time division multiple access

... 13 2.2.1CDMA (Code Division Multiple Access) .13 2.2.2CSMA/CD (Carrier Sense Multiple Access with Collision Detection): .13 2.2.3CSMA/CA (Carrier Sense Multiple Access with Collision ... Multiple Access with Collision Avoidance) 14 2.2.4TDMA (Time Division Multiple Access ) 14 2.2.5FDMA ( Frequency Division Multiple Access ) 15 3.Kỹ thuật truyền dẫn vô tuyến ... hướng đến liên lạc với nút nguồn 2.2.4 TDMA (Time Division Multiple Access ) Đa truy xuất phân chia thời gian Mỗi máy phát (node) có khe thời gian ( slot time ) định, khe thời gian đến, truyền với...

Ngày tải lên: 28/03/2014, 13:20

... 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 ... granular units in the frequency domain, OFDM symbol duration is the smallest granular unit in the time domain in OFDMA systems In WiMAX, subchannels are formed from a group of In LTE, 12 adjacent...

Ngày tải lên: 24/07/2015, 22:26

Ngày tải lên: 24/07/2015, 22:27

... keying (QPSK) Sophisticated multiple access technology like frequency division multiple access (FDMA), time division multiple access (TDMA) and code division multiple access (CDMA) also gained ... systems, multiple access technologies based on orthogonal frequency division multiplexing (OFDM) air interface were chosen [8] In the downlink, the popular orthogonal frequency division multiple access ... CDD Cyclic Delay Diversity CDMA Code Division Multiple Access DFT Discrete Fourier Transform FDE Frequency Domain Equalizer FDMA Frequency Division Multiple Access FEC Forward Error Correcting...

Ngày tải lên: 08/09/2015, 18:24

... Typical OFDM-based multiple access techniques include Time Division Multiple Access (OFDM-TDMA), Code Division Multiple Access (OFDM-CDMA or MC-CDMA) and Frequency Division Multiple Access (OFDM-FDMA) ... S/P sequential to parallel MAI multiple access interference TDMA time division multiple access MF matched filtering WiMAX worldwide interoperability microwave access viii Summary In current broadband ... division multiple access MSE mean square error CFO carrier frequency offset OFDM orthogonal frequency division multiplexing CP cyclic prefix OFDMA orthogonal frequency division multiple access CRLB...

Ngày tải lên: 14/09/2015, 14:03

... 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 ... depicted cases with multiple users, that is, there is virtually no loss in power efficiency compared to the case without MAI We therefore obtain a quasiorthogonal multiple access without the need...

Ngày tải lên: 22/06/2014, 23:20

... proposed in [12] to 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 ... 2.5 1.5 0.5 0 0.5 1.5 2.5 3.5 4.5 Rate of user (nat) ant., time share ant., time share ant., time share 16 ant., time share Figure 4: Time- share bound on 10% outage capacity region with SNR=10 ... applied to multiple- user cases to obtain time- sharing bounds The only difference is that the boundary will be defined by multiple rates and the condition in (19) will be given by the product of multiple...

Ngày tải lên: 23/06/2014, 01:20

... understood orthogonal access techniques such as time division multiple access and frequency division multiple access Additionally, random access schemes such as carrier sense multiple access are examined ... contention-free multiple access is in how the channels are defined In time division multiple access (TDMA), channels are defined according to time slots In frequency division multiple access (FDMA), ... Techniques for Code Division Multiple Access 23 2.1 Forms of Code Division Multiple Access 23 2.2 Direct Sequence Code Division Multiple Access ...

Ngày tải lên: 27/06/2014, 14:20

Ngày tải lên: 25/07/2014, 09:39

... understood orthogonal access techniques such as time division multiple access and frequency division multiple access Additionally, random access schemes such as carrier sense multiple access are examined ... contention-free multiple access is in how the channels are defined In time division multiple access (TDMA), channels are defined according to time slots In frequency division multiple access (FDMA), ... Techniques for Code Division Multiple Access 23 2.1 Forms of Code Division Multiple Access 23 2.2 Direct Sequence Code Division Multiple Access ...

Ngày tải lên: 07/08/2014, 21:20

... Techniques for Code Division Multiple Access In the previous chapter, we reviewed the basic concepts of multiuser communications and the multiple access techniques used to allow multiple users to ... centralized access to avoid collisions (By using a centralized access topology, channel access time is allocated to each user such that two nodes not contend for the same channel time. ) Attempts ... 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 Abramson...

Ngày tải lên: 07/08/2014, 21:20

... 15:54 SPREAD SPECTRUM TECHNIQUES FOR CODE DIVISION MULTIPLE ACCESS 45 structure described is optimal only in the absence of multiple access interference Time hopping can be thought of as DS/SS ... IML MOBK023-Buehrer.cls 36 September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) Time Spectrum Before spreading After spreading Time averaged spectrum FIGURE 2.7: Illustration of spectrum ... MOBK023-Buehrer.cls September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) Frequency 38 BS B Ts Tc Tb Time FIGURE 2.10: Example of a time frequency plot for slow hopping (Tc : hop period,...

Ngày tải lên: 07/08/2014, 21:20

... 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 ... hopping to be incorporated into the coding decision statistics 2.8 MULTIPLE ACCESS PERFORMANCE OF FREQUENCY-HOPPED CODE DIVISION MULTIPLE ACCESS Although the emphasis of this chapter is DS-CDMA, we ... that we have not considered that arise in the multiple cell scenario P2: IML MOBK023-Buehrer.cls September 28, 2006 15:54 CODE DIVISION MULTIPLE ACCESS (CDMA) 10 K=1 K = 10 K = 20 K = 30 K =...

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 ... sharing of a single channel by multiple information streams For example, ten 3-kbps information streams can be time- multiplexed onto a single 30-kbps channel In time- multiplexing, the overall channel ... CELLULAR CODE DIVISION MULTIPLE ACCESS In this section, we will discuss four key principles of CDMA systems, particularly cellular systems: interference averaging, statistical multiplexing, universal...

Ngày tải lên: 07/08/2014, 21:20

... 104 September 28, 2006 15:55 CODE DIVISION MULTIPLE ACCESS (CDMA) Fast Rayleigh fading channel 10 -1 10 -2 10 0.2 0.4 0.6 0.8 1.2 1.4 1.6 1.8 1.2 1.4 1.6 1.8 1.2 Time (sec) 1.4 1.6 1.8 Transmit ... IML/FFX MOBK023-03 P2: IML MOBK023-Buehrer.cls September 28, 2006 15:55 CELLULAR CODE DIVISION MULTIPLE ACCESS 89 Sector interference sources rm ro FIGURE 3.7: Illustration of out-of-cell interference ... (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...

Ngày tải lên: 07/08/2014, 21:20

... ALOHA, CSMA, and busy tone multiple access (BTMA) [43] Note that unlike traditional narrowband random access protocols, channel access strategies for SS/PRNs allow for multiple simultaneous transmissions ... 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 ... contentionbased multiple access Such multiple access techniques are useful in packet radio networks that cannot afford the overhead or infrastructure associated with scheduled access techniques...

Ngày tải lên: 07/08/2014, 21:20

... September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) Solution: For equally likely bits, 1/2 of the time, the bits of the two users reinforce each other, while 1/2 of the time the bits negate ... first P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 130 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) addressed by Schneider [56] for both the synchronous and asynchronous AWGN ... based P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 132 September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) CDMA receivers Single user Matched filter Multiuser Adaptive filters Optimal...

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 ... cancellation) 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 ... (5.79) 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

... 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, ” IEEE ... 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 ... Data Communications, pp 39–49, 1997 [17] Z J Haas and J Deng, “Dual busy tone multiple access (DBTMA)—a multiple access control scheme for ad hoc networks,” IEEE Transactions on Communications,...

Ngày tải lên: 07/08/2014, 21:20

... 1.2 Tiến trình triển khai công nghệ tiêu chuẩn hóa HSPA, HSDPA HSPA (High-Speed Packet Access: Truy cập tốc độ cao) công nghệ truyền dẫn không dây ứng dụng cho thiết bị thông tin di động...

Ngày tải lên: 02/06/2015, 17:26