Showing papers on "Cyclic delay diversity published in 2010"

Method for compensating for frequency attenuation using adaptive cyclic delay diversity, and transmitting apparatus and method and receiving apparatus and method using same

Abstract: The present invention provides a coordinated multipoint transmitting/receiving method using adaptive cyclic delay diversity, a system side apparatus and a receiving apparatus using same, and a method for determining a coordinated base station set, which improve channel performance for a specific frequency band of a specific base station, which requires a coordinated multipoint transmission/reception system (CoMP) using an adaptive cyclic delay diversity (CDD), to thereby enable the relevant base station to be included in the coordinated base station set.

PAPR Analysis for Single-Carrier FDMA MIMO Systems with Space-Time/Frequency Block Codes

Abstract: SC-FDMA(Single carrier-Frequency Division Multiple Access) with lower PAPR(Peak-to-Average Power Ratio) than OFDMA (Orthogonal Frequency Division Multiple Access) has drawn great attention as an attractive alternative to OFDMA. MIMO (Multiple-Input Multiple-Output) can also be extended to SC-FDMA system for uplink transmission so long as the low PAPR is preserved. In this paper we demonstrate and numerically analyze the PAPR characteristics of STBC/SFBC (Space-time block code/Space-frequency block code) SC-FDMA MIMO system for different mapping methods. A scheme of STBC/SFBC SC-FDMA with cyclic delay diversity (CDD) is proposed theoretically. Results reported in this paper show that IFDMA(Interleaved FDMA) has the best PAPR characteristics, LFDMA(Localized FDMA) is the worst but still better than that of OFDMA in STBC/SFBC SC-FDMA MIMO system. We also find that the PAPR increases along with the increase of DFT input block size in such a system.

Coordinated multipoint transmitting/receiving method using adaptive cyclic delay diversity, system side apparatus and receiving apparatus using same, and method for determining a coordinated base station set

Abstract: Disclosed is a coordinated multi-point transmitting/receiving method using adaptive cyclic delay diversity, a system side apparatus and a receiving apparatus using the same, and a method for determining a coordinated base station set, which can cause a particular base station to have a good channel performance in a particular frequency band, which requires coordinated multi-point transmission/reception, by using adaptive cyclic delay diversity (CDD), so as to include the relevant base station in a coordinated base station set.

Selective Random Cyclic Delay Diversity for HARQ in Cooperative Relay

Abstract: In the next generation cellular system, relay has been considered to increase coverage extension and cell-edge throughput. Cooperative relay can provide transmission diversity gain to improve outage probability, overall throughput and energy efficiency. Cooperative beamforming has been considered as one of the cooperative relay if the relay nodes can get the feedback information from the destination. In this paper, a new cooperative relay scheme is proposed for hop-by-hop HARQ in cooperative relay. The scheme is to adopt selective random cyclic delay diversity (CDD) to the retransmission in HARQ, which can get rid of the relative bad relay nodes and form a better frequency selective channel to exploit diversity gain when channel coding is used. Performance evaluation and analysis have shown that the selective random CDD can achieve higher throughput and lower transmission delay than the conventional cooperative beamforming.

Phase-Shift Cyclic-Delay Diversity for MIMO OFDM Systems

Abstract: Phase-shift cyclic-delay diversity (PS CDD) scheme and space-frequency-block-code (SFBC) PS CDD are developed for multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The proposed PS CDD scheme preserves the diversity advantage of traditional CDD in uncorrelated multiantenna channels, and furthermore removes frequency-selective nulling problem of the traditional CDD in correlated multiantenna channels.

Apparatus and method for supporting multiple-input multiple-output and beamforming simultaneously in wireless communication system

Abstract: An apparatus and a method for simultaneously supporting Multiple-Input Multiple-Output (MIMO) and beamforming in a wireless communication system are provided In the method, two data streams are mapped to each of all of 2N transmission antennas; the two data streams are multiplied by different Cyclic Delay Diversity (CDD) phase sequences; the two data streams multiplied by the different CDD phase sequences for each transmission antenna are added; and the added data stream is multiplied by a beamforming coefficient and transmitted for each transmission antenna

Transmitting and receiving apparatuses and methods using a differential cyclic delay diversity mimo scheme

Abstract: Disclosed are a transmitting/receiving apparatus and method using a differential cyclic delay diversity MIMO scheme.

Selection of a Subset of Antennas for Transmission

Abstract: A method and apparatus of a subscriber station selecting a subset of a plurality of antennas for uplink transmission are disclosed. One method includes a base station transmitting a cyclic delay diversity transmission signal. The subscriber station receives the cyclic delay diversity transmission signal through the plurality of antennas. The subscriber station selects a subset of the plurality of antennas based on a received quality signal parameter. The subscriber station transmits uplink signals to the base station through the selected subset of the plurality of antennas.

Pilot Subset Partitioning Based Integer Frequency Offset Estimation for OFDM Systems With Cyclic Delay Diversity

Abstract: Cyclic delay diversity (CDD) is a simple transmit diversity technique for coded OFDM systems with multiple transmit antennas. However, high frequency selectivity caused by CDD degrades the performance of post- FFT estimation, i.e., integer frequency offset (IFO). This paper suggests a simple way of improving the performance of the IFO estimator based on the pilot subset partitioning which is designed to reduce the effect of frequency selective fading by adopting the CDD. By partitioning uncorrelated pilot subcarriers into subsets to satisfy high correlation, and performing frequency estimation for each pilot subset, a robust IFO estimation scheme is derived. The simulation results show that the proposed method can provide benefit to the overall system performance .

Statistical distributions that arise in constrained beamforming with incomplete channel information

Abstract: We examine the statistical distribution of received power when a subscriber terminal with multiple transmit antennas beamforms on the uplink of a wireless orthogonal frequency-division multiplexing system to a basestation with multiple receive antennas. We assume that a time-division duplex terminal has incomplete uplink channel knowledge obtained by measuring the downlink channel during basestation transmissions. The basestation transmissions employ cyclic delay diversity, of which the terminal is unaware. The distribution of uplink power received at the basestation, with and without downlink cyclic delay diversity and with various types of power constraints at the terminal, allow us to make some surprising conclusions about how the power constraints and cyclic delay influence the performance of beamforming. We show that beamforming gains need to be examined critically beyond simple average performance metrics to conclude that they are superior to simpler channel-unaware methods. We also conclude that cyclic delay on the downlink is very beneficial to beamforming on the uplink, even with restrictive types of power constraints.

Data processing method and receiving /sending apparatus for communication system employing cyclic delay diversity and equalization based on energy spreading transform

Abstract: PURPOSE: A data processing method for a communication system in which CDD(Cyclid Delay Diversity) technique and EST(Energy Spreading Transform) based equalization technique is applied, and a transmitting device and a receiving device thereof are provided to more efficiently transceive a signal. CONSTITUTION: A receiving side control unit(140) calculates interference and noises per signal of the received signal. The receiving side control unit determines an index for determining a delay value for each antenna considering the calculated result. A receiving side transmitting unit(164) transmits the determined index to a transmission side. The receiving side control unit calculates a maximum value among possible values of the interference and noises per signal of the received signal. The receiving side control unit determines the index considering the maximum value.

STCDD Cooperative Transmission Scheme for Improvement of Reliability in OFDM Based UWB System

Abstract: Recently, the multi-band orthogonal frequency division multiplexing(MB-OFDM) system, one of UWB system, can satisfy the requirement and can be applied to various wireless communication services because ultra-wideband(UWB) is a wireless communication technique that supports high data rate with low power In this paper, the method applying Alamouti's space time block code(STBC) and cyclic delay diversity(CDD) is proposed The proposed method can be easily applied with arbitrary number of relays and only needs two time slots of quasi stationary assumption And it is applied to the MB-OFDM system Second, an optimal relaying scheme based on decode-and-forward(DF) method is proposed which is provides good error performance compared to conventional schemes

Performance Comparison of Distributed Cooperative STBC and CDD MC-CDMA Multi-Hop Relaying Systems

Abstract: The performance of multi-hop multiple-input, multiple-output (MIMO) communication scenarios is evaluated for space time block coded (STBC) and the proposed distributed cyclic delay diversity (CDD) technique. By increasing the frequency selectivity, multi-stage CDD with low complexity implementation yields significant performance improvement as relaying network. Both diversity techniques based on frequency-correlated MC-CDMA subcarriers networks are investigated by using the moment generating function (MGF) over correlated Nakagami-m fading channels .The system performance evaluation is provided for the exact average symbol error rate (SER) and the end-to-end bit error rate (BER). In order to maximize the end-to-end throughput [bits/s/Hz], explicit allocations strategies are derived and analyzed. Simulation results are also presented which show excellent agreement with the analytical framework

Pilot-aided channel estimation for CDD-OFDM systems

Abstract: Cyclic delay diversity (CDD) is a low-complexity transmit diversity technique for coded orthogonal frequency division multiplexing (OFDM), which transforms a multiple-input channel into an equivalent single-input channel with increased frequency selectivity and provides additional frequency diversity. However, it makes channel estimation more difficult due to the increased frequency selectivity. In this paper, focusing on the direct estimation of the equivalent single-input channel for CDD-OFDM systems, a cyclic cross-correlation channel estimation method based on the equispaced constant-modulus pilot structure is first proposed. Using the statistical parameters of the channel and noise derived by the cyclic cross-correlation channel estimation, an improved channel estimation method based on the Wiener filter is proposed to reduce the estimation error further. Lastly, computation simulations are given to demonstrate the effectiveness of two proposed channel estimation methods for CDD-OFDM systems.

Cooperative Coding Using Cyclic Delay Diversity for OFDM Systems

Abstract: This paper proposes cooperative coding using cyclic delay diversity (CDD) for OFDM systems The cooperative diversity is combined with channel coding while CDD is applied to the cooperative transmission of the multiple relays to improve the beneficial effects of the cooperating relays Analyses of frame error probability (FEP) and the average channel power of the proposed scheme are shown Simulation results show the frame error rate (FER) of the proposed scheme The proposed scheme provides not only a simple code design and low system complexity compared to conventional space-time processing, but better FER and diversity gain compared to direct transmission and conventional cooperative coding without CDD

Method for coordinated multi-point transmission/reception using adaptive cyclic delay diversity, system-side apparatus and receiving apparatus using the same, and method for determining coordinated multiple transmission points set using the same

Abstract: PURPOSE: A multipoint cooperation type transceiving method, a system side device, a receiving device and a cooperation type base station set decision method using adaptive round trip delay diversity are provided to perform the adaptive round trip delay about the specific antenna. CONSTITUTION: A system side device receives feedback information which the specific frequency band information, the delay object antenna information and adaptive cyclic delay are included and the channel response information about each base station from a receiving device(S710-5). The system side device determines a coordinated base station set capable of transceiving multipoint cooperation type based on the channel response information and the feedback information(S720). The system side device transmits a signal which delayed as much as the adaptive round trip delay value about a delay object antenna in the base station which the frequency attenuation compensation is necessary among the base stations included in the base station set(S730).

On the Performance of Hybrid Stacked Cyclic Delay Diversity Schemes in MIMO-OFDM

Abstract: In this paper, a new hybrid stacked cyclic delay diversity (HSCDD) scheme is proposed for the multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems to flexibly maximize the tradeoff between multiplexing and diversity gains. Unlike the existing double space time transmit diversity (DSTTD) and the stacked cyclic delay diversity (SCDD) schemes which are suitable for the integer multiplexing rate, the proposed HSCDD scheme can achieve arbitrary number of multiplexing rate. Another advantage of the proposed HSCDD scheme over the DSTTD and the stacked CDD schemes is the flexibility in selecting the required number of transmit antennas. With this provided flexibility, the HSCDD can optimize the tradeoff between diversity and multiplexing gains to match the user's requirements.

A Cascaded Wireless System of SCCP and FMT with Cyclic Delay Diversity

Abstract: In this paper, a novel wireless transmission system is proposed. The system is composed of two cascaded subsystem: an inner filtered multitone (FMT) modulator with transmission over multiple antennas, and an outer Single carrier cyclic prefix (SCCP) system. The FMT modulator can efficiently avoid the inter-carrier interference, and with multiple antennas the cyclic delay diversity (CDD) can increase frequency-selectivity by inserting virtual echoes into the effective channel, and thus enhances the diversity of the system. The SCCP subsystem copes with the residual subchannel intersymbol interference. Simulation results show that the BER performance of proposed system is better than DMT-FMT system, and more suitable for the uplink Multiple-Access Channel.

Determination of cyclic delay for CDD utilizing RMS delay spread in OFDMA multiuser scheduling systems

Abstract: The multiuser diversity gain increases with the degree and dynamic range of channel fluctuations For a multi-antenna orthogonal frequency division multiplexing (OFDM) system operating in a channel with limited fluctuations, cyclic delay diversity (CDD) was proposed to increase frequency selectivity This is achieved by introducing a cyclic delay between the different transmit antennas thereby increasing the effective number of paths in the resulting channel In this paper, for a multiuser system, we propose a scheme to determine peruser optimal cyclic delay value based on the knowledge of the root-mean-square (RMS) delay spread of the channel We show that the proposed technique achieves better performance than a conventional fixed cyclic delay scheme and that the throughput is very close to the optimal sum rate possible with CDD

Space frequency block coding with grouped phase rotation for asymmetric MIMO-OFDM system

Abstract: To improve quality of wireless communication, transmit/receive diversity techniques in multiple-input multiple-output (MIMO) system have been investigated vigorously. In this paper, we consider an asymmetric MIMO orthogonal frequency division multiplexing (MIMO-OFDM) system in the case of high speed mobility for frequency-selective fading channel. For conventional schemes, e.g., cyclic delay diversity (CDD), space-time/space-frequency block coding (STBC/SFBC), and quasi orthogonal STBC/SFBC (QOSTBC/QOSFBC), it is difficult to obtain high channel quality while keeping high data rate and low computational complexity of demodulation in asymmetric MIMO-OFDM system. Therefore, in this paper, we propose a joint use of SFBC and grouped phase rotation (GPR), and evaluate the average bit error rate (BER) performances by computer simulation.

Method and system for switching between beam forming and cyclic delay diversity

Abstract: A method and system for switching between beam forming and cyclic delay diversity are provided in the present invention. The method includes that a data transmission mode adapted to the current receiver is selected from multi-antenna data transmission modes according to a switch algorithm in a decision period, wherein, the multi-antenna data transmission modes include beam forming and cyclic delay diversity; the selected data transmission mode is used to transmit data. The present invention maximizes the system performance.

Residual symbol timing offset estimation for DRM+ system with cyclic delay diversity

Abstract: In this study, we propose an enhanced residual symbol timing offset(STO) estimation scheme in an orthogonal frequency division multiplexing (OFDM) based digital radio mondiale plus (DRM+) system with cyclic delay diversity (CDD). By proper selection of the amount of cyclic delay and pilot subset partitioning, a robust and low-cost residual STO estimator is derived. By computer simulation, the proposed estimator is shown to benefit from properly designed delay parameter and pilot subsets.

Relationships between Diversity Techniques and Channel Coding Rates for OFDM Systems

Abstract: This paper addresses the relationships between diversity techniques and channel coding rates for OFDM systems. While a low channel coding rates is required if cyclic delay diversity is applied, the necessity of a low channel coding rate is alleviated with space time block coding.

Method for compensating frequency attenuation using adaptive cyclic delay diversity, transmitting apparatus and method using the same, and receiving apparatus and method using the same

Abstract: PURPOSE: A frequency attenuation compensation method using the adaptive round trip delay diversity, a transmission device, a method, a receiving device and a method thereof are provided to recompense the frequency attenuation of the specific frequency band. CONSTITUTION: A receiving device searches the specific frequency band recompensing the frequency attenuation through phase difference correction(S520). The receiving device selects a delay object antenna recompensing the frequency attenuation of the specific frequency band(S530). The receiving device calculates the adaptive cyclic delay value using the searched specific frequency band and the presumed reference signal(S540). The receiving device transmits the calculated adaptive round trip delay value and the delay object antenna information to a transmission device(S550). The receiving device receives the signal which is delayed as much as the adaptive round trip delay value about the delay object antenna from the transmission device(S560).

Timing synchronization for IEEE 802.11a-based non-regenerative wireless relay networks

Abstract: This paper addresses the problem of timing synchronization at the destination node of a non-regenerative wireless relay network which employs the IEEE 802.11a standard for data transmission. The two-hop relay network consists of an IEEE 802.11a-compliant source and destination pair, each equipped with a single antenna, aided by a relay node equipped with two antennas, which operate in half-duplex mode. The source-to-relay link remains a point-to-point system and perfect timing synchronization can be assumed at the relay. The relay performs cyclic prefix (CP) removal and re-insertion operations on the received signal to restore the cyclic structure of the amplified and forwarded signal and also introduces transmit diversity, in the form of cyclic delay diversity (CDD), into the forwarded signal. The maximum likelihood (ML) timing synchronization cost function for the received signal at the destination node of the system is derived to show that the ML solution cannot be implemented in practice due to the high computational complexity involved. The use of correlation-based timing synchronization algorithms is then studied. In addition to the probability of achieving timing synchronization, the packet error rate (PER) performance is used as an additional measure of the performance of the different timing synchronization algorithms. It is seen that the use of a correlation-based timing synchronization algorithm does not result in significant PER performance loss compared to the PER achieved by ML methods. In addition, the introduction of CDD in the forwarded signal, which is transparent to the destination node, is shown to achieve an improvement in the PER performance over a relay which performs conventional amplify-and-forward (A & F) relaying.

A Full Transmit Diversity Using Cyclic Delay Diversity for EST Based Modulation

Abstract: This letter proposes a transmit-diversity scheme using cyclic delay diversity (CDD) and energy spreading transform (EST) based modulation. It achieves full diversity over frequency-selective fading channels as well as flat fading channels for any number of transmit and receive antennas at a rate of one symbol per channel use. Its performance is shown by simulation to be considerably better than the previous full transmit-diversity techniques and approaches the performance bound when the diversity order of the system is sufficiently large.

Method and device for sending data

Abstract: A method and a device for sending data are provided. The method comprises: determining a data sending mode suitable for a receiving terminal from the Beam forming BF mode and the Spatial Diversity Cyclic Delay Diversity SD+CDD mode based on channel state information (S402); and sending the data to the receiving terminal using the determined data sending mode (S404).

Diversity strategies for MIMO communication systems

Abstract: This thesis proposes a joint spatial diversity scheme in MIMO systems in order to improve the transmission reliability of the wireless links, thereby to extend the transmission range and increase the information throughput. Cyclic delay diversity (CDD) and antenna selection are employed here for their low complexity, high flexibility, no spectrum efficiency reduction and high compatibility with many existing standards. A bit error performance bound for CDD system with orthogonal frequency division multiplexing and convolutional coding in multipath Rayleigh fading channel is generated, which renders a fundamental understanding of the mechanism of CDD and can be used instructively for CDD system design. A transmit cyclic delay diversity and receive antenna selection (TCDD/RAS) system is proposed here to achieve a performance gain with lower additional complexity and no data rate reduction compared with a transmit orthogonal space-time block coding (OSTBC) system, which is combined with the optimum receive antenna selection scheme. A hybrid system with both OSTBC and CDD in the transmitter and antenna selection in the receiver is also derived to avoid the high complexity requirement and data rate degradation of the OSTBC system as well as the performance loss of the CDD system. A receive antenna selection criterion for the TCDD/RAS system based on the previous performance analysis results is defined, however it demands high computational complexity. Therefore a much simpler and faster selection rule, named maximum minimum post-processing SNR criterion, is generated for the TCDD/RAS system in flat fading channels and another maximum group minimum post-processing SNR selection principle is developed in frequency selective channels. Both of these two selection rules achieve higher diversity gains with lower additional complexity compared with the traditional norm and capacity selection rules. Two relay systems embedded with the TCDD/RAS scheme are also constructed: the MIMO relay system and the cooperative relay system. The joint diversity scheme in the MIMO relay system obtains a higher diversity gain than in the cooperative relay system. Moreover, these two relay systems could be combined to a system with multiple cooperative relay nodes on which multiple antennas are deployed depending on the practical requirement in the future wireless communication systems.

Method and apparatus for selecting antenna data transmission mode

Abstract: A method and apparatus for selecting an antenna data transmission mode are disclosed in the present invention. In the method, a transmitting end determines the data transmission mode fit for the receiving end from the cyclic delay diversity mode and the spatial multiplexing cyclic delay diversity mode, based on the channel status information; and then the transmitting end transmits data using the determined data transmission mode. By using the technical solution provided in the present invention, the problem that flexibly selecting the data transmission mode as the cyclic delay diversity mode or the spatial multiplexing cyclic delay diversity mode to transmit data according to the system channel condition can not be done due to lack of the solution of selecting the data transmission mode from the cyclic delay diversity mode and the spatial multiplexing cyclic delay diversity mode in the relevant art is solved, and thus the link stability is increased and the system throughput is improved.