mạng nội bộ amp lớp con điều khiển truy cập

Ngày tải lên: 25/07/2014, 09:39

... an example Additionally, important CDMA system functions (often termed radio resource management techniques), such as power control, mobile-assisted hand-off, load control, and admission control, ... discuss the more general concept of multiple access Two basic classes of multiple access are illustrated in Figure 1.1 [2]: contention-based techniques and con ict-free techniques Con ict-free multiple ... now discuss the two major classes of multiple access 1.1 CONFLICT-FREE MEDIUM ACCESS CONTROL As mentioned previously, contention-free (or con ict-free) multiple access involves the division of...

Ngày tải lên: 07/08/2014, 21:20

... in Chapter 1.2 CONTENTION-BASED MEDIUM ACCESS CONTROL Contention-free multiple access techniques are efficient provided that traffic is relatively continuous If traffic is bursty, contention-free ... desired SIR as we can see in the following example Example 1.4 Repeat Example 1.3 if the path loss factor is κ = Solution: Repeating the analysis from Example 1.3 with κ = 3, we have ∗ 101.8 Q= = ... between cells is experienced The previous example showed that the efficiency of frequency reuse improves as the propagation conditions worsen In the next example, we show that the efficiency is also...

Ngày tải lên: 07/08/2014, 21:20

... hop period based on other considerations Specifically, the hop frequency should be chosen on the basis of implementation and performance considerations First, let us consider the case where Tc ... modulation is used Figure 2.10 plots an example of frequency occupancy versus time considering both the data modulation and frequency hopping In this example, Tc = 4Ts , or the frequency is hopped ... the spread bandwidth As can be seen, every Ts seconds, the frequency is changed to one of four symbols based on the data Additionally, every Tc seconds, the center frequency of these symbols is...

Ngày tải lên: 07/08/2014, 21:20

... MHz 1.8 1.6 1.4 1.2 0.8 0.6 0.4 0.2 0 0.5 1.5 2.5 Normalized amplitude FIGURE 2.22: PDF of normalized amplitude of primary path (example from NLOS indoor office environment) Precent power captured ... substantially different For example, consider a case where N = 128, Eb /N0 = 20dB, and K = 30 If all users are received at the same power level (this situation is termed perfect power control), we can determine ... =k p where f P ( p) is the distribution of the desired signal’s power As an example, consider a system where all amplitudes follow independent Rayleigh distributions with equal average power...

Ngày tải lên: 07/08/2014, 21:20

... this idea through the following example Example 3.1 Consider a wireless system where the received signal power at the edge of the coverage area due to power control is log-normally distributed ... negligible when compared to hits from one signal An example is plotted in Figure 2.33 for N = 100, Eb /N0 = 10, and synchronous hopping The figure contains plots for the upper and lower bounds as well ... facilitates the use of soft hand-off In soft hand-off, the mobile makes a connection with the new base station before breaking a connection with the old base station This “make-before-break” approach...

Ngày tải lên: 07/08/2014, 21:20

... through four basic functions: power control, base station assignment (hand-off ), admission control, and load control We will discuss each function in turn 3.4.1 Power Control In Section 2.6, we found ... apply equally well to the downlink Open-Loop Power Control The simplest form of power control is open-loop power control In open-loop power control, the transceiver simply examines the received ... termed inner-loop power control and a second loop that adjusts the received power threshold (sometimes called the Eb set-point) is called outer-loop power control An example of the outer loop...

Ngày tải lên: 07/08/2014, 21:20

... load control can be accomplished by denying “up” power control commands from the mobile More severe actions include amplifier overload control and dropping calls in a controlled fashion Amplifier ... Cell of interest Before amplifier overload control Cell of interest After amplifier overload control FIGURE 3.21: Illustration of cell breathing through amplifier overload control P1: IML/FFX MOBK023-03 ... accepted if it is a soft hand-off request 3.4.4 Load Control In addition to admission control, CDMA systems must exercise load control to avoid amplifier overload on the downlink and excessive interference...

Ngày tải lên: 07/08/2014, 21:20

... over the conventional matched filter u receiver were dramatic [57] We will examine the gains in the following example √ Example 5.1 Consider a synchronous CDMA system with perfect power control ... and a classical example of non-linear equalization is decision feedback [22] As with equalization, the concept of decision feedback can be applied to multiuser channels The concept of using decisions ... resistance Additionally the receiver requires no phase tracking, assuming that the phase is constant over at least two consecutive symbol intervals P1: IML/FFX MOBK023-05 P2: IML MOBK023-Buehrer.cls 136...

Ngày tải lên: 07/08/2014, 21:20

... Figure 5.8 As an example, consider the PIC detector examined in the last section There is no reason why the bit estimates defined by (5.64) couldn’t be used to perform a second round (i.e, stage) ... stages (termed a two-stage receiver) Let us consider the BER performance of a two-stage receiver with parallel cancellation in the second stage and a conventional first stage as compared to a two-stage ... succeeding stage Consequently, when the strong signal is cancelled from the weak signal in second stage of cancellation, it is done inaccurately, degrading the detection of the signal This continues...

Ngày tải lên: 07/08/2014, 21:20

... September 28, 2006 15:56 CODE DIVISION MULTIPLE ACCESS (CDMA) control and FEC are considered together since they are tied together in IS-95 Power control is partially based on frame errors (through the ... in capacity in the presence of power control, we define the capacity as the point at which power control can no longer maintain the target FER Since power control drives the system to a target ... = 9, r = 1/3 convolutional coding, closed-loop power control; OCI factor, C = 0.55; aver¸ age voice activity = 50%; maximum frequency offset is 300Hz; normalization relative to conventional capacity)...

Ngày tải lên: 07/08/2014, 21:20

... in Chapter 1.2 CONTENTION-BASED MEDIUM ACCESS CONTROL Contention-free multiple access techniques are efficient provided that traffic is relatively continuous If traffic is bursty, contention-free ... discuss the more general concept of multiple access Two basic classes of multiple access are illustrated in Figure 1.1 [2]: contention-based techniques and con ict-free techniques Con ict-free multiple ... now discuss the two major classes of multiple access 1.1 CONFLICT-FREE MEDIUM ACCESS CONTROL As mentioned previously, contention-free (or con ict-free) multiple access involves the division of...

Ngày tải lên: 27/06/2014, 14:20

Ngày tải lên: 19/07/2014, 12:32

... chuyển đổi so với Re’99 Trong Re’99 việc điều khiển kế hoạch dựa hoàn toàn vào điều khiển mạng vô tuyến(RNC) trong trạm sở hay node B công nghệ 3GPP điều khiển công suất liên kết chức Trong Re’99 ... để cải thiện việc truy n dẫn liệu gói đường xuống Re’99 Vấn đề đưa việc truy n dẫn qua lớp vật lý tiến trình sở BTS nghiên cứu đề cập đến điều chế mã hóa,kỹ thuật thu nhận truy n dẫn nhiều ănten, ... kênh truy n tải liệu khác phát triển, gồm có HS-SCCH (High Speed Shared Control Channel – kênh điều khiển dùng chung tốc độ cao), HS-DPCCH (High Speed Dedicated Physical Control Channel – kênh điều...

Ngày tải lên: 02/06/2015, 17:26

... to Convolutional Coding 4.5 Convolutional Coding in DS CDMA Systems 4.6 Orthogonal Convolutional Codes 4.7 Coding in FH and PPH CDMA Systems 4.8 Concatenated ... transmitted symbols vanish These symbols can be reconstructed if the system uses coding The following, more complicated example shows how we can this EXAMPLE 1.7 Consider the synchronous FH CDMA system ... of transferring is called handoff Each mobile contains a transceiver (transmitter and receiver), an antenna, and control circuitry The base stations consist of several transmitters and receivers,...

Ngày tải lên: 01/06/2014, 11:27

... cross-correlations are needed We can construct a training sequence with observation length UKCE based on (4) and sample this sequence with a sampling distance U and a userspecific sampling delay u − The resulting ... system load close to capacity and/or in a system with many users The amplitudes au,m include power control For simplicity, all amplitudes are assumed to be the same throughout this paper Further ... for higher pilot-layer power This is due to the constant Eb /N0 When assuming a constant noise level, the power per transmitted info bit is kept constant This also includes the power of the pilot...

Ngày tải lên: 22/06/2014, 23:20

... studies are constrained to either fixed channel condition [11, 12] or ergodic capacity region [13] The space-division multiple-access (SDMA) capacity regions under fixed channel conditions were considered ... Im×m 1290 EURASIP Journal on Applied Signal Processing Consider first the simple case where the channel conditions are fixed, that is, H is constant The capacity region of the multiple-access channel ... fading condition specified by H For convenience, we write this as follows:     R1 ≤ C h   R2 ≤ C h N = H    R1 + R2 ≤ C12 (H) (8) In (6), C(p) has the same interpretation as in (4); it consists...

Ngày tải lên: 23/06/2014, 01:20

... can be used in the second slot of the subframes - This pseudorandom selection of the positions of the subcarriers - Control messages use small bunches of contiguously placed - Control messages are ... symbols, plus primary and secondary synchronization sequences symbols, plus primary and secondary synchronization sequences EVOLUTION OF WIMAX AND LTE The WiMAX and LTE camps have submitted candidate ... MULTIUSER DIVERSITY - In WiMAX, the BAMC organize groups of contiguous subcarriers - Each bin has data &1 pilot subcarriers, and such contiguous bins are grouped in a band user feeds back the best...

Ngày tải lên: 24/07/2015, 22:26

... đường xuống phần lại cho đường truy n lên theo ý muốn nhà điều hành hệ thống,kí hiệu khung sử dụng để truy n phần mào đầu Kiểm soát truy n liệu gửi sử dụng kênh con, hình thành từ nhóm sóng mang ... 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 truy n thông điệp điều khiển ... trình nhập mạng Tất thông điệp điều khiển gửi với trình điều chế tốc độ mã hóa thấp để đảm bảo phát đáng tin cậy cạnh di động Trong LTE, không phụ thuộc vào băng thông số sóng mang con, bước giống...

Ngày tải lên: 24/07/2015, 22:27