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Multiuser interference (MUI) and co-space interference (CSI) are two challenging issues in design of multicarrier code-division multiple-access (MC-CDMA) systems when multiple antennas are used at both the transmitter and receiver sides (MIMO transmission). On the other hand, in cognitive radio (CR) system, the secondary users that use MC-MCDA technique must deactivate the subcarriers used by the...
The evolution of TD-SCDMA is LTE TDD. But the scarcity of spectrum resource below 1GHz is one of the most serious problems in the deployment of LTE TDD. Digital Dividend spectrum, which is free up for the conversion from analog TV to digital TV, is the ideal frequency band to deploy LTE TDD below 1GHz. So the coexistence issue between Digital Terrestrial Television Broadcast (DTTB) and LTE TDD in...
High Altitude Platform Station (HAPS) system is a new, promising means of providing Third Generation (3G) mobile services. While HAPS can be affected by stratospheric winds. In this paper, a novel HAPS-CDMA displacement model is presented. And the impacts of platform displacements in the horizontal and vertical direction are examined. From numerical results, it is observed that the system performances...
Due to the imperfection of transmitter and receiver, Adjacent Channel Interference (ACI) can't be completely avoided when two systems share the adjacent frequency band. This paper investigates the impact of ACI between TD-SCDMA and TD-HSDPA systems operating in macro cell. In stimulation, smart antenna technology is employed and its performance is investigated. Furthermore, the key technologies, Adaptive...
In asynchronous communication system, such as MANET or uplink of CDMA system, MAI (Multiple Access Interference) is a problem that cannot be ignored. To suppress the effect of MAI, this paper introduces a new mix-carrier method in asynchronous CDMA system. The proposed method uses both cosine and Chirp as carriers, by using frequency domain filter and Fractional Fourier domain filter at the receiver...
In this work a novel switched-interleaving algorithm based on limited feedback is proposed to suppress interference for uplink multi-carrier code-division multiple-access (MC-CDMA) multiple antenna systems. A codebook of chip-interleavers is constructed and prestored at both the base station (BS) and mobile stations (MSs). The transmit chip-interleaver is chosen by the BS from the codebook, and the...
In this paper we propose an inverse QR decomposition based recursive least squares algorithm (IQRD-RLS) for the linearly constrained minimum variance (LCMV) receiver for CDMA transmission systems. The proposed algorithm is numerically stable and it is suitable for implementation in systolic arrays or DSP vector architectures. It is shown through computer simulations that the proposed algorithm outperforms,...
TD-SCDMA HNB is proposed to enhance the capability of TD-SCDMA indoor wireless system, reduce the macro system load and increase the coverage of the service. This paper investigates the interference between HNBs for voice services in TDD model. The interference that each HNB is associated with one single UE is compared with the interference that each HNB is associated with several HUEs. The co-channel...
This paper investigates stability and robustness of a gradient-type power control algorithm for multicell CDMA wireless communication networks in the presence of time-delays and disturbances. The time-delays in individual communication channels between mobiles and base stations are allowed to take place independently. The disturbances represent power noises, unmodeled secondary interference and variation...
The principle of CDMA mode in TD-SCDMA(TD), which means how spectrum spreading and scrambling code being used in TD is a basic problem. Comparing with the other two 3G standards, the principle and realization of the CDMA mode used in TD standard has much difference. Both cdma2000 and FDD WCDMA use the CDMA mode of real spectrum spreading and complex scrambling code, which is the traditional concept...
Interference cancelation (IC) has been well studied in literature as a potential capacity approaching scheme for uplink code-division multiple-access (CDMA) systems. With the advance of silicon technology, it is becoming implementationally feasible. In this paper, we study a soft IC algorithm which could be iteratively concatenated with Turbo decoding. The algorithm only relies on a conventional single...
This paper evaluates the performance of variable-step closed loop power control algorithm for CDMA communication employing High Altitude Platforms (HAPs). In HAPs, the channel is predicted to have different characteristics compared to that in terrestrial. Users that are distributed within HAPs coverage will have different channel characteristics depending on their elevation angle. In this work, HAPs...
The vast literature on power control for CDMA systems ignored the fact that propagation delays occur inevitably during data communication between the base station and the mobile units or viceversa. If these delays are not considered into the power control design stage, the performance of the resulting feedback system can be severely deteriorated or even instability could be triggered in a practical...
In this paper, we propose user grouping algorithms to provide power minimization in grouped MC-CDMA systems. Depending on the channel fading conditions, power control is utilized to minimize the total transmitted power under a bit error rate (BER) constraint. When the allocation is performed without a fair data rate requirement, we provide the optimal solution to the minimization problem. However...
In this paper, we propose a modified algorithm based on complex ICA (independent component analysis) for cancelling the feedback interference in the WCDMA repeater under time-varying multi-path channels. The proposed algorithm made use of Non-Gaussian distribution character of the signals and separated feedback from received signals by estimating feedback path adaptively in the frame work of ICA....
This paper presents the performance comparison of interleave division multiple access (IDMA) and code division multiple access (CDMA) systems based on Simulink. We investigate the basic principle that illustrates the similarities and differences of the two different schemes. According to these schemes, we analyze every model function and build simulation platforms for these systems. The simulation...
In this paper, we propose base station assignment method based on minimizing the transmitter power (BSA-MTP) technique in a direct sequence-code division multiple access (DS-CDMA) receiver in the presence of frequency-selective Rayleigh fading. This receiver consists of three stages. In the first stage, with constrained least mean squared (CLMS) algorithm, the desired users' signal in an arbitrary...
In this paper, we propose a multicarrier system for anti-jamming communications. This system employs two sets of spreading codes to spread the signal in both time and frequency domain, while it can use the same bandwidth as the MC-CDMA system. We derive its error probability under multipath fading channels with jammers. Simulation results show that this system is more robust against narrowband partial-time...
A new blind adaptive multi-user detection scheme based on the RLS filter and subspace estimation is proposed. It is shown that the detector can be expressed as an anchored signal in the signal subspace and the coefficients can be estimated by the RLS filter just by using the signature waveform and the timing of the desired user. The subspace- based algorithm brings the benefit from the lower computational...
In Multi-carrier Code Division Multiple Access (MC-CDMA) systems, methods of distributing the spreading sequence to sub-carriers (spreading method) include discrete spreading (DS) and continuous spreading (CS), which have the superiority in obtaining frequency diversity and reducing MAI respectively, but both overall evaluations are not ideal. A novel method "twice spreading (TS)" is presented...
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