Spreading codes

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  • This lecture covers the fundamentals of spread spectrum modulation, which can be defined as any modulation technique that requires a transmission bandwidth much greater than the modulating signal bandwidth, independently of the bandwidth of the modulating signal. After reviewing basic digital modulation techniques, the principal forms of spread spectrum modulation are described. One of the most important components of a spread spectrum system is the spreading code, and several types and their characteristics are described.

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: High sensitivity wake-up radio using spreading codes: design, evaluation, and applications

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  • Contents: • Introduction (gi i thi ớ ệu) • Spread Spectrum Technology (công nghệ trải phổ) • DS-CDMA • Spreading Codes (mã trải phổ) • Features of CDMA Đặc tính của cdma – RAKE Receiver (bộ thu rake) – Power Control (điều khiển công suất) – Frequency Allocation (cấp phép tần số) – Soft Handoff (chuyển giao mềm)

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  • Radio Transmission Systems Mamoru Sawahashi 2.1 Direct Sequence Code Division Multiple Access (DS-CDMA) 2.1.1 Principles of DS-CDMA DS-CDMA is a radio-access technology that enables multiple access based on a spread spectrum system. Figure 2.1a shows how DS-CDMA works [1–3]. The transmitted data sequence is spread across the spectrum after being encoded by spreading codes, each of which is assigned uniquely to each user at a higher rate than the symbol rate of the information data.

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  • Điều này dẫn đến một tổng số (K + 16) × 8 + 6] / R bit. Cuối cùng, các bit thủng nối tiếp song song chuyển đổi và trình mapper biểu tượng. Nếu BER trước khi giải mã RS là đảm bảo được khoảng 2 - 04/10, sau đó đan xen đầy đủ (ví dụ, 8 từ mã RS) cho các giá trị SNR cùng được đưa ra trong Bảng 4-3, một lỗi gần như miễn phí (tức là, BER coding, the systematic structure of the RS code allows one to shorten the code, i.e., remove the filled 239 −...

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  • Mobility is the most important feature of a wireless cellular communication system. Usually, continuous service is achieved by supporting handoff (or handover) from one cell to another. Handoff is the process of changing the channel (frequency, time slot, spreading code, or combination of them) associated with the current connection while a call is in progress. It is often initiated either by crossing a cell boundary or by a deterioration in quality of the signal in the current channel.

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  • Principle of CDMA - Frequency allocation - Principle of DS­CDMA - Transmit power control Basic W­CDMA Transmission Technologies - Two­layer spreading code assignment - Inter­BS asynchronous mode Characteristics of W­CDMA - Statistical Multiplexing effect - MS stand­by time - Coherent RAKE reception (RAKE time diversity) 3G Roll Out Plan - FOMA service content - 3G Roll out plan

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  • You are not covered if your car (including any attached caravan or trailer) was: in an unroadworthy or unsafe condition that contributed to the accident being a condition that was known to and disregarded by you or the driver of your car. carrying more passengers or loaded above the legal limit or loaded in an illegal way. being used for hire or reward. being used during your full-time, part-time or casual working period as an integral means of earning an income, unless you have told us about this use and we...

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  • Wideband Code Division Multiple Access uses direct sequence spread-spectrum technology to transmit a number of independent conversations across 5MHz segments of the radio spectrum.

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Rotated Walsh-Hadamard Spreading with Robust Channel Estimation for a Coded MC-CDMA System

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  • We used the inductive methodology suggested by Glaser and Strauss (1967) to codify the results from each round of testing. 9 We prepared typed transcripts of each testing session. We coded and analyzed the themes and patterns that emerged from each testing about the problems participants encountered. In particular, we noted patterns, clustered comments, looked for relationships, and identified contrasts.

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Particle Filtering for Joint Symbol and Code Delay Estimation in DS Spread Spectrum Systems in Multipath

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  • Corporate bonds differ in two important ways: maturity and credit quality.Maturities vary from short-term (between 1 and 5 years) to intermediate-term (between 5 and 10 years) to long-term (more than 10 years).Most corporate bonds are assigned a letter-coded rating by independent bond rating agencies such as Moody’s Investors Service, Inc., and Standard & Poor’s Corporation to indicate their relative credit quality—the likelihood that the issuer will pay interest and principal in full and on time. (More information about bond ratings is provided on page 10.) ...

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  • This book provides a comprehensive introduction to the underlying theory, design techniques and analytical tools of wireless communications, focusing primarily on the core principles of wireless system design. The book begins with an overview of wireless systems and standards. The characteristics of the wireless channel are then described, including their fundamental capacity limits. Various modulation, coding, and signal processing schemes are then discussed in detail, including state-of-the-art adaptive modulation, multicarrier, spread spectrum, and multiple antenna techniques....

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  • You will understand the physical meaning behind the mathematics of wireless signals and learn the intricacies and tradeoffs in signal selection and design.

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  • Kỹ thuật trải phổ là kỹ thuật tín hiệu được điều chế 2 lần, trong đó có sử dụng một mã giả ngẫu nhiên PN (pseudo noise code) độc lập với dữ liệu thông tin, để trải năng lượng của tín hiệu tin tức trên một băng thông rộng hơn rất nhiều so với băng thông của tín hiệu tin tức, kỹ thuật này gọi là kỹ thuật trải phổ (spread spectrum).

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  • THE UTRA PHYSICAL LAYER DESIGN The UTRA design is comprised basically of three parts, i.e. radio aspects corresponding primarily to the physical layer, radio interface aspects incorporating layers two and three, and network aspects inter-working directly with the core network. This chapter describes the UTRA physical layer including both FDD and TDD modes, as well as spreading and modulation, multiplexing and channel coding, and physical layer procedures.

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  • MD PRMA ON CODE-TIME-SLOTS This chapter is concerned with MD PRMA on perfect-collision code-time-slot channels. The simple and abstract channel model used, representative for a blocking-limited system, allows one to consider an arbitrary number of code-slots E per time-slot, without having to worry about the spreading factor required to meet a certain packet erasure performance.

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  • Spreading Sequences Overview In this chapter we study the structures and properties of orthogonal and pseudoorthogonal sequences. Firstly, we examine several types of pseudo-orthogonal (PN) and Quasi-Orthogonal (QO) sequences, and present their cross-correlation properties under synchronous and asynchronous conditions. Secondly, we survey basic methods of constructing orthogonal code sets. Orthogonal binary (Hadamard) codes may exist for lengths 1, 2 and 4k (for k = 1, 2, 3, ...). Methods for generating all lengths up to 256 are presented.

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