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Method and apparatus for packet acquisition / Adeptence Llc




Title: Method and apparatus for packet acquisition.
Abstract: Certain aspects of the present disclosure relate to a method for acquisition of a received spread spectrum signal transmitted over a wired or wireless medium. ...


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USPTO Applicaton #: #20140219321
Inventors: Ismail Lakkis


The Patent Description & Claims data below is from USPTO Patent Application 20140219321, Method and apparatus for packet acquisition.

BACKGROUND

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1. Field

Certain aspects of the present disclosure generally relate to signal acquisition, more particularly, to a method for joint packet detection, timing and frequency synchronization of a spread-spectrum signal.

2. Background

Spread-spectrum coding is a technique by which signals generated in a particular bandwidth can be spread in a frequency domain, resulting in a signal with a wider bandwidth. The spread signal has a lower power density, but the same total power as an un-spread signal. The expanded transmission bandwidth minimizes interference to others transmissions because of its low power density. At the receiver, the spread signal can be decoded, and the decoding operation provides resistance to interference and multipath fading.

Spread-spectrum coding is used in standardized systems, e.g. GSM, General Packet Radio Service (GPRS), Enhanced Digital GSM Evolution (EDGE), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA or W-CDMA), Orthogonal Frequency Division Multiplexing (OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Time Division Multiple Access (TDMA), Digital European Cordless Telecommunication (DECT), Infrared (IR), Wireless Fidelity (Wi-Fi), Bluetooth, Zigbee, Global Positioning System (GPS), Millimeter Wave (mmWave), Ultra Wideband (UWB), other standardized as well as non-standardized systems, wireless and wired communication systems.

In order to achieve good spreading characteristics in a system using spread spectrum, it is desirable to employ spreading codes which possess a near perfect periodic or aperiodic autocorrelation function, i.e. low sidelobes level as compared to the main peak, and an efficient correlator-matched filter to ease the processing at the receiver side. Spreading codes with high peak and low sidelobes level yields better acquisition and synchronization properties for communications, radar, and positioning applications.

In spread spectrum systems using multiple spreading codes, it is not sufficient to employ codes with good autocorrelation properties since such systems may suffer from multiple-access interference (MAI) and possibly inter-symbol interference (ISI). In order to achieve good spreading characteristics in a multi code DS-CDMA system, it is necessary to employ sequences having good autocorrelation properties as well as low cross-correlations. The cross-correlation between any two codes should be low to reduce MAI and ISI.

Complementary codes, first introduced by Golay in M. Golay, “Complementary Series,” IRE Transaction on Information Theory, Vol. 7, Issue 2, April 1961, are sets of complementary pairs of equally long, finite sequences of two kinds of elements which have the property that the number of pairs of like elements with any one given separation in one code is equal to the number of unlike elements with the same given separation in the other code. The complementary codes first discussed by Golay were pairs of binary complementary codes with elements +1 and −1 where the sum of their respective aperiodic autocorrelation sequence is zero everywhere, except for the center tap.

Polyphase complementary codes described in R. Sivaswamy, “Multiphase Complementary Codes,” IEEE Transaction on Information Theory, Vol. 24, Issue 5, September 1978, are codes where each element is a complex number with unit magnitude.

An efficient Golay correlator-matched filter was introduced by S. Budisin, “Efficient Pulse Compressor for Golay Complementary Sequences,” Electronic Letters, Vol. 27, Issue 3, January 1991, along with a recursive algorithm to generate these sequences as described in S. Budisin “New Complementary Pairs of Sequences,” Electronic Letters, Vol. 26, Issue 13, June 1990, and in S. Budisin “New Multilevel Complementary Pairs of Sequences,” Electronic Letters, Vol. 26, Issue 22, October 1990. The Golay complementary sequences described by Budisin are the most practical, they have lengths that are power of two, binary or complex, 2 levels or multi-levels, have good periodic and aperiodic autocorrelation functions and most importantly possess a highly efficient correlator-matched filter receiver.

However, Golay sequences are not without drawbacks. First, Golay sequences don't exist for every length, for example binary complementary Golay sequences are known for lengths 2M as well as for some even lengths that can be expressed as sum of two squares. Second, an efficient Golay correlator-matched filter exists only for Golay sequences generated by Budisin's recursive algorithm and that are of length that is a power of two (i.e. 2M). Third, the Golay sequences generated using Budisin's recursive algorithm might not possess the desired correlation properties. Furthermore, good spreading sequences such as m-sequences, Gold sequences, Barker sequences and other known sequences do not possess a highly efficient correlator-matched/mismatched filter.

Therefore, there is a need in the art for a method of spread spectrum coding applied at the transmitter and an efficient method for de-spreading at the receiver.

In high speed spread spectrum systems, a known signal, such as a preamble, is transmitted to aid receiver algorithms related to AGC setting, antenna diversity or pattern selection, DC offset and IQ imbalance estimation, packet detection, timing acquisition, frequency offset estimation, frame synchronization and channel estimation. In high speed systems, a large portion of the preamble is allocated for frequency estimation which is typically performed after packet detection.

Therefore, there is a need in the art for a method of joint packet detection and synchronization in order to shorten the preamble and therefore reduce the overhead associated with the preamble.

SUMMARY

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Certain aspects provide a method for wireless and wired communications. The method generally includes spreading at least one of the fields of a data stream with one or plurality of spreading sequences wherein at least one of the spreading sequences is based on Golay or generalized Golay sequences, and transmitting the spread data stream.

Certain aspects provide a method for wireless and wired communications. The method generally includes receiving a spread data stream wherein at least one of the fields is spread with one or plurality of spreading sequences, and performing a joint signal detection, timing and frequency synchronization.

BRIEF DESCRIPTION OF THE DRAWINGS

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So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 illustrates an example wireless communication system, in accordance with certain aspects of the present disclosure.

FIG. 2 illustrates various components that may be utilized in a wireless device in accordance with certain aspects of the present disclosure.

FIG. 3 illustrates an example transceiver that may be used within a wireless communication system in accordance with certain aspects of the present disclosure.

FIG. 4A illustrates an efficient Golay generator/correlator that may be used to generate a pair of Golay complementary codes or to perform matched filtering operations.

FIG. 4B illustrates an alternative efficient Golay generator/correlator that may be used to generate a pair of Golay complementary codes or to perform matched filtering operations.

FIG. 5A illustrates a preferred Golay generator in accordance with certain aspect of the present disclosure which may be used at a transmitter to generate one or multiple generalized Golay codes that may be used for spreading one or multiple fields of a data stream to be transmitted.

FIG. 5B illustrates one of the stages of the preferred binary Golay generator in accordance with certain aspect of the present disclosure.

FIG. 5C illustrates one of the stages of the preferred non-binary Golay generator in accordance with certain aspect of the present disclosure.

FIG. 6A illustrates a generalized Golay code in accordance to one aspect of the present disclosure which may be used at a transmitter to generate one or multiple generalized Golay codes that may be used for spreading one or multiple fields of a data stream to be transmitted.

FIG. 6B illustrates a preferred generalized Golay generator in accordance to one aspect of the present disclosure which may be used at a transmitter to generate one or multiple generalized Golay codes that may be used for spreading one or multiple fields of a data stream to be transmitted.

FIG. 7 a millimeter wave frame format using Golay and Generalized Golay codes in accordance to one aspect of the present disclosure.

FIG. 8A illustrates an example generalized efficient Golay correlator that may be used within a wireless communication system in accordance with certain aspects of the present disclosure.

FIG. 8B illustrates example implementation generalized efficient Golay correlator that may be used within a wireless communication system in accordance with certain aspects of the present disclosure.

FIG. 9 illustrates an example generalized efficient parallel Golay correlator that may be used within a wireless communication system in accordance with certain aspects of the present disclosure.

FIG. 10A illustrates an acquisition algorithm that may be used within a wireless communication system.




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stats Patent Info
Application #
US 20140219321 A1
Publish Date
08/07/2014
Document #
File Date
12/31/1969
USPTO Class
Other USPTO Classes
International Class
/
Drawings
0


Wireless Spread Spectrum

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Adeptence Llc


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Pulse Or Digital Communications   Spread Spectrum   Direct Sequence   Receiver   Multi-receiver Or Interference Cancellation  

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20140807|20140219321|packet acquisition|Certain aspects of the present disclosure relate to a method for acquisition of a received spread spectrum signal transmitted over a wired or wireless medium. |Adeptence-Llc
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