phân chia mã cdma code division multiple access

Ngày tải lên: 25/07/2014, 09:39

... Techniques for Code Division Multiple Access 23 2.1 Forms of Code Division Multiple Access 23 2.2 Direct Sequence Code Division Multiple Access ... difference between CDMA and more widely understood orthogonal access techniques such as time division multiple access and frequency division multiple access Additionally, random access schemes such ... 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) Multiple access techniques Conflict-free Contention-based Random access Collision resolution ALOHA, CSMA, CSMA/CA, RTS/CTS, etc TREE, WINDOW, etc TDMA, CDMA, ...

Ngày tải lên: 07/08/2014, 21:20

... of CDMA We will focus on the two basic forms of CDMA: direct sequence CDMA (DSCDMA) and frequency-hopped CDMA (FH -CDMA) We will also briefly mention a third type of CDMA termed time-hopped CDMA ... systems 2.1 FORMS OF CODE DIVISION MULTIPLE ACCESS CDMA is also known as spread spectrum multiple access or SSMA because the use of spread spectrum waveforms is fundamental to CDMA. 1 Spread spectrum ... IML September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) 1.2.1 ALOHA The most common contention-based methods are random access methods The first random access method was developed by...

Ngày tải lên: 07/08/2014, 21:20

... September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) FIGURE 2.4: Comparison of original/despread signal and spread signal spectra for DS/SS with square pulses 2.2.2 Multiple Access The DS/SS ... MOBK023-Buehrer.cls 34 September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) The benefit of Gold codes is that a large number of these codes are available for a given length N while having ... SPECTRUM IN CODE DIVISION MULTIPLE ACCESS Now that we have described the main types of CDMA, let us now turn to the performance of CDMA systems This discussion will start with DS -CDMA specifically,...

Ngày tải lên: 07/08/2014, 21:20

... statistics 2.8 MULTIPLE ACCESS PERFORMANCE OF FREQUENCY-HOPPED CODE DIVISION MULTIPLE ACCESS Although the emphasis of this chapter is DS -CDMA, we would like to examine the performance of FH -CDMA systems ... additional channel estimation, which can be substantial 2.6 MULTIPLE ACCESS PERFORMANCE OF DIRECT SEQUENCE CODE DIVISION MULTIPLE ACCESS The previous section examined the performance of a single ... P1: IML/FFX MOBK023-02 P2: IML MOBK023-Buehrer.cls 54 September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) Rake receiver can provide substantial improvement in performance even if the...

Ngày tải lên: 07/08/2014, 21:20

... 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) 3.1.4 Statistical Multiplexing The final fundamental CDMA concept that we will discuss in this section is termed statistical multiplexing, which ... MOBK023-03 P2: IML MOBK023-Buehrer.cls 78 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) One of the primary advantages of CDMA systems is universal frequency reuse That is, since the ... OF CELLULAR CODE DIVISION MULTIPLE ACCESS In this section, we will discuss four key principles of CDMA systems, particularly cellular systems: interference averaging, statistical multiplexing,...

Ngày tải lên: 07/08/2014, 21:20

... 1.25 ms in IS-95 and cdma2 000 and half that length in UMTS P1: IML/FFX MOBK023-03 P2: IML MOBK023-Buehrer.cls 102 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) AWGN channel 1.5 ... (3.38) P1: IML/FFX MOBK023-03 P2: IML MOBK023-Buehrer.cls 90 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) In a similar fashion, we can show that var I P dm = · 1− Q 2κ e [σ ln(10)/10]2 ... )req K i=1 N PTi (3.45) P2: IML MOBK023-Buehrer.cls 92 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) Defining the right-hand side of the inequality as δ, an outage occurs if the...

Ngày tải lên: 07/08/2014, 21:20

... 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) Synchronization Destination Source address address header Spread with receiver's code Data Spread with transmitter's code FIGURE 4.4: R-T code assignment ... September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) 3.5 SUMMARY In this chapter, we have described the application of CDMA to cellular systems Specifically, we showed that CDMA provides several ... MOBK023-Buehrer.cls 118 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) indicator of the success or failure of packet access since multiple transmissions are possible Simply sensing...

Ngày tải lên: 07/08/2014, 21:20

... spreading codes as the cross-correlation between codes ρ varies between and 0.95 P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 140 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) ... random spreading codes, the signal of the (K − 1)th decoded user is P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 144 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) only affected ... model of DS -CDMA from Chapter The received signal on the uplink can be P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 128 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) represented...

Ngày tải lên: 07/08/2014, 21:20

... P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 148 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) b Matched filter User - Σ+ - Matched filter User b1 - + Σ - Matched filter ... P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 150 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) Mathematically, we can represent the bit decisions for an S-stage parallel ... P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 152 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) Now, if the estimates of b are correct we have ˆ ˆ Pr b = −1 | b = 1, b =...

Ngày tải lên: 07/08/2014, 21:20

... 2006 17:14 CODE DIVISION MULTIPLE ACCESS (CDMA) [14] F A Tobagi and L Kleinrock, “Packet switching in radio channels: Part III—Polling and (dynamic) split-channel reservation multiple access, ” ... random -access packet switched code division multiple access channels,” IEEE Transactions on Communications, vol 29, pp 895–901, June 1981 [46] M Joa-Ng and I Lu, “Spread spectrum medium access ... MOBK023-Buehrer.cls 178 T1: IML September 28, 2006 17:14 CODE DIVISION MULTIPLE ACCESS (CDMA) [69] Z Zvonar and D Brady, “Suboptimum multiuser detector for synchronous CDMA frequency-selective Rayleigh fading...

Ngày tải lên: 07/08/2014, 21:20

... Techniques for Code Division Multiple Access 23 2.1 Forms of Code Division Multiple Access 23 2.2 Direct Sequence Code Division Multiple Access ... difference between CDMA and more widely understood orthogonal access techniques such as time division multiple access and frequency division multiple access Additionally, random access schemes such ... - CODE DIVISION MULTIPLE ACCESS (CDMA) Multiple access techniques Conflict-free Contention-based Random access Collision resolution ALOHA, CSMA, CSMA/CA, RTS/CTS, etc TREE, WINDOW, etc TDMA, CDMA, ...

Ngày tải lên: 27/06/2014, 14:20

Ngày tải lên: 19/07/2014, 12:32

... triển dựa công nghệ W -CDMA, sử dụng phương pháp chuyển đổi mã hóa liệu khác Nó tạo kênh truyền liệu bên W -CDMA gọi HS-DSCH (High Speed Downlink Shared Channel), hay gọi kênh chia sẻ đường xuống ... thông tin di động tế bào cho HSDPA HSUPA đạt kết tốt phát hành công nghệ đa truy cập phân chia theo mã băng rộng WCDMA Hơn thế, 3GPP chịu trách nhiệm cho việc chuẩn hóa giải pháp toàn cầu tốc độ ... ích chất lượng dung lượng HSDPA sở có dung lượng tế bào cao gấp lần WCDMA HSDPA cải tiến có dung lượng tế bào cao gấp lần WCDMA Hiệu suất trải phổ HSDPA cải tiến bị giới hạn 1bit/s/Hz/cell.Mức...

Ngày tải lên: 02/06/2015, 17:26

... THEORY OF CODE DIVISION MULTIPLE ACCESS COMMUNICATION Kamil Sh Zigangirov A JOHN WILEY & SONS, INC., PUBLICATION THEORY OF CODE DIVISION MULTIPLE ACCESS COMMUNICATION IEEE Press ... 1.2 Frequency Division and Time Division Multiple Access 1.3 Direct Sequence CDMA 1.4 Frequency-Hopped CDMA 1.5 Pulse Position-Hopped CDMA ... actually consists of two simplex channels Frequency division multiple access (FDMA) and time division multiple access (TDMA) are the two major access techniques used to share the available bandwidth...

Ngày tải lên: 01/06/2014, 11:27

... spread-spectrum multiple- access channels,” IEEE Journal on Selected Areas in Communications, vol 8, no 4, pp 641–649, 1990 [7] P A Hoeher and H Schoeneich, “Interleave -division multiple access from ... downlink multiple access capacity for Beyond 3G,” IEEE Communications Magazine, vol 43, no 1, pp 61–69, 2005 [10] J C Fricke, H Schoeneich, and P A Hoeher, “An interleavedivision multiple access ... 135– 144, 2000 [2] R H Mahadevappa and J G Proakis, “Mitigating multiple access interference and intersymbol interference in uncoded CDMA systems with chip-level interleaving,” IEEE Transactions...

Ngày tải lên: 22/06/2014, 23:20

... of multiple- access system with multiple antennas at the base station Most previous studies are constrained to either fixed channel condition [11, 12] or ergodic capacity region [13] The space -division ... maximize the sum capacity of a time invariant Gaussian MIMO multiple- access channel The ergodic capacity region for MIMO multiple- access channel with covariance feedback has been studied in [13] ... with multiple antennas,” IEEE Transactions on Information Theory, vol 47, no 4, pp 1273–1289, 2001 [11] B Suard, G Xu, H Liu, and T Kailath, “Uplink channel capacity of space -division- multiple- access...

Ngày tải lên: 23/06/2014, 01:20

... technologies with subtle differences.The main common technology is orthogonal frequency -division multiple access (OFDMA) - There are many good reasons for choosing OFDMA such as multipath handling ... bandwidths, the ability to handle different data rates, and the ability to easily combine with multiple antenna techniques Nhóm - The focus of this article is on the comparative use of OFDMA ... OFDMA related features are very similar in both resourceunits (DRUs and LRUs) The aggregation of multiple carriers to obtain wider Forming fixed size physical resource units (PRUs) Nhóm Base on...

Ngày tải lên: 24/07/2015, 22:26

... hép song công phân chia theo thời gian (TDD) dùng phổ biến Thời gian khung (ms) với băng thông triển khai từ đến 10 MHz [1, 5] Khung chia thành số kí hiệu OFDM (ví dụ, 48), số phân bổ cho đường ... pháp chia nhỏ kênh quan trọng, nguyên tắc bắt buộc dựa nhóm sóng mang phân tán, gọi sóng mang sử dụng phần (PUSCs), phương pháp tùy chọn khác dựa nhóm sóng mang liền kề, gọi điều bang thích ứng mã ... đơn vị tối thiểu phân bổ cho khung điều có nghĩa tối thiểu 168 sóng mang phân bổ trường hợp LTE Tốc độ lớp PHY tối thiểu hỗ trợ đường xuống 16,8 kb/s giả sử nguồn tài nguyên phân bố khung Để...

Ngày tải lên: 24/07/2015, 22:27