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The performance of a coordinated multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system is limited by the presence of the local oscillator frequency mismatch, where each transmitter and receiver is driven by an independent local oscillator. This paper proposes a simple pilot assisted estimation of symbol-by-symbol carrier offset for every pair of the transmitter...
An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300 MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-frequency...
The cost of building high data rate (≈100 Mb/s per user) wireless internet access networks in rural areas can be significantly reduced by minimizing the number of access points to be deployed, each covering a larger area with a larger user capacity. Given that the available spectrum is limited even in rural areas especially at a lower frequency (VHF and UHF), which typically has an advantage of efficiently...
Multi-user multiple-input multiple-output (MU-MIMO) has a potential to realize cost effective high data rate internet access to the homes in rural areas. We propose the novel Ngara Access system where the central access point (AP) is equipped with a uniform circular array (UCA) installed on a high tower while each UT is equipped with a directional antenna free of clutter, providing predominantly line-of-sight...
The SKA will be the mainstay of centimeter astronomy much of this century. It will have a sensitivity that is more than an order of magnitude greater than current radio telescopes. A second area for improved performance is the field of view (FoV). For frequencies above 1GHz a greater FoV may be achieved by placing a Phased Array Feed (PAF) at the focus of each of the SKA dishes. The design of the...
Previous works on carrier frequency offset (CFO) estimation for a multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) uplink typically assume CFO being constant over multiple OFDM symbol periods. The assumption may not hold when an inexpensive global positioning system (GPS) receiver is used to generate a frequency reference. We propose a new channel...
When multi-user multiple-input multiple-output (MU-MIMO) is applied to predominantly line-of-sight (LoS) environments, such as in the case of fixed wireless access in rural areas where a central access point (AP) equipped with an antenna array with NAP antenna elements serves NUT user terminals (UTs) each equipped with a single antenna, the problem of ill-conditioned channels arises. This paper investigates...
An all electronic 6 Gbps millimetre wave point-to-pont link in the 85 GHz band has been developed. The complete link has been built including RF, IF and digital baseband modules. 8PSK (phase shift keying) modulation has been used to achieve 2.4 bit/Hz spectral efficiency. According to our knowledge this is the highest spectral efficiency to date for a millimeter wave link with a demonstrated 6 Gbps...
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