CN101313619B - Adjusting the Positioning of Emitters Using Phase - Google Patents

Abstract

The present invention provides a system and method for determining location information in a wireless network. In one embodiment, timing offset information is communicated between multiple transmitters and one or more receivers. This information enables accurate position or location determination that accounts for timing differences throughout the network. In another embodiment, a transmitter phase adjustment is made that advances or delays transmission from the transmitter to account for potential timing differences at the receiver. In yet another embodiment, a combination of timing offset delivery and/or transmitter phase adjustment may be used in the wireless network to facilitate position location determination.

Description

Adjusting the Positioning of Emitters Using Phase

Claiming priority under 35 U.S.C. §119

This patent application claims priority to Provisional Application No. 60/721,505, filed September 27, 2005, entitled "POSITION LOCATION USINGTRANSMITTERS WITH TIMING OFFSET," assigned to the present assignee and hereby expressly incorporated herein by reference.

technical field

The present technology relates generally to communication systems and methods, and more particularly to systems and methods for determining a position fix from a wireless network by using timing offset or transmitter phase adjustment techniques in the network.

Background technique

One technology dominating wireless systems is Code Division Multiple Access (CDMA) digital wireless technology. In addition to CDMA, air interface specifications define FLO (forward link only) technology that has been developed by an industry-leading group of wireless providers. In general, FLO has taken advantage of the most advantageous features of available wireless technologies and has used the latest advances in coding and system design to consistently achieve the highest quality performance. One goal of FLO is to become a globally adopted standard.

In one instance, FLO technology was designed for use in a mobile multimedia environment and exhibits performance characteristics well suited for cellular handsets. It uses the latest advances in encoding and interleaving to achieve the highest quality reception at any time for real-time content streaming and other data services. FLO technology provides robust mobile performance and high capacity without compromising power consumption. The technique also reduces the network cost of delivering multimedia content by greatly reducing the number of transmitters to be deployed. In addition, multimedia multicast based on FLO technology complements wireless carriers' cellular network data and voice services, delivering content to the same cellular handsets used on 3G networks.

In addition to non-real-time services, the FLO wireless system is designed to broadcast real-time audio and video signals to mobile users. Individual FLO transmissions are carried out using tall and high powered transmitters to ensure wide coverage in a given geographic area. Additionally, in most markets, typically 3 to 4 transmitters are deployed to ensure that the FLO signal reaches a majority of the population in a given market. Due to the coverage of the FLO transmitter, it is possible, for example, to determine a position based on triangulation techniques. Traditional positioning techniques utilize satellite-based GPS signals for distance measurement. However, a problem with satellite-based signals is that they are not available in indoor environments (eg, where line-of-sight to a satellite is not available). In contrast, FLO networks are typically designed for indoor coverage, and thus the respective waveforms can provide positioning information to devices located indoors.

Contents of the invention

A simplified summary of various embodiments is presented below in order to provide a basic understanding of some aspects of the embodiments. This summary is not an extensive overview. It is not intended to identify key/critical elements or to delineate the scope of the embodiments disclosed herein. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

Systems and methods are provided for determining position or positioning information in a wireless network in place of (or in conjunction with) conventional Global Positioning System (GPS) technology. In one embodiment, multiple transmitters are used, which account for timing differences between transmitters, to determine position in the broadcast network. Many positioning algorithms assume that transmitters transmitting signals for distance measurements are aligned in time, for example using a common central clock such as GPS. However, in some broadcast systems there are certain advantages to advancing/delaying transmissions from certain transmitters relative to a central clock to facilitate signal reception and quality in the network. In such cases, the positioning algorithm utilizes the transmitter's timing offset information to obtain a more accurate distance measurement than conventional positioning components. Thus, in some embodiments, overhead parameter information (eg, timing offset information) may be transmitted and this additional information used at the receiver to obtain accurate distance measurements.

In another embodiment, signal transmission timing may be advanced or delayed at the respective transmitters to alleviate the need to account for timing offsets at the receiver. By adjusting the timing of the transmitted signal at the transmitter, accurate position information can be determined at the respective receivers, while timing offset calculations are eased because the timing mismatch with the central clock has been resolved at the transmitter. As can be appreciated, certain systems may include a combination of timing offsets communicated to the receiver and/or timing adjustments at the transmitter to facilitate accurate position determination.

To the accomplishment of the foregoing and related ends, certain illustrative embodiments are described herein in conjunction with the following description and accompanying drawings. These aspects illustrate various ways in which the described embodiments may be practiced, and all are intended to be encompassed.

Description of drawings

FIG. 1 is a schematic block diagram illustrating a wireless network location system.

2 is an example system that uses timing offset information to determine a position fix.

3 illustrates an example technique for transmitting timing offset information.

4 illustrates an example system for adjusting timing information in a Wireless Location System.

5 is a diagram illustrating example network layers for a Wireless Location System.

6 is a diagram illustrating example data structures and signals for a Wireless Location System.

7 illustrates an example timing process for a Wireless Location System.

8 is a diagram illustrating an example user device for a wireless system.

9 is a diagram illustrating an example base station for a wireless system.

10 is a diagram illustrating an example transceiver for a wireless system.

Detailed ways

Systems and methods are provided for determining location information in a wireless network. In one embodiment, timing offset information is communicated between multiple transmitters and one or more receivers. This information enables accurate position or positioning determinations that account for timing differences in the network. In another embodiment, a transmitter phase adjustment is performed that advances or delays transmissions from the transmitter to account for potential timing differences between the transmitter and a common clock. In this way, position determination can be made at the receiver without further timing adjustments. In another aspect, a combination of timing offset transfer and/or transmitter phase adjustment may be used in a wireless network to facilitate position location calculations or determinations.

It should be noted that a timing offset can be viewed as a timing mismatch between the transmitter clock and the common clock source, which causes the synchronization symbols at the transmitter to be transmitted with an offset compared to the common clock synchronization signal. For example, in the case of a forward link only (FLO) signal, it is generally expected that the superframe boundaries at the transmitter are synchronized with the 1 PPS signal from GPS. However, in practice the superframe boundaries may be advanced or delayed relative to the 1 PPS signal from GPS due to timing mismatches or sometimes intentionally for network optimization purposes. This is called timing offset at the transmitter.

In terms of phase adjustment at the transmitter, the transmitter waveform is essentially modified to adjust the propagation delay perceived by the receiver, regardless of the timing offset at the transmitter. In this case, even though the transmitter's clock (and thus transmission) may be precisely synchronized with the common clock source, the transmitter waveform may be modified resulting in skewed propagation delay measurements at the receiver. For example, where FLO uses OFDM signaling, the superframe boundaries can be synchronized with the 1 PPS signal from GPS. However, the transmitter can adjust the transmission phase by using a cyclic shift to the OFDM symbol buffer. A cyclic prefix of an OFDM symbol may be formed based on a cyclically shifted OFDM symbol. With this signal modification, the delay perceived by the receiver varies with the chosen transmission phase (or equivalently, the amount of cyclic shift over the OFDM symbol). This is called phase adjustment at the transmitter.

As used in this application, the terms "component," "network," "system" and similar terms are intended to refer to a computer-related entity, be it hardware, a combination of hardware and software, software, or software in execution. For example, a component can be, but is not limited to being, a process executing on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, an application executing on a communication device and the device may be components. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. Also, these components can execute from various computer readable media having various data structures stored thereon. The components can communicate (e.g., in accordance with signals having one or more data packets) over local and/or remote processes (e.g., data from one component in a local system, in a distributed system, and/or via a wired system such as the Internet) or interact wirelessly with another component).

FIG. 1 illustrates a wireless network location system 100 . The system 100 includes one or more transmitters 110 that communicate with one or more receivers 120 via a wireless network. The receiver 120 may comprise substantially any type of communication device, such as a cellular telephone, computer, personal assistant, handheld or laptop device, and the like. The system 100 employs one or more positioning components 130 to facilitate determining the location or location of the receiver 120 . In general, timing synchronization information between the transmitter 110 and the receiver 120 may need to be adjusted in various embodiments described herein to facilitate accurate position determination at the receiver. In one case, a timing offset component 140 can be passed between the transmitter 110 and receiver 120 to represent a timing difference or adjustment in the wireless network to be accounted for in a position determination component or algorithm. Another scenario uses a phase adjustment component 150 at the transmitter 110 to advance or delay a signal, which phase adjustment component 150 has the effect of compensating for timing mismatches or differences that may occur in the system 100 . In other embodiments, various combinations of timing offset component 140 and/or phase adjustment component 150 may be used simultaneously to facilitate position determination in wireless network location system 100 . As illustrated, one or more pilot symbols 154 may be provided for delay measurements.

In general, conventional positioning techniques utilize satellite-based GPS signals for distance measurements. However, one problem with satellite-based signals is that the signal is unavailable, for example, in indoor environments where line-of-sight to the satellite is not available. On the other hand, the high power nature of forward link only (FLO) transmissions facilitates the use of FLO waveforms in indoor environments where GPS signals are unavailable. Therefore, when FLO signals from multiple transmitters are available, there is an alternative method of positioning based on measurements made from FLO signals. In the following description, it may be assumed that a FLO receiver is capable of accessing signals from at least three different FLO transmitters (other configurations are possible) that may or may not be transmitting the same information content.

FLO networks are typically deployed for a single frequency network (SFN) mode of operation in which transmitters are synchronized to a common clock source. The clock source may, for example, be derived from a 1 PPS signal from GPS. The FLO waveform is based on Orthogonal Frequency Division Multiplexing (OFDM) signaling and can be designed assuming, for example, that the delay spread of the channel will be less than about 135 us. When multiple transmitters 110 are visible to a receiver 120, the delay spread perceived by the receiver is a function of the receiver's relative position from the various transmitters. In some cases, the receiver 120 may be close to one of the transmitters 110 and far away from the other transmitter, thus resulting in a larger delay spread. If the resulting delay spread exceeds the design specification (or other reference) of 135 us, it can result in a significant loss of system performance. However, by delaying or advancing superframe boundaries relative to the synchronization pulse from the central clock, it is possible to control the delay spread perceived by the receiver 120 at various points in the network. Therefore, it may also be realistic to assume a fixed timing offset between different transmitters 110 in an optimized FLO network deployment.

In an SFN deployment of a FLO network, the transmitters 110 may be tuned to operate with a fixed timing offset relative to a central clock (and thus relative to each other) to optimize the delay spread seen at the receiver 120 , and thus optimize system performance. Relative timing offsets at the transmitters, if not accounted for, can adversely affect range measurements used for positioning. However, in mobile-based positioning and network-based positioning, it is possible to account for transmitter timing offset by modifying the distance calculation. This may include having the FLO network provide transmitter timing offset information to the receiver 120 in the mobile-based positioning system, adjusting the transmission timing and phase signal or a combination of timing offset and signal adjustment.

2 illustrates an example system 200 that uses timing offsets to determine a position fix. In this example, transmitters A, B, and C at 210 may be three different FLO transmitters carrying FLO signals that are within receiving range of receiver 220 at a given point in time. Additionally, assume da, _db , and _dc represent the timing offset 230 _of the respective transmitters relative to the common clock source 240 . Here, a positive offset would mean advancing transmission relative to the central clock 240, while a negative offset would mean delaying transmission relative to the central clock. It may be assumed that the receiver clock is synchronized with the common clock source 240 in phase and frequency.

Commonly available FLO air interface specifications allow each transmitter 210 to insert symbols unique to that transmitter (called positioning pilot channels). These symbols may be designed to allow the receiver 220 to estimate the propagation delay from each of the transmitters 210 . The positioning pilot channel is essentially a set of pilot tones specific to each transmitter, designed with high processing gain so that channels with long delay spread and weak energy can still be detected at the receiver 220 arrive. In the case of line-of-sight propagation from transmitter 210 to receiver 220 without significant scatter, channel estimates derived via positioning pilots generally contain a single path. The distance of the receiver 220 from the transmitter 210 is determined based on the location of the channel path in the channel estimate.

In system example 200, it is assumed that τ _a is a location based on a single path (or the path that arrives first in the multipath case) in the channel estimate from transmitter A's location pilot channel. Similarly, assume _τb and _τc are the delays of the first-arriving path in the channel estimates from transmitters B and C, respectively. If the clocks at the three transmitters 210 and the receiver 220 are synchronized in frequency and phase, then the distance from the receiver to the transmitter is calculated as the speed of light (c) multiplied by the propagation delay measured via the channel estimate. distance. However, in case there is a timing offset at the transmitter 210, the delay measured at the receiver 220 should be corrected by the timing offset 230 between transmitter and receiver. Therefore, the distance of the receiver from the transmitter A is given by:

S _a =(d _a +τ _a )×c, where c is the speed of light.

Similarly, S _b =(d _b +τ _b )×c and S _c =(d _c +τ _c )×c. When the relative distances of the receiver 220 to three known locations are determined (in this case, the known locations are the FLO transmitters), the receiver's location can be obtained by well-known triangulation methods. The triangulation method essentially determines a single point of intersection of circles drawn around the three emitters _A , _B and _C with radii Sa, Sb and Sc, respectively. Thus, it is apparent that in the event of a relative timing offset at the transmitter 210, it is useful for the receiver 220 to know the timing offset value 230 in order to accurately determine a position or position.

FIG. 3 illustrates an example method for communicating timing information 300 . As can be appreciated, there are several possible techniques for transmitting the timing offset information 300 to the receiver. It should be noted that it is sufficient for the receiver to know the timing offset of each of the transmitters relative to a common central clock, such as a GPS clock or other common clock.

At 310, one possible transmission mechanism is for the transmitter to broadcast information about the timing offset using overhead symbols. For example, in a FLO system, timing information from all transmitters in a particular local area may be included in a local OIS field (overhead information symbol) that is specific to a given local area but Vary over different local areas within a given wide-area area. One advantage of this approach is that the transmitter timing information is localized. It should be noted that the method does not provide the receiver with the advantage of receiving timing offset information about the transmitter if the receiver is unable to receive the positioning pilot channel from the transmitter. On the other hand, partial OIS fields may be more susceptible to interference at the edge of the coverage area than the positioning pilot channel. Therefore, a receiver may be able to successfully decode the positioning pilot channel, but fail to obtain timing information from the local OIS channel. A variation on this approach would be to include timing information in a wide area OIS, which eliminates the coverage edge problem at the expense of broadcasting transmitter timing information over a wider geographic area (and thus useful bandwidth).

At 320, another possible technique for transmitting timing information is to embed transmitter timing information in a positioning pilot channel (PPC). In this case, the receiver may first use the PPC from a given transmitter to estimate the channel from that transmitter, and then decode the timing information embedded in the PPC. In this case, it may be necessary to increase the processing gain of the PPC sufficiently to facilitate not affecting the detection probability of the PPC in the presence of additional information embedded in the symbol.

At 330, a third possible technique for transmitting timing information is to periodically broadcast the transmitter's almanac as a non-real-time MLC (Media FLO Logical Channel) and facilitate receiver decoding of this specific information MLC. At 340, another attractive technique mitigates timing offset information at the transmitter by modifying the transmitter waveform for the PPC symbols to account for the timing offset, as discussed below with reference to FIG. 4 .

4 illustrates an example system 400 for adjusting timing information in a Wireless Location System. In this example, two transmitters A and B are shown at 410 . At 420, the signal from transmitter 410 may be advanced or delayed to account for possible timing differences in the system. Accordingly, receiver 430 may be able to determine a position fix without having to determine an offset from a central clock as described above. The concept of advancing or retarding transmitter timing at 420 is introduced in the FLO system in order to accommodate the effective channel delay spread as perceived by the receiver 430 . In one case, in an OFDM system, if the delay spread of the channel is smaller than the cyclic prefix used by the OFDM signal, then the linear convolution of the channel with the transmitted signal can be treated as a cyclic convolution.

In this example, assume that transmitters A and B at 410 have timing offsets d _a and d _b . Let τ′ _a be the actual delay that will be perceived by the line-of-sight propagation component based on the distance between transmitter A and receiver 430 . Similarly, assume _τ'b is the actual delay from transmitter B to receiver 430 that will be perceived by the line-of-sight component. It should be noted that when the delay spread _τ'b - _τ'a exceeds the cyclic prefix, additional delays d _a and d _b are introduced at the transmitters (assuming one line-of-sight component from each of the transmitters). With delays d _a and d _b at the transmitter, the signal received at the receiver is given by:

Equation 1

y(n)=h _a (n)*x _a (nd _a )+h _b (n)*x _b (nd _b )+w(n),

where h _a (n) and x _a (n) are the channel and signal at transmitter A, * represents a linear convolution operation, and w(n) is the noise added at the receiver. In the case of a traffic channel in a wide area network, x _a (n) is substantially the same as x _b (n) (say x(n)).

Using the properties of linear convolution, the above equation can be written as,

Equation 2

y(n)=h _a (nd _a )*x(n)+h _b (nd _b )*x(n)+w(n)

The perceived channel delay spread is thus now given by (τ' _b - d _b ) - (τ' _a - d _a ), and can be controlled by introducing a timing offset at the transmitter. When the effective delay spread is smaller than the cyclic prefix, the received signal in Equation 1 can be written as a circular convolution rather than a linear convolution. therefore:

Equation 3

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

or equivalently,

Equation 4

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$

表示环形卷积。如果循环前缀足够长，那么可通过在等式3中以d_a环形旋转x_a(n)来实现在等式1中使信号x_a(n)延迟d_a以得到等式3的操作。in

Represents circular convolution. If the cyclic _prefix is long enough, the _{operation of} delaying the signal x _a (n) in Eq.

Based on the above situation, the following viewpoints are put forward with regard to the conventional traffic channel and the pilot positioning channel. During regular traffic channels, the cyclic prefix used is usually shorter (512 chips in the case of FLO) and thus the cyclic shift technique discussed in Equation 3 cannot be used to adjust the effective delay spread of the channel. Therefore, the transmissions from the respective transmitters will be physically delayed (in this example, transmitters A and B are delayed by d _a and d _b ) to meet the cyclic prefix requirement. On the other hand, for the positioning pilot channel, a long cyclic prefix (approximately 2500 chips in FLO, where a chip refers to the bits encoded into the data packet) can be used in order to be able to estimate delays from distant weak transmitters. In addition, the delay _da and _db introduced by the transmitter for the traffic channel affects the delay observations made in the positioning pilot channel, so this overhead information is required at the receiver as previously discussed.

Assuming that the long cyclic prefix of the pilot positioning channel is available, the transmitter can cancel the influence of actual physical delays d _a and _db by cyclic shifting of the positioning signal. If x _a,p (n) is the intended positioning signal from transmitter A with a timing delay _da , then the transmitter may send a cyclically shifted version given by x _a,p (n+d _a ). Similarly, the signal from transmitter B is cyclically shifted. Equation 3 is still valid due to the presence of long cyclic prefixes, and thus:

Equation 5

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

The need to communicate transmitter delay information to the receiver is thus alleviated. This technique can be used to account for transmitter timing offsets caused by delays introduced as part of network planning, as well as other possible timing delays due to, for example, filters, cables, and other such components.

Regarding another embodiment, the above discussion may assume that distance measurements are computed at the mobile receiver. However, it is possible to perform the calculations in a network where timing information is available off-line. In this case, the receiver may measure pseudoranges _S'a , _S'b, and _S'c , where, for example, _S'a = _τa x c, regardless of transmitter timing offset. The receiver will relay the pseudorange _S'a to the network, and further corrections by timing offsets can easily be performed at the network, since the entire almanac can be made available at the network.

The above discussion assumes that the receiver clock is tightly synchronized to the common clock and that there is a mismatch between the common clock and the transmitter clock due to timing offsets or phase adjustments at the transmitter. However, it should be noted that this may be considered a special case and the receiver clock does not have to be synchronized with the common clock. When the receiver clock is not synchronized to the common clock, the delay measurements from the individual transmitters may also include a common bias term, which is the amount of mismatch between the common clock and the receiver clock. The common deviation is now another unknown to be calculated in addition to the spatial coordinates of the receivers. The unknowns of the spatial coordinates as well as the clock bias can all be resolved by means of measurements from additional transmitters. Specifically, having measurements from, for example, four different transmitters (where timing offset information is available relative to a common clock source, and assuming the receiver is located on the Earth's surface) is sufficient to find the spatial coordinates at the receiver standard and common clock skew. In cases where there is no common clock skew at the receiver (ie the receiver clock is synchronized to the common clock), it is sufficient to have delay measurements from eg three different transmitters.

5 illustrates an example network layer 500 of the Wireless Location System.

Figure 5 shows a forward link only (FLO) air interface protocol reference model. In general, the FLO air interface specification covers protocols and services corresponding to OSI6 with layer 1 (physical layer) and layer 2 (data link layer). The data link layer is further divided into two sublayers, ie, a media access (MAC) sublayer and a streaming sublayer. The upper layer may include compression of multimedia content, access control to multimedia, and content and formatting of control information.

FLO air interface specifications generally do not specify upper layers to allow design flexibility to support various applications and services. These layers are shown to provide context. The stream layer includes multiplexing of up to three upper layer streams into one logical channel, binds upper layer packets to each logical channel's stream, and provides packetization and residual error handling functions. The functions of the Media Access Control (MAC) layer include controlling access to the physical layer, performing mapping between logical channels and physical channels, multiplexing logical channels for transmission on physical channels, demultiplexing at the mobile device Logical channels, and/or enforce Quality of Service (QOS) requirements. The characteristics of the physical layer include providing the channel structure and defining the frequency, modulation and coding requirements for the forward link.

Typically, FLO technology utilizes Orthogonal Frequency Division Multiplexing (OFDM), which is also used by Digital Audio Broadcasting (DAB)7, Terrestrial Digital Video Broadcasting (DVB-T)8 and Terrestrial Integrated Services Digital Broadcasting (ISDB-T) ) 9 use. Generally, OFDM technology can achieve high spectral efficiency while effectively meeting mobility requirements in large-cell SFNs. Also, OFDM can handle long delays from multiple transmitters with cyclic prefixes of appropriate length; a guard interval (which is a copy of the last part of the data symbol) is added to the front of the symbol to promote orthogonality and mitigate inter-carrier interference . As long as the length of this interval is greater than the maximum channel delay, reflections of previous symbols are canceled and orthogonality is maintained.

Proceeding to FIG. 6 , the FLO physical layer 600 is illustrated. The FLO physical layer uses 4K mode (resulting in a transform size of 4096 subcarriers), thereby providing superior mobility performance compared to 8K mode while maintaining a sufficiently long guard interval to be useful in relatively large SFN cells. Fast channel acquisition can be achieved through optimized pilot and interleaver structure design. The interleaving mechanism incorporated into the FLO air interface facilitates time diversity. The pilot structure and interleaver design optimize channel utilization without bothering users with long acquisition times. Typically, the signals transmitted by the FLO are organized into superframes as illustrated at 600 . Each superframe contains four data frames, including TDM pilot (time division multiplexing), overhead information symbols (OIS), and frames containing wide-area and local-area data. TDM pilots are provided to enable fast acquisition of OIS. The OIS describes the location of data for each media service in a superframe.

Typically, each superframe consists of 200 OFDM symbols per MHz of allocated bandwidth (a total of 1200 symbols for 6MHz), and each symbol contains 7 interlaces of active subcarriers. Each interlace is spread evenly in frequency so that complete frequency diversity is achieved within the available bandwidth. These interlaces are assigned to logical channels that vary in duration and the actual number of interlaces used. This provides flexibility in the time diversity achieved by any given data source. Lower data rate channels may be assigned fewer interlaces to improve time diversity, while higher data rate channels utilize more interlaces to minimize the radio's on-time and reduce power consumption.

The acquisition time is usually the same for both low data rate channels and high data rate channels. Thus, frequency and time diversity can be maintained without compromising acquisition time. Often, FLO logical channels are used to carry real-time (live streaming) content at variable rates to obtain possible statistical multiplexing gains through variable rate codecs (compressor and decompressor in one). Each logical channel may have a different coding rate and modulation to support various reliability and quality of service requirements of different applications. The FLO multiplexing mechanism enables a device receiver to demodulate the content of a single logical channel of interest to it to minimize power consumption. A mobile device can simultaneously demodulate multiple logical channels to enable sending video and associated audio on different channels.

Error correction and encoding techniques may also be used. Typically, FLO incorporates a Turbo inner 13 and a Reed Solomon (RS) 14 outer. Typically, turbo codes include a cyclic redundancy check (CRC). For correctly received data, no RS code needs to be calculated, which leads to additional power savings under favorable signal conditions. On the other hand, the FLO air interface is designed to support frequency bandwidths of 5, 6, 7 and 8 MHz. The use of a single radio frequency channel allows ideal service provisioning.

FIG. 7 illustrates a location and location process 700 for a wireless system. Although the methods are shown and described in terms of a series or several acts for simplicity of explanation, it is to be understood and understood that since certain acts may occur in different orders and/or concurrently with other acts shown and described herein, The processes described herein are therefore not limited by the order of actions. For example, those skilled in the art will appreciate and understand that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with the subject matter disclosed herein.

Proceeding to 710, various timing corrections are determined. This may include performing calculations to determine timing differences between transmitters, receivers, and/or a central clock source. Such differences can be used to determine a timing offset that can be used at the receiver to correct for differences from the clock, or such calculations can be used to determine how much to advance or delay the transmitter broadcast in order to account for timing differences. Test fixtures may be used to monitor potential system changes, with feedback received from such fixtures to facilitate determination of offsets or transmitter signal adjustments. At 720, one or more timing offsets are transmitted as part of the data packet to indicate how a potential receiver should adjust position or position calculations. Alternatively, the signal may be advanced or delayed at 730 to account for timing differences in the wireless network relative to a central clock. As can be appreciated, both methods at 720 and 730 can be applied simultaneously. For example, it may be advantageous to transmit a constant time offset at 720 and utilize an adjustable signal advance or delay at 730 if environmental or electrical conditions change. These changes can be monitored and a closed loop mechanism can be used to automatically adjust system transmission or timing. In another aspect, an advance or delay in transmission timing may be applied as a constant time offset dynamically calculated and transmitted at 720 to account for potential detected variations.

At 740, a corrected or adjusted signal and/or time offset is received. As described above, a time offset may be received, an adjusted signal relative to a clock may be received, or a combination of a time offset and an adjusted signal may be received. At 750, the time offset and/or phase adjusted signal may be used to determine position at one or more receivers. This information can be used to automatically calculate positioning information that accounts for possible discrepancies between the clock and the reference source. For example, time shifted or phase adjusted signals may be received indoors to determine the location of the receiver.

8 is an illustration of a user device 800 for use in a wireless communication environment in accordance with one or more aspects set forth herein. User device 800 includes a receiver 802 that receives signals from, for example, a receive antenna (not shown), and performs typical actions thereon (eg, filtering, amplifying, downconverting, etc.) Adjusted signal to obtain samples. Receiver 802 may be a non-linear receiver, such as a Maximum Likelihood (ML)-MMSE receiver or similar. A demodulator 804 can demodulate and provide received pilot symbols to a processor 806 for channel estimation. A FLO channel component 810 is provided to process the FLO signal as previously described. This may (among other things) include digital stream processing and/or position calculations. Processor 806 may be a processor dedicated to analyzing information received by receiver 802 and/or generating information for transmission by transmitter 816, may be a processor that controls one or more components of user device 800, and/or may is a processor that analyzes information received by receiver 802 , generates information for transmission by transmitter 816 , and controls one or more components of user device 800 .

The user device 800 may additionally include a memory 808 that is operatively coupled to the processor 806 and that stores information related to the calculated ratings of the user device 800, a rating calculation protocol, a lookup table containing information related thereto, and for supporting Decoding of list-spheres to compute any other suitable information of rank in a non-linear receiver in a wireless communication system as described herein. Memory 808 may additionally store protocols related to rank calculations, matrix generation, etc., such that user device 800 may use the stored protocols and/or algorithms to implement rank determination in a nonlinear receiver as described herein.

It will be understood that the data storage (eg, memories) components described herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. By way of illustration, and not limitation, nonvolatile memory can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM), which acts as external cache memory. By way of illustration and not limitation, RAM is available in many forms such as Synchronous RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), Synchlink DRAM ( SLDRAM) and Direct Rambus RAM (DRRAM). Memory 808 of the subject systems and methods is intended to include, but is not limited to, these and any other suitable types of memory. The user device 800 further includes a background monitor 812 for processing FLO data, a symbol modulator 814 and a transmitter 816 for transmitting modulated signals.

9 illustrates an example system 900 that includes a base station 902 having a receiver 910 that receives signals from one or more user devices 904 through a plurality of receive antennas 906, and transmits signals to one or more user devices through a transmit antenna 908. 904 to the transmitter 924 that transmits. Receiver 910 may receive information from receive antenna 906 and is operatively associated with demodulator 912 that demodulates received information. The demodulated symbols are analyzed by a processor 914 similar to the processor described above with reference to FIG. Any other suitable information relevant to performing the various actions and functions set forth herein. Processor 914 is further coupled to a FLO channel 918 component that facilitates processing FLO information associated with one or more respective user devices 904 .

Modulator 920 may multiplex a signal for transmission by transmitter 924 to user device 904 through transmit antenna 908 . The FLO channel component 918 can append information to signals related to the updated data stream for a given transport stream in communication with the user device 904, which can be transmitted to the user device 904 to provide the identified and confirmed new latest data stream. Instructions for the best channels. In this manner, base station 902 can interact with user devices 904 that provide FLO information and use decoding protocols in conjunction with non-linear receivers such as ML-MIMO receivers.

FIG. 10 shows an exemplary wireless communication system 1000 . For simplicity, the wireless communication system 1000 depicts a base station and a terminal. It should be understood, however, that the system may include more than one base station and/or more than one terminal, wherein additional base stations and/or terminals may be substantially similar to or different from the exemplary base stations and terminals described below.

Referring now to FIG. 10, on the downlink, at access point 1005, transmit (TX) data processor 1010 receives, formats, codes, interleaves, and modulates (or symbol maps) traffic data and provides modulation symbols (“data symbol"). A symbol modulator 1015 receives and processes data symbols and pilot symbols and provides a stream of symbols. A symbol modulator 1020 multiplexes data and pilot symbols and provides them to a transmitter unit (TMTR) 1020 . Each transmission symbol may be a data symbol, pilot symbol, or a signal value of zero. Pilot symbols may be sent continuously during each symbol period. Pilot symbols can be Frequency Division Multiplexing (FDM), Orthogonal Frequency Division Multiplexing (OFDM), Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), or Code Division Multiplexing Multiplexing (CDM).

TMTR 1020 receives a stream of symbols and converts the stream of symbols into one or more analog signals, and further conditions (e.g., amplifies, filters, and up-converts) the analog signals to produce a downlink signal suitable for transmission over a wireless channel . The downlink signal is then transmitted to the terminal via the antenna 1025 . At terminal 1030 , an antenna 1035 receives the downlink signal and provides the received signal to a receiver unit (RCVR) 1040 . Receiver unit 1040 conditions (eg, filters, amplifies, and downconverts) the received signal and digitizes the conditioned signal to obtain samples. A symbol demodulator 1045 demodulates received pilot symbols and provides them to a processor 1050 for channel estimation. The symbol demodulator 1045 further receives frequency response estimates for the downlink from the processor 1050, performs data demodulation on the received data symbols to obtain data symbol estimates (which are estimates of the transmitted data symbols), and The data symbol estimates are provided to an RX data processor 1055, which demodulates (ie, symbol demaps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data. The processing by symbol demodulator 1045 and RX data processor 1055 is complementary to that performed at access point 1005 by symbol modulator 1015 and TX data processor 1010, respectively.

On the uplink, a TX data processor 1060 processes traffic data and provides data symbols. A symbol modulator 1065 receives and multiplexes the data symbols with pilot symbols, performs modulation, and provides a stream of symbols. A transmitter unit 1070 then receives and processes the symbol stream to generate an uplink signal, which is transmitted by antenna 1035 to access point 1005 .

At access point 1005, uplink signals from terminals 1030 are received by antenna 1025 and processed by receiver unit 1075 to obtain samples. A symbol demodulator 1080 then processes the samples and provides received pilot symbols and data symbol estimates for the uplink. RX data processor 1085 processes the data symbol estimates to recover traffic data transmitted by terminal 1030 . Processor 1090 performs channel estimation for each active terminal transmitting on the uplink. Multiple terminals can simultaneously transmit pilot on the uplink on their respective assigned sets of pilot subbands, where the sets of pilot subbands can be interleaved.

Processors 1090 and 1050 direct (eg, control, coordinate, manage, etc.) operation at access point 1005 and terminal 1030, respectively. Respective processors 1090 and 1050 can be associated with memory units (not shown) that store program codes and data. Processors 1090 and 1050 can also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively.

For multiple access systems (eg, FDMA, OFDMA, CDMA, TDMA, etc.), multiple terminals can transmit simultaneously on the uplink. For such systems, pilot subbands can be shared among different terminals. The channel estimation technique may be used where the pilot subbands for each terminal span the entire operating band (except possibly the band edges). The pilot subband structure will be needed to obtain frequency diversity for each terminal. The techniques described herein can be implemented in a variety of ways. For example, these techniques may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing unit for channel estimation may be implemented in one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or combinations thereof. With software, implementation may be through modules (eg, procedures, functions, and so on) that perform the functions described herein. Software program codes may be stored in memory units and executed by processors 1090 and 1050 .

For a software implementation, the techniques described herein can be implemented using modules (eg, procedures, functions, and so on) that perform the functions described herein. Software program codes may be stored in memory units and executed by processors. The memory unit can be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various methods as is known in the art.

What has been described above includes exemplary embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the embodiments, but one of ordinary skill in the art can recognize that many additional combinations and permutations are possible. Accordingly, these embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "comprises" is used in the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprises", since in the claims "comprises" is included in Interpreted as a transitional term when used.

Claims (30)

1. A method for adjusting location information in a wireless network, comprising: determining time difference information between the common clock and at least one transmitter clock; adjusting the phase of at least one transmitter clock in view of the determined time difference information in response to the amount of cyclic shift in the adjusted signal; and determining a position of at least one receiver based on the adjusted phase of the transmitter clock; Wherein determining the time difference information further includes: generating at least two timing offsets denoted by d _a and d _b ; determining a first parameter _{τ'a which} is the actual delay perceived by the line-of-sight propagation component based on the distance between the first transmitter A and the at least one receiver; and A second parameter _τ'b is determined, said _τ'b being the actual delay from the second transmitter B to the at least one receiver as perceived by the line-of-sight propagation component. 2. The method of claim 1, further comprising generating a signal from at least two transmitters, the signal being advanced or delayed to account for timing differences in a wireless network. 3. The method of claim 1, further comprising advancing or retarding transmitter timing in a forward link-only network to adjust a delay spread of a channel perceived by the at least one receiver. 4. The method of claim 3, further comprising: it further comprising performing a linear convolution on a channel and a transmitted signal if the delay spread of the channel is less than that determined by Orthogonal Frequency Division Multiplexing (OFDM) cyclic prefix used by the signal, then the linear convolution is treated as a circular convolution. 5. The method of claim 1, further comprising: when the delay spread _τ'b - _τ'a exceeds the cyclic prefix, Timing offsets d _a and d _b are processed at said first and second transmitters. 6. The method of claim 5, further comprising processing the following equation: y(n)=h _a (n)*x _a (nd _a )+h _b (n)*x _b (nd _b )+w(n), wherein y(n) represents at the at least one receiver The received signal, h _a (n) and x _a (n) is the channel and signal with respect to the first transmitter A, h _b (n) and x _b (n) is with respect to the second transmitter B channel and signal, * denotes a linear convolution operation, w(n) is the noise added at the at least one receiver. 7. The method of claim 6, further comprising processing the following equation: y(n)=h _a (nd _a )*x(n)+h _b (nd _b )*x(n)+w(n), where the delay spread is given by (τ′ _b -d _b )-(τ′ _a - d _a ) are given and are controlled by introducing a timing offset at the first or second transmitter. 8. The method of claim 6, further comprising: when the delay spread is less than the cyclic prefix, determining the cyclic convolution as in the following equation: $\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$ or $\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$ in

Represents circular convolution. 9. The method of claim 8, further comprising delaying transmissions from transmitters to meet cyclic prefix requirements. 10. The method of claim 8, further comprising using a long cyclic prefix to enable estimation of delays from distant weak transmitters. 11. The method of claim 10, further comprising canceling the effect of physical delay by cyclic shifting of positioning signals, where x _a,p (n) is the signal from the transmitter A with timing offset d _a A positioning signal is given, and the transmitter sends a cyclically shifted version given by x _a,p (n+d _a ). 12. The method of claim 11 , further comprising processing the following equation $\mathrm{the\; y}\left(\mathrm{no}\right)=h_a\left(\mathrm{no}\right)\&CircleTimes;x_{a,p}\left(\mathrm{no}\right)+h_b\left(\mathrm{no}\right)\&CircleTimes;x_{b,p}\left(\mathrm{no}\right)+w\left(\mathrm{no}\right),$ To ease sending transmitter delay information to receiver. 13. The method of claim 1, further comprising determining transmitter timing adjustments from an offline network source. 14. The method of claim 13, further comprising measuring pseudoranges of the transmitter timing adjustments. 15. The method of claim 14, further comprising relaying the pseudoranges to a network almanac. 16. A system for adjusting location information in a wireless network, comprising: means for determining time difference information between at least two transmitters and at least one receiver in a wireless network; and means for adjusting the signal phase or signal frequency of the at least two transmitters in view of the determined time difference information in response to the adjusted amount of cyclic shift applied to the signal by each of the at least two transmitters ; Wherein the device for determining time difference information further includes: means for generating at least two timing offsets denoted by _da and _db ; means for determining a first parameter _τ'a , said _τ'a being the actual delay perceived by the line-of-sight propagation component based on the distance between the first transmitter A and said at least one receiver; and Means for determining a second parameter _τ'b which is the actual delay from the second transmitter B to the at least one receiver as perceived by the _line -of-sight propagation component. 17. The system of claim 16, further comprising means for determining a position at the at least one receiver in view of the adjusted signal phase or signal frequency. 18. A method of adjusting at least one transmitter clock, comprising: determining time difference information between the common clock relative to a subset of transmitter clocks; and adjusting the phase or frequency of at least one transmitter clock of the subset of transmitter clocks in view of the determined time difference information in response to the adjusted amount of cyclic shift applied to the signal by the transmitter; Wherein determining the time difference information further includes: generating at least two timing offsets denoted by d _a and d _b ; determining a first parameter _{τ'a which} is the actual delay perceived by the line-of-sight propagation component based on the distance between the first transmitter A and the at least one receiver; and A second parameter _τ'b is determined, said _τ'b being the actual delay from the second transmitter B to the at least one receiver as perceived by the line-of-sight propagation component. 19. The method of claim 18, further comprising determining a position of at least one receiver based on the adjusted phase or frequency of the transmitter. 20. The method of claim 19, further comprising determining the position using triangulation techniques and the subset of transmitter clocks. 21. The method of claim 18, further comprising determining at least one forward link-only parameter. 22. The method of claim 18, further comprising a layer component having at least one of a physical layer, a streaming layer, a media access layer, and an upper layer. 23. The method of claim 22, the physical layer further comprising at least one of a frame field, a pilot field, an overhead information field, a wide area field, and a local area field. 24. The method of claim 23, further comprising an error correction field. 25. A wireless communication device comprising: means for determining an adjusted timing between a receiver and a transmitter on a wireless network; and means for adjusting the phase of the signal in response to the adjusted amount of cyclic shift of the signal transmitted by at least one of the transmitters so as to determine the position of at least one receiver; wherein said means for determining an adjusted time base further comprises: means for generating at least two timing offsets denoted by _da and _db ; means for determining a first parameter _τ'a , said _τ'a being the actual delay perceived by the line-of-sight propagation component based on the distance between the first transmitter A and said at least one receiver; and Means for determining a second parameter _τ'b which is the actual delay from the second transmitter B to the at least one receiver as perceived by the _line -of-sight propagation component. 26. The apparatus of claim 25, further comprising means for determining a position of the receiver. 27. The apparatus of claim 25, further comprising means for decoding a forward link-only data stream. 28. An apparatus for operating base station resources in a wireless network, comprising: means for determining time difference information between a subset of transmitters and at least one receiver; means for adjusting the phase of the signal in view of the determined time difference information in response to the adjusted amount of cyclic shift of the signal applied at the subset of transmitters; and means for determining the position of the at least one receiver based on the adjusted signal phase; Wherein the device for determining time difference information further includes: means for generating at least two timing offsets denoted by _da and _db ; means for determining a first parameter _τ'a , said _τ'a being the actual delay perceived by the line-of-sight propagation component based on the distance between the first transmitter A and said at least one receiver; and Means for determining a second parameter _τ'b which is the actual delay from the second transmitter B to the at least one receiver as perceived by the _line -of-sight propagation component. 29. The apparatus of claim 28, further comprising means for generating signals from at least two transmitters of the subset of transmitters, the signals being advanced or delayed to account for timing differences in a wireless network. 30. The apparatus of claim 29, further comprising means for computing a linear convolution of the channel estimate with the transmitted signal.

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