نتایج جستجو برای: multi carrier system
تعداد نتایج: 2620546 فیلتر نتایج به سال:
This paper proposes a carrier phase estimation of a power efficient APSK signal with a honeycombed constellation at a receiver in point-to-multi-point fixed wireless access systems using quasimillimeter frequency band. The signal has a lower amplitude level of a maximum signal vector than a conventional QAM signal. The signal also has a lower average output power. A reference carrier phase of t...
The fundamental limit that is imposed on any wireless system is due to the radio channel. Propagation and channel models are essential for the analysis and simulation of wireless systems. Knowledge of the radio channel is essential to the development and deployment of a wireless system. Radio channel models are used to support research into methods for mitigating channel impairments, such as th...
Wireless broadband access is an appealing solution to the projected trend towards reliable and easily deployable high-speed connections. In order to enhance system capacity and tolerate volatility of the wireless medium, sophisticated adaptation techniques are required. In this paper, we consider the problem of efficient resource allocation with adaptive modulation techniques in a multi-carrier...
The dominate factors caused by reasons of losing the orthogonality in fading channel including FBC (fading branch correlation), CFO (carrier frequency offset), and even the CPN (carrier phase noise) are novel discussion in this letter. The first one factor causes the ISI (inter-symbol interference), and, however, the latter two will lead to the phenomenon of CPE (common phase error) and ICI (in...
In this paper multi-user detection techniques, such as Parallel and Serial Interference Cancellations (PIC & SIC), General Minimum Mean Square Error (GMMSE) and polynomial MMSE, for the downlink of a broadband Multi-Carrier Code Division Multiple Access (MCCDMA) system are investigated. The Bit Error Rate (BER) and Frame Error Rate (FER) results are evaluated, and compared with single-user dete...
In this article, a multiuser single carrier frequency division multiple access (SC-FDMA) system is considered, based on which an adaptive subcarrier and bit allocation algorithm is investigated. The algorithm has been used to achieve a subcarrier mapping mode in this system, which combines the advantages of singleand multi-carrier transmissions, such as, low peak to average power ratio, orthogo...
CSMA (carrier sense multiple access) is random access protocol for multi-user data communication; it was development to be used in wired (Ethernet) systems, and eventually adopted as the main access scheme of wireless LANs. Because of some intrinsic imperfections and unpredictability of wireless channel, pure CSMA system can not completely use the channel resources; the methods offered in the 8...
In this paper, a method of Transmission Power Control (TPC) for Orthogonal Frequency Division Multiplexing Direct Sequence Code Division Multiple Access (OFDM-DSCDMA), in order to compensate for power attenuation at each subcarrier, is proposed. Instead of assigning same power levels for all-subcarriers, different trasmission power levels are assigned to different subcarriers, according to the ...
Frequency synchronization is a critical requirement for single-carrier frequency division multiple-access (SC-FDMA) uplink transmissions. Based on the key observation that the received signal at the base station can be formulated as the parallel factor analysis model, we present a joint carrier frequency offset (CFO) estimation and compensation scheme for SC-FDMA uplink transmissions with inter...
In this paper, we investigate the influence of the carrier phase jitter of a phase-locked local oscillator on the performance of a multi-carrier code-division multipleaccess (MC-CDMA) system in a non-dispersive channel. This carrier phase jitter degrades the signal-to-noise ratio at the input of the decision device. When all users have the same power level and phase jitter spectrum, it is shown...
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