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In this paper two multi-cell interference cancellation (MCIC) schemes are proposed for the TD-SCDMA compatible mobile satellite service (MSS) system, including the parallel scheme and the serial scheme. In the MCIC schemes inter-cell interference is reconstructed and cancelled with the initial data, which is obtained through traditional single-cell joint detection (SCJD). Both intra-cell and inter-cell...
Inter carrier interference (ICI) is deemed as a critical issue in orthogonal frequency division multiple access (OFDMA) systems. Though ICI caused by Doppler spread is negligible in femtocell systems, frequent reception of signals over misaligned subcarriers will introduce severe ICI. Successive interference cancellation and decision feedback equalizers are some of the techniques proposed to mitigate...
The impact of outdated channel state information (CSI) on the performance of variable-rate adaptive M-ary quadrature amplitude modulation (M-QAM) in an amplify-and-forward (AF) opportunistic relaying system over Rayleigh fading channels is analyzed. Closed-form expressions are derived for the average spectral efficiency, outage probability and the average bit error rate under outdated CSI. Using numerical...
This paper proposes resource allocation method for transmitting video streams intended to multiple users over time-varying wireless channel. Medium grain scalable video coding is employed to compress the video streams. The video coding method provides packets which can be dropped for bit rate adaptation at the cost of decoded video quality. This paper also employs adaptive modulation. It can provide...
Channel estimation is a significant component of any receiver implementation. This paper presents a fast non-iterative channel estimation and equalization algorithm for TDS-OFDM systems. The proposed method is a hybrid of CP-OFDM and ZP-OFDM systems. By discarding the initial portion of the PN-sequence that absorbs all the ISI, the channel can be estimated from the remaining PN-sequence by using the...
This paper proposes time, frequency and clock synchronization technique for a Q transmit and L receive (Q x L), Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) for Wireless Local Area Network (WLAN) systems. OFDM is a multi-carrier modulation scheme that transmits a large number of closely spaced sub-carriers to be modulated with a conventional modulation technique...
In this paper, we develop Prioritized Adaptive Code-Enhanced (PACE) link-layer protocol to achieve preferred data recovery order across connections, while maintaining stable and reliable data flow over a wireless network. We classify link-layer traffic arrivals into different priorities based on delay constraint and distortion associated with that traffic. We formulate the link-layer buffer as a multiclass...
We present an embedded jitter measurement system for on-chip diagnostics of serial high-speed interfaces. A Virtex-5 FPGA uses a 3Gbit reference signal to retrieve timing jitter distributions from a system under test (SUT). Using a recently developed fitting method, the total jitter of the system is determined, which allows for judging the quality of transmission lines, PLLs or transceiver structures...
In this paper, we propose a new robust closed-loop extended orthogonal space-time block coding (EO-STBC) scheme for two-way four relay networks over frequency selective fading channels with imperfect synchronization. It is a three time slot scheme where the first one is specified for the two terminals while the other two are specified for amplify-and-forward (AF) relays. An orthogonal frequency division...
In previous works, delay tolerant codes were proposed with variable length ensuring a full transmit diversity for a certain interval of delay profiles. The code performances are enhanced when the code length is incremented; however, this causes an increasing complexity at the receiver which motivates our research for low complexity decoding methods. First, it is shown that optimal decoding methods...
Interplanetary Overlay Network (ION) is an implementation of delay/disruption tolerant networking (DTN) developed as infrastructure for space communications in interplanetary flight mission systems. To date, no work has been done in evaluating the effectiveness of ION when it is applied to an interplanetary Internet involving very long link delay and highly asymmetric channel rates. In this paper,...
To fully exploit frequency diversity in cyclic delay diversity orthogonal frequency division multiplexing (CDD-OFDM) system, accurate channel estimation is crucial. Due to the excessive channel delay spread in CDD, traditional in-band pilot assisted channel estimation with limited frequency resolution fails to track the considerable variation in the frequency domain. Alternatively, increasing pilot...
In this treatise, we propose a novel family of Asynchronous Cooperative Linear Dispersion Codes (ACLDCs), which is capable of maintaining full diversity in cooperative scenarios even at the presence of asynchronous reception. The linear dispersion structure is employed in order to accommodate the dynamic topology of cooperative networks, as well as to achieve higher throughput than conventional space...
Modification of the 1-tap parallel look-ahead decision feedback equalizer (DFE) architecture is developed using Boolean algebra to enable its operation at 80 Gbps and beyond. Measurement techniques which can be generally applied to the testing of this as well as to other DFE architectures are devised. The equalizer's wide band clock distribution network enables its operation from 25 to 80 Gbps. The...
In this paper, we investigate the impact of the a priori channel state information (CSI) on the orthogonal frequency-division multiplexing (OFDM) system performance. A joint iterative channel estimation, detection and decoding receiver involving the dual diagonal linear-minimum-mean-square-error (DD-LMMSE) algorithm is employed. We show that the discrepancy between the a priori CSI and true CSI has...
Energy detectors (ED) and transmitted reference (TR) systems are known as promising candidates for noncoherent UWB receivers. One way of non-coherent communication, is to use a transmitted reference (TR) pulse for detection. In conventional TR, the reference pulse and data bearing pulse are multiplexed in time domain. In frequency shifted reference (FSR) method, these pulses are multiplexed in the...
High speed serial links, consisting of SerDes devices, require the Bit Error Rate (BER) to be at the level of 10-12 or lower. The excessive test time for comparing each captured bit for error detection in the traditional BER measurement and the costly instrumentation are major drawbacks for high volume production test of SerDes devices. In this paper, we propose a design for BER estimation methodology...
In this paper, we propose to use the Discrete-Time Rake receiver for Cooperative DS-CDMA systems. We compare the Bit Error Rate (BER) performance of the Continuous Time, Discrete Time and Decorrelating Discrete Time Rake receivers (CTR, DTR, DDTR) using Decode and Forward (DF) relaying. The former receiver is the most used and consists in combining the output of correlators locked on the most significant...
An optimal scheme on uplink pilot time interval (UPTI) to maximize average post-processing SNR (signal to noise ratio) is proposed in order to overcome the impact of channel estimation error and delay on a time division duplex (TDD) multiple input single output (MISO) beamforming system. In TDD system, the base station estimates the channel state information (CSI) at transmitter based on uplink pilots...
In Multiuser Multiple-Input Multiple-Output (MU-MIMO) downlink systems, the zero-forcing algorithm is a simple and effective technique for separating users and data streams of each user at the transmitter side, but its performance depends greatly on the accuracy of the available channel state information (CSI) at the transmitter. Due to the existence of the CSI delay and channel estimation error in...
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