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In this paper an analytical model of a MC-DS-CDMA with TF-domain spreading for wireless communication system with spatial diversity considering channel fading, Doppler shift, multi-access interference (MAI) along with AWGN channel is presented. The analysis presents a novel approach to the development of an analytical expression of signal to interference plus noise ratio (SINR) considering fading...
Direct Sequence Spread Spectrum modulation is widely used in wireless commercial communication systems for code division multiple-access supporting multiple users simultaneously. The spreading sequences employed are often drawn from a finite set of spreading sequences that are orthogonal or exhibit good cross-correlation properties and therefore mitigate interference caused by simultaneous multiple...
In this paper, we study the dynamic uplink power allocation problem in a multi-cell multi-user CDMA-based cellular cognitive radio (CR) system, in which the concept of hierarchical interference bound is introduced to describe the coexistence of the multi-user interference. We propose a novel differential game-based dynamic power allocation model via two formulated cost functions. Furthermore, we present...
In recent years, smart antenna technology has became the most attractive technology in the 3rd generation systems, it has perfect performances in many aspects such as improving system capacity, expanding cell coverage, reducing the transmit power of mobile station and rejecting multiple access interference (MAI). Beamforming is one of the most important applications in DS-CDMA. Minimum variance is...
The combination of multiple antennas and multi-carrier code division multiple access (MC-CDMA) is a strong candidate for the downlink of future mobile communications. The study of such systems in scenarios that model real life transmissions is an additional step towards an optimised achievement. Nevertheless, when transmitting over fading channel multi-cell interference occurs and this degrades the...
Because of the lack of dedicated frequency bands, the TD-LTE system is possibly deployed in the same band with other existed mobile systems. In this paper, the coexistence studies for the TD-LTE system with the radar system which has been widely deployed in the band 2300-2400 MHz, is presented. The dynamical system simulation methodology is utilized in the coexistence studies, and simulation results...
This paper evaluates the end-to-end performance of a CDMA based static multi-hop wireless sensor network (WSN) in shadowed environment. An interference model for multi-hop is presented using correlated interferers. Three different information delivery mechanisms are studied using regenerative relays with or without error correction capability. Energy requirement for successful delivery of a data packet...
The paper evaluates the performance of a CDMA based wireless sensor networks (WSN) with layered architecture in terms of energy consumption for successful transmission of data packets, considering only correlation among interferers in shadowed environment. We consider a model of interference at the sink for a layered architecture of CDMA based WSN with two kinds of interference, multiple access interference...
Call Admission control (CAC) is an important part of radio resource management (RRM) according to certain criteria, CAC determines whether the call is admitted to access or not. CAC is an important means to guarantee the quality of service (QoS) in wireless network. This paper analyses the multi-user detection factor on the uplink load of TD-SCDMA system and the effects of adjacent cell interference...
In this paper, a simulation study has been carried out to evaluate performance of joint admission and power control (JAPC) algorithms in Cognitive - CDMA Networks. Performance has been evaluated for SU in an uplink scenario of CDMA network consisting primary user (PU) and secondary user (SU). A numbers of algorithms have been investigated. Long term fading has been assumed in addition to path loss...
In this paper, we deal with the time slot allocation in time-hopping ultra-wide band (TH-UWB) ad-hoc networks in order to maximize the total sum rate. This problem is known to be a discrete NP-hard optimization problem and hence cannot be solved with a computationally efficient algorithm. Moreover, the sum rate maximization often leads to starvation of links experiencing bad channel conditions. Our...
The DS-CDMA system has a serious problem that is the multiple-access interference (MAI). Usually, people use the Multi-User detection (MUD) to cancel the MAI. The Multi-User detection makes the best use of the information of other users to cancel the MAI. Indeedly, MUD can cancel the MAI completely, but it has very large computational burden and it increase the noise of the system, besides, it needs...
The feedback interference that comes into receiving antenna from the transmitting antenna has a bad effect on the normal work of the radio repeater. What's worse, serious feedback interference will incur feedback oscillation. The introduction of Adaptive Interference Cancellation (AIC) solves this problem effectively. When AIC is employed, the feedback time that feedback interference transmits between...
In this paper we present a new “dynamical” spectral encoding method for the optical code division multiple access (OCDMA) indoor wireless communication system. In contrast with the classical OCDMA systems, where one user transmits all the information bits using the same spreading code sequence, in the proposed “dynamical” case one user transmits a fixed number of bits using one code sequence, and...
Cochannel interference is the most important issue in cellular mobile systems. It can be reduced by increasing the frequency re-use distance among the cochannel cells while keeping constant cell radius which improves the quality of a cellular mobile system. But this will decrease the overall network capacity because cluster size, which is inversely proportional to network capacity, also increases...
This paper examines the problem of coupling in on-channel repeaters for a WCDMA wireless system. Unwanted feedback between the donor and coverage antennas of a repeater are created by radio echoes from local scatterers; as well as direct path antenna isolation limitations. These radio echoes create interference not only in the incoming signal from the base station, but also cause instability in the...
In this contribution we investigate the spectral-efficiency of a two-hop cooperative network using multicarrier code-division multiple-access (MC-CDMA) transmission scheme. The two-hop network constitutes K source users transmitting signals to K destinations with the aid of N relays. Our focus is on the relay optimization, when assuming that the N relays cooperate or do not cooperate with each other...
In this contribution the asymptotic signal-to-interference-plus-noise ratio (SINR) performance of multicarrier direct-sequence code-division multiple-access systems employing time-frequency-domain spreading, i.e., of the TF/MC DS-CDMA systems, is studied, when separate minimum mean-square error multiuser detection (MMSE-MUD) is considered. The separate MMSE-MUD detects signals first in the time (T)-domain...
In this paper, a static system level simulator is used to investigate the capacity loss in case of co-existence of macro WCDMA and micro HSUPA. The capacity loss under different frequency spacing or ACIRs is obtained. The simulation results show that the micro HSUPA cell has little impact on the macro WCDMA cell with frequency spacing of 5 MHz, while the macro WCDMA cell has larger impact on the micro...
This paper extends the discrete Verhulst power equilibrium method, previously suggested in to the power-rate optimal allocation problem. Multirate users associated with different types of traffic are aggregated to distinct user' classes, with the assurance of target rate allocation per user and QoS. Therein, single-rate Verhulst power allocation algorithm was adapted to the multirate DS/CDMA power...
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