Wideband Code Division Multiple Access Cellular Network Research Articles

Mobile Positioning System using Signal Strength Measurement for WCDMA System

The precise position of the mobile station is critical for the ever increasing number of applications based on location . In this paper a new approach for mobile positioning in WCDMA (Wideband Code Division Multiple Access ) cellular network is proposed . Radio Received Signal Strength Indication (RSSI) can be measured from a number of nearby base stations . Three proposed approaches (3-BS's , 5-BS's and 7-BS's) are simulated using three propagation models and the rmserror is calculated for each model. As a simulation study case, the University of Mosul area is choosed to find the position of a mobile user in the university campus .

Performance evaluation of MIMO–WCDMA cellular networks in multiuser frequency selective fading environments

ABSTRACTThis paper investigates the performance of different transmission strategies for multiple input multiple output (MIMO) networks with the wideband code division multiple access (WCDMA) air interface as the physical layer protocol. Performance is evaluated statistically with extended Monte Carlo (MC) simulations in terms of achievable bit‐error (BER) rate in frequency selective fading cellular environments. As results indicate, for a MIMO configuration with Mt antennas at the base station (BS), Mr antennas per mobile station (MS) and L resolvable multipath components, the transmission strategy based on signal to noise ratio (SNR) enhancement is the optimum transmit solution for Mt ≤ Mr. However, the pre‐RAKE maximal ratio combining transmission strategy outerperforms the SNR enhancement strategy with post‐RAKE processing for Mt > Mr, high number of resolvable multipath components and channel estimation error up to 40%. Moreover, a transmission scheme based on the maximization of the ratio of the desired MS's signal to the total amount of interference that causes to the network is proposed, and is shown that outerperforms the conventional transmission schemes for high data rate services. For symmetric MIMO configurations (Mt = Mr) and two resolvable multipath components, this strategy provides 30% BER gain compared to the maximization of SNR strategy. This gain can be further improved by 25% with a proposed adjacent sector cooperation algorithm. Copyright © 2011 John Wiley & Sons, Ltd.

Indoor Planning for High Speed Downlink Packet Access in WCDMA Cellular Network

The aim of this paper is to show the special characteristics of the indoor environment related to radio propagation and furthermore to radio network planning. The aspects of the radio network planning are highlighted especially for Wideband Code Division Multiple Access (WCDMA) radio access technology that is used widely in the third generation mobile networks. Moreover, the detailed planning parameters in indoor environment are studied for High Speed Downlink Packet Access (HSDPA) in order to support high throughput data applications in Universal Mobile Telecommunications System (UMTS). The final target of the paper is to compare pico cell, distributed antenna system (DAS), and radiating cable network configurations in indoor environment to provide the optimal radio conditions for the data applications, and thus to serve highest number of mobile users. Several measurement campaigns with different antenna configurations have been conducted in order to study the effect of multi path related parameters, as delay spread of the signal. Also other capacity related parameters as received signal levels, interference, throughput, and transmit power levels have been studied in order to find out the optimal solution for HSDPA in UMTS. The results clearly show that pico cells and distributed antenna system have outstanding performance in indoor propagation channel compared to radiating cable. In sense of signal quality, pico cell performance is slightly better compared to distributed antenna system. However, measurements with HSDPA indicate that practical capacity of DAS outperforms pico cells. The measurements also show that separation of the antennas is a key capacity related parameter when planning WCDMA based indoor systems.

Simulation, implementation and performance evaluation of a diversity enabled WCDMA mobile terminal

Smart antenna array technology has been shown to greatly improve the performance of wireless communication systems. In this article, we describe the impact of smart antenna array processing at the mobile terminal for Wideband Code Division Multiple Access (WCDMA) cellular networks. Using system simulations we demonstrate the quality of service, network coverage, and network capacity improvement provided by a WCDMA dual antenna receiver and we establish a relationship between this improvement and the link level performance. We then describe a receiver architecture for a dual antenna WCDMA mobile receiver. The proposed receiver was implemented, as part of a complete mobile terminal solution, in an ASIC using a 0.18 μm, 1.8 V CMOS technology. The ASIC was integrated with RF, analog and digital components in a PCMCIA card form factor. The PCMCIA is a 3GPP compliant user equipment and has been submitted to standardized performance and conformance tests. Experimental measurements gathered with the PCMCIA card illustrate the impact of a diversity enabled mobile data terminal on the link level performance. For various propagation environments and transmission data rates, improvements in the range of 2.7 – 10 dB in the required DPCH Ic/Ior for a 1% Block Error Rate (BLER) were observed. These measurements are within 1.4 dB of the ideal link level simulations which indicates that the predicted improvement at the network level should also materialize. The results presented in this paper show the tremendous potential of smart antenna arrays in 3G WCDMA cellular networks and establish diversity as a viable solution for high-speed cellular communications.

Quality of Service provisioning for UMTS network users with immediate and advance radio resource reservations

Wideband code division multiple access (WCDMA) is selected as the air interface scheme for 3G wireless networks. This scheme offers a high data rate that makes the wireless networks a suitable environment for real-time packet data services. 3G networks can be used to deliver multimedia traffic with guaranteed quality of service, but faces the scalability challenge in terms of the number of connections that can be setup in the cellular network. The more connections take place in WCDMA based network, the more interference is created, which yields more QoS degradation. To handle this issue, several algorithms that are collectively alleviate the QoS degradation have been developed and implemented. In this paper, we provide a system link simulator that models the WCDMA cellular network with the necessary radio resource management algorithms. The downlink direction has been simulated as it is usually the limiting link in setting up multimedia sessions, and interactive web sessions. The simulation environment provides, through the implementation of new wrap-around technique, a fair source of intra-cell and inter-cell interference, and avoids session disconnections due to the limited simulation area. Then, we suggest an admission control algorithm for admitting immediate and advance radio resource reservation requests. The admission control algorithm decision is based on the amount of interference that the new request will add to the network. The algorithm relies on the radio resource reservation states that stores all admitted immediate and advance sessions.

Call admission control in wideband CDMA cellular networks by using fuzzy logic

In this paper, a novel call admission control (CAC) scheme using fuzzy logic is proposed for the reverse link transmission in wideband code division multiple access (CDMA) cellular communications. The fuzzy CAC scheme first estimates the effective bandwidths of the call request from a mobile station (MS) and its mobility information, then makes a decision to accept or reject the connection request based on the estimation and system resource availability. Numerical results are given to demonstrate the effectiveness of the proposed fuzzy CAC scheme in terms of new call blocking probability/handoff call dropping probability, outage probability, and resource utilization.

Fair resource allocation with guaranteed statistical QoS for multimedia traffic in wideband CDMA cellular network

A dynamic fair resource allocation scheme is proposed to efficiently support real-time and non-real-time multimedia traffic with guaranteed statistical quality of service (QoS) in the uplink of a wideband code-division multiple access (CDMA) cellular network. The scheme uses the generalized processor sharing (GPS) fair service discipline to allocate uplink channel-resources, taking into account the characteristics of channel fading and intercell interference. In specific, the resource allocated to each traffic flow is proportional to an assigned weighting factor. For real-time traffic, the assigned weighting factor is a constant in order to guarantee the traffic statistical delay bound requirement; for non-real-time traffic, the assigned weighting factor can be adjusted dynamically according to fading, channel states and the traffic statistical fairness bound requirement. Compared with the conventional static-weight scheme, the proposed dynamic-weight scheme achieves capacity gain. A flexible trade-off between the GPS fairness and efficient resource utilization can also be achieved. Analysis and simulation results demonstrate that the proposed scheme enhances radio resource utilization and guarantees statistical QoS under different fairness bound requirements.

Dynamic Fair Scheduling With QoS Constraints in Multimedia Wideband CDMA Cellular Networks

A class of dynamic fair scheduling schemes based on the generalized processor sharing (GPS) fair service discipline, under the generic name code-division GPS (CDGPS), is proposed for a wideband direct-sequence code-division multiple-access (CDMA) cellular network to support multimedia traffic. The CDGPS scheduler makes use of both the traffic characteristics in the link layer and the adaptivity of the wideband CDMA physical layer to perform fair scheduling on a time-slot by time-slot basis, by using a dynamic rate-scheduling approach rather than the conventional time-scheduling approach. Soft uplink capacity is characterized for designing an efficient CDGPS resource allocation procedure. A credit-based CDGPS (C-CDGPS) scheme is proposed to further improve the utilization of the soft capacity by trading off the short-term fairness. Theoretical analysis shows that, with the C-CDGPS scheme, tight delay bounds can be provided to delay-sensitive traffic, and short-term unfairness can be bounded so that long-term weighted fairness for all users can still be satisfied. Simulation results show that bounded delays, increased throughput, and long-term fairness can be achieved for both homogeneous and heterogeneous traffic.