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Although Orthogonal Frequency Division Multiplexing (OFDM) technology has been widely used in LTE and other systems, the problem of large band leakage caused by the Doppler effect restricts the further improvement of performance when the user moves at high speed. The Filter bank based multi-carrier (FBMC) technology is one of the effective techniques which could replace OFDM in 5G communication systems...
For digital terrestrial television broadcasting (DT-TB) systems, orthogonal frequency division multiplexing (OFDM) technique is considered to be an effective method to combat the frequency selective channel cause by multi-path effect. In the single frequency network (SFN) scenario, Alamouti space frequency block coding (SFBC) is introduced to provide spatial diversity gain and improve the link stability...
Inter-carrier interference (ICI) caused by time-variant multi-path channels degrades the performance of orthogonal frequency division multiplexing (OFDM) based digital terrestrial television broadcasting systems, especially for large number of sub-carriers and high speed mobile reception. In this paper, we propose an minimum mean square error (MMSE) based equalization and ICI mitigation scheme for...
We investigated the adaptive power allocation in an point-to-point orthogonal frequency Division multiplexing (OFDM) cooperative system subject to the individual power constraint with an objective of maximize the sum transmission rate, and derived the optimal power allocation by assuming independent and identically distributed (i.i.d.) sub-channels in each Decode-and-Forward (DF) relay. To improve...
Orthogonal frequency division multiplexing (OFDM) is one of the key technologies adopted in modern communication systems. However, it suffers from high peak-to-average power ratio (PAPR) problem, which limits the efficiency of the power amplifier (PA). This paper presents a novel PAPR reduction method for amplitude phase shift keying (APSK) modulation. The amplitude of the transmit signal in time...
Time domain synchronous OFDM (TDS-OFDM) has higher spectral efficiency than cyclic prefix OFDM (CP-OFDM), but suffers from severe performance loss over fast fading channels. In this paper, a novel transmission scheme called time-frequency training OFDM (TFT-OFDM) is proposed. The time-frequency joint channel estimation for TFT-OFDM utilizes the time-domain training sequence without interference cancellation...
this paper proposed a time and frequency synchronization algorithm for LTE-TDD (Long Term Evolution-Time Division Duplex) system downlink, which can provide accurate symbol timing synchronization and frequency synchronization for UE (User Equipment). We introduce a simplified ML (Maximum Likelihood) algorithm and present a method using PSS (Primary Synchronization Signal) in wireless frame to get...
To reduce the complexity of existing transmit diversity solutions for time domain synchronous OFDM (TDS-OFDM), a simple transmit diversity scheme is proposed in this paper. The space shifted constant amplitude zero autocorrelation (CAZAC) sequence is used for time-domain channel estimation. Two types of flexible frame structures are investigated for cyclicity reconstruction of the received inverse...
Time domain synchronous OFDM (TDS-OFDM) with higher spectral efficiency than cyclic prefix OFDM (CP-OFDM)was originally proposed for downlink broadcasting transmission. To support multi-user uplink scenarios, this paper proposes a novel multiple access scheme called time domain synchronous frequency division multiple access (TDS-FDMA), wherein an uniform frame structure and its corresponding receiver...
The existing transmit diversity schemes for time domain synchronous OFDM (TDS-OFDM) is only suitable either for fast time-varying but weakly frequency-selective channels, or strongly frequency-selective but slow fading channels. In this paper, the space-time shifted constant amplitude zero autocorrelation (CAZAC) sequence based TDS-OFDM transmit diversity scheme is proposed for doubly selective channels...
The digital television terrestrial broadcasting (DTTB) system is a promising candidate for positioning due to the high power level and wide coverage of DTTB signals. This paper proposes a positioning scheme for Chinese DTTB system whose key technology is time domain synchronous OFDM (TDS-OFDM). The transmission parameter signaling (TPS) embedded in TDS-OFDM signals are firstly regarded as pilots,...
This paper illustrates some key features for future Chinese digital television terrestrial broadcasting (DTTB) systems including newly proposed frame structure, preamble design, multi-service support, transmit diversity, time-frequency positioning and etc.
In view of the new feature after introducing the relay nodes (RNs) into the conventional cellular networks, a novel soft frequency reuse (SFR)-based inter-cell interference coordination (ICIC) scheme is proposed in the relay enhanced cellular networks. On the basis of original ICIC scheme for conventional cellular network, RNs in the proposed SFR scheme reuses part of neighboring cell-edge bands to...
Compared with the global positioning system (GPS), the digital television (DTV) broadcasting signal is a promising candidate for position location due to low implementation cost and strong signal reception. Without changing the current infrastructure of the Chinese DTV broadcasting network, this paper proposes a novel positioning scheme using the multi-carrier pseudo-noise (PN-MC) training sequence...
To improve the system capacity of conventional orthogonal frequency division multiplexing (OFDM) systems, the layered modulation OFDM scheme is proposed. The modulated OFDM symbols are separated into two layers as differential modulated symbols and coherent symbols. The differential symbols are used as pilots, which are combined with the coherent modulated data and sent out by the transmitter. At...
In this paper, a simple and effective synchronization scheme for NC-OFDM systems is proposed. To keep the autocorrelation in the scenario of subcarriers deficiency, the preamble is consists of two identical pseudo-noise (PN) sequences instead of ZC sequences. Coarse timing estimation and fractional CFO(carrier frequency offset) estimation are completed according to the correlation between the received...
Carrier Interferometry Orthogonal frequency division multiplexing (CI/OFDM) has gained a great deal of attention recently because of its good bit error rate (BER) and low peak-to-average power ratio (PAPR) performance. In this paper, we investigate the performance of CI/OFDM based on a new implementation model for both zero forcing (ZF) and minimum mean square error (MMSE) equalization. We further...
Cognitive radio has been seen as a promising technique to address the frequency resource scarcity problem. It is a key issue to reliably detect the activity of primary users' (PUs) for cognitive radio users. As orthogonal frequency division multiplexing (OFDM) has becoming a popular technique for modern wireless communications systems. It is necessary to identify the existence and estimate the key...
In orthogonal frequency division multiplexing (OFDM) systems, the estimated channel impulse response (CIR) can be recovered by transforming the initial channel frequency response (CFR) to time domain. The CIR is preferred to be filtered before transforming to frequency domain and using as accurate CFR. In orthogonal frequency division multiplexing access (OFDMA) systems, subcarriers are allocated...
Time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) outperforms cyclic prefixed-OFDM (CP-OFDM) in spectrum efficiency at the expense of higher complexity. Up to now, TDS-OFDM has only been used in unidirectional transmission, such as broadcasting applications. The overwhelming complexity of removing the implicitly superposed interferences between the PN sequences and IDFT...
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