Patent Description:
As the number of applications and services for digital data continues to explode, the demands and challenges placed on network resources and operators will continue to increase. Being able to deliver a wide variety of network performance characteristics that future services will demand is one of the primary technical challenges faced by service providers today.

Radio frequency (RF) circuits in wireless communications may generate phase noise (PN) due to factors such as jitter and instability of a crystal oscillator circuit. Phase noise may be especially acute (e.g., relatively larger) with a higher frequency carrier frequency. Phase noise can be deleterious for communications as, for example, phase noise may interfere with symbol modulation and degrade demodulation performance at a receiver. Current techniques of phase noise compensation (e.g., reduction) may require a significant amount of communication resources and processing power but still fail to produce satisfactory results. Therefore, current techniques for phase noise compensation may not be entirely satisfactory.

The exemplary embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation.

Various exemplary embodiments of the invention are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the invention. Thus, the present invention is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged.

Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the invention is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

The discussion below may refer to functional entities or processes which are similar to those mentioned above with respect to conventional communication systems. As would be understood by persons of ordinary skill in the art, however, such conventional functional entities or processes do not perform the functions described below, and therefore, would need to be modified or specifically configured to perform one or more of the operations described below. Additionally, persons of skill in the art would be enabled to configure functional entities to perform the operations described herein after reading the present disclosure.

<FIG> illustrates an exemplary wireless communication network <NUM> in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure. Such an exemplary network <NUM> includes a base station <NUM> (hereinafter "BS <NUM>") and multiple user equipment devices <NUM> (hereinafter "UEs <NUM>") that can communicate with each other via respective communication links <NUM> (e.g., a wireless communication channel), and a cluster of notional cells <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> overlaying a geographical area with a network <NUM>. Each UE <NUM> may undergo a random access procedure to join the network <NUM>. In <FIG>, the BS <NUM> and each UE <NUM> are contained within a respective geographic boundary of cell <NUM>. Each of the other cells <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may include at least one BS operating at its allocated bandwidth to provide adequate radio coverage to its intended users. Accordingly, reference to a cell may be a short hand reference to a BS with an associated coverage region or area (e.g., cell). In certain embodiments, a cell may be interchangeably referred to as a BS or a node.

For example, the BS <NUM> may operate at an allocated channel transmission bandwidth (e.g., spectrum) to provide adequate coverage to each UE <NUM>. The spectrum may be regulated to define a licensed range and/or an unlicensed range. The BS <NUM> and each UE <NUM> may communicate via a downlink radio frame <NUM>, and an uplink radio frame <NUM> respectively. The radio frames may also be referred to more simply as a frame. Each frame <NUM>/<NUM> may be further divided into sub-frames <NUM>/<NUM> which may include data symbols <NUM>/<NUM>. In the present disclosure, the BS <NUM> and each UE <NUM> are described herein as non-limiting examples of devices, generally, which can practice the methods disclosed herein. Such devices may be capable of wireless and/or wired communications, in accordance with various embodiments of the invention. In certain embodiments, a communication device may refer more specifically to a UE in relationship to a BS and a communication node may refer more specifically to a BS in relation to the UE.

<FIG> illustrates a block diagram of an exemplary wireless communication system <NUM> for transmitting and receiving wireless communication signals (e.g., modulated signals such as orthogonal frequency-division multiplexing (OFDM) / orthogonal frequency-division multiple access (OFDMA) signals) in accordance with some embodiments of the invention. The system <NUM> may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one exemplary embodiment, system <NUM> can be used to transmit and receive data symbols in a wireless communication environment such as the wireless communication environment or network <NUM> of <FIG>, as described above.

The BS <NUM> communicates with the UE <NUM> via a communication channel <NUM>, which can be any wireless channel or other medium known in the art suitable for transmission of data as described herein.

In accordance with some embodiments, the UE transceiver module <NUM> may be referred to herein as an "uplink" transceiver module <NUM> that includes a RF transmitter and receiver circuitry that are each coupled to the antenna <NUM>. Similarly, in accordance with some embodiments, the BS transceiver module <NUM> may be referred to herein as a "downlink" transceiver module <NUM> that includes RF transmitter and receiver circuity that are each coupled to the antenna <NUM>. The operations of the two transceiver modules <NUM> and <NUM> are coordinated in time such that the uplink receiver is coupled to the uplink antenna <NUM> for reception of transmissions over the wireless transmission link <NUM> at the same time that the downlink transmitter is coupled to the downlink antenna <NUM>.

The UE transceiver module <NUM> and the BS transceiver module <NUM> are configured to communicate via the wireless data communication link <NUM>, and cooperate with a suitably configured RF antenna arrangement <NUM>/<NUM> that can support a particular wireless communication protocol and modulation scheme. In some exemplary embodiments, the UE transceiver module <NUM> and the BS transceiver module <NUM> are configured to support industry standards such as the Long Term Evolution (LTE) and emerging <NUM> standards, and the like. It is understood, however, that the invention is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver module <NUM> and the BS transceiver module <NUM> may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

The memory modules <NUM> and <NUM> may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage and/or computer-readable medium known in the art. In this regard, memory modules <NUM> and <NUM> may be coupled to the transceiver modules <NUM> and <NUM>, respectively, such that the transceiver modules <NUM> and <NUM> can read information from, and write information to, memory modules <NUM> and <NUM>, respectively. The memory modules <NUM> and <NUM> may also be integrated into their respective transceiver modules <NUM> and <NUM>. In some embodiments, the memory modules <NUM> and <NUM> may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by transceiver modules <NUM> and <NUM>, respectively. Memory modules <NUM> and <NUM> may also each include non-volatile memory for storing instructions to be executed by the transceiver modules <NUM> and <NUM>, respectively.

The network communication module <NUM> generally represents the hardware, software, firmware, processing logic, and/or other components of the base station <NUM> that enable bidirectional communication between the BS transceiver module <NUM> and other network components and communication nodes configured to communication with the base station <NUM>. In a typical deployment, without limitation, network communication module <NUM> provides an <NUM> Ethernet interface such that the BS transceiver module <NUM> can communicate with a conventional Ethernet based computer network. The terms "configured for," "configured to" and conjugations thereof, as used herein with respect to a specified operation or function, refer to a device, component, circuit, structure, machine, signal, etc., that is physically or virtually constructed, programmed, formatted and/or arranged to perform the specified operation or function.

A single carrier system (e.g., discrete fourier Transform OFDM (DFT-S-OFDM) and single carrier quadrature amplitude modulation (SC_QAM)) may provide a relatively better candidate waveform for high frequency communications (e.g., communications at a higher frequency carrier frequency) than multi-carrier systems. For example, a single carrier system may have a lower peak-to-average ratio than a multi-carrier system.

As noted above, phase noise for higher frequency communications may be relatively larger than for lower frequency communications. A common phase error (CPE) compensation technique may be utilized to reduce phase noise. CPE compensation techniques generally include finding a mean value of a phase rotation in each OFDM symbol according to a continuous pilot signal or a scattered pilot signal. This mean value may be utilized to compensate for phase nose. CPE compensation techniques may also include monitoring for repeated data characteristics of a cyclic prefix (CP) to determine a phase deviation of data to compensate for phase noise. CPE compensation techniques may be utilized at lower frequency communications where phase noise is relatively low. However, CPE compensation techniques may not be as useful to reduce phase noise for high frequency communications as it is for lower frequency communications.

Accordingly, when the carrier frequency is high and the phase noise is large, it may be desirable to consider compensating for phase noise in each data block or in each OFDM symbol. However, the compensation of phase noise in each data block or OFDM symbol may lead to additional communication overhead due to the addition of pilot signals in each data block or OFDM symbol. This issue may be more acute in single-carrier data modulation schemes for wireless communication which may utilize a higher frequency but be susceptible to channel fading and a low signal to noise ratio (SNR).

Accordingly, systems and methods in accordance with various embodiments are directed to conjugate data modulation that modulates user data for communications in a manner that reduces phase error. Conjugate data modulation may include modulating (e.g., phase shift key (PSK) modulating) user data into modulated user data elements, which are interleaved with conjugate data elements (discussed further below). For ease of discussion, these modulated user data elements may be referred to as first data. These user data elements (e.g., first data) may be interleaved with conjugate data elements. For ease of discussion, these conjugate data elements may also be referred to as second data. These conjugate data elements may each be a conjugate or opposite conjugate of different modulated user data elements. Furthermore, the combination of the modulated user data elements (e.g., first data) interleaved with conjugate data elements (e.g., second data) may be referred to as a user data sequence. For ease of discussion this user data sequence may be referred to as a third data sequence. This user data sequence (e.g., third data sequence) may then be transmitted to a receiver. In certain embodiments, to create a fourth data sequence, this user data sequence may be concatenated with a first pilot sequence at a front (e.g., an earliest transmitted data element of the user data sequence) and a second pilot sequence at a rear (e.g., a last transmitted data element of the user data sequence). The first pilot sequence and the second pilot sequence may be a predetermined set or collection of data elements known to the receiver prior to demodulating the first pilot sequence and/or second pilot sequence. For ease of discussion, the first pilot sequence may be referred to as a first sequence or S1. Also, for ease of explanation , the second pilot sequence may be referred to as a second sequence or S2.

Accordingly, in certain embodiments, conjugate data elements (e.g., second data) may be inserted between individual data elements of user data elements (e.g., first data) to obtain a user data sequence (e.g., third data sequence). In the user data sequence (e.g., third data sequence), each data element of the second data is conjugated or oppositely conjugated with an adjacent one of the user data elements (e.g., first data). Furthermore, a first pilot sequence (e.g., S1) and a second pilot sequence (e.g., S2) may be inserted in front of and behind the user data sequence (e.g., third data sequence), respectively, to obtain a fourth data sequence that may be transmitted to a receiver. The first pilot sequence (e.g., S1) and second pilot sequence (e.g., S2) may be reference sequences, that is sequences known to the receiving end (e.g., receiver).

In certain embodiments, the user data sequence (e.g., third data sequence) comprises an equal number of modulated user data elements and conjugate data elements (e.g., second data). Stated another way, the user data sequence (e.g., first data) is equal in length to the conjugate data elements (e.g., second data) such that each user data element (e.g., first data) is adjacent to a corresponding conjugate data element (e.g., second data).

In certain embodiments, the user data sequence (e.g., third data sequence) comprises the modulated user data elements (e.g., first data) interleaved with the conjugate data elements (e.g., second data) in consistent intervals. Stated another way, the conjugate data elements (e.g., second data) may be uniformly inserted among the modulated user data elements (e.g., first data). That is, in the user data sequence (e.g., third data sequence), adjacent data intervals of the conjugate data elements (e.g., second data) are the same.

In certain embodiments, the user data sequence (e.g., third data sequence) comprises the modulated user data elements (e.g., first data) interleaved with the conjugate data elements (e.g., second data) at predetermined time domain locations. For example, every modulated user data element (e.g., first data) may be followed by a corresponding one of the conjugate data elements (e.g., second data), every conjugate data element (e.g., second data) may be followed by a corresponding one of the user data elements (e.g., first data), every second modulated user data element (e.g., first data) may be followed by a corresponding one of the conjugate data elements (e.g., second data), every conjugate data element (e.g., second data) may be followed by a corresponding one of every second modulated user data elements (e.g., first data), every third modulated user data element (e.g., first data) may be followed by a corresponding one of the conjugate data elements (e.g., second data), every conjugate data element (e.g., second data) may be followed by a corresponding one of every third modulated user data elements (e.g., first data), every fourth modulated user data element (e.g., first data) may be followed by a corresponding one of the conjugate data elements (e.g., second data), every conjugate data element (e.g., second data) may be followed by a corresponding one of every fourth modulated user data element (e.g., first data), and so on. Stated another way, the conjugate data elements (e.g., second data) are inserted among the modulated user data elements (e.g., first data) at predefined time domain locations. For example, the predefined position may be: inserted at a position of 2n, 3n or 4n in the time domain, where n is a positive integer. When the predefined position is 2n, one conjugate data element (e.g., second data) is inserted every other modulated user data element (e.g., first data); when the predefined position is 3n, one conjugate data element (e.g., second data) is inserted every two modulated user data element (e.g., first data); when the predefined position is 4n, one conjugate data element (e.g., second data) is inserted every three modulated user data element (e.g., first data). Although certain embodiments describe how conjugate data elements (e.g., second data) may immediately follow (e.g., be later in the time domain) and be adjacent to a corresponding modulated user data element (e.g., first data) of a conjugate pair, any ordering of conjugate pairs may be utilized as desired for different applications in various embodiments. For example, other embodiments may have a modulated user data element (e.g., first data) immediately follow (e.g., be later in the time domain) and be adjacent to a corresponding conjugate data element (e.g., second data) of a conjugate pair.

In certain embodiments, a combination of the front pilot sequence (e.g., S1), the user data sequence (e.g., third data sequence), and the rear pilot sequence (e.g., S2) is a predetermined number of data elements. Stated another way, the fourth data sequence has a constant length. For example, a combination of the front pilot sequence (e.g., S1), the user data sequence (e.g., third data sequence), and the rear pilot sequence (e.g., S2) may occupy a single Fourier window (e.g., a window length of subsequent FFT processing).

In certain embodiments, the front pilot sequence begins at a beginning of the single Fourier window and the rear pilot sequence ends at an end of the single Fourier window. Stated another way, the starting and ending position of the fourth data sequence may be at a starting and ending position of subsequent FFT processing. Also, the start and stop positions of subsequent FFT processing may be at the beginning of the front pilot sequence (e.g., S1) and the end of the rear pilot sequence (e.g., S2), respectively.

In certain embodiments, when the length of the front pilot sequence (e.g., S1) or rear pilot sequence (e.g., S2) is changed, the length of the conjugate data elements (e.g., second data) may also change while the length of the modulated user data element (e.g., first data) may be kept constant. Alternatively, when the length of the length of the modulated user data element (e.g., first data) or conjugate data elements (e.g., second data) is changed, the length of the front pilot sequence (e.g., S1) or rear pilot sequence (e.g., S2) may be changed as well.

In certain embodiments, the user data sequence is transmitted after filtering and conversion from a digital signal to an analog signal. For example, transmitting the fourth data sequence (e.g., a combination of the front pilot sequence (e.g., S1), the user data sequence (e.g., third data sequence), and the rear pilot sequence (e.g., S2)) further includes performing FFT processing on the fourth data sequence, and then performing subcarrier mapping, and then performing inverse fast Fourier transform (IFFT) processing. This may result in a fifth data sequence that is transmitted via the IFFT. In various embodiments, FFT processing may broadly refer to discrete Fourier transform (DFT) processing, and IFFT processing includes the concept of inverse discrete Fourier transform (IDFT) processing. In particular embodiments, transmitting the fourth data sequence may include filtering and digital-to-analog converting the fourth data sequence, and then transmitting the digital-to-analog converted signal (e.g., without FFT and IFFT processing).

In certain embodiments, control information may be transmitted. This control information may include time domain locations associated with the conjugate data elements (e.g., second data) to a recipient of the user data sequence (e.g., third data sequence). This control information may be in a control information format where the control information may be used to indicate a location of the conjugate data elements (e.g., second data) predefined in the time domain. In various embodiments, the control information format may be a control information format transmitted by a downlink or uplink control channel. In further embodiments, the control information may be transmitted as part of a control channel or radio resource control (RRC) signaling (e.g., in a control information format for downlink or uplink RRC signaling transmissions).

As noted above, reference to conjugation of the conjugate data elements (e.g., second data) with the modulated user data (e.g., first data) may refer to conjugation or negative conjugation. Accordingly, in the user data sequence (e.g., third data sequence), each data element of the conjugate data elements (e.g., second data) is conjugated or oppositely conjugated with an adjacent one of the modulated user data (e.g., first data), which has the advantage of reducing phase noise in the processing at a receiver. For example, the phase noise of adjacent data elements in the time domain may be approximately equal, thus phase noise can be estimated based on joint processing of adjacent data elements that form conjugate pairs that are conjugated or opposite conjugated. Moreover, since the data elements are conjugated or oppositely conjugated to each other, joint demodulation can be performed to improve the received signal to noise ratio.

In certain embodiments, the conjugate data elements (e.g., second data) may be equal in quantity to the modulated user data (e.g., first data). This may improve the density of phase noise estimation in the time domain (e.g., due to introducing conjugate pairs for each modulated user data (e.g., first data)). Also, the user data sequence (e.g., third data sequence) can then be directly demodulated by joint processing without first estimating the phase noise of each data element insertion position. This may be because the locations of modulated user data elements and conjugate data elements are predetermined or known to the transmitter and receiver.

In particular embodiments, it may be advantageous to concatenate the user data sequence (e.g., third data sequence) with the front pilot sequence (e.g., S1) at one end (e.g., a front end) and the rear pilot sequence (e.g., S2) at the other end (e.g., a back end). For example, this would allow for CPE compensation in an entire symbol to be estimated based on pilot signals including the front pilot sequence (e.g., S1) and the rear pilot sequence (e.g., S2). More specifically, once the CPE is estimated, the CPE can be compensated (e.g., removed) from the fourth data sequence during demodulation.

In further embodiments, it may be advantageous to insert the conjugate data elements (e.g., second data) among the modulated user data elements (e.g., first data) at predefined time domain positions. For example, these time domain positions may represent an embodiment where not every modulated user data element (e.g., first data) is adjacent to a corresponding conjugate data element (e.g., second data). This arrangement enables the increase of user data throughput for a same amount of overall time domain resource as fewer time domain resources need to be utilized for the conjugate data elements (e.g., second data). Additionally, insertion of conjugate data element (e.g., second data) at predefined time domain positions may be performed when the phase noise within a data block or within an OFDM symbol does not change much. Thus, the insertion of conjugate data element (e.g., second data) at predefined time domain positions may be used selectively in situations where the phase noise is known to be relatively smaller (e.g., as based on an actual phase noise variation degree, and the position density of the estimated phase noise is appropriately reduced, thereby improving the spectral efficiency) and/or where greater user data throughput is desired.

As noted above, in certain embodiments the length of the fourth data sequence may be a length of a Fourier transform window of subsequent FFT processing. This may simplify demodulation as the subcarrier spacing in the frequency domain can be kept unchanged, and orthogonality can be more easily achieved for frequency division multiplexing.

In particular embodiments, control information may be transmitted to a receiver in a control information format, where the indication information may be used to indicate a predetermined location of the conjugate data elements (e.g., second data) in the time domain. Accordingly, the time domain locations of the conjugate data elements (e.g., second data) and the lengths of the front pilot sequence (e.g., S1) and the rear pilot sequence (e.g., S2) can be adjusted in real time according to the magnitude of the delay and phase noise, thereby improving the system's ability to resist phase noise and multipath delay. This may also improve spectrum utilization as a receiver of the fourth data sequence may more easily demodulate the fourth data sequence using the control information.

<FIG> is a conceptual block diagram <NUM> of a fourth data sequence <NUM> in the time domain, in accordance with some embodiments. This fourth data sequence <NUM> may include a user data sequence <NUM> (e.g., third data sequence) concatenated with the front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location). Furthermore, the user data sequence <NUM> (e.g., third data sequence) may include modulated user data elements <NUM> (e.g., first data) interleaved with conjugate data elements <NUM> (e.g., second data). Additionally, the size of the fourth data sequence <NUM> may be equivalent to a single data block <NUM>.

More specifically, the interleaving may result in having each modulated user data element <NUM> (e.g., first data) be adjacent with a respective conjugate data element <NUM> (e.g., second data) so that conjugate pairs <NUM> are formed between the adjacent modulated user data elements <NUM> (e.g., first data) and respective conjugate data element <NUM> (e.g., second data). As noted above, a conjugate data element <NUM> (e.g., second data) may be a conjugate or a negative conjugate of a respective modulated user data element <NUM> (e.g., first data). For example, suppose the modulated user data elements <NUM> (e.g., first data) are: [<NUM>+i, <NUM>-i, -<NUM>+i, -<NUM>-i,. , -<NUM>+i, <NUM>+i]. Assuming that the conjugate data elements <NUM> (e.g., second data) are evenly inserted among the modulated user data elements <NUM> (e.g., first data), the second data sequence, as a conjugate of respective modulated user data elements <NUM> (e.g., first data) is: [<NUM>-i, <NUM>+i, -<NUM>-i, -<NUM> +i,. , -<NUM>-i, <NUM>-i]. Then, after interleaving, the obtained user data sequence <NUM> (e.g., third data sequence) may be: [<NUM>+i, <NUM>-i, <NUM>-i, <NUM>+i, -<NUM>+i, -<NUM>-i, -<NUM>-i, -<NUM>+i. , -<NUM>+i, -<NUM>-i, <NUM>+i, <NUM>-i]. Also, assuming that the conjugate data elements <NUM> (e.g., second data) are oddly inserted among the modulated user data elements <NUM> (e.g., first data), then, after interleaving, the obtained user data sequence <NUM> (e.g., third data sequence) may be: [<NUM>-i, <NUM>+i, <NUM>+i, <NUM>-i, -<NUM>-i, -<NUM>+i, -<NUM>+i, -<NUM>-i. , -<NUM>-i, -<NUM>+i, <NUM>-i, <NUM>+i].

In certain embodiments, the number of modulated user data elements <NUM> (e.g., first data) and conjugate data elements <NUM> (e.g., second data) may be the same (e.g., they may have the same length). Stated another way, the conjugate data elements <NUM> (e.g., second data) may be evenly or oddly inserted among the modulated user data elements <NUM> (e.g., first data). That is, in the user data sequence <NUM> (e.g., third data sequence) obtained after the insertion, the adjacent data intervals of the conjugate data elements <NUM> (e.g., second data) are the same. Inserting front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location) may result in the fourth data sequence <NUM>. In certain embodiments, the lengths of the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) may be the same or different, depending on the multipath nature of the wireless channel. In further embodiments, a length adjustment may be such that the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) are the same length. In various embodiments, the size of the fourth data sequence <NUM> may be equivalent to a single data block <NUM>.

In particular embodiments, the conjugate data elements <NUM> (e.g., second data) may have a predefined position in the time domain of 2n, where n is a positive integer. Stated another way, the conjugate data elements <NUM> (e.g., second data) may be at an even position of the user data sequence <NUM> (e.g., third data sequence). The control information may be indicated from the transmitter of the fourth data sequence to a receiver of the fourth data sequence via a control information format (e.g., Info-<NUM>).

<FIG> is a conceptual block diagram <NUM> of a fourth data sequence <NUM> in the time domain, in accordance with some embodiments. The embodiments of <FIG> may differ from that of <FIG> in that <FIG> illustrates the fourth data sequence to be equivalent to a single Fourier window (e.g., a window length for FFT processing).

This fourth data sequence <NUM> may include a user data sequence <NUM> (e.g., third data sequence) concatenated with the front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location). Furthermore, the user data sequence <NUM> (e.g., third data sequence) may include modulated user data elements <NUM> (e.g., first data) interleaved with conjugate data elements <NUM> (e.g., second data). Additionally, the size of the fourth data sequence <NUM> may be equivalent to a single Fourier window <NUM> (e.g., a window length for FFT processing).

In certain embodiments, the number of modulated user data elements <NUM> (e.g., first data) and conjugate data elements <NUM> (e.g., second data) may be the same (e.g., they may have the same length). Stated another way, the conjugate data elements <NUM> (e.g., second data) may be evenly or oddly inserted among the modulated user data elements <NUM> (e.g., first data). That is, in the user data sequence <NUM> (e.g., third data sequence) obtained after the insertion, the adjacent data intervals of the conjugate data elements <NUM> (e.g., second data) are the same. Inserting front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location) may result in the fourth data sequence. In certain embodiments, the lengths of the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) may be the same or different, depending on the multipath nature of the wireless channel. In further embodiments, a length adjustment may be such that the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) are the same length. In various embodiments, the size of the fourth data sequence <NUM> may be equivalent to a single Fourier window <NUM> (e.g., a window length for FFT processing).

<FIG> is a conceptual block diagram <NUM> of a fourth data sequence <NUM> with relatively longer pilot sequences in the time domain, in accordance with some embodiments. This fourth data sequence <NUM> may include a user data sequence <NUM> (e.g., third data sequence) concatenated with the front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location). Furthermore, the user data sequence <NUM> (e.g., third data sequence) may include modulated user data elements <NUM> (e.g., first data) interleaved with conjugate data elements <NUM> (e.g., second data).

More specifically, the interleaving may result in having every second modulated user data element <NUM> (e.g., first data) be adjacent with a respective conjugate data element <NUM> (e.g., second data) so that conjugate pairs <NUM> are formed between every second modulated user data elements <NUM> (e.g., first data) and respective conjugate data element <NUM> (e.g., second data). Stated another way, at least one modulated user data element <NUM> (e.g., first data) may be concatenated with another modulated user data element <NUM> (e.g., first data) and concatenated with a conjugate data element <NUM> (e.g., second data) that is its conjugate pair. As noted above, a conjugate data element <NUM> (e.g., second data) may be a conjugate or a negative conjugate of a respective modulated user data element <NUM> (e.g., first data). Additionally, the size of the fourth data sequence <NUM> may be equivalent to a single Fourier window <NUM> (e.g., a window length for FFT processing).

In certain embodiments, the number of modulated user data elements <NUM> (e.g., first data) may be twice that of the conjugate data elements <NUM> (e.g., second data). Stated another way, in the user data sequence <NUM> (e.g., third data sequence) obtained after the insertion, the adjacent data intervals of the conjugate data elements <NUM> (e.g., second data) are the same. Inserting front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location) may result in the fourth data sequence <NUM>. In certain embodiments, the lengths of the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) may be the same or different, depending on the multipath nature of the wireless channel. In further embodiments, a length adjustment may be such that the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) are the same length. In various embodiments, the size of the fourth data sequence <NUM> may be equivalent to a single Fourier window <NUM> (e.g., a window length for FFT processing).

As illustrated in <FIG>, the quantity and/or length of the modulated user data elements <NUM> (e.g., first data) may be greater than that of the conjugate data elements <NUM> (e.g., second data). Also, the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) may be relatively longer than that as illustrated in <FIG> (assuming the same FFT window length or fourth data sequence length). Accordingly, the fourth data sequence <NUM> of <FIG> may reflect a situation where multipath delay is big and the phase noise changes slowly in the time domain (no change across every three sample points (e.g., three data elements)). Also, the length of the fourth data sequence <NUM> may be the length of a single Fourier window <NUM> (e.g., a window length for FFT processing). Accordingly, the starting and ending position of the fourth data sequence <NUM> may be the starting and ending position of the single Fourier window <NUM> (e.g., a window length for FFT processing).

In particular embodiments, the conjugate data elements <NUM> (e.g., second data) may have a predefined position in the time domain of 3n, where n is a positive integer. Accordingly, the conjugate data elements <NUM> (e.g., second data) may be at every third position of the user data sequence <NUM> (e.g., third data sequence). The control information may be indicated from the transmitter of the fourth data sequence to a receiver of the fourth data sequence via a control information format (e.g., Info-<NUM> or Info-<NUM>).

<FIG> is a conceptual block diagram <NUM> of a fourth data sequence <NUM> with relatively shorter pilot sequences with greater user data throughput in the time domain, in accordance with some embodiments. This fourth data sequence <NUM> may include a user data sequence <NUM> (e.g., third data sequence) concatenated with the front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location). Furthermore, the user data sequence <NUM> (e.g., third data sequence) may include modulated user data elements <NUM> (e.g., first data) interleaved with conjugate data elements <NUM> (e.g., second data).

More specifically, the interleaving may result in having every second modulated user data element <NUM> (e.g., first data) be adjacent with a respective conjugate data element <NUM> (e.g., second data) so that conjugate pairs <NUM> are formed between every second modulated user data elements <NUM> (e.g., first data) and respective conjugate data element <NUM> (e.g., second data). Accordingly, at least one modulated user data element <NUM> (e.g., first data) may be concatenated with another modulated user data element <NUM> (e.g., first data) and concatenated with a conjugate data element <NUM> (e.g., second data) that is its conjugate pair. As noted above, a conjugate data element <NUM> (e.g., second data) may be a conjugate or a negative conjugate of a respective modulated user data element <NUM> (e.g., first data). Additionally, the size of the fourth data sequence <NUM> may be equivalent to a single Fourier window <NUM> (e.g., a window length for FFT processing).

In certain embodiments, the number of modulated user data elements <NUM> (e.g., first data) may be twice that of the conjugate data elements <NUM> (e.g., second data). Stated another way, in the user data sequence <NUM> (e.g., third data sequence) obtained after the insertion, the adjacent data intervals of the conjugate data elements <NUM> (e.g., second data) are the same. Inserting front pilot sequence <NUM> (e.g., S1) at one end (e.g., a front end with an earlier time domain location) and the rear pilot sequence <NUM> (e.g., S2) at the other end (e.g., a back end with a later time domain location) may result in the fourth data sequence. In certain embodiments, the lengths of the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) may be the same or different, depending on the multipath nature of the wireless channel. In further embodiments, a length adjustment may be such that the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) are the same length. In various embodiments, the size of the fourth data sequence <NUM> may be equivalent to a single Fourier window <NUM> (e.g., a window length for FFT processing).

As illustrated in <FIG>, the quantity and/or length of the modulated user data elements <NUM> (e.g., first data) may be greater than that of the conjugate data elements <NUM> (e.g., second data). Also, the front pilot sequence <NUM> (e.g., S1) and the rear pilot sequence <NUM> (e.g., S2) may be relatively smaller than that as illustrated in <FIG> (assuming the same FFT window length or fourth data sequence length). <FIG> may reflect an embodiment with greater user data throughput per unit time given that the fourth data sequence <NUM> is constant between <FIG>. Furthermore, the fourth data sequence <NUM> of <FIG> may reflect a situation where multipath delay is small and the phase noise changes slowly in the time domain (e.g., no change every three sample points). The length of the fourth data sequence <NUM> may be the length of a single Fourier window <NUM> (e.g., a window length for FFT processing). Stated another way, the starting and ending position of the fourth data sequence <NUM> may be the starting and ending position of the single Fourier window <NUM> (e.g., a window length for FFT processing).

In particular embodiments, the conjugate data elements <NUM> (e.g., second data) may have a predefined position in the time domain of 3n, where n is a positive integer. Stated another way, the conjugate data elements <NUM> (e.g., second data) may be at every third position of the user data sequence <NUM> (e.g., third data sequence). The control information may be indicated from the transmitter of the fourth data sequence to a receiver of the fourth data sequence via a control information format (e.g., Info-<NUM> or Info-<NUM>).

It is also understood that any reference to an element or embodiment herein using a designation such as "first," "second," and so forth does not generally limit the quantity or order of those elements.

Skilled artisans can implement the described functionality in various ways for each particular application.

Additionally, one or more of the functions described in this document may be performed by means of computer program code that is stored in a "computer program product", "computer-readable medium", and the like, which is used herein to generally refer to media such as, memory storage devices, or storage unit. These, and other forms of computer-readable media, may be involved in storing one or more instructions for use by processor to cause the processor to perform specified operations. Such instructions, generally referred to as "computer program code" (which may be grouped in the form of computer programs or other groupings), which when executed, enable the computing system to perform the desired operations.

Claim 1:
A method performed by a device, comprising:
modulating user data into modulated user data elements;
determining conjugate data elements, wherein each conjugate data element is a conjugate or opposite conjugate of a respective one of the modulated user data elements; and
transmitting, over a time domain, a front pilot sequence immediately followed by a user data sequence comprising the modulated user data elements interleaved with the conjugate data elements, and a rear pilot sequence immediately following the user data sequence, wherein the front pilot sequence and the rear pilot sequence are predetermined collections of data elements.