Signal structures for terrestrial 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. Specifically, 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 signal may include, for example, a comb-1, comb-2, or comb-3 signal structure. Other signal aspects such as muting schemes, modulation, frequency offset, etc. may vary depending on the desired functionality.

Description

Technical Field

[0001] The present invention relates generally to the field of terrestrial positioning and, more particularly, to determining the position of a receiver using wireless signals broadcast from a terrestrial transmitter. Background Art

[0002] LORAN-C is a LORAN (Long Range Navigation) system used by many countries for decades to provide land-based hyperbolic radio navigation for air and sea navigation. Using timing reference signals broadcast from various transmitters, sailors and pilots could determine their position to within an accuracy of hundreds of feet. With the rise of global navigation satellite systems (GNSS) such as the Global Positioning System (GPS), LORAN-C eventually became obsolete. Many countries, including the United States, have recently shut down their LORAN-C systems. Summary of the invention

[0003] 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 timing reference signals and enabling data communications. Specifically, embodiments may utilize an orthogonal frequency division multiplexing (OFDM) signal structure to broadcast timing reference signals and data signals in consecutive symbols of an OFDM resource block. The signal may include, for example, a comb-1, comb-2, or comb-3 signal structure. Other signal aspects such as muting schemes, modulation, frequency offset, etc. may vary depending on the functionality required. This modernized broadcast system will be able to provide timing and navigation if the GNSS system fails.

[0004] An example method of transmitting a wireless RF timing reference signal from a broadcast station according to the present disclosure includes: transmitting the timing reference signal using one or more subcarriers during one or more symbols of a first OFDM resource block set occurring at a first subframe, wherein each OFDM resource block in the first OFDM resource block set includes a contiguous subcarrier set and a series of consecutive symbols. The method also includes: for each of the one or more symbols in which the timing reference signal is transmitted, transmitting data in at least one of the one or more subcarriers in a symbol following the corresponding symbol in which the timing reference signal is transmitted.

[0005] An example method for using a wireless RF timing reference signal at a receiver according to the present disclosure includes: receiving a timing reference signal and data transmitted from one or more broadcast stations, wherein, for each of the one or more broadcast stations, a corresponding timing reference signal is received during one or more symbols of a corresponding OFDM resource block set, wherein each OFDM resource block in the corresponding OFDM resource block set includes a corresponding set of adjacent subcarriers and a corresponding series of consecutive symbols, and the corresponding data is received in a symbol after each of the one or more symbols in which the corresponding timing reference signal is transmitted. The method also includes: obtaining information about each of the one or more broadcast stations based on the corresponding timing reference signal or the corresponding 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 the corresponding timing reference signal and the obtained information about at least one of the one or more broadcast stations, or (ii) determining a position of the receiver based at least in part on the corresponding timing reference signal and the obtained information about each of the one or more broadcast stations.

[0006] An example broadcast station for sending a wireless RF timing reference signal according to the present invention 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 functions, including: using one or more subcarriers to send a timing reference signal during one or more symbols of a first OFDM resource block set occurring at a first subframe via the wireless communication interface, wherein each OFDM resource block in the first OFDM resource block set includes a set of adjacent subcarriers and a series of consecutive symbols. The one or more processing units are also configured to: for each symbol in which the timing reference signal is sent, send data in at least one of the one or more subcarriers of the symbol after the corresponding symbol in which the timing reference signal is sent via the wireless communication interface.

[0007] An example receiver configured to use a wireless RF timing reference signal according to the present invention 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 functions, including: receiving a timing reference signal and data transmitted from one or more broadcasting stations via the wireless communication interface, wherein, for each of the one or more broadcasting stations, a corresponding timing reference signal is received during one or more symbols in a corresponding OFDM resource block set, wherein each OFDM resource block in the corresponding OFDM resource block set includes a corresponding set of adjacent subcarriers and a corresponding series of consecutive symbols, and the corresponding data is received in a symbol after each of the one or more symbols in which the corresponding timing reference signal is transmitted. The one or more processing units are also configured to perform functions, including: obtaining information about each of the one or more broadcasting stations based on the corresponding timing reference signal or the corresponding data transmitted by each broadcasting station; and performing one or both of the following operations: (i) determining a clock offset of the receiver based at least in part on the corresponding timing reference signal and the information obtained about at least one of the one or more broadcasting stations, or (ii) determining a position of the receiver based at least in part on the corresponding timing reference signal and the information obtained about each of the one or more broadcasting stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of a broadcasting system according to an embodiment.

[0009] Figure 2 The envelope shape of a Loran-C pulse is shown, which can be used in the timing reference signal in Loran-C.

[0010] Figure 3 is a graph showing the sky wave delay over the downlink distance for different ionospheric altitudes, which can be applied using Figure 1 The broadcast system transmits the Roland-C and / or other signals.

[0011] Figure 4 is a graph illustrating an OFDM signal structure scheme that may be used to send a timing reference signal according to some embodiments.

[0012] Figure 5 is a diagram of two signal structure options for various embodiments.

[0013] Figure 6 and Figure 7 is an illustration of what a signal structure using comb-1, comb-2, and comb-3 may look like according to some embodiments.

[0014] Figure 8is an illustration of how some embodiments use v-shift jumps.

[0015] Fig. 9 is a table showing how a broadcast system according to an embodiment may implement v-shift jumping.

[0016] Fig.10 is a block diagram of an embodiment of a receiver that may be used as described herein.

[0017] Fig.11 is a block diagram of an embodiment of a computer system that may be used by a broadcast station to cause the broadcast station to perform techniques as described herein.

[0018] Fig.12 is a flow chart of a method of transmitting a wireless RF timing reference signal from a broadcast station according to an embodiment.

[0019] Fig.13 is a flow chart of a method for determining a location of a receiver using a wireless radio frequency (RF) timing reference signal at the receiver according to an embodiment.

[0020] According to some example embodiments, similar reference symbols in various drawings indicate similar elements. In addition, multiple instances of an element can be indicated by using a letter or a hyphen and a second digit after the first digit of the element. For example, multiple instances of element 110 can be indicated as 110-1, 110-2, 110-3, etc. or 110A, 110B, 110C, etc. When only the first digit is used to refer to such an element, it can be understood that it is any instance of the element (for example, the element 110 in the previous example refers to elements 110-1, 110-2 and 110-3, or refers to elements 110a, 110b and 110c). DETAILED DESCRIPTION

[0021] Several illustrative embodiments will now be described with reference to the accompanying drawings which form a part hereof. Although specific embodiments are described below in which one or more aspects of the present disclosure may be implemented, other embodiments may be used and various modifications may be made without departing from the scope of the present disclosure or the spirit of the appended claims.

[0022] As used herein, the terms "position" and "fix" are used synonymously. In addition, the terms "position estimate", "estimated position", "position", "fix", "fix estimate", "fix fix", "estimated fix", "position fix", or "fix" may be used to describe a determined or estimated position of a receiver. The determination may include an absolute position (e.g., latitude and longitude and possibly altitude) or a relative position (e.g., a position expressed as a distance north or south, east or west, and possibly above or below some other known fixed position or some other position, such as the position of the receiver at some known previous time). Position may also be specified as a geodetic position (e.g., latitude and longitude). Position may also include an uncertainty or error indication, such as a horizontal distance and possibly a vertical distance over which the position is expected to have an error, or an indication of an area or volume (e.g., a circle or ellipse) in which the receiver is expected to be located with some confidence level (e.g., 95% confidence).

[0023] Steps have been taken to provide backup position and timing services to GNSS, including modernizing the existing Loran-C broadcast system. For example, the National Timing Resilience and Security Act established requirements for backup position and timing systems that provide precise, high-power 100kHz signals (formerly used by Loran-C) and use Loran infrastructure and spectrum. Such systems can help ensure that critical infrastructure continues to operate in the event of a GNSS failure or outage. Positioning and other timing-related functions can be performed using such systems. Figure 1 It is shown how the positioning is determined in such a system.

[0024] Figure 1 is a schematic diagram of an embodiment of a broadcast system 100 that may be used in a Loran-C or other Loran system and may additionally or alternatively be used to broadcast a modernized signal structure as shown in the embodiments described in more detail below. Broadcast system 100 includes a plurality of broadcast stations 110-1, 110-2, and 110-3 (generally 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." Receiver 120 may determine its position upon receipt of these timing reference signals by identifying broadcast station 110 that issued the corresponding timing reference signal and using the known location of broadcast station 110 to determine the position of receiver 120. (For simplicity, receiver 120 is shown in FIG. 1 ) Figure 1 1 is shown as a ship, but it will be understood that the receiver 120 may include an electronic device or group of devices, which may be located on a ship, vehicle, aircraft or other watercraft. Example components of the receiver 120 are shown in FIG. Fig.10 , which will be described in more detail below. )

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

[0026] For example, using the first and second timing reference signals received by the first broadcast station 110-1 and the second broadcast station 110-2 (together with known information about the locations of these broadcast 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 and the second distance 130-2, which outlines the first hyperbola 140-1. Similarly, the second and third timing reference signals can be used to determine the hyperbola 140-2 (outlining 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 (outlining the difference between the distances 130-1 and 130-3). The estimated position of the receiver may 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) may be performed using data from other forms of navigation such as dead reckoning.

[0027] Under Loran-C, the broadcast system 100 may provide a series of pulses where each pulse has a duration of approximately 200 μs, with an interval of approximately 1-2 milliseconds between pulses, and each pulse series may be spaced 60-100 milliseconds apart. The pulses may use a center frequency of 100 kHz (yielding a 3 km wavelength) with a bandwidth of approximately 20 kHz. The identity of the broadcast station 110 emitting the timing reference signal may be determined based on the series of pulses having a unique pattern or frequency, and the location of the broadcast station may be determined by using a lookup table (e.g., an index or almanac) to link the unique series of pulses to that location. With a typical transmit power of approximately 1 megawatt, the baseline (e.g., distance 130) may reach 1000 kilometers or more.

[0028] The propagation of Loran-C signals can introduce additional complexity to the broadcast system 100. For example, "sky wave", which is a reflection of the timing reference signal outside the ionosphere, often proves to be a major source of error in the timing reference signal received at the receiver 120 because it travels an additional 50 to 1000 kilometers (and is therefore significantly delayed). Lightning can also be a source of interference. In addition, "ground wave", which is a direct path signal used to determine the position of the receiver 120, can be affected by seasonal variations in ground conductivity, humidity, etc.

[0029] Figure 2 2 shows an envelope shape of a Loran-C pulse 210, which may be used in a timing reference signal in a Loran-C system in the manner previously described. For Loran-C positioning, receiver 120 may estimate envelope 220 of pulse 210 in order to determine a coarse time of arrival (ToA) of pulse 210 and ultimately determine the position of receiver 120 in the manner previously described. Additionally, receiver 120 may look for periodic zero crossings 230 of a carrier 240 of pulse 210 to obtain a finer estimate of the ToA. For example, in some applications, a third zero crossing may be used based on a balance of having a relatively favorable signal-to-noise ratio (SNR) within pulse 210 but also being located near the beginning of the signal to help reduce multipath interference (which would be relevant to Figure 3 Detailed discussion further). For example, the Loran-C broadcast system uses a 100 kHz carrier 240, which is a 3 km wavelength system. The third zero crossing occurs approximately 9 km from the pulse start point. When analyzing multipath from sky wave, the delay of the multipath signal can be compared to this 9 km zero crossing occurrence to determine when multipath may become a problem. That is, when the receiver 120 observes the ground wave signal to determine the third zero crossing with a 9 km delay, if the delay from the sky wave is 9 km or less, the receiver may experience multipath interference from the sky wave will occur.

[0030] Figure 3is a graph that plots sky wave delay over downlink distance for a signal sent at 100 kHz. The different curves on the graph represent different ionospheric altitudes, ranging from 100 km to 1000 km. (The curve representing the delay from a 100 km sky wave reflection has the lowest delay in the graph, while the curve representing the delay from a 1000 km sky wave reflection has the highest delay in the graph.) It can be seen that the sky wave delay from a higher ionospheric reflection (e.g., 1000 km) is much longer than the sky wave delay from a lower ionospheric reflection (e.g., 100 km), and is therefore much less likely to cause multipath interference. However, as shown in the figure, the sky wave delay from a 100 km ionospheric reflection may be 9 km or less at greater distances (starting at about 900 km), and may therefore cause multipath interference to ground waves at these greater distances.

[0031] In order to provide a modern broadcast system that can provide adequate backup timing and position in the event of a GNSS failure, the embodiments provided herein can provide various improvements to the previous Loran-C system to help optimize the use of the available spectrum while modernizing the signal structure itself. As discussed in more detail below, embodiments can enable a 100kHz broadcast system that not only provides a timing reference signal (also referred to herein and in the figures as a "reference signal," "RS," or "timing RS") for position determination, but can also enable data communications (e.g., downlink communications from broadcast station 110 to receiver 120) via a dedicated communication channel. In addition, the modernized signal structure can have a significantly reduced peak-to-average ratio of transmit power, which can reduce power amplifier output requirements, thereby reducing equipment costs.

[0032] Figure 4 is a graph illustrating an OFDM signal structure scheme that may be used to send a timing reference signal according to some embodiments. Figure 4 The various boxes shown in the figure represent resources in both the time and frequency domains, which are separated into various blocks as shown, echoing the OFDM schemes used in modern telecommunications (such as Long Term Evolution (LTE)). It will be appreciated that other attached Figure 1 Sample, Figure 4 are provided as non-limiting examples. Alternative embodiments may partition time and / or frequency resources in different ways. For example, an OFDM scheme with a different number of time slots and / or symbols may be used, similar to the scheme currently used in the fifth generation new radio (5G NR, or simply "NR").

[0033] Regarding time, time can be divided into a series of consecutive radio frames, each with T F The radio frame can be divided into subframes, each subframe has T SFAs indicated, a subframe may be divided into slots and symbols. (For example, each subframe may include two slots of 12 symbols. In some embodiments, slots may not be used.)

[0034] Regarding frequency, the available spectrum can be divided into multiple subcarriers. In this scheme, a subcarrier can include a basic unit of frequency. In an embodiment where the carrier frequency is centered at 100kHz and the bandwidth is 20kHz, the subcarrier can therefore be a frequency division from 90kHz to 110kHz.

[0035] As shown in the figure, Figure 4 The basic unit of the OFDM scheme shown may include a resource element spanning a single subcarrier and a single symbol.A resource block may be formed by a group of resource elements that are contiguous in both time and frequency, and is used to transmit timing reference signals and other signals.

[0036] Returning to the example where the carrier frequency is centered at 100kHz with a bandwidth of 20kHz, the values ​​in the OFDM scheme adopt a version of the LTE scheme, scaled by a factor of 1000 relative to the subcarrier spacing. Thus, the OFDM scheme can use subcarriers of 15Hz instead of 15kHz. This allows the radio frame to have a duration T of 10 seconds. F , where 10 subframes each have a duration of 1 second SF The minimum time unit T in this scheme S It is calculated as the subcarrier spacing multiplied by the inverse of the number of useful bits per symbol (bits minus the cyclic prefix): T S = 1 / (15 x 2048) = 32.55 ms. When multiplied by the speed of light, this length is approximately 9.75 kilometers per bit. In some embodiments, a sequence frame number (SFN) of 10,240 seconds may be used for frame tracking (again, a scaled version of the 10.24 second SFN used in LTE).

[0037] According to an embodiment, positioning of the receiver 120 may 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 is received. Thus, an embodiment may use a correlation sequence (such as a Gold code sequence). It may be noted that for the scaling value of the example 100 kHz system described in the previous paragraph, the zero-to-zero correlation peak will be approximately 33 kilometers, which exceeds the 9 km accuracy of multipath isolation in a conventional Loran-C system (using the third zero crossing discussed previously). However, an embodiment may utilize multiple samples of the correlation peak, with each sample being spaced a fraction of the 33 kilometers apart. For example, if the sampling rate is one-quarter of the zero-to-zero width of the correlation peak, the resulting resolution will be slightly better than 8 kilometers, which is higher accuracy than a conventional Loran-C system.

[0038] As mentioned above, modern broadcast systems may send data communications in addition to timing reference signals. Therefore, some embodiments may use a cyclic prefix, which may be used to mitigate inter-symbol interference. When determining an appropriate cyclic prefix, the previous discussion of Figure 3 The only interference consideration discussed is at low frequencies (e.g., 100 kHz). For example, in some embodiments, an extended cyclic prefix (ECP) may be used instead of a normal cyclic prefix (NCP) because ECP (512×T S ) is about 5000 km long, which exceeds the maximum sky-wave delay interference. Figure 3 As shown in Figure 2, the maximum sky wave delay interference from the 1000 km ionosphere altitude is less than 2000 km. ) On the other hand, NCP (144×T S ) is about 1400 km long, which will experience sky wave delay interference.

[0039] As described above, embodiments may use a Gold code sequence for a timing reference signal. Thus, a Gold code sequence generator using other technologies (e.g., NR) may be used. Additionally, as discussed in more detail below, each resource block may use the full spectrum (e.g., each resource block may include data transmission using each subcarrier frequency). If correlation peaks are aggregated from reference signal elements from an entire subframe (e.g., a group of 6 symbols out of 12 symbols in a subframe including a comb-6 signal), no ambiguity or aliasing terms are caused in the corresponding time domain correlation peaks.

[0040] For data communication, the data rate can vary based on the amount and modulation of the resource elements used by each resource block. As discussed in more detail below, embodiments can utilize comb-6, comb-3, comb-2 or comb-1 schemes to send data. In addition, different forms of modulation can be used, including QPSK, 16QAM and 64QAM. As an example, an embodiment utilizing comb-6 will be able to communicate 12 resource elements per resource block. Utilizing a bandwidth of 20kHz, broadcast station 110 may be able to send 100 resource blocks per second. This will achieve 1200 resource blocks per second. QPSK modulation can achieve two bits per resource element, thereby achieving 2400 baud per broadcast station 110. Broadcast station 110 can send different data, thereby increasing the total capacity of broadcast system 100 for broadcast data.

[0041] Depending on the desired functionality, embodiments may also employ muting. That is, different broadcast stations 110 may avoid sending timing reference signals during certain time periods, and optionally also avoid sending data signals, so that a receiver can receive signals from other broadcast stations without interference. Additional details on how embodiments employ muting are provided below. Muting may be enabled, for example, at a symbol level, a subframe level, or a frame level.

[0042] Because embodiments of modern broadcast systems as described herein may implement unidirectional communications (rather than bidirectional communications as used in modern telecommunications), considerations for uplink communications may not need to be considered. Thus, embodiments may exclude the use of random access channels, other (non-positioning) reference signals, etc. used in wireless bidirectional communications. Even so, such considerations may be made in some embodiments where bidirectional communications are desired.

[0043] Figure 5 is an illustration of two signal structure options for various embodiments shown in resource blocks 500-1 and 500-2 (generally referred to herein as resource blocks 500). As noted in the above examples, the length of each resource block 500 can be extended a second time, and each subcarrier can be 15 Hz, although the length of the symbol and the frequency of the subcarrier can vary depending on the desired functionality, as can the number of symbols. As will be appreciated by one of ordinary skill in the art, there can be many resource blocks per subframe. (As previously described, in order to utilize more of the 20 kHz available bandwidth, each subframe can have 100 resource blocks, located at different frequencies and with different subcarriers). As shown in the difference between the signal structures of the first resource block 500-1 and the second resource block 500-2, multiple resource elements from multiple resource blocks can be used to send reference signals and data. As can be seen, embodiments can employ a signal structure in which resource elements used to send timing reference signals are followed by resource elements used to send data.

[0044] Regarding subcarrier usage, embodiments may send a timing reference signal and data on each subcarrier of a resource block. Figure 5 As shown, for example, each subcarrier within a resource block is used once to send a timing reference signal. Furthermore, this pattern may be repeated for all resource blocks across the carrier bandwidth. Thus, when coherent integration of the timing reference signal is performed across one second (the length of a resource block), the resulting frequency domain impulse response will be full bandwidth. This helps prevent correlation and ambiguity in the resulting position determination.

[0045] Depending on the desired functionality, different signal structures may be employed to provide a more robust broadcast situation for symbol interruption. For example, the second signal structure 500-2 structure provides the full bandwidth frequency domain response discussed above by using each subcarrier, similar to the first signal structure 500-1. However, since the second signal structure 500-2 moves to adjacent subcarriers after sending the timing reference signal and data, the structure may be more susceptible to continuous symbol interruption. This is because such a structure makes it relatively difficult to resolve ambiguities (caused by aliasing terms caused by holes in the frequency domain response). On the other hand, the first signal structure 500-1 helps 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 frequency holes resulting from symbol interruption will be more "spread around" in the spectrum, and the resulting ambiguity will be easier to resolve. As will be appreciated, alternative embodiments may employ a variety of alternative signal structures using similar mechanisms.

[0046] As previously described, when coherent integration is performed across subframes, using all subcarriers in a resource block used to send a timing reference signal in a given subframe can provide a full spectrum signal, thereby reducing ambiguous terms that may arise due to partial spectrum usage. However, embodiments may not be limited to this. For example, in some embodiments, coherent integration may occur over a portion of a resource block, allowing faster integration if the ambiguity can be resolved. For example, resolving ambiguities may be facilitated by using a tracking technique in which an initial integration over an entire subframe (e.g., one second) is used to resolve any ambiguities, followed by subsequent integrations over only a portion of the subframe (e.g., if performed on a per-symbol basis, the coherent integration may only take, for example, 1 / 12 of a second). Ambiguities arising from these subsequent integrations may then be resolved by utilizing a priori information obtained from the initial integration. Additional or alternative sources of information may allow resolution of ambiguities caused by partial spectrum usage.

[0047] Because the resource elements used to transmit data can be immediately following the resource elements used to transmit the timing reference signal, demodulation of the data at the receiver 120 can be simpler. That is, the receiver 120 can use the signal used to transmit the timing reference signal as a phase reference in the demodulation of the subsequent data. For example, in the case of modulating a signal using a QPSK modulation scheme (with four phases), since the phases used in the modulation of the timing reference signal are known, they can be used as a phase reference for demodulating the following data.

[0048] It can be noted that although Figure 5The embodiment shown in uses a comb-6 structure, but alternative embodiments are not limited thereto. As will be appreciated by those of ordinary skill in the art, comb-6 is a structure in which data is broadcast in every 6 subcarriers, enabling a broadcast station to effectively increase transmission power. However, alternative embodiments may utilize comb-1, comb-2, or comb-3 structures, depending on the desired functionality.

[0049] For example, Figure 6 1 shows what an embodiment utilizing comb-1, comb-2, and comb-3 signal structures may look like. The example shown initiates transmission of the timing reference signal and the data signal at the third and fourth symbols of each resource block, but the embodiments are not limited thereto. Different embodiments may initiate transmissions at different times, may utilize different patterns, and / or may utilize different numbers of resource elements. With respect to the use of resource elements, Figure 6 The example shown in uses Figure 5 The example in FIG. 1 shows the same number of resource elements, two resource elements (one for the timing reference signal and the other for data). However, the embodiment is not limited thereto. For example, Figure 7 It shows what an embodiment using comb-1, comb-2 and comb-3 signal structures may look like, where transmissions occur during all symbols of a resource block. Other embodiments may vary.

[0050] Some embodiments may utilize a code space to identify different broadcast stations 110, where each broadcast 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 may be reduced to the number of stations whose transmissions are detectable at any given receiver. Thus, embodiments may utilize a "soft requirement" where broadcast stations 110 may be organized into orthogonal groups where the resulting broadcast station ID space size is divisible by the comb number. For example, where 10 groups are used for a comb-6 signal structure, the resulting broadcast station ID space size would be 60. Given that the number of Loran-C stations in North America is 28, such a space size may be sufficient. In fact, alternative embodiments may use a smaller space size, although using a code space size of 60 may also help future-proof the design if additional broadcast stations 110 are used in the future.

[0051] A code sequence generator (e.g., a Gold code sequence generator) may be used to generate the code. In some embodiments, the code sequence generator may generate a unique sequence as a function of a symbol and a subframe or time slot in a manner similar to NR / LTE. Generating a unique code based on a symbol and a subframe / time slot number in this manner may increase the code space by 10 times. Continuing with the example of a station ID space of 60, this may result in 600 searchable codes. That is, the embodiments may not be limited thereto. In some embodiments, for example, the code may additionally or alternatively be a function of the number of frames, which may increase the code size by 1024 times.

[0052] According to some embodiments, v-shift "hopping" may be used to account for the fact that timing reference signals from different broadcast stations 110 may collide. In v-shift hopping, a group of broadcast stations may shift subcarrier usage as a function of subframes and / or time slots, thereby allowing signals that may collide in one subframe to avoid colliding in another subframe.

[0053] Figure 8 An illustration of a v-shift hop is provided. The first resource block 800-1 shows a pattern of timing reference and data signals without a shift. This can be considered a base or standard pattern from which a v-shift offset can be made. 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 conflicts between broadcast stations 110. For a comb-6 pattern in a resource block 800 having 12 subcarriers, the pattern can be offset by up to 5 subcarriers before the pattern repeats. Therefore, including a shift of 0, there are six available v-shift offsets. (Similarly, there are three available V-shift offsets for a comb-3 signal structure and two available V-shift offsets for a comb-2 signal structure.) The broadcast station 110 can perform a V-shift hop by applying different V-shift offsets at different times, thereby using different subcarriers to send different timing reference signals and data signals. Fig. 9 An example of how this can be accomplished is shown in .

[0054] Fig. 9 is a table showing how the broadcast system 100 can implement v shift jumping according to an embodiment. The table shows the offsets used by different groups of broadcast stations 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 used by each group for a given subframe. (The offsets here are similar to Figure 81. Comb-6 signal structure in a resource block with 12 subcarriers. As previously described, since the signal is broadcast on two subcarriers at a time in a resource block, there are 6 available offsets: 0-5. ) At subframe 0, none of the groups use an offset. In the following subframe, half of the groups use an offset of 1. Additional groups of broadcast station 110 use additional offsets in subsequent subframes. Ultimately, the various groups of the broadcast station cycle through the offsets so that each group will avoid colliding with each other in at least one subframe. As will be appreciated, Fig.10 The table shown in provides only one example of how to implement v-shift jumping. Alternative embodiments may utilize additional or alternative v-shift jumping modes.

[0055] Additionally or alternatively, as previously described, embodiments may use muting in a similar manner, where broadcast stations of different groups refrain from broadcasting signals according to subframes to help prevent signal collisions. More specifically, broadcast station 110 may transmit timing reference and data signals on a predetermined time schedule or period. Muting occurs when broadcast station 110 refrains from broadcasting a timing reference signal and optionally a data signal in a given scheduled period instance. Similar to Fig. 9 , the broadcast station 110 can be divided into different groups, where each group uses a different muting pattern to help reduce signal conflicts between groups. For example, for every 10 subframes, the first group can be muted on subframes zero, two, four, six, and eight; the second group can be muted on subframes zero, one, two, three, and four; the third group can be muted on subframes zero, three, six, and nine; and so on.

[0056] Some embodiments may include techniques for mitigating inter-symbol interference and inter-carrier interference. As previously described, for example, an embodiment may utilize an ECP with a length greater than the maximum ionospheric delay to help reduce inter-symbol interference. Additionally or alternatively, an embodiment may take into account inter-carrier interference caused by different broadcast stations not being aligned in frequency. For example, the frequency change due to Doppler at Mach 1 is 0.1133 Hz, which is much smaller than the 15 Hz subcarrier spacing that can be used in some embodiments. Therefore, the clock accuracy target can be determined by the subcarrier spacing and Doppler requirements. A target example with a maximum value of 0.15 Hz (greater than the frequency offset at Mach 1) will result in an offset of 1.5 parts per million (PPM). A clock with this quality will enable the receiver to avoid frequency searches and move directly to performing a time search for the broadcast signal.

[0057] As previously described, the data signal may be accompanied by a timing reference signal, providing a downlink data channel from the broadcast station 110 to the receiver 120. However, in some cases, such data may not be needed. Therefore, some embodiments may engage in data throttling so that data is only sent in a portion of the subframe. For example, data may be communicated in one subframe out of every 10 subframes, resulting in a baud rate of 1 / 10. A greater or lesser number of subframes may be used for data as needed. According to some embodiments, this may be dynamically set and communicated to the receiver 120 to accommodate increases or decreases in data demand.

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

[0059] In some embodiments, the data may be encoded with a Zadoff Chu code, which results in a correlation gain. For example, for a comb-6 implementation with a bandwidth of 20 kHz and a subcarrier spacing of 15 Hz, there may be 200 resource elements per symbol. Zadoff Chu codes use prime length sequences, so a Zadoff Chu code of length 199 (which is a prime number) may be used. A differential Zadoff Chu code may be assigned to the data. Because there are 198 sequences with a length of 199, a range of bits may be assigned to each of the 198 sequences, resulting in a capacity of approximately 7.5 bits per symbol, or 45 baud.

[0060] In some embodiments, pi / 2-BPSK modulation may be used (e.g., instead of QPSK or other modulation schemes). Like Zadoff Chu codes, this type of modulation may result in a reduced peak-to-average ratio of the signal, which may result in an increased signal level. While this may reduce data capacity, it is particularly beneficial to provide greater range for broadcast signals without saturating the power amplifier of the broadcast station transmitter. Similarly, embodiments may use Alamouti coding to extend reception range.

[0061] Fig.10 An embodiment of a receiver 120 that can be used as described above is shown. It should be noted that Fig.10 It is meant only to provide a generalized illustration of various components, any or all of which may be used as appropriate. It may be noted that in some instances, Fig.10The components shown may be localized to a single physical device and / or distributed among various network devices that may be located at different physical locations. For example, receiver 120 may be integrated into and / or used by an aircraft, ship, or other vehicle and may include various components arranged at different locations on the vehicle.

[0062] Receiver 120 is shown as including hardware elements that may be electrically coupled via bus 1005 (or may otherwise communicate where appropriate). The hardware elements may include a processing unit 1010, which may include, but is not limited to, one or more general-purpose processors, one or more special-purpose processors (such as digital signal processing (DSP) chips, graphics acceleration processors, application-specific integrated circuits (ASICs), etc.), and / or other processing structures or components. Fig.10 As shown, some embodiments may have a separate digital signal processor (DSP) 1020, depending on the desired functionality. Position determination and / or other determinations based on wireless communications may be provided in the processing unit 1010 and / or the communication interface 1030 (discussed below). The receiver 120 may also include one or more input devices 1070, which may include but are not limited to a keyboard, a touch screen, a touch pad, a microphone, a button, a dial, a switch, etc.; and one or more output devices 1015, which may include but are not limited to a display, a light emitting diode (LED), a speaker, etc.

[0063] The receiver 120 may also include a communication interface 1030, which may include, but is not limited to, a modem, a network card, an infrared communication device, a wired communication device, a wireless communication device, and / or a chipset, etc., which may enable the receiver 120 to send and / or receive data communications via wired and / or wireless components. This may include wireless communications such as cellular, Wi-Fi, Bluetooth, traditional marine and / or aeronautical radio frequency (RF) communications, and / or wired communications using optical fiber, coaxial cable, twisted pair, and / or similar wired components in addition or as an alternative. Such wired communications may occur via a wired communication interface 1031, which may be a subcomponent of the communication interface 1030 as shown. In an alternative embodiment, the wired communication interface 1031 may be separate from the communication interface 1030. Therefore, the communication interface 1030 may allow communication (e.g., sending and receiving) data and signaling with a network and / or network components, a computer system, and / or any other electronic device.

[0064] Specifically, depending on the required functionality, the communication interface 1030 may include a separate transceiver to wirelessly communicate with base stations and other ground transceivers such as wireless devices and access points. The receiver 120 can 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 (IEEE 802.16) network, etc. A CDMA network may implement one or more radio access technologies (RATs) such as CDMA2000, Wideband CDMA (WCDMA), etc. Cdma2000 includes IS-95, IS-2000 and / or IS-856 standards. A TDMA network may implement a global system for mobile communications (GSM), a digital advanced mobile phone system (D-AMPS), or some other RATs. An OFDMA network may use LTE, advanced LTE, 5G NR, etc. 5G NR, LTE, Advanced LTE, GSM, and WCDMA are described in documents from the Third Generation Partnership Project (3GPP). Cdma2000 is described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). 3GPP and 3GPP2 documents 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, IEEE 802.15x, or some other type of network. The techniques described herein may also be used for any combination of WWAN, WLAN, and / or WPAN. Communication may be performed via one or more wireless communication antennas 1032 that send 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.

[0065] Receiver 120 may also include sensor 1040. Sensor 1040 may include, but is not limited to, one or more inertial sensors and / or other sensors (e.g., accelerometers, gyroscopes, cameras, magnetometers, altimeters, microphones, proximity sensors, light sensors, barometers, etc.), some of which may be used to supplement and / or facilitate the positioning determinations described herein in some instances. As previously described, for example, receiver 120 may use dead reckoning to resolve ambiguities in positioning determinations. Sensor 1040 may include one or more motion sensors that may be used to perform dead reckoning.

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

[0067] Some embodiments of the receiver 120 may also include a GNSS receiver (not shown) (such as GPS), which may be used when no GNSS interruption occurs. The GNSS receiver may be able to receive signals 1084 from one or more GNSS satellites using antenna 1082 (which may be the same as antenna 1032). Positioning based on GNSS signal measurements may be used to supplement and / or combine the techniques described herein. The GNSS receiver may use conventional techniques to extract the positioning of the receiver 120 from GNSS satellites of GNSS systems, GPS, Galileo, GLONASS, Quasi-Zenith Satellite System (QZSS) over Japan, Indian Regional Navigation Satellite System (IRNSS) over India, BeiDou Navigation Satellite System (BDS) over China, etc. In addition, GNSS receivers can be used with various augmentation systems (e.g., satellite-based augmentation systems (SBAS)), which can be associated with or otherwise enabled for use with one or more global and / or regional navigation satellite systems (e.g., Wide Area Augmentation System (WAAS), European Geostationary Navigation Overlay Service (EGNOS), Multifunction Satellite Augmentation System (MSAS), and Geo-Augmented Navigation System (GAGAN), etc.).

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

[0069] The memory 1060 of the receiver 120 may also include software elements ( Fig.101060), including an operating system, device drivers, executable libraries, and / or other code (such as one or more applications), as described herein, which may include computer programs provided by various embodiments, and / or may be designed to implement methods and / or configure systems provided by other embodiments. By way of example only, one or more processes described with respect to the methods discussed above may be implemented as code and / or instructions in memory 1060 that may be executed by receiver 120 (and / or processing unit 1010 or DSP 1020 within receiver 120). 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 according to the described methods.

[0070] Fig.11 An embodiment of a computer system 1100 is shown, which may be utilized and / or incorporated into one or more components of broadcast station 110 as described herein. Fig.11 A schematic diagram of one embodiment of a computer system 1100 is provided that can perform the methods provided by various other embodiments. It should be noted that Fig.11 It is meant only to provide a generalized illustration of various components, any or all of which may be used as appropriate. Fig.11 It is broadly shown how the various system elements can be implemented in a relatively separate or relatively more integrated manner. In addition, it can be noted that Fig.11 The components shown may be localized to a single device and / or distributed among various networked devices. As noted in the previously described embodiments, the broadcast station 110 (or more specifically, the transmitter of the broadcast station 110, which may be Fig.11 The location of the broadcast station 110 (part of the wireless communication interface 1133 of the wireless communication interface 1133 and described below) can be known and used for positioning determination of one or more receivers 120. The known location of the broadcast station 110 can be stored in a lookup table (e.g., a database or yearbook) of one or more receivers 120.

[0071] Computer system 1100 is shown as including hardware elements that may be electrically coupled via bus 1105 (or may be in communication in other ways where appropriate). The hardware elements may include a processing unit 1110, which may include, but is not limited to, one or more general-purpose processors, one or more special-purpose processors (such as digital signal processing chips, graphics acceleration processors, etc.), and / or other processing structures, which may be configured to perform one or more of the methods described herein, including with respect to Fig.11The computer system 1100 may also include one or more input devices 1115, which may include but are not limited to a mouse, a keyboard, a camera, a microphone, etc., and one or more output devices 1120, which may include but are not limited to a display device, a printer, etc.

[0072] The computer system 1100 may also include (and / or communicate with) one or more non-transitory storage devices 1125, which may include, but are not limited to, local and / or network accessible memory, and / or may include, but are not limited to, disk drives, drive arrays, optical storage devices, solid-state storage devices (such as RAM and / or ROM), which may be programmable, flash-updatable, etc. Such storage devices may be configured to implement any suitable data storage, including, but not limited to, various file systems, database structures, etc.

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

[0074] In many embodiments, the computer system 1100 will also include a working memory 1135, which may include RAM and / or ROM devices. The software elements shown as being located within the working memory 1135 may include an operating system 1140, device drivers, executable libraries, and / or other code (such as applications 1145), which, as described herein, may include computer programs provided by various embodiments, and / or may be designed to implement methods and / or configuration systems provided by other embodiments. By way of example only, one or more of the processes described with respect to the methods discussed above may be implemented as code and / or instructions stored (e.g., temporarily) in the working memory 1135 and executable by a computer (and / or a processing unit within the computer, such as the processing unit 1110); 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.

[0075] The set of these instructions and / or codes may be stored on a non-transitory computer-readable storage medium, such as the storage device 1125 described above. In some cases, the storage medium may be incorporated into a computer system, such as the computer system 1100. In other embodiments, the storage medium may be separate from the computer system (e.g., a removable medium such as an optical disk), and / or provided in an installation package so that the storage medium can be used to program, configure, and / or adapt a general-purpose computer having the instructions / code stored thereon. The instructions may take the form of executable code that can be executed by the computer system 1100, and / or may take the form of source code and / or installable code that, when compiled and / or installed on the computer system 1100 (e.g., using any of a variety of commonly available compilers, installers, compression / decompression utilities, etc.), takes the form of executable code.

[0076] Fig.12 1 is a flow chart of a method 1200 for transmitting a wireless RF timing reference signal from a broadcast station according to an embodiment. Figure 1 Sample, Fig.12 are provided as non-limiting examples. Alternative embodiments may include Fig.12 The components for performing the functions of the blocks may include, for example, Fig.11 The hardware and / or software components of the computer system shown and previously described may be integrated into broadcast station 110 .

[0077] The functions at block 1210 include sending a timing reference signal using one or more subcarriers during one or more symbols of a first set of OFDM resource blocks occurring at a first subframe, wherein each OFDM resource block in the first set of OFDM resource blocks includes a set of adjacent subcarriers and a series of consecutive symbols. As described with respect to resource blocks in the above embodiments, a resource block may include any number of adjacent subcarriers and symbols. Means for performing the functions at block 1210 may include a processing unit 1110, a bus 1105, a working memory 1135, a communication subsystem 1130, a wireless communication interface 1133, and / or a computer system (such as Fig.11 Other components of the computer system 1100 shown in and described above may be integrated into the broadcast station 110.

[0078] The functions at block 1220 include, for each of the one or more symbols in which a timing reference signal is transmitted, transmitting data in at least one of the one or more subcarriers in the one or more symbols following the symbol in which the corresponding timing reference is transmitted. As previously described, transmitting data in a symbol immediately following a symbol for a timing reference signal can result in efficiency because the receiver 120 can then use the timing reference signal as a phase reference for demodulating the data. Means for performing the functions at block 1220 may include a processing unit 1110, a bus 1105, a working memory 1135, a communication subsystem 1130, a wireless communication interface 1133, and / or a computer system such as Fig.11 Other components of the computer system 1100 shown in and described above may be integrated into the broadcast station 110.

[0079] As described in detail in the previously described embodiments, embodiments may include additional features depending on the desired functionality. According to some embodiments, the timing reference signal and data are transmitted using a frequency band centered around substantially 100 kHz. Additionally or alternatively, the timing reference signal and data are transmitted using a comb-6, comb-3, comb-2, or comb-1 signal structure. Figure 5 As shown, the timing reference signal and the data signal may be sent using paired subcarriers to send the signals on consecutive symbols. Thus, an alternative embodiment of method 1200 may include sending the timing reference signal and the data such that, for each resource block in the first set of OFDM resource blocks, a first pair of one or more subcarriers is used for a first plurality of consecutive symbols of the corresponding OFDM resource block, and a second pair of one or more subcarriers is used for a second plurality of consecutive symbols immediately following the first plurality of consecutive symbols of the corresponding OFDM resource block. In addition, as Figure 5As shown, the signal structure may enable the use of non-adjacent subcarriers in consecutive symbols to reduce the impact of subcarrier interruption. Therefore, according to some embodiments, any subcarrier in the second pair of subcarriers is not directly adjacent to any subcarrier in the first pair of subcarriers.

[0080] Depending on the desired functionality, embodiments may additionally or alternatively include muting and / or hopping patterns. According to some embodiments, for example, method 1200 may implement muting by also including the following operations: sending additional timing reference signals and data in multiple subsequent OFDM resource block sets, such that the muting pattern is performed to omit the transmission of a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets. To achieve frequency hopping, some embodiments may additionally include sending additional timing reference signals and data in multiple subsequent OFDM resource block sets, such that a frequency offset is implemented to offset the frequency of the transmission of at least a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

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

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

[0083] Fig.13 is a flow chart of a method 1300 of using wireless radio frequency (RF) timing reference signals at a receiver according to an embodiment. As indicated in the previously described embodiments, these signals can be used to determine the position of the receiver and / or determine the clock offset of the receiver. Fig.13Provided as non-limiting examples. Alternative embodiments may include Fig.13 The components for performing the functions of these blocks may include hardware and / or software components of the receiver 120, including Fig.11 Components of the computer system shown and previously described.

[0084] The functions at block 1310 include 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) a corresponding timing reference signal is received during one or more symbols of a corresponding set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block in the corresponding set of OFDM resource blocks includes a corresponding set of adjacent subcarriers and a corresponding series of consecutive symbols, and (ii) corresponding data is received in a symbol following each of the one or more symbols in which the corresponding timing reference signal is transmitted. Figure 5-Figure 8 An example of a timing reference signal and corresponding data is shown in FIG. 13. Likewise, according to some embodiments, the timing reference signal and the data are transmitted using a frequency band in the LF spectrum. This may include, for example, a frequency band centered around substantially 100 kHz. Means for performing the functions at block 1310 may include processing unit 1010, bus 1005, memory 1060, low frequency receiver 1080, and / or other components of receiver 120, such as Fig.10 The components shown in and described above.

[0085] The functions at box 1320 include: obtaining information about each of one or more broadcasting stations based on the corresponding timing reference signal or the corresponding data sent by each broadcasting station. As previously described, the broadcasting station may send a timing reference signal using a code unique to the corresponding broadcasting station within the code space used for the broadcasting station, thereby enabling the receiver 120 to identify the broadcasting station. In some embodiments, a Gold code may be used. In a similar manner, an embodiment may use a code to transmit information bits in the data. As described above, according to some embodiments, the data may be encoded using a Zadoff Chu code. Additionally or alternatively, the data provided by the broadcasting station may transmit identity and / or location information about the broadcasting station. For example, according to some embodiments, for each of the one or more broadcasting stations, the obtained information may include information indicating the identity of the corresponding broadcasting station, the location of the corresponding broadcasting station, or the system time of the corresponding broadcasting station, or any combination thereof. The components for performing the functions at box 1320 may include the processing unit 1010, the bus 1005, the memory 1060 and / or other components of the receiver 120, such as Fig.10 The components shown in and described above.

[0086] The functions at block 1330 include performing one or both of (i) determining a clock offset of the receiver based at least in part on the corresponding timing reference signal and the information obtained about at least one of the one or more broadcast stations, or (ii) determining a position of the receiver based at least in part on the corresponding timing reference signal and the information obtained about each of the one or more broadcast stations. Figure 1 As described, if timing reference signals are received from multiple broadcast stations (e.g., three or more), the location of the receiver 120 may be determined using the known differences in the timing of the timing reference signals transmitted by the paired broadcast stations 110, the differences in the times at which the timing reference signals are received, and the known locations of the broadcast stations 110 to outline a hyperbola 140 that may be used to determine the distance from each broadcast station 110 and ultimately determine the location of the receiver 120. The known locations of the broadcast stations 110 and the known differences in the timing of the timing reference signals transmitted by the broadcast stations 110 may be stored in a memory at the receiver 120, such as a database, a lookup table, etc. Alternative embodiments may use the timing reference signals to determine the location of the receiver 120 using different location determination methods. For example, where the timing of the reference signals broadcast by the different broadcast stations 110 is known and the receiver 120 is synchronized with the broadcast stations 110, the distance 130 between the receiver 120 and the broadcast station 110 may be determined directly from the time at which the receiver 120 receives the timing reference signals. In some embodiments, additional inputs (e.g., sensor inputs) may be used to resolve ambiguities in the location of the receiver 120 determined from the timing reference signal. If the location of the receiver is known (or obtained using timing reference signals from multiple broadcast stations), the receiver may also use the timing reference signal from a single broadcast station to determine its clock offset. Means for performing the functions at block 1330 may include processing unit 1010, bus 1005, memory 1060, and / or other components of receiver 120, such as Fig.10 The components shown in and described above.

[0087] It will be apparent to those skilled in the art that substantial variations may be made depending on specific requirements. For example, custom hardware may also be used, and / or specific elements may be implemented in hardware, software (including portable software, such as applets, etc.), or both. In addition, connections to other computing devices such as network input / output devices may be employed.

[0088] With reference to the accompanying drawings, the components that may include memory may include non-temporary machine-readable media. The terms "machine-readable medium" and "computer-readable medium" used herein refer to any storage medium that participates in providing data that enables a machine to operate in a particular manner. In the embodiments provided above, various machine-readable media may participate in providing instructions / codes to a processing unit and / or other devices for execution. Additionally or alternatively, a machine-readable medium may be used to store and / or carry such instructions / codes. In many implementations, a computer-readable medium is a physical and / or tangible storage medium. This medium may take a variety of 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 hole patterns, RAM, programmable ROM (PROM), erasable PROM (EPROM), flash EPROM, any other storage chip or storage box, carrier waves described below, or any other medium from which a computer can read instructions and / or codes.

[0089] The methods, systems and devices discussed herein are examples. Various embodiments may omit, replace or add various processes or components as desired. For example, features described with respect to certain 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 of the accompanying drawings provided herein may be implemented in hardware and / or software. Moreover, technology is evolving, and therefore, many elements are examples that do not limit the scope of the present disclosure to those specific examples.

[0090] Mainly for general reasons, it has sometimes proven convenient to refer to such signals as bits, information, values, elements, symbols, characters, variables, terms, numbers, numerals, etc. However, it should be understood that all of these or similar terms will be associated with appropriate physical quantities and are merely convenient labels. Unless otherwise specifically stated, as will be apparent from the above discussion, it should be understood that throughout the specification, discussions using terms such as "processing," "computing," "calculating," "determining," "judgment," "identification," "association," "testing," "execution" refer to the actions or processes of a specific device, such as a special-purpose computer or similar special-purpose electronic computing device. Therefore, in the context of this specification, a special-purpose computer or similar special-purpose electronic computing device is capable of controlling or transforming a signal, which is typically represented as a physical electronic, electrical, or magnetic quantity within a memory, register, or other information storage device, a transmitting device, or a display device of a special-purpose computer or similar special-purpose electronic computing device.

[0091] The terms "and" and "or" used herein may include multiple meanings, and it is expected that these meanings also depend at least in part on the context in which the terms are used. Typically, if used to associate a list (such as A, B, or C), "or" is intended to represent A, B, and C used in an inclusive sense here, and A, B, or C used in an exclusive sense here. In addition, the term "one or more" used herein may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe some combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example, and the subject matter claimed is not limited to this example. In addition, the term "at least one", if used to associate a list such as A, B, or C, may be interpreted to mean any combination of A, B, and / or C, such as A, AB, AA, AAB, AABBCCC, etc.

[0092] Several embodiments have been described, and various modifications, alternative configurations, and equivalents may be used without departing from the spirit of the present disclosure. For example, the above elements may be components of a larger system, where other rules may take precedence over or otherwise modify the application of the various embodiments. Moreover, many steps may be performed before, during, or after consideration of the above elements. Therefore, the above description does not limit the scope of the present disclosure.

[0093] In view of this description, embodiments may include different combinations of features. The following numbered clauses describe implementation examples:

[0094] Clause 1. A method of transmitting a wireless radio frequency (RF) timing reference signal from a broadcast station, the method comprising:

[0095] transmitting a timing reference signal using one or more subcarriers during one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring at a first subframe, wherein each OFDM resource block in the first set of OFDM resource blocks includes a contiguous set of subcarriers and a series of consecutive symbols; and

[0096] For each of the one or more symbols in which the timing reference signal is sent, data is sent in at least one of the one or more subcarriers in a symbol following the corresponding symbol in which the timing reference signal is sent.

[0097] Clause 2. A method according to clause 1, wherein the timing reference signal and the data are transmitted using a frequency band centered around substantially 100 kHz.

[0098] Clause 3. A method according to clause 1 or clause 2, wherein the timing reference signal and the data are sent using a comb-6 signal structure.

[0099] Clause 4. A method according to any of clauses 1 to 3, wherein the timing reference signal and the data are transmitted such that for each resource block in the first set of OFDM resource blocks:

[0100] A first pair of one or more subcarriers is used for a first plurality of consecutive symbols of a corresponding OFDM resource block, and

[0101] A second pair of one or more subcarriers is used for a second plurality of consecutive symbols of a corresponding OFDM resource block immediately following the first plurality of consecutive symbols.

[0102] Clause 5. The method of clause 4, wherein any subcarrier of the second pair of one or more subcarriers is not directly adjacent to any subcarrier of the first pair of one or more subcarriers.

[0103] Clause 6. A method according to any of clauses 1 to 5, wherein the timing reference signal and the data are sent using a comb-1 signal structure, a comb-2 signal structure or a comb-3 signal structure.

[0104] Clause 7. The method according to any one of Clauses 1 to 6 further includes sending additional timing reference signals and data in multiple subsequent OFDM resource block sets, so that a muting mode is performed to omit sending a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

[0105] Clause 8. The method according to any one of Clauses 1 to 7 further includes sending additional timing reference signals and data in multiple subsequent OFDM resource block sets, so that a frequency offset is implemented to offset the frequency of the transmission of at least a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

[0106] Clause 9. A method according to any of clauses 1 to 8, wherein the timing reference signal and the data are sent using pi / 2 BPSK, QPSK, 8-PSK, 16QAM or 64QAM modulation or any combination thereof.

[0107] Clause 10. A method according to any of clauses 1 to 9, wherein the timing reference signal and the data are transmitted such that for each resource block in the first set of OFDM resource blocks, all subcarriers of the corresponding OFDM resource block are used.

[0108] Clause 11. The method of any of clauses 1 to 10, wherein the timing reference signal is transmitted using a code unique to the broadcast station within a code space for the broadcast station.

[0109] Clause 12. The method of any of clauses 1 to 11, further comprising including in the data information indicating:

[0110] The identity of the broadcasting station,

[0111] the location of the broadcast station, or

[0112] The system time of the broadcast station, or

[0113] Any combination of them.

[0114] Clause 13. A method of using a wireless radio frequency (RF) timing reference signal at a receiver, the method comprising:

[0115] receiving a timing reference signal and data transmitted from one or more broadcast stations, wherein for each of the one or more broadcast stations:

[0116] receiving a respective timing reference signal during one or more symbols of a respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block in the respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols; and

[0117] receiving respective data in a symbol following each of the one or more symbols in which the respective timing reference signal is transmitted;

[0118] obtaining information about each of the one or more broadcasting stations based on a corresponding timing reference signal or corresponding data transmitted by each broadcasting station; and

[0119] Do one or both of the following:

[0120] (i) determining a clock offset of the receiver based at least in part on the corresponding timing reference signal and information obtained about at least one of the one or more broadcast stations, or

[0121] (ii) determining a location of the receiver based at least in part on the corresponding timing reference signal and the information obtained about each of the one or more broadcast stations.

[0122] Clause 14. The method of clause 13, wherein the timing reference signal and the data are transmitted using a frequency band centered around substantially 100 kHz.

[0123] Clause 15. A method according to clause 13 or clause 14, wherein for each of the one or more broadcasting stations, the obtained information includes information indicating:

[0124] The identity of the corresponding broadcast station,

[0125] the location of the corresponding broadcast station, or

[0126] The system time of the corresponding broadcast station, or

[0127] Any combination of them.

[0128] Clause 16. The method of any of Clauses 13-15, wherein identifying each of the one or more broadcast stations comprises: for each of the one or more broadcast stations, determining a code within a code space of the broadcast station that is unique to the respective broadcast station.

[0129] Clause 17. A broadcast station for transmitting a wireless radio frequency (RF) timing reference signal, the broadcast station comprising:

[0130] Wireless communication interface;

[0131] Memory; and

[0132] One or more processing units communicatively coupled to the wireless communication interface and the memory and configured to perform functions including:

[0133] transmitting, via a wireless communication interface, a timing reference signal using one or more subcarriers during one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring at a first subframe, wherein each OFDM resource block in the first set of OFDM resource blocks includes a contiguous set of subcarriers and a series of consecutive symbols; and

[0134] For each of the one or more symbols in which the timing reference signal is sent, data is sent via the wireless communication interface in at least one subcarrier of the one or more subcarriers in a symbol following the corresponding symbol in which the timing reference signal is sent.

[0135] Clause 18. The broadcast station of clause 17, wherein the one or more processing units are configured to transmit the timing reference signal via the wireless communication interface and transmit the data using a frequency band centered around substantially 100 kHz.

[0136] Clause 19. A broadcast station according to clause 17 or clause 18, wherein the one or more processing units are configured to transmit the timing reference signal and the data via the wireless communication interface using a comb-6 signal structure.

[0137] Clause 20. A broadcast station according to any of clauses 17 to 19, wherein the one or more processing units are configured to send the timing reference signal and the data via the wireless communication interface such that for each resource block in the first set of OFDM resource blocks:

[0138] A first pair of one or more subcarriers is used for a first plurality of consecutive symbols of a corresponding OFDM resource block, and

[0139] A second pair of one or more subcarriers is used for a second plurality of consecutive symbols of a corresponding OFDM resource block immediately following the first plurality of consecutive symbols.

[0140] Clause 21. The broadcast station of clause 20, wherein any subcarrier of the second pair of one or more subcarriers is not directly adjacent to any subcarrier of the first pair of one or more subcarriers.

[0141] Clause 22. A broadcast station according to any of clauses 17 to 21, wherein the one or more processing units are configured to send the timing reference signal and the data via the wireless communication interface using a comb-1 signal structure, a comb-2 signal structure or a comb-3 signal structure.

[0142] Clause 23. A broadcast station according to any one of clauses 17 to 22, wherein one or more processing units are further configured to send additional timing reference signals and data in multiple subsequent OFDM resource block sets via a wireless communication interface, so that a muting mode is performed to omit sending a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

[0143] Clause 24. A broadcast station according to any of clauses 17 to 23, wherein one or more processor units are also configured to send additional timing reference signals and data in multiple subsequent OFDM resource block sets via a wireless communication interface, so that a frequency offset is implemented to offset the frequency of the transmission of at least a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

[0144] Clause 25. A broadcast station according to any of clauses 17 to 24, wherein one or more processing units are configured to send timing reference signals and data via a wireless communication interface using pi / 2BPSK, QPSK, 8-PSK, 16QAM or 64QAM modulation or any combination thereof.

[0145] Clause 26. A broadcast station according to any of clauses 17 to 25, wherein one or more processing units are configured to send a timing reference signal and data via a wireless communication interface such that for each resource block in the first OFDM resource block set, all subcarriers of the corresponding OFDM resource block are used.

[0146] Clause 27. A broadcast station according to any of clauses 17 to 26, wherein the one or more processing units are configured to include in the data information indicating:

[0147] The identity of the broadcasting station,

[0148] the location of the broadcast station, or

[0149] The system time of the broadcast station, or

[0150] Any combination of them.

[0151] Clause 28. A receiver configured to use a wireless radio frequency (RF) timing reference signal, the receiver comprising:

[0152] Wireless communication interface;

[0153] Memory; and

[0154] One or more processing units communicatively coupled to the wireless communication interface and the memory and configured to perform functions including:

[0155] 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:

[0156] receiving a respective timing reference signal during one or more symbols of a respective set of orthogonal frequency division multiplexing (OFDM) resource blocks, wherein each OFDM resource block in the respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols; and

[0157] receiving respective data in a symbol following each of the one or more symbols in which the respective timing reference signal is transmitted;

[0158] obtaining information about each of the one or more broadcasting stations based on a corresponding timing reference signal or corresponding data transmitted by each broadcasting station; and

[0159] Do one or both of the following:

[0160] (iii) determining a clock offset of the receiver based at least in part on the corresponding timing reference signal and information obtained about at least one of the one or more broadcasting stations, or

[0161] (iv) determining a location of the receiver based at least in part on the corresponding timing reference signal and the information obtained about each of the one or more broadcast stations.

[0162] Clause 29. The receiver of clause 28, wherein the wireless communication interface is configured to receive the timing reference signal and the data via a frequency band centered around substantially 100 kHz.

[0163] Clause 30. A receiver according to clause 28 or clause 29, wherein the one or more processing units are configured to determine the following from the information obtained about each of the one or more broadcasting stations:

[0164] The identity of the corresponding broadcast station,

[0165] the location of the corresponding broadcast station, or

[0166] The system time of the corresponding broadcast station, or

[0167] Any combination of them.

Claims

1. A method for transmitting a radio frequency (RF) timing reference signal from a broadcast station, the method comprising: transmitting a timing reference signal using one or more subcarriers during one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring at a first subframe, wherein each OFDM resource block in the first set of OFDM resource blocks includes a contiguous set of subcarriers and a series of consecutive symbols; and for each of the one or more symbols in which the timing reference signal is sent, sending data in at least one of the one or more subcarriers in a symbol immediately following the corresponding symbol in which the timing reference signal is sent, wherein the timing reference signal and the data are sent such that for each resource block in the first set of OFDM resource blocks, all subcarriers of the corresponding OFDM resource block are used, The timing reference signal and the data are sent using paired subcarriers, so that the timing reference signal and the data are sent on consecutive symbols.

2. The method according to claim 1, wherein: The timing reference signal and data are transmitted using a frequency band centered around substantially 100 kHz.

3. The method according to claim 1, wherein: The timing reference signal and data are sent using a comb-6 signal structure.

4. The method according to claim 3, wherein: The timing reference signal and data are sent such that for each resource block in 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 a corresponding OFDM resource block, and The second pair of the one or more subcarriers is used for a second plurality of consecutive symbols of the corresponding OFDM resource block immediately following the first plurality of consecutive symbols.

5. The method according to claim 4, wherein: Any subcarrier in the second pair of the one or more subcarriers is not directly adjacent to any subcarrier in the first pair of the one or more subcarriers.

6. The method according to claim 1, wherein: The timing reference signal and data are transmitted using a comb-1 signal structure, a comb-2 signal structure, or a comb-3 signal structure.

7. The method according to claim 1 also includes sending additional timing reference signals and data in multiple subsequent OFDM resource block sets, so that a muting mode is performed to omit sending a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

8. The method according to claim 1 also includes sending additional timing reference signals and data in multiple subsequent OFDM resource block sets, so that a frequency offset is implemented to offset the frequency of the transmission of at least a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

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

10. The method according to claim 1, wherein: The timing reference signal is transmitted using a code unique to a broadcast station within a code space for the broadcast station.

11. The method of claim 1 , further comprising including in the data information indicating: the identity of the broadcasting station, the location of the broadcast station, or the system time of the broadcast station, or Any combination of them.

12. A method for using a wireless radio frequency (RF) timing reference signal at a receiver, the method 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: receiving a corresponding timing reference signal on one or more subcarriers during one or more symbols of a corresponding set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring at a first subframe, wherein each OFDM resource block in the corresponding set of OFDM resource blocks includes a corresponding set of adjacent subcarriers and a corresponding series of consecutive symbols; for each of the one or more symbols in which the timing reference signal is received, receiving data in at least one of the one or more subcarriers in a symbol immediately following the corresponding symbol in which the timing reference signal is received, wherein the timing reference signal and the data are received such that for each resource block of the corresponding set of OFDM resource blocks, all subcarriers of the corresponding OFDM resource block are used; and using each received timing reference signal as a phase reference in demodulation of the corresponding data, The timing reference signal and the data are received using paired subcarriers so as to receive the timing reference signal and the data on consecutive symbols.

13. The method according to claim 12, further comprising: obtaining information about each of the one or more broadcasting stations based on the corresponding timing reference signal or the corresponding data transmitted by each broadcasting station; as well as Do one or both of the following: (i) determining a clock offset of the receiver based at least in part on the corresponding timing reference signal and information obtained about 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 corresponding timing reference signal and the information obtained about each of the one or more broadcast stations.

14. The method according to claim 12, wherein: The timing reference signal and data are transmitted using a frequency band centered around substantially 100 kHz.

15. The method according to claim 13, wherein: For each of the one or more broadcasting stations, the obtained information includes information indicating: the identity of the corresponding broadcasting station, the location of the corresponding broadcasting station, or the system time of the corresponding broadcast station, or Any combination of them.

16. The method according to claim 13, wherein: Identifying each of the one or more broadcast stations includes determining, for each of the one or more broadcast stations, a code within a code space of the broadcast station that is unique to the respective broadcast station.

17. A broadcast station for transmitting a wireless radio frequency (RF) timing reference signal, the broadcast station comprising: Wireless communication interface; Memory; as well as One or more processing units communicatively coupled to the wireless communication interface and the memory and configured to perform functions including: transmitting, via the wireless communication interface, a timing reference signal using one or more subcarriers during one or more symbols of a first set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring at a first subframe, wherein each OFDM resource block in the first set of OFDM resource blocks comprises a contiguous set of subcarriers and a series of consecutive symbols; and for each of the one or more symbols in which the timing reference signal is sent, sending data via the wireless communication interface in at least one of the one or more subcarriers in a symbol immediately following the corresponding symbol in which the timing reference signal is sent, wherein the timing reference signal and the data are sent such that for each resource block of the first set of OFDM resource blocks, all subcarriers of the corresponding OFDM resource block are used, The timing reference signal and the data are sent using paired subcarriers, so that the timing reference signal and the data are sent on consecutive symbols.

18. The broadcast station according to claim 17, wherein: The one or more processing units are configured to transmit the timing reference signal via the wireless communication interface and to transmit data using a frequency band centered around substantially 100 kHz.

19. The broadcast station according to claim 17, wherein: The one or more processing units are configured to transmit the timing reference signal and data via the wireless communication interface using a comb-6 signal structure.

20. The broadcast station of claim 19, wherein: The one or more processing units are configured to send the timing reference signal and data via the wireless communication interface such that, for each resource block in 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 a corresponding OFDM resource block, and The second pair of the one or more subcarriers is used for a second plurality of consecutive symbols of the corresponding OFDM resource block immediately following the first plurality of consecutive symbols.

21. The broadcast station according to claim 20, wherein Any subcarrier in the second pair of the one or more subcarriers is not directly adjacent to any subcarrier in the first pair of the one or more subcarriers.

22. The broadcast station of claim 17, wherein: The one or more processing units are configured to send the timing reference signal and data via the wireless communication interface using a comb-1 signal structure, a comb-2 signal structure, or a comb-3 signal structure.

23. The broadcast station of claim 17, wherein: The one or more processing units are also configured to send additional timing reference signals and data in multiple subsequent OFDM resource block sets via the wireless communication interface, so that a muting mode is performed to omit sending a portion of the additional timing reference signals and data during at least one OFDM resource block set in the multiple subsequent OFDM resource block sets.

24. The broadcast station of claim 17, wherein: The one or more processor units are also configured to send additional timing reference signals and data in multiple subsequent OFDM resource block sets via the wireless communication interface, so that a frequency offset is implemented to offset the frequency of the transmission of at least a portion of the additional timing reference signals and data during at least one of the multiple subsequent OFDM resource block sets.

25. The broadcast station of claim 17, wherein: The one or more processing units are configured to send the timing reference signal and data via the wireless communication interface using pi / 2BPSK, QPSK, 8-PSK, 16QAM or 64QAM modulation or any combination thereof.

26. The broadcast station of claim 17, wherein: The one or more processing units are configured to include in the data information indicating: the identity of the broadcasting station, the location of the broadcast station, or the system time of the broadcast station, or Any combination of them.

27. A receiver configured to use a wireless radio frequency (RF) timing reference signal, the receiver comprising: Wireless communication interface; Memory; as well as One or more processing units communicatively coupled to the wireless communication interface and the memory and configured to perform functions including: 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: receiving a respective timing reference signal on one or more subcarriers during one or more symbols of a respective set of orthogonal frequency division multiplexing (OFDM) resource blocks occurring at a first subframe, wherein each OFDM resource block in the respective set of OFDM resource blocks comprises a respective set of adjacent subcarriers and a respective series of consecutive symbols; for each of the one or more symbols in which the timing reference signal is received, receiving data in at least one of the one or more subcarriers of a symbol immediately following a symbol in which the corresponding symbol of the timing reference signal is received, wherein the timing reference signal and the data are received such that for each resource block of the corresponding set of OFDM resource blocks, all subcarriers of the corresponding OFDM resource block are used; and In demodulation of the corresponding data, each received timing reference signal is used as a phase reference, The timing reference signal and the data are received using paired subcarriers so as to receive the timing reference signal and the data on consecutive symbols.

28. The receiver of claim 27, wherein the one or more processing units are further configured to perform the following functions: obtaining information about each of the one or more broadcasting stations based on the corresponding timing reference signal or the corresponding data transmitted by each broadcasting station; and Do one or both of the following: (iii) determining a clock offset of the receiver based at least in part on the corresponding timing reference signal and the information obtained about at least one of the one or more broadcasting stations, or Those (iv) determining a location of the receiver based at least in part on the corresponding timing reference signal and the obtained information about each of the one or more broadcast stations.

29. The receiver of claim 27, wherein: The wireless communication interface is configured to receive the timing reference signal and data via a frequency band centered around substantially 100 kHz.

30. The receiver of claim 28, wherein: The one or more processing units are configured to determine the following from the obtained information about each of the one or more broadcasting stations: the identity of the corresponding broadcasting station, the location of the corresponding broadcasting station, or the system time of the corresponding broadcast station, or Any combination of them.

31. A computer readable medium having stored thereon instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 11.

32. A computer readable medium having stored thereon instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 12 to 16.

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