A Novel Architecture for Antenna Arrangement in Wireless Cellular CDMA Systems (original) (raw)
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A New Approach for Wireless Cellular Network Design
Int'l J. of Communications, Network and System Sciences, 2013
Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called Microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all the antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.
Performance Study and System Capacity Analysis of a Two-Tier Cdma System
International Conference on Aerospace Sciences & Aviation Technology, 2007
One of the main factors that affects the performance of a Code Division Multiple Access (CDMA) system is the out of-cell interference. While the in-cell interference is controlled within each cell using a power control algorithm, the out of-cell interference is not and can greatly impact network coverage and the total user capacity, so that CDMA capacity is an interference limited capacity. One design technique to reduce the effect of the out of-cell interference in cellular CDMA systems is to use cells of different radii, hierarchically organized in overlapping layers, this is the multitier system. In This paper the user capacity on the reverse link direction of a certain two-tier CDMA system that consists of a small microcell embedded in a larger macrocell, i.e. a two cell system is examined. The effect of the users' mobility on the call blocking and call dropping probabilities is examined depending on the system feasibility. The simulation results show that at different call arrival rates the system capacity is increased as compared with the previous work. The dominant parameters affecting the system performance are the users' velocity and the distance between the two cells.
Assessment of Network Layouts for CDMA Radio Access
EURASIP Journal on Wireless Communications and Networking, 2008
The aim of this paper is to perform an overall comparison of different network layouts for CDMA-based cellular radio access. Cellular network layout, including base station site locations and theoretical azimuth directions of antennas, can be defined by tessellations in order to achieve a continuous coverage of the radio network. Different tessellation types-triangle, square, and hexagon-result in different carrier-to-interference scenarios, and thus will provide nonequal system-level performance. This performance of a cellular network is strongly related to configuration parameters as base station antenna height, beamwidth, and sectoring. In this paper, a theoretical model is defined for the assessment, which includes numerical analysis and system-level simulations. A numerical analysis was performed first, and then system-level Monte-Carlo simulations were conducted to verify and to extend numerical results. The obtained results of the numerical analysis indicate that a hexagonal "clover-leaf " layout is superior, but the results of system-level simulation give similar performance for the triangular and square layouts. These results indicate also the importance of the antenna height optimization for all layouts. Moreover, the simulation results also pointed out that 6-sector configuration is superior both in coverage and in capacity compared to nominal 3-sector configuration that is typically preferred in coverage-related network deployments in practice.
SIR Improvement of Different Antenna Arrays Structures in CDMA Cellular Systems
In this paper, the signal-to-interference ratio (SIR) improvement capability for linear and circular arrays at base station of CDMA cellular systems is analyzed and compared. This SIR improvement capability is the basis for introducing smart antenna systems and is a function of the number and spatial distribution of antenna elements, the direction of arrival of the desired user and interferers. We find that a circular array provides a more uniform improvement in terms of SIR than a linear array. Furthermore, analytical and simulation results for average SIR improvement, signal to interference plus noise power ratio SINR and BER are provided. These results show that a triangular panel array would require employing three times the total number of antenna elements to obtain comparable performance to a circular array.
Performance Analysis of MIMO-CDMA System
RF and Microwave …, 2006
Nowadays, the demand on communication system is towards high capacity and faster data transmission with minimum error or losses. In Wireless Communication, Multiple Input Multiple Output (MIMO) is one of the techniques that can increase spectral efficiency and link reliability. Therefore, the performance of MIMO -CDMA with comparison to conventional Code Division Multiple Access (CDMA) system has been analyzed. The simulations models are simulated with different number of antenna which are two transmittwo receive (2Tx2Rx) and four transmitfour receive (4Tx4Rx). System specification is based on voice application. The simulation results shows that the proposed MIMO -CDMA (2Tx2Rx) is improved by 43% of BER and MIMO -CDMA (4Tx4Rx) improved by 63% of BER performance compared to conventional CDMA. Capacity performance of MIMO-CDMA (2Tx2Rx) improved by 50% and MIMO-CDMA (4Tx4Rx) improved by 75% compared to conventional CDMA.
IEICE Transactions on Communications
The demand for wireless mobile communications has grown at a very high rate, recently. In order to solve the non-uniform traffic rates, the use of cell splits is unavoidable for balancing the traffic rate and maximizing total system capacity. For cell planning, a DS-CDMA cellular system can be comprise of different cell sizes because of different demands and population density of the service area. In this paper, we develop a general model to study the forward link capacity and outage probability of a DS-CDMA cellular system with mixed cell sizes. The analysis of outage probability is carried out using the log-normal approximation. When a macrocell is split into the three microcells, as an example, we calculate the multi-cross interferences between macrocells and microcells, and the forward link capacities for the microcells and the neighboring macrocells. The maximum allowable capacity plane for macrocell and microcell is also investigated. The numerical results and discussions with...
Effect of cell shape on design of CDMA systems for urban microcells
IEEE Transactions on Wireless Communications, 2000
Placing antennas of low power base stations below surrounding buildings, as in urban microcells, makes propagation characteristics strongly dependent on the building environment. As a result, propagation in these urban microcells is nonisotropic, so that the assumption of circular cells used in planning of conventional cellular systems is no longer valid. Assuming circular cells leads to a more conservative system design, implying more base stations. This work investigates the effect of cell shape, due to non-isotropic propagation, on the out-of-cell interference and Erlang capacity of CDMA system. Propagation is described by measurement derived models for low antennas in a rectangular urban street grid. The analysis is done for soft handoff protocols.
IMPROVED PERFORMANCE OF MC-CDMA USING SMART ANTENNA TECHNIQUE
TJPRC, 2014
To improve coverage and performance in the MC-CDMA network with the help of simulation model and an evaluation method for the smart antenna system is presented. The proposed method that can show the impact o f smart antenna system on the Ec/Io coverage area is also presented as function of antenna type and beam width. The performance improvements are remarkable in the smart antenna systems. Here the data service users as well as the voice services users are considered. The performance of the system is evaluated in terms of Ec/Io Difference. We can observe the throughput with Number of users per sector. Results are discussed based on various parameters like flat urban type morphology, Okumura Model for omni direct ional antennas air link, orthogonality factor and antenna beam width. It also reduces multipath fading, cochannel interferences, system complexity &cost, BER, and outage probability.
Performance of Wireless CDMA with Mary Orthogonal Modulation and Cell Site Antenna Arrays
IEEE Journal on Selected Areas in Communications, 1996
Publisher Item Identifier S 0733-87 16(96)05239-0. the 0733-8716/96$05.00 0 1996 IEEE several disciplines, emphasizing estimation theory, sensor signal processing, antenna array processing, parallel computer architectures/algorithms and communication systems. He is currently a Professor of Electrical Engineering at Stanford University working in the area of mobile communications. He is the author of about 90 research papers and holds several patents. Dr. Paulraj has received a number of national awards in India for his contributions to technology development.
As k approaches infinity, the Rician distribution becomes a delta function, which matches the simple line-of-sight model. As k approaches zero, the Rician distribution transforms into a Rayleigh distribution. The AWGN, Rayleigh, and Rician channel models are simple, compact models for approximating the effects of radio propagation. An overview of more complicated models is available in [ 1 I]. 1.5 Wireless Standards It is vital to use the radio spectrum efficiently and to share the limited resource among multiple users. That requires multiple-access schemes that separate users by frequency, time, and/or orthogonal codes, as shown in Figure 1.15. Most systems divide the radio spectrum into frequency channels and strategically assign those channels, a practice known as frequency division multiple access (FDMA). The channel assignment strategies minimize interference between users in different cells. Interference is caused by transmitted signals that extend outside the intended coverage area into neighboring cells. To limit interference, frequency channels are generally assigned based on the The CDMA Concept CDMA is a multiple-access scheme based on spread-spectrum communication techniques [l-3]. It spreads the message signal to a relatively wide bandwidth by using a unique code that reduces interference, enhances system processing, and differentiates users. CDMA does not require frequency or time-division for multiple access; thus, it improves the capacity of the communication system. This chapter introduces spread-spectrum modulation and CDMA concepts. It presents several design considerations tied to those concepts, including the structure of the spreading signal, the method for timing synchronization, and the requirements for power control. This chapter also points out CDMA IS95 [4] details to illustrate practical solutions to these design issues. 2.1 Direct-Sequence Spread-Spectrum Communications Spread-spectrum communications is a secondary modulation technique. In a typical spread-spectrum communication system, the message signal is first modulated by traditional amplitude, frequency, or phase techniques. A pseudorandom noise (PN) signal is then applied to spread the modulated waveform over a relatively wide bandwidth. The PN signal can amplitude modulate the message waveform to generate direct-sequence spreading, or it can shift the carrier frequency of the message signal to produce frequency-hopped spreading, as shown in Figure 2.1. The direct-sequence spread-spectrum signal is generated by multiplying the message signal d(t) by a pseudorandom noise signal pn (t): g(t) = pn W&)