Adaptive Beamforming and Adaptive Modulation-Assisted Network Performance of Multiuser Detection-Aided FDD and TDD CDMA Systems

The network performance of a frequency division duplex and time division duplex (TDD) code division multiple access (CDMA)-based system is investigated using system parameters similar to those of the Universal Mobile Telecommunication System. The new call blocking and call dropping probabilities, the probability of low-quality access, and the required average transmit power are quantified both with and without adaptive antenna arrays (AAAs), as well as when subjected to shadow fading. In some of the scenarios investigated, the system’s user capacity is doubled with the advent of adaptive antennas. The employment of adaptive modulation techniques in conjunction with AAAs resulted in further significant network capacity gains. This is particularly so in the context of TDD CDMA, where the system’s capacity becomes poor without adaptive antennas and adaptive modulation owing to the high base station (BS) to BS interference inflicted as a consequence of potentially using all time slots in both the uplink and downlink of the emerging wireless Internet. Index Terms—Adaptive beamforming, adaptive modulation, code division multiple access (CDMA) systems, Universal Mobile Telecommunication System Terrestrial Radio Access (UTRA), wireless network performance

A New Combination of RAKE Receiver and Adaptive Antenna Array Beamformer for Multiuser Detection in WCDMA Systems

The aim of this paper is to combine smart antenna beamforming and RAKE receiver in wideband code division multiple access (WCDMA). The proposed method combines spatial diversity as well as temporal diversity to improve the performance and overcome both interferences and multipath fading. This investigation has focused on one of the new proposed blind beamforming algorithms. It is based on constrained constant modulus (CCM) algorithm which is used for deriving a recursive-least-squares (RLS-) type optimization algorithm. We illustrate the comparison of bit error rate (BER) of the proposed receiver with simple correlator and also 1D-RAKE receiver in multiuser detection (MUD) WCDMA. The simulation results show that the proposed 2D-RAKE receiver offers lower BER rather than conventional ones, that is, it is an effective solution for decreasing the effect of interference and increasing the capacity, in a joint state

Improving Frequency Reuse and Cochannel Interference Coordination in 4G HetNets

This report describes my M.A.Sc. thesis research work. The emerging 4th generation (4G) mobile systems and networks (so called 4G HetNets) are designed as multilayered cellular topology with a number of asymmetrically located, asymmetrically powered, self-organizing, and user-operated indoor small cell (e.g., pico/femto cells and WLANs) with a variety of cell architectures that are overlaid by a large cell (macro cell) with some or all interfering wireless links. These designs of 4G HetNets bring new challenges such as increased dynamics of user mobility and data traffic trespassing over the multi-layered cell boundaries. Traditional approaches of radio resource allocation and inter-cell (cochannel) interference management that are mostly centralized and static in the network core and are carried out pre-hand by the operator in 3G and lower cellular technologies, are liable to increased signaling overhead, latencies, complexities, and scalability issues and, thus, are not viable in case of 4G HetNets. In this thesis a comprehensive research study is carried out on improving the radio resource sharing and inter-cell interference management in 4G HetNets. The solution strategy exploits dynamic and adaptive channel allocation approaches such as dynamic and opportunistic spectrum access (DSA, OSA) techniques, through exploiting the spatiotemporal diversities among transmissions in orthogonal frequency division multiple access (OFDMA) based medium access in 4G HetNets. In this regards, a novel framework named as Hybrid Radio Resource Sharing (HRRS) is introduced. HRRS comprises of these two functional modules: Cognitive Radio Resource Sharing (CRRS) and Proactive Link Adaptation (PLA) scheme. A dynamic switching algorithm enables CRRS and PLA modules to adaptively invoke according to whether orthogonal channelization is to be carried out exploiting the interweave channel allocation (ICA) approach or non-orthogonal channelization is to be carried out exploiting the underlay channel allocation (UCA) approach respectively when relevant conditions regarding the traffic demand and radio resource availability are met. Benefits of CRRS scheme are identified through simulative analysis in comparison to the legacy cochannel and dedicated channel deployments of femto cells respectively. The case study and numerical analysis for PLA scheme is carried out to understand the dynamics of threshold interference ranges as function of transmit powers of MBS and FBS, relative ranges of radio entities, and QoS requirement of services with the value realization of PLA scheme.1 yea

UMTS multi-service uplink capacity and interference statistics of femtocells

The final publication is available at Springer via http://dx.doi.org/10.1007/s11277-012-0860-7In this work, the multiservice uplink capacity of single and multiple femtocells is given. The COST231 multiwall and multifloor indoor propagation model has been used to calculate the indoor propagation loss. Results show that the uplink capacity of a deployed femtocell will reduce by 2 % if two extra femtocells are deployed in the same building higher and lower of it. Results also show that the uplink capacity is slightly affected if there are several femtocells deployed in the buildings around the one at which the femtocell under study is already exists. It is demonstrated that uplink capacity is interference limited if the femtocell is deployed to serve the users in three floors. Results show that the uplink capacity will be interference and noise limited if the femtocell is deployed to serve the users in five floors. Finally, it is found that the effect of the interference due to the uniformly distributed users within the macrocell around the femtocell is insignificant

Analisa Performansi Received Total Wideband Power (Rtwp) Terhadap Kualitas Performansi Jaringan Pada Jaringan Wcdma Ibc Telkomsel

Pada aplikasi jaringan inbuilding coverage gangguan interferensi menjadi faktor utama penurunan kinerja jaringan. Pada jurnal ini telah dilakukan analisa pengaruh performansi RTWP terhadap kualitas performansi jaringan atau Key Performance Indicator (KPI). Analisa dilakukan dengan mengamati performansi nilai RTWP menggunakan Huawei Local Maintenance Terminal iManager U2000 dan didapati high RTWP sehingga menyebabkan nilai Key Performance Indikator (KPI) menurun.Pada penelitian ini analisa yang dilakukan adalah mencari penyebab high RTWP dengan melakukan pengecekan dari sisi BTS sampai ke sisi Distributed Antenna System (DAS) dan penggantian perangkat triplexer juga perbaikan konektor pada sisi Distributed Antenna System (DAS).Setelah dilakukan penggantian perangkat triplexer dan perbaikan konektor pada sisi Distributed Antenna System (DAS) nilai RTWP mengalami perbaikan. Dari hasil analisa pada penelitian ini setelah diketahui nilai RTWP mengalami perbaikan maka nilai parameter KPI juga mengalami perbaikan. Nilai KPI Accessibility mengalami perbaikan yang awalnya hanya 92,5% menjadi 99%. Nilai KPI Retainibility mengalami perbaikan yang awalnya hanya 96% menjadi 99,6%. Nilai KPI Mobility mengalami perbaikan yang awalnya hanya 81% menjadi 97,5%. Sehingga kinerja jaringan juga mengalami perbaikan.Kata Kunci – Interferensi Uplink, RTWP, W-CDMA, NodeB, KP

Journal of Telecommunications and Information Technology, 2001, nr 2

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