53,205 research outputs found
Latest Results on and at high
Recent progress from Jefferson Lab has significantly improved our
understanding of the nucleon spin structure in the high- region. Results of
a precision measurement of the neutron spin asymmetry, , in the high-
(valence quark) region are discussed. The up and down quark spin distributions
in the nucleon were extracted. was also measured. The results were
used, in combination with existing data, to extract the second moment, .
Preliminary results on and in the high- region have also
become available. Finally, the results of a precision measurement of the
structure function to study higher twist effects will be presented.Comment: 4 pages, 2 figures, to appear in the DIS2005 Proceedings (AIP
Optimal Power Allocation for A Massive MIMO Relay Aided Secure Communication
In this paper, we address the problem of optimal power allocation at the
relay in two-hop secure communications under practical conditions. To guarantee
secure communication during the long-distance transmission, the massive MIMO
(M-MIMO) relaying techniques are explored to significantly enhance wireless
security. The focus of this paper is on the analysis and design of optimal
power assignment for a decode-and-forward (DF) M-MIMO relay, so as to maximize
the secrecy outage capacity and minimize the interception probability,
respectively. Our study reveals the condition for a nonnegative the secrecy
outage capacity, obtains closed-form expressions for optimal power, and
presents the asymptotic characteristics of secrecy performance. Finally,
simulation results validate the effectiveness of the proposed schemes
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