadcasting stations or both; and A method comprising the above.

[0094] Clause 14: The method according to clause 13, wherein the timing reference signal and data are transmitted using a frequency band centered substantially at 100 kHz.

[0095] Clause 15: For each of one or more broadcast stations, the information obtained comprises identification information of each respective broadcast station, the location of each respective broadcast station, or the system time of each respective broadcast station, or any combination thereof and is the method according to clause 13 or 14 that includes information indicating

[0096] Clause 16: Identifying each of one or more of the broadcast stations comprises determining, for each of one or more of the broadcast stations, a code unique to each respective broadcast station within a code space for the broadcast stations, and is the method according to any of clauses 13 to 15.

[0097] Clause 17: A broadcast station for transmitting a wireless radio frequency (RF) timing reference signal, comprising a wireless communication interface, a memory, and one or more processing units communicatively coupled to the wireless communication interface and the memory, the processing unit transmits a timing reference signal via the wireless communication interface using one or more subcarriers during the period of one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring in a first subframe, wherein each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols, for each symbol of the one or more symbols during which the timing reference signal is transmitted, transmits data via the wireless communication interface on at least one of one or more subcarriers in a symbol following each respective symbol during which the timing reference signal is transmitted, and is configured to perform functions including

[0098] Clause 18: The broadcasting station according to clause 17, wherein one or more processing units are configured to transmit a timing reference signal via a wireless communication interface and transmit data using a frequency band centered substantially at 100 kHz. Clause 19: The broadcasting station according to clause 17 or 18, wherein one or more processing units are configured to transmit a timing reference signal and data via a wireless communication interface using a COFDM 6 signal structure.

[0099] Clause 20: For each resource block of the first set of OFDM resource blocks, one or more processing units a first pair of one or more subcarriers is used for the first plurality of consecutive symbols of each OFDM resource block, a second pair of one or more subcarriers is used for the second plurality of consecutive symbols of each OFDM resource block immediately following the first plurality of consecutive symbols such that the broadcasting station according to any of clauses 17 to 19, which is configured to transmit a timing reference signal and data via a wireless communication interface.

[0100] Clause 21: The broadcasting station according to clause 20, wherein any subcarrier in the second pair of one or more subcarriers is not directly adjacent to any subcarrier in the first pair of one or more subcarriers.

[0101] Clause 22: The broadcasting station according to any of clauses 17 to 21, wherein one or more processing units are configured to transmit a timing reference signal and data via a wireless communication interface using a COFDM 1 signal structure, a COFDM 2 signal structure, or a COFDM 3 signal structure.

[0102] Clause 23: The one or more processing units are further configured to transmit additional timing reference signals and a portion of data in a plurality of subsequent sets of OFDM resource blocks via a wireless communication interface such that a muting pattern is executed during a period of at least one set of OFDM resource blocks out of the plurality of subsequent sets of OFDM resource blocks to omit transmission of the additional timing reference signals and the portion of data, the broadcasting station according to any one of Clauses 17 to 22.

[0103] Clause 24: The one or more processing units are further configured to transmit additional timing reference signals and data in a plurality of subsequent sets of OFDM resource blocks via a wireless communication interface such that a frequency offset is implemented to offset the frequency of transmission of the additional timing reference signals and at least a portion of the data during a period of at least one set of OFDM resource blocks out of the plurality of subsequent sets of OFDM resource blocks, the broadcasting station according to any one of Clauses 17 to 23.

[0104] Clause 25: The one or more processing units are configured to transmit a timing reference signal and data via a wireless communication interface using pi / 2 BPSK, QPSK, 8-PSK, 16QAM, or 64QAM modulation, or any combination thereof, the broadcasting station according to any one of Clauses 17 to 24.

[0105] Clause 26: The one or more processing units are configured to transmit a timing reference signal and data via a wireless communication interface such that all subcarriers of each resource block of a first set of OFDM resource blocks are used, the broadcasting station according to any one of Clauses 17 to 25.

[0106] Clause 27: The one or more processing units include, in the data, identification information of the broadcasting station, the location of the broadcast station, or the system time of the broadcast station, or any combination thereof A broadcast station according to any of clauses 17 to 26, configured to include information indicating the same.

[0107] Clause 28: A receiver configured to use a wireless radio frequency (RF) timing reference signal, comprising a wireless communication interface, a memory, one or more processing units communicatively coupled to the wireless communication interface and the memory, the processing unit being configured to receive, via the wireless communication interface, a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations, each respective timing reference signal is received during the period of one or more symbols of each respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, where each OFDM resource block of each respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols, each respective data is received in a symbol following each symbol of the one or more symbols during which the respective timing reference signal is transmitted, acquire information regarding each of the one or more broadcast stations based on each respective timing reference signal or each respective data transmitted by each broadcast station, the following operations, namely (iii) determining a clock offset of the receiver based at least in part on each respective timing reference signal and the acquired information regarding at least one of the one or more broadcast stations, or (iv) determining a location of the receiver based at least in part on each respective timing reference signal and the acquired information regarding each of the one or more broadcast stations performing either or both of A receiver configured to perform a function including

[0108] Clause 29: The wireless communication interface of the receiver according to Clause 28, configured to receive a timing reference signal and data via a frequency band centered substantially at 100 kHz.

[0109] Clause 30: One or more processing units are configured to determine, from information obtained for each of one or more broadcast stations, the identification information of each broadcast station, the location of each broadcast station, or the system time of each broadcast station, or any combination thereof in the receiver according to Clause 28 or 29. The invention described in the claims of the present application at the time of filing is appended below. [C1] A method for transmitting a wireless radio frequency (RF) timing reference signal from a broadcasting station, comprising: transmitting a timing reference signal using one or more subcarriers during the period of one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks generated in a first subframe, wherein each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols; transmitting data in at least one of the one or more subcarriers in a symbol following each symbol in which the timing reference signal is transmitted, for each symbol of the one or more symbols in which the timing reference signal is transmitted; A method comprising the above. [C2] The method according to C1, wherein the timing reference signal and the data are transmitted using a frequency band centered substantially at 100 kHz. [C3] The method according to C1, wherein the timing reference signal and the data are transmitted using a COFDM 6 signal structure. [C4] For each resource block of the first set of OFDM resource blocks, the timing reference signal and the data are transmitted such that: a first pair of the one or more subcarriers is used for a first plurality of consecutive symbols of each respective OFDM resource block; a second pair of the one or more subcarriers is used for a second plurality of consecutive symbols of each respective OFDM resource block immediately following the first plurality of consecutive symbols. The method according to C3, wherein the transmission is performed as described above. [C5] The method according to C4, wherein no subcarrier in the second pair of the one or more subcarriers is directly adjacent to any subcarrier in the first pair of the one or more subcarriers. [C6] The method according to C1, wherein the timing reference signal and the data are transmitted using a COFDM 1 signal structure, a COFDM 2 signal structure, or a COFDM 3 signal structure. The method according to C1, further comprising transmitting the additional timing reference signal and a portion of the data in at least one set of the plurality of subsequent sets of OFDM resource blocks such that a muting pattern is executed during a period of at least one set of OFDM resource blocks of the plurality of subsequent sets of OFDM resource blocks to omit transmission of the additional timing reference signal and a portion of the data. The method according to C1, further comprising transmitting the additional timing reference signal and the data in at least one set of the plurality of subsequent sets of OFDM resource blocks such that a frequency offset is implemented to offset the frequency of transmission of the additional timing reference signal and at least a portion of the data during a period of at least one set of OFDM resource blocks of the plurality of subsequent sets of OFDM resource blocks. The method according to C1, wherein the timing reference signal and the data are transmitted using pi / 2BPSK, QPSK, 8-PSK, 16QAM, or 64QAM modulation, or any combination thereof. The method according to C1, wherein the timing reference signal and the data are transmitted such that all subcarriers of each of the OFDM resource blocks of the first set of OFDM resource blocks are used. The method according to C1, wherein the timing reference signal is transmitted using a code unique to the broadcast station within a code space for the broadcast station. identification information of the broadcast station, the location of the broadcast station, or the system time of the broadcast station, or any combination thereof The method according to C1, further comprising including information indicating the same. [C13] A method of using a wireless radio frequency (RF) timing reference signal in a receiver, comprising: receiving a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations, ​ Each timing reference signal is received during the period of one or more symbols of each set of orthogonal frequency division multiplexing (OFDM) resource blocks, where each OFDM resource block of each of the sets of OFDM resource blocks comprises each set of adjacent subcarriers and each series of consecutive symbols. Each data is received in a symbol following each of the one or more symbols during which the respective timing reference signal is transmitted. Obtaining information regarding each of the one or more broadcast stations based on the respective timing reference signal or the respective data transmitted by each broadcast station; and performing either or both of: (i) determining a clock offset of the receiver based at least in part on the respective timing reference signal and the obtained information regarding at least one of the one or more broadcast stations; or (ii) determining a location of the receiver based at least in part on the respective timing reference signal and the obtained information regarding each of the one or more broadcast stations. A method comprising. [C14] The method according to C13, wherein the timing reference signal and the data are transmitted using a frequency band centered substantially at 100 kHz. [C15] For each of the one or more broadcast stations, the obtained information is identification information of each of the respective broadcast stations, the location of each of the respective broadcast stations, or the system time of each of the respective broadcast stations, or any combination thereof The method according to C13, comprising information indicating. [C16] Identifying each of the one or more of the broadcast stations comprises determining, for each of the one or more of the broadcast stations, a code unique to each of the respective broadcast stations within a code space for the broadcast stations. The method according to C13. [C17] A broadcast station for transmitting a wireless radio frequency (RF) timing reference signal, comprising a wireless communication interface, a memory, one or more processing units communicatively coupled to the wireless communication interface and the memory, the processing units comprising During the period of one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring in the first subframe, one or more subcarriers are used to transmit a timing reference signal via the wireless communication interface, wherein each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols. For each symbol of the one or more symbols during which the timing reference signal is transmitted, data is transmitted via the wireless communication interface on at least one of the one or more subcarriers in a symbol following the respective symbol during which the timing reference signal was transmitted. A broadcast station configured to perform a function including the above. [C18] The broadcast station according to C17, wherein the one or more processing units are configured to transmit data and the timing reference signal via the wireless communication interface using a frequency band centered at substantially 100 kHz. [C19] The broadcast station according to C17, wherein the one or more processing units are configured to transmit the timing reference signal and data via the wireless communication interface using a COFDM6 signal structure. [C20] For each resource block of the first set of OFDM resource blocks, the one or more processing units a first pair of the one or more subcarriers is used for a first plurality of consecutive symbols of the respective OFDM resource block, a second pair of the one or more subcarriers is used for a second plurality of consecutive symbols of the respective OFDM resource block immediately following the first plurality of consecutive symbols The broadcast station according to C19, wherein the one or more processing units are configured to transmit the timing reference signal and data via the wireless communication interface as described above. [C21] The broadcast station according to C20, wherein none of the subcarriers in the second pair of the one or more subcarriers are directly adjacent to any of the subcarriers in the first pair of the one or more subcarriers. [C22] The broadcast station according to C17, wherein the one or more processing units are configured to transmit the timing reference signal and data via the wireless communication interface using a COFDM 1 signal structure, a COFDM 2 signal structure, or a COFDM 3 signal structure. [C23] The broadcast station according to C17, wherein the one or more processing units are further configured to transmit the additional timing reference signal and a portion of the data in a plurality of subsequent sets of OFDM resource blocks via the wireless communication interface such that a muting pattern is executed to omit transmission of the additional timing reference signal and a portion of the data during a period of at least one set of OFDM resource blocks of the plurality of subsequent sets of OFDM resource blocks. [C24] The broadcast station according to C17, wherein the one or more processing units are further configured to transmit the additional timing reference signal and the data in a plurality of subsequent sets of OFDM resource blocks via the wireless communication interface such that a frequency offset is implemented to offset a frequency of transmission of at least a portion of the additional timing reference signal and the data during a period of at least one set of OFDM resource blocks of the plurality of subsequent sets of OFDM resource blocks. [C25] The broadcast station according to C17, wherein the one or more processing units are configured to transmit the timing reference signal and data via the wireless communication interface using pi / 2 BPSK, QPSK, 8-PSK, 16-QAM, or 64-QAM modulation, or any combination thereof. [C26] The broadcast station according to C17, wherein the one or more processing units are configured to transmit the timing reference signal and data via the wireless communication interface such that all subcarriers of each respective OFDM resource block of the first set of OFDM resource blocks are used. [C27] The one or more processing units include in the data, identification information of the broadcast station, the location of the broadcast station, or the system time of the broadcast station, or any combination thereof The broadcast station according to C17, configured to include the information indicating [C28] A receiver configured to use a wireless radio frequency (RF) timing reference signal, A wireless communication interface, A memory, One or more processing units communicatively coupled to the wireless communication interface and the memory, wherein the processing unit Receives a timing reference signal and data transmitted from one or more broadcast stations via the wireless communication interface, wherein for each of the one or more broadcast stations, Each respective timing reference signal is received during a period of one or more symbols of each respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block of the respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols, Each respective data is received in a symbol following each symbol of the one or more symbols during which the respective timing reference signal is transmitted, Obtaining information regarding each of the one or more broadcast stations based on the respective timing reference signal or the respective data transmitted by each broadcast station; and (iii) determining the clock offset of the receiver based at least in part on the respective timing reference signal and the obtained information regarding at least one of the one or more broadcast stations, or (iv) determining the location of the receiver based at least in part on the respective timing reference signal and the obtained information regarding each of the one or more broadcast stations, performing either or both of A receiver configured to perform a function including [C29] The receiver according to C28, wherein the wireless communication interface is configured to receive the timing reference signal and data via a frequency band centered substantially at 100 kHz. [C30] The one or more processing units, for each of the one or more broadcast stations, from the obtained information, The identification information of each respective broadcast station, The location of each respective broadcast station, or the system time of each of the broadcast stations, or any combination thereof A receiver according to C28, configured to determine.

Claims

Claim 1 A method for transmitting a wireless radio frequency (RF) timing reference signal from a broadcasting station, comprising: transmitting the timing reference signal using one or more subcarriers during a period of one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks generated in a first subframe, wherein each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols; transmitting data in at least one of the one or more subcarriers in a symbol immediately following each symbol in which the timing reference signal is transmitted, for each of the one or more symbols in which the timing reference signal is transmitted; and transmitting the timing reference signal using a code specific to the broadcasting station within a code space for the broadcasting station. Claim 2 The method according to claim 1, wherein the timing reference signal and the data are transmitted using a frequency band centered substantially at 100 kHz. Claim 3 The timing reference signal and the data are transmitted using a COFDM 6 signal structure, and for each resource block of the first set of OFDM resource blocks, a first pair of the one or more subcarriers is used for a first plurality of consecutive symbols of each respective OFDM resource block, and a second pair of the one or more subcarriers is used for a second plurality of consecutive symbols of each respective OFDM resource block immediately following the first plurality of consecutive symbols, such that no subcarrier in the second pair of the one or more subcarriers is directly adjacent to any subcarrier in the first pair of the one or more subcarriers. The method according to claim 1. Claim 4 The method according to claim 1, wherein the timing reference signal and the data are transmitted using a COFDM 1 signal structure, a COFDM 2 signal structure, or a COFDM 3 signal structure. Claim 5 During a period of at least one set of OFDM resource blocks out of a plurality of sets of OFDM resource blocks in a plurality of subframes, a muting pattern is executed so as to omit transmission of the timing reference signal and data. In the plurality of sets of OFDM resource blocks, the method according to claim 1, further comprising transmitting the timing reference signal and data.

6. The method according to claim 1, further comprising transmitting the timing reference signal and data in a plurality of sets of OFDM resource blocks such that a frequency offset is implemented to offset the frequency of transmission of the timing reference signal and data during a period of at least one set of OFDM resource blocks out of a plurality of sets of OFDM resource blocks in a plurality of subframes.

7. The method according to claim 1, wherein the timing reference signal and data are transmitted using pi / 2 BPSK, QPSK, 8-PSK, 16QAM, or 64QAM modulation, or any combination thereof.

8. For each resource block in the first set of OFDM resource blocks, the method according to claim 1, wherein the timing reference signal and data are transmitted such that all subcarriers of each respective OFDM resource block are used.

9. In the data, identification information of the broadcast station, the location of the broadcast station, or the system time of the broadcast station, or any combination thereof The method according to claim 1, further comprising including information indicating the same.

10. A method of using a wireless radio frequency (RF) timing reference signal in a receiver, comprising: receiving a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations, each respective timing reference signal is received during a period of one or more symbols of each respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block in each respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols. each piece of data is received in a symbol that directly follows each symbol of the one or more symbols in which the respective timing reference signal is transmitted, obtaining information regarding each of the one or more broadcast stations based on the respective timing reference signal or the respective data transmitted by each broadcast station, wherein each of the one or more broadcast stations is identified based on the respective timing reference signal transmitted using a code unique to each broadcast station within a code space for the broadcast station, performing either or both of: (i) determining a clock offset of the receiver based at least in part on the respective timing reference signal and the obtained information regarding at least one of the one or more broadcast stations; or (ii) determining a location of the receiver based at least in part on the respective timing reference signal and the obtained information regarding each of the one or more broadcast stations, A method comprising.

11. A broadcast station for transmitting a wireless radio frequency (RF) timing reference signal, comprising: a wireless communication interface; a memory; one or more processing units communicatively coupled to the wireless communication interface and the memory, the one or more processing units configured to: transmit a timing reference signal via the wireless communication interface using one or more subcarriers during a period of one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring in a first subframe, wherein each OFDM resource block of the first set of OFDM resource blocks comprises a set of adjacent subcarriers and a series of consecutive symbols; for each symbol of the one or more symbols in which the timing reference signal is transmitted, transmit data in at least one of the one or more subcarriers in a symbol that directly follows the respective symbol in which the timing reference signal is transmitted via the wireless communication interface; configured to perform functions including. The broadcast station, wherein the timing reference signal is transmitted using a code unique to the broadcast station within the code space for the broadcast station.

12. The broadcast station according to claim 11, wherein the one or more processing units are further configured to execute the method according to any one of claims 2 to 9.

13. A receiver configured to use a wireless radio frequency (RF) timing reference signal, a wireless communication interface, a memory, and one or more processing units communicatively coupled to the wireless communication interface and the memory, the one or more processing units being configured to: receive, via the wireless communication interface, a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations, each respective timing reference signal is received during a period of one or more symbols of each respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block of each respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols, each respective data is received in a symbol directly following each symbol of the one or more symbols during which the respective timing reference signal is transmitted, acquire information regarding each of the one or more broadcast stations based on the respective timing reference signal or the respective data transmitted by each broadcast station, wherein each of the one or more broadcast stations is identified based on the respective timing reference signal transmitted using a code unique to each broadcast station within the code space for the broadcast station, perform either or both of: (i) determining a clock offset of the receiver based at least in part on the respective timing reference signal and the acquired information regarding at least one of the one or more broadcast stations; or (ii) determining a location of the receiver based at least in part on the respective timing reference signal and the acquired information regarding each of the one or more broadcast stations, A receiver configured to perform functions including the above.

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