The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Persona...The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45 dB at BER of 10 -5.展开更多
We propose a method to determine the solvability of the diophantine equation x^2 - Dy^2 = n for the following two cases：the following two cases：（1） D = pq, where p, q ≡ 1 mod 4 are distinct primes with （q） = 1 ...We propose a method to determine the solvability of the diophantine equation x^2 - Dy^2 = n for the following two cases：the following two cases：（1） D = pq, where p, q ≡ 1 mod 4 are distinct primes with （q） = 1 and p q （p/q（q/p）4 = -1.（2） D = 2p1P2 ... Pro, where Pi ≡ 1 mod 8, 1 ≤ i ≤m are distinct primes and D = r2 ＋s2 with r, s ≡±3 mod 8.展开更多
The linear arboricity la(G) of a graph G is the minimum number of linear forests which partition the edges of G. Akiyama, Exoo and Harary conjectured that la(G) = [△(G)+1/2] for any regular graph G. In this paper, we...The linear arboricity la(G) of a graph G is the minimum number of linear forests which partition the edges of G. Akiyama, Exoo and Harary conjectured that la(G) = [△(G)+1/2] for any regular graph G. In this paper, we prove the conjecture for some composition graphs, in particular, for complete multipartite graphs.展开更多
Let G be a finite group. The degree(vertex) graph Γ(G) attached to G is a character degree graph.Its vertices are the degrees of the nonlinear irreducible complex characters of G, and different vertices m, n are adja...Let G be a finite group. The degree(vertex) graph Γ(G) attached to G is a character degree graph.Its vertices are the degrees of the nonlinear irreducible complex characters of G, and different vertices m, n are adjacent if the greatest common divisor(m, n) > 1. In this paper, we classify all graphs with four vertices that occur as Γ(G) for nonsolvable groups G.展开更多
基金National Natural Science Foundation ofChina( No.6972 5 0 0 1)
文摘The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45 dB at BER of 10 -5.
基金supported by National Natural Science Foundation of China(Grant No.10901150)the Deutsche Forschungsgemeinschaft(Grant No.DE 1646/2-1)
文摘We propose a method to determine the solvability of the diophantine equation x^2 - Dy^2 = n for the following two cases：the following two cases：（1） D = pq, where p, q ≡ 1 mod 4 are distinct primes with （q） = 1 and p q （p/q（q/p）4 = -1.（2） D = 2p1P2 ... Pro, where Pi ≡ 1 mod 8, 1 ≤ i ≤m are distinct primes and D = r2 ＋s2 with r, s ≡±3 mod 8.
基金This work is partially supported by National Natural Science foundation of China Doctoral foundation of the Education Committee of China.
文摘The linear arboricity la(G) of a graph G is the minimum number of linear forests which partition the edges of G. Akiyama, Exoo and Harary conjectured that la(G) = [△(G)+1/2] for any regular graph G. In this paper, we prove the conjecture for some composition graphs, in particular, for complete multipartite graphs.
基金supported by National Natural Science Foundation of China(Grant No.10871032)
文摘Let G be a finite group. The degree(vertex) graph Γ(G) attached to G is a character degree graph.Its vertices are the degrees of the nonlinear irreducible complex characters of G, and different vertices m, n are adjacent if the greatest common divisor(m, n) > 1. In this paper, we classify all graphs with four vertices that occur as Γ(G) for nonsolvable groups G.
