A differential modulation scheme using space-time block codes is put forward. Compared with other schemes, our scheme has lower computational complexity and has a simpler decoder. In the case of three or four transmit...A differential modulation scheme using space-time block codes is put forward. Compared with other schemes, our scheme has lower computational complexity and has a simpler decoder. In the case of three or four transmitter antennas, our scheme has a higher rate a higher coding gain and a lower bit error rate for a given rate. Then we made simulations for space-time block codes as well as group codes in the case of two, three, four and five transmit antennas. The simulations prove that using two transmit antennas, one receive antenna and code rate of 4 bits/s/Hz, the differential STBC method outperform the differential group codes method by 4 dB. Useing three, four and five transmit antennas, one receive antenna, and code rate of 3 bits/s/Hz are adopted, the differential STBC method outperform the differential group codes method by 5 dB, 6. 5 dB and 7 dB, respectively. In other words, the differential modulation scheme based on space-time block code is better than the corresponding differential modulation scheme展开更多
It is generally known that the solutions of deterministic and stochastic differential equations （SDEs） usually grow linearly at such a rate that they may become unbounded after a small lapse of time and may eventual...It is generally known that the solutions of deterministic and stochastic differential equations （SDEs） usually grow linearly at such a rate that they may become unbounded after a small lapse of time and may eventually blow up or explode in finite time. If the drift and diffusion functions are globally Lipschitz, linear growth may still be experienced, as well as a possible blow-up of solutions in finite time. In this paper, a nonlinear scalar delay differential equation with a constant time lag is perturbed by a multiplicative Ito-type time - space white noise to form a stochastic Fokker-Planck delay differential equation. It is established that no explosion is possible in the presence of any intrinsically slow time - space white noise of Ito - type as manifested in the resulting stochastic Fokker- Planck delay differential equation. Time - space white noise has a role to play since the solution of the classical nonlinear equation without it still exhibits explosion.展开更多
By introducing a space-time coding scheme based on amicable orthogonality, we develop a distributed differential space-time coding scheme with the amplify-and-forward （AF） method for wireless cooperative networks. T...By introducing a space-time coding scheme based on amicable orthogonality, we develop a distributed differential space-time coding scheme with the amplify-and-forward （AF） method for wireless cooperative networks. The scheme requires no knowledge of the channel state information at both transmitters and receivers, and effectively decreases the realization complexity due to no channel estimation. Moreover, it has lower decoding complexity and higher coding advantage than the existing scheme, thus avoiding the shortcoming of exponential decoding complexity of some existing schemes. According to the pairwise error probability （PEP） analysis of the system, the power allocations of source and relay terminals are jointly optimized, and as a result, the PEP is minimized, which will provide a helpful guideline for system design. Numerical calculation and simulation results show that the developed scheme is superior to the existing scheme. Moreover, the scheme with optimal power allocation yields obvious performance improvement over that with equal power allocation.展开更多
MIMO technology proposed in recent years can effectively combat the multipath fading of wireless channel and can considerably enlarge the channel capacity, which has been investigated widely by researchers. However, i...MIMO technology proposed in recent years can effectively combat the multipath fading of wireless channel and can considerably enlarge the channel capacity, which has been investigated widely by researchers. However, its performance analysis over correlated block-fading Rayleigh channel is still an open and challenging objective. In this article, an analytic expression of bit error rate （BER） is presented for multiple phase shift keying （MPSK） space-time code, with differential detection over correlated block-fading Rayleigh channel. Through theoretical analysis of BER, it can be found that the differential space-time scheme without the need for channel state information （CSI） at receiver achieves distinct performance gain compared with the traditional nonspace-time system. And then, the system simulation is complimented to verify the above result, showing that the diversity system based on the differential space-time block coding （DSTBC） outperforms the traditional nonspacetime system with diversity gain in terms of BER. Furthermore, the numerical results also demonstrate that the error floor of the differential space-time system is much lower than that of the differential nonspace-time system.展开更多
A new differential space-time code, called differential space-time block-diagonal code （DSTBDC）, is proposed for multiple-input multiple-output （MIMO） wireless communication systems. By exploiting the block-diagon...A new differential space-time code, called differential space-time block-diagonal code （DSTBDC）, is proposed for multiple-input multiple-output （MIMO） wireless communication systems. By exploiting the block-diagonal construction of DSTBDC, we can design a variety of high-performance DSTBDC, especially for the cases of large numbers of transmit antennas and high date rates. In flat fading channels, DSTBDC outperforms traditional differential space-time codes if the data rate is higher than 1 bps/Hz, especially when the number of transmit antennas is large. In frequency-selective fading channels, multiple-input multiple-output orthogonal frequency-division multiplexing （MIMO-OFDM） systems using DSTBDC have the powerful ability to achieve very high diversity gain in space, time, and frequency simultaneously. Due to the special orthogonal construction, DSTBDC has a simple decoding algorithm. In addition, DSTBDC can significantly save the cost of radio frequency circuits.展开更多
Fully diverse unitary space-time codes are useful in multiantenna communications, especially in multiantenna differential modulation. Recently, two constructions of parametric fully diverse unitary space-time codes fo...Fully diverse unitary space-time codes are useful in multiantenna communications, especially in multiantenna differential modulation. Recently, two constructions of parametric fully diverse unitary space-time codes for three antennas system have been introduced. We propose a new construction method based on the constructions. In the present paper, fully diverse codes for systems of odd prime number antennas are obtained from this construction. Space-time codes from present construction are found to have better error performance than many best known ones.展开更多
正交频分复用技术可以有效的消除信号符号间干扰并具有较高的频带利用率。空时分组码可以弥补正交频分复用技术对移动造成的多普勒频移比较敏感的缺陷,所以这两种技术的结合在下一代无线通信中的应用引起了越来越多的关注。本文研究了DS...正交频分复用技术可以有效的消除信号符号间干扰并具有较高的频带利用率。空时分组码可以弥补正交频分复用技术对移动造成的多普勒频移比较敏感的缺陷,所以这两种技术的结合在下一代无线通信中的应用引起了越来越多的关注。本文研究了DSTBC(D ifferential Space-Tim e B lockCodes,差分空时分组编码)和OFDM(O rthogonal Frequency D ivisionMu ltip lexing,正交频分复用)技术相结合的系统收发机结构。由于接收端不需要进行信道估计,可大大简化接收机复杂度。通过仿真给出了DSTBC-OFDM系统与STBC-OFDM系统及纯OFDM系统在Rayle igh衰落信道及SUI信道下的比特差错性能。通过比较可看出,在静止情况下或中速移动但信道条件较好的情况下,DST-BC-OFDM系统可作为STBC-OFDM系统的替代。展开更多
基金This project was supported by the National Natural Science Foundation of China (60172018) .
文摘A differential modulation scheme using space-time block codes is put forward. Compared with other schemes, our scheme has lower computational complexity and has a simpler decoder. In the case of three or four transmitter antennas, our scheme has a higher rate a higher coding gain and a lower bit error rate for a given rate. Then we made simulations for space-time block codes as well as group codes in the case of two, three, four and five transmit antennas. The simulations prove that using two transmit antennas, one receive antenna and code rate of 4 bits/s/Hz, the differential STBC method outperform the differential group codes method by 4 dB. Useing three, four and five transmit antennas, one receive antenna, and code rate of 3 bits/s/Hz are adopted, the differential STBC method outperform the differential group codes method by 5 dB, 6. 5 dB and 7 dB, respectively. In other words, the differential modulation scheme based on space-time block code is better than the corresponding differential modulation scheme
文摘It is generally known that the solutions of deterministic and stochastic differential equations （SDEs） usually grow linearly at such a rate that they may become unbounded after a small lapse of time and may eventually blow up or explode in finite time. If the drift and diffusion functions are globally Lipschitz, linear growth may still be experienced, as well as a possible blow-up of solutions in finite time. In this paper, a nonlinear scalar delay differential equation with a constant time lag is perturbed by a multiplicative Ito-type time - space white noise to form a stochastic Fokker-Planck delay differential equation. It is established that no explosion is possible in the presence of any intrinsically slow time - space white noise of Ito - type as manifested in the resulting stochastic Fokker- Planck delay differential equation. Time - space white noise has a role to play since the solution of the classical nonlinear equation without it still exhibits explosion.
基金Supported partially by the China Postdoctoral Science Foundation (Grant No. 2005038242)the startup fund of Nanjing University of Aeronautics and Astronautics (Grant No. S0855-041)
文摘By introducing a space-time coding scheme based on amicable orthogonality, we develop a distributed differential space-time coding scheme with the amplify-and-forward （AF） method for wireless cooperative networks. The scheme requires no knowledge of the channel state information at both transmitters and receivers, and effectively decreases the realization complexity due to no channel estimation. Moreover, it has lower decoding complexity and higher coding advantage than the existing scheme, thus avoiding the shortcoming of exponential decoding complexity of some existing schemes. According to the pairwise error probability （PEP） analysis of the system, the power allocations of source and relay terminals are jointly optimized, and as a result, the PEP is minimized, which will provide a helpful guideline for system design. Numerical calculation and simulation results show that the developed scheme is superior to the existing scheme. Moreover, the scheme with optimal power allocation yields obvious performance improvement over that with equal power allocation.
文摘MIMO technology proposed in recent years can effectively combat the multipath fading of wireless channel and can considerably enlarge the channel capacity, which has been investigated widely by researchers. However, its performance analysis over correlated block-fading Rayleigh channel is still an open and challenging objective. In this article, an analytic expression of bit error rate （BER） is presented for multiple phase shift keying （MPSK） space-time code, with differential detection over correlated block-fading Rayleigh channel. Through theoretical analysis of BER, it can be found that the differential space-time scheme without the need for channel state information （CSI） at receiver achieves distinct performance gain compared with the traditional nonspace-time system. And then, the system simulation is complimented to verify the above result, showing that the diversity system based on the differential space-time block coding （DSTBC） outperforms the traditional nonspacetime system with diversity gain in terms of BER. Furthermore, the numerical results also demonstrate that the error floor of the differential space-time system is much lower than that of the differential nonspace-time system.
基金Supported by the National 863 Program of China (Grant No. 2003AA12331004)
文摘A new differential space-time code, called differential space-time block-diagonal code （DSTBDC）, is proposed for multiple-input multiple-output （MIMO） wireless communication systems. By exploiting the block-diagonal construction of DSTBDC, we can design a variety of high-performance DSTBDC, especially for the cases of large numbers of transmit antennas and high date rates. In flat fading channels, DSTBDC outperforms traditional differential space-time codes if the data rate is higher than 1 bps/Hz, especially when the number of transmit antennas is large. In frequency-selective fading channels, multiple-input multiple-output orthogonal frequency-division multiplexing （MIMO-OFDM） systems using DSTBDC have the powerful ability to achieve very high diversity gain in space, time, and frequency simultaneously. Due to the special orthogonal construction, DSTBDC has a simple decoding algorithm. In addition, DSTBDC can significantly save the cost of radio frequency circuits.
基金supported by National Natural Science Foundation of China (Grant No. 60673074)
文摘Fully diverse unitary space-time codes are useful in multiantenna communications, especially in multiantenna differential modulation. Recently, two constructions of parametric fully diverse unitary space-time codes for three antennas system have been introduced. We propose a new construction method based on the constructions. In the present paper, fully diverse codes for systems of odd prime number antennas are obtained from this construction. Space-time codes from present construction are found to have better error performance than many best known ones.
文摘正交频分复用技术可以有效的消除信号符号间干扰并具有较高的频带利用率。空时分组码可以弥补正交频分复用技术对移动造成的多普勒频移比较敏感的缺陷,所以这两种技术的结合在下一代无线通信中的应用引起了越来越多的关注。本文研究了DSTBC(D ifferential Space-Tim e B lockCodes,差分空时分组编码)和OFDM(O rthogonal Frequency D ivisionMu ltip lexing,正交频分复用)技术相结合的系统收发机结构。由于接收端不需要进行信道估计,可大大简化接收机复杂度。通过仿真给出了DSTBC-OFDM系统与STBC-OFDM系统及纯OFDM系统在Rayle igh衰落信道及SUI信道下的比特差错性能。通过比较可看出,在静止情况下或中速移动但信道条件较好的情况下,DST-BC-OFDM系统可作为STBC-OFDM系统的替代。
