4th Generation Wireless Networks Research Articles

Capacity Analysis and Linear Detection in Massive MIMO for 5G Wireless Systems

Multiple Input Multiple Output (MIMO) is an attractive air interface solution which is used in the 4th generation wireless networks to achieve higher data rate. With a very large antenna array in Massive MIMO the capacity will increase drastically. In this paper channel capacity comparison for MIMO using known Channel State Information (CSI) and unknown CSI has been carried out for a higher number of antennas at transmitter and receiver side. It has shown that at lower SNR known CSI will give better performance compared to unknown CSI. At higher SNR known CSI and unknown CSI will provide similar results. Capacity comparison has been evaluated with help of MATLAB for known CSI and unknown CSI from a small number of antennas to hundred of antennas. Also, the performance evaluated with MATLAB simulation of linear detectors zero-forcing (ZF) and maximum ratio combining (MRC) method for large number of antennas at Base station (BS) which are serving a small number of single antenna users. Performance is evaluated in terms of Symbol Error Rate (SER) for ZF and MRC, and results show that ZF will outperform MRC. It has also been analyzed that increasing the antennas at BS for a small number of users will also help to reduce SER.

An integrated MIH-FPMIPv6 mobility management approach for evolved-packet system architectures

Following the Always Best Connection (ABC) principle of the 4th generation wireless networks users of mobile services would be provided with connectivity to the best access technology all the time. In such a context, mobile devices are equipped with multiple radio interfaces allowing connectivity to the most suitable network environment based on users’ requirements and operators' policies. Seamless vertical handover plays the key role for mobility across various access networks offering service continuity to users. The Evolved Packet core (EPC) network architecture of the 3GPP (Third Generation Partnership Project) provides optimized mechanisms to achieve Vertical Handover (VHO) using the Fast Proxy Mobile IPv6 (FPMIPv6) mobility management standard. However the EPC solution fails to provide seamless handover for real time applications due to lack of information when the source and the target networks are on different domains as well as due to existing limitations in FPMIPv6. The IEEE 802.21 Media Independent Handover (MIH) framework is another promising standard which facilitates the VHO procedures by providing generic interfaces and primitives independent of the access technology. In this paper a seamless handover solution is proposed between 3GPP (Third Generation Partnership Project) and non-3GPP wireless access technologies which includes several signaling enhancements complementing the functionalities of the EPC network of the LTE-A with the IEEE 802.21 standard. Also an improved FPMIPv6 scheme is included, addressing the identified shortcomings of the protocol. The presented architecture provides low latencies, supporting services QoS constraints, as well as user requirements and provider policies. The proposed framework is compared with the existing EPC approach while a comparative analysis and evaluation of the enhanced FPMIPv6 is provided.

Multi-Threshold based Scheduling for Multi-User Multiple-Input Multiple-Output Systems

Problem statement: Multi-User Multi-Input Multi-Output (MU-MIMO) system had eventually used in 4th generation wireless networks either to achieved diversity gain or multiplexing gain. Many recent scheduling addresses the threshold based resource allocation where in resource were not utilized properly. Approach: In this study a new Multi Threshold Based Channel Aware Scheduling (MTCAS) was proposed for performance improvement and proper resource utilization. This approach was projected for multiuser Multiple-Input Multiple-Output (MU-MIMO) system under Space-Time Block Coding (STBC) transmission. The goal of this scheduler was to offer improved performance in terms of a low Bit Error Rate (BER), high Packet Delivery Ratio (PDR), high average capacity and service fairness among the users. This scheme allows the set of users to send data based on their channel quality. Results: Simulation compares this scheduler performance with other scheduling schemes such as Fair Scheduling (FS), Normalized Priority Scheduling (NPS) and Threshold based Fair Scheduling (TFS). Conclusion: The obtained results prove that MTCAS has significant improvement in average bit error rate performance as compared to the other scheduling schemes.

STBCs with orthogonal decoder for highly time-selective channels

We present bit-error-rate (BER) analyses of Orthogonal Space-Time Block Codes (O-STBCs) and their modified version (MO-STBCs) combined with the Orthogonal Decoder (OD) over uncorrelated and time-selective fading channels of generalized statistics. First, we quantify the effective diversity achieved by STBCs (O-STBCs and MO-STBCs) by resorting to a statistical characterization of the diversity gain of both schemes with OD. We, then, expand the theoretical BER expressions of O-STBCs, derived for the block fading channels, to MO-STBCs with OD in a more practical time-selective fading channel with Gray-code-mapped M-ary phase-shift-keying (PSK) modulation and M-ary quadratic-amplitude modulation (QAM). Moreover, through our BER expressions, we pinpoint the relationship between the effective diversity and BER performance of STBCs with OD, which elucidates the reason why MO-STBCs with OD architecture is very robust to the highly time-selective fading expected in 4th Generation Wireless Networks (4G). Finally, the theoretical results in conformity with the simulated ones demonstrates the accuracy of our analysis.

Scheduling and Traffic Policing for Variably Demanding Video Traffic Integrated with Voice and Data Traffic in 4th Generation Wireless Networks

In this paper, we present an effective mechanism for scheduling and traffic policing in 4th generation wireless networks. More specifically, we: a) extend our previous work on a Multiple Access Control (MAC) scheme for the multiplexing of voice, video and bursty data traffic over a very high-speed wireless TDMA channel, and we study our scheme's performance when MPEG-4 videoconference users of various traffic characteristics are present in the system, and b) we combine the MAC mechanism with an improved version of an efficient traffic policing mechanism. Our results are derived for cases with and without handoff traffic in the uplink channel, and it is shown that although the burstiness of MPEG-4 traffic and channel errors impedes the maximization of channel throughput, our scheme still achieves high channel throughput for all the combined voice/video/data loads examined.