RU2411680C2 - Methods and tools to expand coverage of ofdm system broadcasting transmitter through shift with anticipation of transfer synchronisation - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: proposed systems and methods determine phase adjustments of transmitter, which are shifted with anticipation or delay of transfer from one or more transmitters, in order to increase coverage of wireless network and soften noise in the network. In systems and methods a tool of analysis is provided, which considers various parameters in this configuration of network and generates predictions for phase adjustments of transmitter with accounts of such configurations.

EFFECT: increased throughput capacity.

26 cl, 10 dwg

Description

Priority Claim Under Section 35 §119 of the US Code

This application claims the priority of provisional application for US patent No. 60/789265, filed April 4, 2006, entitled "METHODS FOR EXTENDING THE COVER OF THE WIDTH TRANSMITTER OFDM SYSTEM THROUGH SHIFT FROM SYNCHRONIZATION TRANSMISSION USED No. 64, No. 64, AND SUBMISSION FROM 64, AND SUBMISSION FROM 64, AND UNDERSTANDING FROM SECONDARY REPRESENTATIVE OF US Patent Application No. 60, No. 64, No. 64 January 27, 2006, entitled "METHOD AND DEVICE FOR DETERMINING THE SIGNAL TO NOISE AND INTERFERENCE (SINR)", which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The subject technology relates to communication systems and methods in general and, in particular, to systems and methods for expanding broadcast coverage in an orthogonal frequency division multiplexing (OFDM) system by means of phase-shifting transmitter technology in wireless networks. Also provided are tools for predicting network and phase adjustments based on differing network configurations.

State of the art

One technology that prevailed in wireless systems is Code Division Multiple Access (CDMA) digital wireless technology. In addition to CDMA technology, the wireless interface specification defines forward link only (FLO) transmission technology, which was developed by an industry group of wireless service providers and is related to orthogonal frequency division multiplexing (OFDM) protocol. In general, the FLO technology has leveraged the most cost-effective features of the available wireless access technologies and used the latest enhancements in coding and system design to consistently achieve superior performance. One goal for FLO technology is to be a globally accepted standard, and it is supplied as part of the OFDM technology single frequency communication network (SFN).

The technology mentioned above was designed in one case for a mobile multimedia environment and shows performance characteristics that perfectly suit the use in cell phones. It uses the latest coding and interleaving enhancements to achieve the highest quality reception for both real-time streaming content and other data services. This technology can provide robust mobile performance and high throughput without the risk of high power consumption. The technology also reduces the network cost of delivering multimedia content by significantly reducing the number of transmitters needed. In addition, this technology-based multimedia broadcasting complements the data and voice services of wireless operators by providing information content to the same cell phones used in third-generation networks.

Wireless systems have been designed to broadcast real-time audio and video signals separately from non-real-time service for mobile users. Appropriate transmission for such systems is performed using high and powerful transmitters to ensure wide coverage in a given geographic area. In addition, 3-4 transmitters are typically deployed in most markets to ensure that the radio signal reaches a substantial portion of the population in a given market. When an OFDM signal is designed or configured for an SFN network operation, it has the indicated cyclic prefix duration. This cyclic prefix has a specific duration. The longer the duration relative to the OFDM symbol, the lower the signal efficiency in terms of data throughput. The shorter the cyclic prefix, the more transmitters are required to cover a given geographic area. Unfortunately, when the distance between the transmitting nodes becomes sufficiently large, various transmitters in a single frequency OFDM communication network may begin to experience mutual interference.

Disclosure of invention

The following is a simplified description of the disclosure of various embodiments of the invention to provide a common understanding of some aspects of the embodiments. This description of the disclosure is not a complete overview and is not intended to indicate key / critical elements or to determine the scope of the embodiments disclosed herein. Its sole purpose is to present some concepts in a simplified form as an introduction to a more detailed description in the section of the invention that is presented later.

Systems and methods are presented for expanding OFDM broadcast coverage and mitigating mutual interference in a wireless network. The embodiment makes it possible to reduce the number of transmitters required to cover a particular broadcast area, essentially without loss of data throughput. Additionally, the average signal-to-noise-to-noise ratio (SINR) can be improved by shifting ahead or delaying the broadcast of the transmitter. In addition, by shifting ahead or delaying the wireless broadcast, interference noise patterns can be shifted to locations where interference is usually not a problem, such as shifting interference into a desert region where few wireless communications actually occur. Software tools can be provided for determining noise patterns and predicting the amount of shift ahead of or delaying the transmitter to account for such patterns.

In an embodiment, the software tools take measurements that make it possible to predict a shift ahead of or delaying a transmitter signal that is used in a broadcast network using multiple transmitters. Many algorithms assume that transmitters emitting signals are time-aligned using a common central clock, such as a global positioning system (GPS). However, in some broadcast systems, there is some advantage for advancing / delaying transmission from some of the transmitters relative to the central clock to facilitate signal reception and quality throughout the network, for example, mitigating interference patterns at the edge of the respective networks and / or between the broadcast areas of the transmitters. Various network configurations can be analyzed, such as transmitter heights, transmitter powers, transmission times and channel estimates by respective receivers, the software tools then predicting the signal-to-noise and interference ratio (SINR), which allows you to adjust the offset ahead or delay for a given network. In addition, suitable corrections can be determined for a combination of log-normal signal distributions, which is used as part of the network analysis process.

To accomplish the foregoing and related tasks, some illustrative embodiments are described herein together with the following description and the attached drawings. These aspects show the various ways in which embodiments can be implemented, each of which is intended to be encompassed.

Brief Description of the Drawings

1 is a block diagram illustrating a wireless network system employing phase adjustments to mitigate signal interference.

Figure 2 is a block diagram illustrating a prediction tool for determining phase adjustments of a network.

Figure 3 illustrates the logic modules for determining phase adjustments of the transmitter.

Figure 4 depicts an illustrative system for adjusting synchronization information in a wireless system.

5 is a diagram showing illustrative network layers for a wireless system.

6 is a diagram showing an illustrative data structure and signal for a wireless system.

7 shows an illustrative phase adjustment process for a wireless system.

Fig. 8 is a diagram showing an illustrative user device for a wireless system.

9 is a diagram showing an illustrative base station for a wireless system.

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

The implementation of the invention

Systems and methods are presented for determining phase adjustments of a transmitter that shift ahead or delayed transmission from one or more transmitters to increase wireless network coverage and mitigate network interference. An analysis tool is presented, which considers various parameters in a given network configuration and generates predictions for phase adjustments of the transmitter taking into account such configurations. In an embodiment, a method for increasing broadcast coverage in a wireless network is provided. The method comprises the steps of adjusting the phase of the signal of at least one transmitter clock, taking into account certain information about the parameters of the transmitter, and broadcasting the phase of the signal in the wireless network to increase the broadcast coverage of the wireless network. In another embodiment, a method for determining signal to noise and interference ratio (SINR) is provided. It comprises the steps of configuring a network containing a number of transmitting nodes at certain locations within a geographic area, and determining a signal level related to respective transmitting nodes for mobile stations located at locations within a geographic area. In addition, the signal-to-noise-noise ratio (SINR) is then calculated based on the determined signal levels and the calculated signal-to-noise-noise ratio (SINR) is adjusted based on the appropriate number of transmitting nodes.

It should be noted that the synchronization bias can be considered as a mismatch in the synchronization between the transmitter clock and the common clock source, which leads to the transmission of synchronization symbols in the transmitter with an offset compared to the synchronization signals of the common clock. For example, in the case of forward link only (FLO) technology signals, it is usually expected that the border of the superframe in the transmitter will be synchronized with the 1PPS signal from the global positioning system (GPS). However, due to a synchronization mismatch, or sometimes intentionally in order to optimize the network, the super-frame boundary may actually be earlier or later relative to the 1PPS signal from the GPS system. This is called a clock offset in the transmitter.

With phase adjustments in the transmitter, the shape of the transmitter signal changes significantly to control the propagation delay perceived by the receiver, regardless of the timing offset in the transmitter. In this case, even though the transmitter clock (and therefore transmission) can be precisely synchronized with a common clock source, it is possible that the transmitter waveform changes to result in distorted measurements of the propagation delay in the receiver. For example, in the case of transmission on the forward link only (FLO) using OFDM overhead, the super-frame boundary may be synchronized with the 1PPS signal from the GPS system. However, the transmitter can fine-tune the transmission phase by cyclic shifting the OFDM symbol buffer. The cyclic prefix for the OFDM symbol may be generated based on the cyclically shifted OFDM symbol. With this modification of the signal, the delay perceived by the receiver changes with the selected transmission phase (or equivalently with the value of the cyclic shift of the OFDM symbol). This is called phase tuning in the transmitter.

Used in this application, the terms "component", "network", "system", etc. designed to refer to a computer-related object that is either hardware, or a combination of hardware and software, or software, or executable software. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable program, a thread of execution, a program, and / or a computer. By way of illustration, both an application running on a communication device and a device can be a component. One or more components may be located in the process and / or thread of execution, and the component may be located on one computer and / or distributed between two or more computers. In addition, these components can be executed from various computer-readable media storing various data structures. Components can communicate through local and / or remote processes, for example, in accordance with a signal containing one or more data packets (for example, data from one component interacting with another component in a local system, distributed system, and / or through a wired or wireless network such as the Internet).

FIG. 1 illustrates a wireless network system 100 utilizing a phase shifter of a transmitter to mitigate signal interference. System 100 includes one or more transmitters 110 that communicate via wireless network 114 with one or more receivers 120. Receivers 120 may include communication devices of substantially any type, such as a cell phone, a computer, a personal digital assistant, laptop or laptop device etc. In general, the timing or phase of a signal between transmitters 110 and receivers 120 may require adjustment in the various embodiments described herein to contribute to increased coverage for wireless radio transmission. In an embodiment, one or more phase-tuning components 130 may be used in the transmitters 110 for shifting ahead or delaying the broadcast signals 134, which have the effect of increasing the coverage of the transmitters 110 by mitigating the potential interference patterns associated with the respective transmitter. Thus, the phase-tuning components 130 contribute to reducing the number of transmitters 110 required to cover a specific area without significant loss of data throughput. In addition, the average C / (N + I) (signal-to-noise + interference at carrier frequency) or signal-to-noise-to-noise ratio (SINR for short) can be improved.

In general, to increase the cell size of an OFDM network, the cyclic prefix duration is increased. Larger cells can be included in a single frequency communication network (SFN), over which smaller cells nominally dominate, but with a cyclic prefix limitation, by shifting ahead of the transmission time of transmitters 110 for transmitting nodes with higher power and / or very high transmitting nodes . Adding these cells ahead of time and with high power increases the average coverage area for each cell, which reduces the overall cost of network deployment. In addition, the transmission time of neighboring cells with a nominal size can be advanced ahead by positively affecting the signal-to-noise and interference ratio (SINR) observed in the network 114. Large cells have longer delays at the edge of their respective coverage area, which is potentially experiencing mutual interference with surrounding smaller cells. By shifting ahead of the transmission time of large cells through phase-tuning components 130, the delay at the edges of their coverage is compensated back to the equilibrium of the network 114.

Based on some network configuration containing a number of transmitting nodes at certain locations within a geographic area, a prediction tool 140 may be provided for determining a signal level related to each transmitting node, and it may be determined for each mobile station located at each location within a geographical area through the use of several parameters related to the transmitting node, including transmission height, power, and so on, as It is described in more detail below. In some embodiments, such specific signal levels are combined based on the arrival times of different signals at each mobile station or receiver 120, and an estimation mask is used to calculate the signal-to-noise and interference ratio (SINR). Such a calculated signal-to-noise-to-noise ratio (SINR) can be adjusted based on a suitable number of transmitting nodes 110 in a geographical area and by assuming that signals transmitted from transmitting nodes to each mobile station at each location within a geographical area are attenuated, distributed according to a log-normal law.

The calculated or adjusted signal-to-noise-to-noise ratio (SINR) can then be used by a prediction tool 140 that has calculated or determined such a signal-to-noise-noise ratio (SINR), or other tool, for example, for network planning. Such scheduling can be performed for several types of networks, such as, for example, CDMA, TDMA, and OFDM networks. Prediction tool 140 also provides for the analysis of OFDM single-frequency communication networks (SFNs), networks containing several transmitters 110, specialized estimation masks, transmission time offsets, and combination correction factors with a log-normal distribution. Prediction tool 140 provides a predicted signal-to-noise-to-noise ratio (SINR) for arbitrarily configuring transmitter heights, powers, transmission times, and channel estimates through receiver 120. A suitable correction for combining log-normal signal distributions can be applied as part of the phase adjustment process.

In one example of the above network 114, the network may be deployed for a single frequency communication network (SFN) mode of operation in which transmitters 110 are synchronized with a common clock source. A clock source, for example, can be obtained from a 1PPS signal from a global positioning system (GPS). The transmitted waveform may be based on OFDM overheads and may be designed in accordance with the assumption that the channel propagation delay will be, for example, less than about 135 μs. When several transmitters 110 are visible to the receiver 120, the propagation delay perceived by the receiver is a function of the position of the receiver relative to the various transmitters.

In some cases, it is possible that the receiver 120 is close to one of the transmitters 110 and far from the other transmitter, thereby causing a large propagation delay. If the resulting propagation delay exceeds a design norm of 135 μs (or another reference value), this can lead to a significant deterioration in system performance. However, it is possible to control the propagation delay perceived by the receiver 120 at various points in the network by delaying or advancing the border of the superframe relative to the synchronization pulse from the central clock. Therefore, with optimized network deployments, one can also realistically assume that there is a fixed synchronization bias between different transmitters 110. When deploying a single frequency communication network (SFN) with forward link only (FLO) transmission, for example, transmitters 110 are likely to be configured to working with a fixed clock offset relative to the central clock (and therefore each other) to optimize the propagation delay observed at receiver 120, and thereby voditelnosti system.

FIG. 2 illustrates a prediction tool 200 for determining phase adjustments of a network. As noted above, the prediction tool 200 determines the predicted signal-to-noise and interference (SINR) ratio and allows you to determine the appropriate phase adjustments in block 210 for a subset of the transmitters. To fulfill these definitions for an arbitrary transmitter configuration, one or more network parameters 220 are considered. These parameters 220 may include transmitter heights, corresponding transmit powers, transmission times, geographical considerations, channel estimates by one or more receiving devices, etc. Also, if desired, this includes the application of appropriate corrections for combinations of log-normal signal distributions.

Other input for the instrument optionally includes signal strengths 230 at locations and for each transmitter. Such data can be imported into tool 200 from an appropriate transmitter database. In blocks 240 and 250, the corresponding transmission delays and estimation masks for the target receiver are considered and then applied in the specified geographical area, which can also be imported as part of the network parameters 220. Then, the signal-to-noise-to-noise ratio (SINR) 210 is calculated according to time differences and adjusted for known corrections related to the number of transmitted signals and their relative levels. This process actually includes statistics of several attenuations with partially independent log-normal distributions for a subset of signals. The output of the tool in block 210 is the signal-to-noise and interference (SINR) ratio for a specified geographic area, which can be loaded back into an existing tool or otherwise implemented as a built-in function in a network planning tool for adjusting transmitter phases in a given transmitter network

FIG. 3 illustrates logic modules 300 for determining a phase adjustment of a transmitter. In this example, the logic modules 300 interact to determine the phase adjustments of the network for a subset of the transmitters in a given geographic area. This includes a logic module 310 for analyzing a network containing a subset of transmitting nodes at locations within a geographic area. Such a module may include software tools or algorithms that examine one or more network parameters. Block 320 provides a logic module for determining signal levels related to a subset of transmitting nodes for mobile stations within a geographic area. Such mobile stations may include cell phones or other transceivers or more complex components, such as computing tools, that assist in analyzing network conditions.

Block 330 provides a logic module for determining an interference pattern based on certain signal levels. This may include measurements taken from mobile devices that indicate the relative strength or weakness of a given signal based on a given transmitter phase setting. In block 340, a logic module is presented for adjusting the phase of at least one of the transmitting nodes based on a certain interference pattern. A module of this type may include electronic or software controls that allow the respective transmitter to shift ahead of or delay the corresponding broadcast signal to optimize signal performance in a given network.

4 shows an example system 400 for fine-tuning timing information in a wireless positioning system. In this example, the number 410 denotes two transmitters A and B, however more than two transmitters can be used. The signal from transmitters 410 may be advanced or delayed, as indicated by 420, to account for possible differences in timing or interference in the system. The concept of a shift ahead of or delaying the synchronization of the transmitter, as indicated by 420, is also introduced into the system to control the actual propagation delay of the channel received by the receiver 430. In one case, in the OFDM system, the linear convolution of the channel with the transmitted signal can be considered as a cyclic convolution if the propagation delay the channel is smaller than the cyclic prefix used in the OFDM signal.

является фактической задержкой, которая будет воспринята компонентом распространения в пределах видимости на основе расстояния между передатчиком A и приемником 430. Аналогично, пусть

является фактической задержкой, которая будет воспринята компонентом распространения в пределах видимости от передатчика B до приемника 430. Следует отметить, что в передатчиках вносятся дополнительные задержки d_a и d_b, когда задержка распространения

превышает циклический префикс (в предположении одного компонента луча от каждого из передатчиков). При задержках d_a и d_b в передатчиках принятый в приемнике сигнал задается следующим уравнением:In this example, consider transmitters A and B, designated 410, with synchronization offsets d _a and d _b . Let be

is the actual delay that will be perceived by the propagation component within visibility based on the distance between transmitter A and receiver 430. Similarly, let

is the actual delay that will be perceived by the propagation component within sight from transmitter B to receiver 430. It should be noted that additional delays d _a and d _b are introduced into the transmitters when the propagation delay

exceeds the cyclic prefix (assuming one component of the beam from each of the transmitters). With delays d _a and d _b in the transmitters, the signal received at the receiver is given by the following equation:

Equation 1

x_a(n-d_a)+h_b(n)

x_b(n-d_b)+w(n),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) is the channel and signal relative to transmitter A, * represents the linear convolution operation and w (n) is the noise added to the receiver. In the case of an information channel in the global network, x _a (n) and x _b (n) are generally the same (for example, x (n)).

Using the linear convolution property, the above equation can be written as:

Equation 2

x_a(n)+h_b(n-d_b)

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

x _a (n) + h _b (nd _b )

x (n) + w (n),

и ею можно было управлять посредством ввода смещений синхронизации в передатчике. Когда фактическая задержка распространения меньше циклического префикса, принятый сигнал в Уравнении 1 может быть записан как циклическая свертка вместо линейной свертки. Таким образом:so that the perceived channel propagation delay is now set as

and it could be controlled by entering synchronization offsets at the transmitter. When the actual propagation delay is less than a cyclic prefix, the received signal in Equation 1 can be written as a cyclic convolution instead of a linear convolution. In this way:

Equation 3

x_a(n-d_a)+h_b(n)

x_b(n-d_b)+w(n)y (n) = h _a (n)

x _a (nd _a ) + h _b (n)

x _b (nd _b ) + w (n)

or equivalent

Equation 4

x_a(n)+h_b(n-d_b)

x_b(n)+w(n),y (n) = h _a (nd _a )

x _a (n) + h _b (nd _b )

x _b (n) + w (n),

обозначает циклическую свертку. Если циклический префикс является достаточно длинным, то операция задержки сигнала x_a(n) на d_a в Уравнении 1 для приведения к Уравнению 3 может быть достигнута посредством кругового вращения x_a(n) на d_a в Уравнении 3.Where

denotes a cyclic convolution. If the cyclic prefix is long enough, then the operation of delaying the signal x _a (n) by d _a in Equation 1 to bring to Equation 3 can be achieved by circular rotation x _a (n) by d _a in Equation 3.

Based on the cases mentioned above, the following is proposed for the control positioning channel with respect to regular information channels. During a regular information channel, the cyclic prefix used is usually short (512 chips in the case of transmission on the forward link only (FLO)), and therefore the cyclic shift technique discussed in Equation 3 cannot be used to adjust the actual propagation delay of the channel. Therefore, transmissions from the respective transmitters will be physically delayed (transmitters A and B on d _a and d _b in this example) to satisfy the requirements of the cyclic prefix. On the other hand, a long cyclic prefix can be used for the positioning control channel (of the order of 2500 chips in the case of transmission on the forward link only (FLO), where chips encoded in data packets are called chips) to allow estimation of delay from weak transmitters that are far away. In addition, the delays d _a and d _b introduced by the transmitters for the information channel affect the delays observed in the positioning control channel, so this overhead is required at the receiver, as previously discussed.

Given the presence of a long cyclic prefix for the control channel positioning, the transmitter can cancel the effect of the actual physical delays d _a and d _b by cyclically shifting the positioning signal. If x _{a, p} (n) is the planned positioning signal from the transmitter with synchronization delay d _a , then the transmitter can send a cyclically shifted version specified by the expression x _{a, p} (n + d _a ). Similarly, the signal from the transmitter B cyclically shifts. Due to the presence of a long cyclic prefix, Equation 3 remains valid and therefore:

Equation 5

x_a,p(n)+h_b(n)

x_b,p(n)+w(n),y (n) = h _a (n)

x _{a, p} (n) + h _b (n)

x _{b, p} (n) + w (n),

thus, the need for sending transmitter delay information to the receiver is reduced. This technique can be used to account for transmitter clock offsets resulting from delays introduced as part of network planning, as well as other clock delays that can occur, for example, from filters, cables, and other similar components.

With respect to another embodiment, the discussion above may suggest that range measurements are computed in a mobile receiver. However, it is possible that the calculations are performed on a network where synchronization information is available offline. In this case, the receiver can measure pseudo-ranges S _'a, S' _b and S _'c, where, for _{example, S' a = τa S '} a × c exclude displacement transmitter synchronization. The receiver would have relayed pseudorange S _'a network, and further displacements synchronization correction may be easily performed in the network since the entire almanac can be made available in the network.

The discussion above suggested that the receiver clock is closely synchronized with the common clock, and the mismatch between the common clock and the transmitter clock exists due to a clock bias or phase adjustment in the transmitter. However, it should be noted that this can be considered as a special case, and the receiver clock does not have to be synchronized with a common clock. When the receiver clock is not synchronized with the common clock, the delay measurements from the respective transmitters may also include a common offset period, which is the amount of the mismatch between the common clock and the receiver clock. The total offset is now another unknown quantity that must be calculated, in addition to the spatial coordinates of the receiver. Unknown values of the spatial coordinates, as well as the displacement of the clock can be found using measurements from additional transmitters. In particular, it is enough to have measurements, for example, from four different transmitters (with information about the synchronization offset available relative to the common source of clock pulses, and under the assumption that the receiver is on the ground) to find both spatial coordinates and the total clock offset in the receiver. In the absence of a common clock offset in the receiver (that is, the receiver clock is synchronized with the common clock), it is sufficient to have delay measurements, for example, from three different transmitters.

5 shows illustrative network layers 500 for a wireless system in which data received from it can be used in the frequency blocks described above. In general, the specification for a wireless forward link only (FLO) transmission interface covers protocols and services that comply with the Open Systems Interconnection Network Model (OSI), which has layer 1 (physical layer) 502 and layer 2 (link layer) 504. Link layer further is subdivided into two sublevels, namely, a medium access control (MAC) sublayer 506 and a streaming sublayer 508. The upper layers 510 include layers 3-7 of the OSI model and may include compression of multimedia content, controls access to the media along with information content and layout control information. The medium access control (MAC) layer 506 includes multiplexing and quality of service (QoS) functions 512. The medium access control (MAC) layer 506 also includes logical channels 514.

The Forward Link Only Wireless Interface (FLO) specification usually does not define upper layers to provide design flexibility to support various applications and services. These levels are shown for contextual purposes only. The stream layer includes multiplexing up to three top-level streams into one logical channel, linking the upper-level packets to the streams for each logical channel and provides packetization and residual error handling functions. The functionality of a medium access control (MAC) layer includes physical layer access control, mapping between logical channels and physical channels, multiplexing of logical channels for transmission over a physical channel, demultiplexing of logical channels in a mobile device, and / or enforcement of quality requirements service (QoS). The functionality of the physical layer includes providing a channel structure for the forward link and determining frequency, modulation and coding requirements.

In general, forward link only (FLO) transmission technology uses orthogonal frequency division multiplexing (OFDM), which is also used in digital broadcasting (DAB), terrestrial digital television (DVB-T) and terrestrial integrated digital broadcasting service (ISDB) -T). In general, OFDM technology can achieve high spectral efficiency while effectively meeting mobility requirements in a large cell network (SFN). In addition, OFDM technology can handle long delays from multiple transmitters with a suitable cyclic prefix length; a guard interval is added at the beginning of the symbol (which is a copy of the last part of the data symbol) to facilitate orthogonality and mitigate interference between carriers. As long as the length of this interval is greater than the maximum channel delay, the reflections of previous characters are removed and the orthogonality is preserved.

6, a superframe 600 of a physical layer of a forward link only (FLO) transmission is illustrated. In an embodiment, the superframe is 1200 OFDM symbols with a duration of one second. The forward link only (FLO) physical layer uses a 4K mode (giving an output transform size of 4096 subcarriers) that provides superior mobile performance compared to 8K mode while maintaining a sufficiently long guard interval that is useful in fairly large SFN cells . Fast channel establishment can be achieved through optimized pilot signals and interleave block structure. Interleaving schemes included in the forward link only (FLO) wireless interface facilitate time diversity. The structure of the control data and the interleaving unit optimize the use of the channel without annoying the user with long setup times. In general, forward link only (FLO) transmission signals are organized into superframes, as illustrated by 600. Each superframe consists of four data frames and includes time division multiplexed (TDM) pilot signals 604, service information symbols 606 (OIS ) and frames 608, 610, 612, 614 containing global 616 and local 618 data. TDM pilots are provided for quick establishment of service information symbols (OIS). Service Information Symbols (OIS) describe the location of data for each multimedia service in a superframe.

Typically, each superframe consists of 200 OFDM symbols for each megahertz of the allocated bandwidth (1200 symbols for 6 MHz), and each symbol contains 7 interlaces of active subcarriers. Each interlace is uniformly distributed in frequency so as to achieve full frequency diversity within the available bandwidth. These interlaces are assigned to logical channels that change in terms of the duration and number of actual interlaces used. This provides the diversity flexibility achieved by any given data source. Channels with a lower data rate may be assigned fewer interlaces to improve time diversity, while channels with a higher data rate may use more interlaces to minimize airtime usage and reduce energy consumption.

The settling time for both low and high data rate channels is generally the same. Thus, frequency and time diversity can be maintained without impairing settling time. Most often, logical channels of transmission only on a direct communication line (FLO) are used to transmit in real time (live stream transmission) information content with variable speeds to obtain a statistical increase in multiplexing, which is possible using codecs (compressors and decompressors) with a variable speed. Each logical channel can have different coding rates and modulation to support different reliability and quality of service requirements for different applications. The forward link only (FLO) multiplexing scheme enables device receivers to demodulate the content of one logical channel of interest to minimize energy consumption. Mobile devices can demodulate several logical channels at the same time to enable the sending of video and its related audio in different channels.

Error correction and coding techniques may also be used. Typically, forward link only (FLO) transmission includes an internal turbo code 13 and an external Reed-Solomon code (RS) 14. Typically, a turbo code packet contains cyclic redundancy check (CRC). The Reed-Solomon code (RS) does not need to be calculated for data that is received correctly, which leads to additional power savings when the signal is in good condition. Another aspect is that a forward link only (FLO) wireless interface is designed to support bandwidths such as 5, 6, 7, and 8 MHz. A highly desirable service offer can be achieved with a single radio frequency channel.

7 illustrates a phase adjustment process 700 for wireless systems. Although, for the sake of ease of explanation, the methodology is shown and described as a sequence or set of actions, it should be understood that the processes described here are not limited by the order of actions, since some actions can occur in a different order and / or simultaneously with other actions compared to how described here. For example, those skilled in the art will understand that a methodology can alternatively be represented as a sequence of interrelated states or events, as in a state diagram. In addition, not all illustrated acts may be required to implement a methodology in accordance with the subject methodologies disclosed herein.

At block 710, a subset of the transmitters for phase analysis is selected. This may include determining which group or which subset of transmitters is likely to interfere or interfere with each other in a given geographic area. At 720, signal strength measurements are collected on the network, for example, at various locations for mobile devices distributed at various locations relative to a previously determined subset of transmitters. At block 730, various network parameters are determined and calculated. As noted above, these parameters may include transmitter heights, transmit powers, transmission times, geographical considerations, channel estimates by mobile devices, etc. At step 750, one or more transmitters in the subset determined at step 710 undergoes phase adjustment. This may include adjusting the transmitter clock relative to the common clock to mitigate mutual interference between the transmitters. Such adjustments can be made in increments for which the signal-to-noise-noise ratio (SINR) is calculated, and the phases are adjusted until the corresponding signal-to-noise-noise ratio (SINR) is maintained above or below a predetermined threshold.

FIG. 8 is an illustration of a user device 800 that is used in a wireless communication environment in accordance with one or more of the aspects set forth herein. User device 800 comprises a receiver 802 that receives a signal, for example, from a receiving antenna (not shown) and then performs typical actions (e.g., filters, amplifies, downconverts, etc.) with the received signal and translates the processed signal into digital form for taking samples. Receiver 802 may be a non-linear receiver, such as a maximum probability / minimum mean square error (ML-MMSE) receiver, and the like. A demodulator 804 may demodulate and provide received pilot symbols to a processor 806 for channel estimation. A forward link only (FLO) channel component 810 is provided for processing FLO signals as previously described. Other processes may include digital stream processing and / or location calculations. Processor 806 may be a processor dedicated to analyzing information received by receiver 802 and / or generating information for transmission by transmitter 816, a processor that controls one or more components of user device 800, and / or a processor that analyzes information received by the receiver 802, and generates information for transmission using the transmitter 816, and controls one or more components of the user device 800. The user device 800 may optionally comprise a memory 808 that is operatively coupled to a processor 806.

It should be understood that the storage components described herein (eg, memory blocks) may be either volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. By way of illustration, but without limitation, non-volatile memory may include read-only memory (ROM; ROM), programmable ROM (EPROM; PROM), electrically programmable ROM (EEPROM; EPROM), electrically erasable ROM (EEPROM; EEPROM) or flash memory. Volatile memory may include random access memory (RAM; RAM), which acts as an external cache. By way of illustration, but without limitation, RAM is available in many forms, such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), synchronous dynamic RAM with dual data rate (DDR SDRAM), advanced synchronous dynamic RAM (ESDRAM), Synchlink Dynamic RAM (SLDRAM) and Rambus Direct RAM (DRRAM). It is assumed that the memory of 808 subject systems and methods contains, but without limitation, these and any other suitable types of memory. User device 800 further comprises a background recorder 812 for processing forward link only (FLO) data, a symbol modulator 814 and a transmitter 816 that transmits a modulated signal.

FIG. 9 shows an example system 900 that includes a base station 902 with a receiver 910 that receives signal (s) from one or more user devices 904 through multiple receive antennas 906, and a transmitter 924 that transmits to one or more user devices 904 through transmit antenna 908. Receiver 910 may receive information from receive antennas 906 and is operatively coupled to a demodulator 912 that demodulates received information. The demodulated symbols are analyzed by a processor 914, which is similar to the processor described above and connected to a memory 916, which stores information related to the ranks of users, lookup tables related to them, and / or any other suitable information related to the implementation of the various actions and functions set forth herein . A processor 914 is also coupled to a forward link only (FLO) channel component 918, which facilitates the processing of FLO transmission information related to one or more respective user devices 904. A modulator 922 can multiplex a signal for transmission using a transmitter 924 via transmit antennas 908 user devices 904. Forward link component 918 can only attach to the signal information related to the updated data stream for a given Aci for communication with a user device 904 that may be transmitted to the user device 904 to provide an indication that was identified and confirmed by a new optimum channel.

10 shows an exemplary wireless communications system 1000. The wireless communication system 1000 for brevity depicts one base station and one terminal. However, it should be understood that the system may contain more than one base station and / or more than one terminal, and additional base stations and / or terminals may be substantially similar to or different from the illustrative base station and terminal described below.

As shown in FIG. 10, on a downlink at an access point 1005, a data processor 1010 receives, formats, encodes, interleaves, and modulates (or symbolizes) information data and provides modulation symbols (“data symbols”). A symbol modulator 1015 receives and processes data symbols and pilot symbols and provides a stream of symbols. A symbol modulator 1020 multiplexes the data symbols and pilot symbols and provides them to the transmitter unit 1020 (TMTR). Each transmitted symbol may be a data symbol, a control symbol, or a null signal value. Control characters can be sent continuously in each character period. The pilot symbols may be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), or code division multiplexed (CDM).

A transmitter 1020 (TMTR) receives and converts a symbol stream into one or more analog signals and further processes (e.g., amplifies, filters, and upconverts) the analog signals to generate a downlink signal suitable for transmission over a wireless channel. Then, the downlink signal is transmitted through the antenna 1025 to the terminals. At terminal 1030, an antenna 1035 receives a downlink signal and provides a received signal to a receiver unit (RCVR) 1040. The receiver unit 1040 processes (e.g., filters, amplifies, and downconverts) the received signal and digitizes the processed signal to obtain samples. A symbol demodulator 1045 demodulates and provides received pilot symbols to a processor 1050 for channel estimation. A symbol demodulator 1045 also receives a downlink frequency response estimate from a processor 1050, demodulates the data on the received data symbols to obtain data symbol estimates (which are estimates of the transmitted data symbols), and provides data symbol estimates to the receiver processor 1055, which demodulates (i.e. performs inverse symbol conversion), performs reverse rotation and decodes data symbol estimates to recover the transmitted information data. Processing by a symbol demodulator 1045 and a receiver processor 1055 is complementary to processing by a symbol modulator 1015 and a transmitter processor 1010 at an access point 1005, respectively.

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

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

Processors 1090 and 1050 direct operations (e.g., manage, coordinate, direct, etc.) at access point 1005 and at terminal 1030, respectively. Corresponding processors 1090 and 1050 may be associated with memory units (not shown) that store program codes and data. Processors 1090 and 1050 can also perform calculations to obtain frequency and impulse response estimates for the uplink and downlink, respectively.

In a multiple access system (e.g., FDMA, OFDMA, CDMA, TDMA, etc.), multiple terminals can simultaneously transmit on the uplink. For such a system, the control subbands may be shared between different terminals. Channel estimation techniques can be used in cases where the control subbands for each terminal cover the entire operating range (possibly with the exception of the edges of the range). Such a control subband structure would be desirable to obtain frequency diversity for each terminal. The techniques described here can be implemented by various means. For example, these techniques may be implemented in hardware, software, or a combination thereof. In a hardware implementation, the processors used to estimate the channel can be implemented in one or more specialized integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), programmable gate arrays ( FPGA), processors, controllers, microcontrollers, microprocessors, other electronic elements configured to perform the functions described herein, or combinations thereof. Using software, an implementation can be performed through modules (e.g., procedures, functions, and so on) that perform the functions described herein. Software codes may be stored in a memory unit and executed by processors 1090 and 1050.

In a software implementation, the techniques described here can be implemented using modules (eg, procedures, functions, and so on) that perform the functions described here. Program codes can be stored in memory blocks and executed by processors. The memory unit can be implemented within the processor or outside the processor, in the latter case, it can be connected with the possibility of interaction with the processor through various means known in the art.

The above description includes illustrative embodiments. Of course, it is impossible to describe every conceivable combination of components or methodologies in order to describe embodiments, but one of ordinary skill in the art will understand that many additional combinations and permutations are possible. Accordingly, it is intended that these embodiments cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. In addition, in cases where the term “includes” is used either in the detailed description or in the claims, it is assumed that this term is encompassing, like the term “contains” when “contains” is used as a transition word in the formula inventions.

Claims (26)

1. A method of increasing a broadcast zone in a wireless network, comprising the steps of:
register field strength within a wireless network;
determining a signal to interference and noise ratio (SINR) in a wireless network based on a determined field strength as information about transmitter parameters;
adjust the phase of the signal of at least one clock generator of the transmitter, taking into account certain information about the parameters of the transmitter; and
carry out broadcast transmission with the adjusted phase of the signal in the wireless network to increase the broadcast area of the wireless network. 2. The method according to claim 1, further comprising stages in which the broadcast signals are shifted ahead or delayed. 3. The method according to claim 1, further comprising the step of increasing or decreasing the duration of the cyclic prefix. 4. The method of claim 1, further comprising adjusting a transmission time limit of a nominal size transmitting cell to improve SINR in a wireless network. 5. The method according to claim 1, additionally containing stages, which determine the field strength related to the transmitting node, and determine the field strengths for each mobile station located within the geographic area served by the transmitting node. 6. The method according to claim 5, in which the field strengths are combined based on the arrival time of various signals at each mobile station. 7. The method according to claim 6, further comprising the step of using an estimation mask to calculate the SINR. 8. The method of claim 7, further comprising determining a SINR based on a log-normal distribution of the signal. 9. The method according to claim 6, further comprising analyzing single frequency communication networks (SFNs), specialized evaluation masks, transmission time offsets, and correction factors for combining log-normal distributions. 10. The method of claim 9, further comprising analyzing the heights of the transmitters, transmitter powers, transmission times and channel estimates by one or more receiving devices. 11. The method of claim 10, further comprising determining corrections for the set of log-normal signal distributions that are used as part of the signal phase adjustment process. 12. The method of claim 10, further comprising determining a spread of delays at one or more receivers. 13. The method according to item 12, further comprising the step of shifting the leading edge of the superframe relative to the synchronization pulse from the central clock generator with advance or delay. 14. A computer-readable medium storing computer-readable instructions for performing the following steps:
Configuring a network containing a certain number of transmitting nodes at locations within a geographic area;
determination of field strength related to transmitting nodes for mobile stations within a geographical area;
calculating the signal-to-noise and noise ratio (SINR) based on the determined field strengths; and
fine-tuning one or more signal phases at SINR-based transmitting nodes. 15. The machine-readable medium of claim 14, wherein the tuning step further comprises
the use of signals transmitted from transmitting nodes that have a log-normal distribution. 16. The computer-readable medium of claim 14, further comprising using SINR to plan network configuration. 17. The computer-readable medium of claim 14, further comprising processing one or more network parameters, which include transmitter heights, transmit powers, transmission times, geographical factors, or channel estimates by one or more receiving devices. 18. The computer-readable medium of claim 14, further comprising determining one or more relative transmission delays and estimation masks for the target receiver that apply to the specified geographic area. 19. The computer-readable medium of claim 14, further comprising calculating time differences and adjusting for known corrections associated with the number of transmitted signals, which include relative field strengths. 20. The computer-readable medium of claim 19, further comprising incorporating statistical attenuation characteristics with partially independent log-normal shading for a subset of the signals. 21. A component for determining phase adjustments of network signals, comprising:
means for analyzing a network containing a subset of transmitting nodes at locations within a geographical area;
means for determining field strengths related to a subset of transmitting nodes for mobile stations within a geographical area;
means for determining an interference pattern based on certain field strengths; and
means for determining a signal-to-noise-to-noise ratio (SINR) in a wireless network based on a determined field strength; and
means for adjusting the phase of the signal of at least one of the transmitting nodes based on a specific SINR. 22. A wireless communications processor, comprising:
a memory that includes a component for analyzing wireless field strengths in a given geographic area and for determining a signal to interference and noise ratio (SINR) in a wireless network based on a determined field strength;
at least one processor for phase adjustment of the signal for at least one transmitter in a subset of SINR-based transmitters. 23. A wireless transmission device, comprising:
a component for determining field strengths from a subset of transmitters and for determining a signal to interference and noise ratio (SINR) in a wireless network based on a determined field strength; a processor for adjusting the phase of the signal for at least one transmitter from a subset of transmitters based on SINR; and
a generator for transmitting phase adjustment of a signal in a wireless network. 24. The device according to item 23, further containing a component for determining the signal-to-noise-to-noise ratio (SINR) for a wireless network. 25. A base station for a wireless communication system, comprising:
a component for adjusting the phase of the signal of the wireless transmitter based on the signal to interference and noise ratio (SINR);
a processor for determining field strengths from a subset of transmitters and for determining SINR in a wireless network based on a determined field strength; and
a transmitter for broadcasting with a tuned phase of the signal over a wireless network. 26. An access point for a wireless communication system, comprising:
a component for receiving a signal from a subset of wireless transmitters;
a component for determining field strengths from a subset of transmitters and for determining a signal to interference and noise ratio (SINR) for a subset of wireless transmitters; and
component for adjusting one or more phases of signals from wireless transmitters based on SINR.

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