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.
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
Radio Transmission Systems
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.
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 −...
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.
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
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...
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
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
We used the inductive methodology suggested by Glaser and Strauss (1967) to codify the
results from each round of testing.
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.
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.) ...
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....
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).
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.
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.
Public health officials have long been concerned about the effect of
the environment on human health. In the nineteenth century, public
health efforts in the United States were focused on controlling
the spread of infectious disease, and advances in sanitation and the
provision of clean water contributed to improvements in the health
of the population.
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.