• Title/Summary/Keyword: Amplitude shift keying

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Design of a New 3-D 16-ary Signal Constellation with Constant Envelope (상진폭 특성을 가지는 새로운 3차원 16진 신호성상도의 설계)

  • Choe, Chae-Cheol;Kang, Seog-Geun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.10
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    • pp.2149-2156
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    • 2011
  • In this paper, design of a new 3-dimensional (3-D) 16-ary signal constellation with constant envelope is presented and analyzed. Unlike the conventional 16-ary constellations, all signal points of the new constellation are uniformly located on the surface of a sphere so that they have a unique amplitude level and a symmetrical structure. When average power of the constellations is normalized, the presented 16-ary constellation has around 11.4% increased minimum Euclidean distance (MED) as compared to the conventional ones that have non-constant envelope. As a result, a digital communication system which exploits the presented constellation has 1.2dB improved symbol error rate (SER). While signal points of the conventional constant-envelope constellation are not distributed uniformly on the surface of a sphere, those of the proposed constellation has a completely symmetric distribution. In addition, the new signal constellation has much lower computational complexity for practical implementation than the conventional one. Hence, the proposed 3-D 16-ary signal constellation is appropriate for the application to a communication system which strongly requires a constant-envelope characteristic.

A Nulling Anti-Jamming Scheme for the Polyphase Filter Bank-Based Satellite Repeat System (다상 필터 뱅크 기반의 위성 중계시스템을 위한 항재밍 기법의 연구)

  • Oh, Jin-O;Im, Sung-Bin;Ko, Hyun-Suk
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.7
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    • pp.39-47
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    • 2012
  • The combination of the broadband property and the wide area coverage of satellite communications enables high speed transmission. Every user in the region under the satellite beam coverage can tranceiver and one can simultaneously communicate with multiple users. For these reasons, it is one of commendable telecommunication networks for information transfer. Since the satellite communications use open channels, it is likely to cause jamming with unwanted interference signals. In the thesis, APSK (Amplitude Phase Shift Keying) is employed, which is recommended for DVB-S2 due to high-speed transmission and excellent bandwidth efficiency. For obtaining reliable communication under the jamming environments, the communication satellite transponder rests on the polyphase filter bank structure, which enables switching among the subchannels and gain control on each subchannel, resulting in effectively eliminating jamming. Furthermore, the nulling scheme, one of the various anti-jamming approaches, is investigated, in which unwanted jamming signals are eliminated in the frequency domain after passing through the analysis part of the polyphase filter bank. The performance of the nulling scheme is evaluated for tone jamming and partial band jamming in terms of BER and EVM. The simulation results indicate that the nulling scheme improve the BER and EVM performance over the case without any anti-jamming approach.