نتایج جستجو برای: frequency division multiple access
تعداد نتایج: 1558997 فیلتر نتایج به سال:
Single carrier time division multiple access (TDMA) and orthogonal frequency division multiple access (OFDMA) are promising for broadband fixed radio access (FRA) in terms of flexibility, bandwidth-efficiency and implementation cost. Coherent detection of QPSK-symbols requires adaptive equalization. We focus on equalizer adaptation in time-variant frequency-selective FRA-channels in the presenc...
In this paper, to improve the energy efficiency (EE) of multi-user multiple-input multiple-output (MIMO) orthogonal frequency-division multiple access (OFDMA) system, an Energy-efficient multiple access (EMA) scheme is proposed. It improves EE by selecting either time-division multiple access (TDMA) or space-division multiple access (SDMA) based on the no. of users or power consumption. Here, w...
Recently, a distributed estimation, a type of parameter estimation problem, has been widely studied from the viewpoint of wireless sensor network (WSN) applications (1) (2). In particular, distributed estimation has been well-studied for certain WSN applications, such as environmental monitoring and precision agriculture (3)-(8). In such applications, measurements are acquired by the combinatio...
Long Term Evolution (LTE) uses single carrier frequency division multiple access (SCFDMA) technique as the multiple access scheme in the uplink, due to its low peak to average power ratio (PAPR) compared to orthogonal frequency division multiple access (OFDMA). This advantage is achieved when the Resource Blocks (RBs) allocated to a user are contiguous in frequency domain. Considering this cons...
Brevity is the soul of wit. William Shakespeare A cyclically permutable code is a set of codewords having the property that no codeword is a cyclic shift of another codeword. We study the problem of constructing cyclically permutable codes of large size and low correlation. Cyclically permutable codes are used in code-division multiple-access systems realized by e.g. direct-sequence modulation ...
This paper presents a novel multiple access scheme for future mobile communications using Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA) and Code Division Multiple Access (CDMA). The proposed system can support different classes of users each with different data rates and can provide very high spectral and system efficiency for the uplink and downlink. It is abl...
In the present scenario, improvement in the data rate, network capacity, scalability, and the network throughput are some of the most serious issues in wireless mesh networks (WMN). Specifically, a major obstacle that hinders the widespread adoption of WMN is the severe limits on throughput and the network capacity. This chapter presents a discussion on the potential use of a combined orthogona...
The challenges of future wireless networks imply that the physical layer of the next generation mobile communication system needs to be compatible with multiple-input multiple-output and allow a flexible multiple access scheme. Time-reversal space-time coding can be applied to a recent filtered multicarrier modulation scheme, named generalized frequency division multiplexing, to achieve a multi...
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