Ensuring robust and uniform network coverage is crucial for mobile network operators, particularly at the cell edges, where interference remains a persistent challenge. Traditional solutions such as network densification are complex, costly, and prone to increased interference. This paper presents the performance of recently proposed Cell-Sweeping base stations deployment in a typical 4G LTE network with Single User-Multiple Input Multiple Output (SU-MIMO) operation, use of higher-order modulation schemes, i.e. 256-Quadrature Amplitude Modulation (256-QAM), as well as using 3D antenna radiation patterns. By dynamically sweeping the antenna radiation patterns, cell-sweeping aims to significantly enhance the cell-edge performance while at the same time also harmonises the distribution of throughput in the whole cell. System-level simulations conducted using the 3rd Generation Partnership Project (3GPP) configurations reveal significant performance gain of cell-sweeping of up to 147% improvement in cell-edge throughput observed under open-loop spatial multiplexing, i.e. Transmission Mode 3 (TM3) in 3GPP LTE compared to conventional (i.e. non cell-sweeping) cellular network deployment. The results demonstrate that integrating cell-sweeping with advanced modulation and MIMO configurations is feasible and significantly improves Signal-to-Interference-plus-Noise Ratio (SINR), throughput, and Channel Quality Indicators (CQI) distribution, particularly in dense urban environments. These findings highlight the potential of cell-sweeping as an effective and simpler deployment strategy for future radio access networks.

In this paper, we propose a novel composition aided generalized quadrature spatial modulation (C-GQSM) scheme to improve the spectral efficiency (SE) of the GQSM systems by exploiting the power domain degree of freedom. The C-GQSM scheme constitutes a hybridization of GQSM and composition modulation (CM) principles, allowing the information bits to encompass not only the antenna activation patterns (AAPs) and amplitude/phase modulated (APM) constellation symbols, but also the energy allocation patterns (EAPs). In addition, we present two low-complexity detection techniques for the proposed C-GQSM system. The first one is based on the ordered successive interference cancellation (OSIC) technique, while the other based on the weighted coordinate descent (WCD) algorithm. Moreover, the upper bound of the average bit error probability (ABEP) of the proposed C-GQSM scheme is derived under both uncorrelated and correlated channel conditions. Simulation results show that the proposed C-GQSM outperforms both the conventional CM and GQSM systems in terms of SE without sacrificing the bit error rate (BER) performance.

In this paper, we propose the Turbo principle (of using parallel concatenated channel encoders separated by an interleaver and iterative soft-input and soft-output decoding between the constituent decoders) onto Polar and LDPC codes resulting in Turbo-Polar, Turbo-LDPC-Polar and Turbo-LDPC schemes with the aim of enhancing the BLER performance while also reducing the decoding complexity. All the proposed turbo-coded schemes are decoded using the traditional Belief Propagation (BP) algorithm based on low-density parity-check iterative decoding through a factor graph. Monte Carlo simulation results confirm the superiority of Turbo-LDPC and Turbo-LDPC-Polar schemes in BLER performance over state-of-the-art cyclic redundancy check-aided successive cancellation List decoding (CA-SCL) of Polar Codes with a large list size of 32 for large block lengths (larger than 3072 bits) while having reduced computational decoding complexity in comparison to CA-SCL decoding in an additive white Gaussian noise (A WGN) channel. Furthermore, Turbo-LDPC (based on 5G New Radio specifications for LDPC code) outperforms the standalone 5G-NR LDPC code and achieves about 1 dB gain at a BLER of 10–4over correlated slow fading Rayleigh channel; however, being turbo-iterative in nature, it has higher complexity (about six-fold) than the standalone 5GNR LDPC code.

Guessing random additive noise decoding (GRAND) is a universal decoding that estimates the transmitted codewords by guessing the noise bit sequences and reversing their impact until legitimate codewords are found. This paper investigates one of its variants, namely Soft-GRAND (or SGRAND) of Polar codes over an interference channel where power domain non-orthogonal multiple access (NOMA) channel access protocol is in operation. Monte Carlo simulation results confirm the robustness of the SGRAND decoding over these channels. More specifically, the joint CRC-aided SGRAND decoding outperforms state-of-the-art CRC-aided list decoding (of Polar codes) with a list size of 32 by approximately 0.5 dB and 1.5 dB at block error rate (BLER) of 10−4over additive white Gaussian noise (AWGN) and Rayleigh fading channels, respectively, and also offers lower complexity at mid-to-high signal to noise ratios (beyond 5 dB).

Adequate and uniform network coverage provision is one of the main objectives of cellular service providers. Additionally, the densification of cells exacerbates coverage and service provision challenges, particularly at the cell-edges. In this paper, we present a new approach of cell-sweeping-based Base Stations (BSs) deployments in cellular Radio Access Networks (RANs) where the coverage is improved by enhancing the cell-edge performance. In essence, the concept of cell-sweeping rotates/sweeps the sectors of a site in azimuth continuously/discretely resulting in near-uniform distribution of the signal-to-interference-plus-noise ratio (SINR) around the sweeping site. This paper investigates the proposed concept analytically by deriving expressions for the PDF/CDF of SINR and achievable rate; and with the help of system-level simulations, it shows that the proposed concept can provide throughput gains of up to 125% at the cell-edge. Then, using a link-budget analysis, it is shown that the maximum allowable path loss (MAPL) increases by 2.1 dB to 4.1 dB corresponding to the gains in wideband SINR and post-equalized SINR, respectively. This increase in MAPL can be translated to cell-radius/area with the help of the Okumura-Hata propagation model and results in cell-coverage area enhancement by 30% to 66% in a Typical Urban cell deployment scenario.

In this paper, we propose a transmission mechanism for fluid antennas (FAs) enabled multiple-input multiple-output (MIMO) communication systems based on index modulation (IM), named FA-IM, which incorporates the principle of IM into FAs-assisted MIMO system to improve the spectral efficiency (SE) without increasing the hardware complexity. In FA-IM, the information bits are mapped not only to the modulation symbols, but also the index of FA position patterns. Additionally, the FA position pattern codebook is carefully designed to further enhance the system performance by maximizing the effective channel gains. Then, a low-complexity detector, referred to efficient sparse Bayesian detector, is proposed by exploiting the inherent sparsity of the transmitted FA-IM signal vectors. Finally, a closed-form expression for the upper bound on the average bit error probability (ABEP) is derived under the finite-path and infinite-path channel condition. Simulation results show that the proposed scheme is capable of improving the SE performance compared to the existing FAs-assisted MIMO and the fixed position antennas (FPAs)-assisted MIMO systems while obviating any additional hardware costs. It has also been shown that the proposed scheme outperforms the conventional FA-assisted MIMO scheme in terms of error performance under the same transmission rate.

In this paper, a new approach has been proposed and investigated with the help of variational auto-encoder (VAE) as a probabilistic model to reconstruct the transmitted symbol without sending the data bits out of the transmitter. The novelty of the proposed End-to-end (E2E) wireless system is in representing the symbol as a image hot vector (IHV) that contains the features of the shape such as spikes, closed squared frame, pixels index location and pixels grey-scale colours. The previously mentioned features are inferred by latent random variables (LRVs). The LRVs are used for fronthaul and backhaul data representation. The LRVs parameters have only been transmitted through the physical wireless channel instead of the original bits as in the classical modulations or the hot vectors in the Auto-encoders (AE) E2E systems. The new proposed VAE architecture achieved the reconstruction of the symbol from the received LRV. The results show that the VAE with a simple classifier can provide a better symbol error rate (SER) than both AE baseline and classical Hamming code with hard decision decoding, especially at high$E_{b}/N_{o}$.

Network coverage is an increasing concern for the Quality of Service (QoS) targets of new mobile technologies. New solutions designed to fulfill the requirements of the existing fifthgeneration (5G) and upcoming sixth-generation (6G) emerging scenarios are based on deploying a high number of network access points (APs), which tend to considerably degrade coverage and cell-edge performance due to added interference and increase the energy consumption of cellular systems. In this paper, we present new results on our recently proposed novel concept of cell-sweeping that aims to minimize the coverage dead-spots and improve cell-edge user performance. More specifically, the concept is explored further in this paper analyzing the impact of different cell-sweeping configurations and evaluating the potential benefits towards achieving energy efficiency. By means of system level computer simulations, it is shown that cell-sweeping provides energy savings of 11% and 26.5% for a similar average and cell-edge user throughput performance, respectively, when compared to the conventional static cell deployment in a typical urban macro cell scenario.

At 5G and beyond networks, accurate localization services and nanosecond time synchronization are crucial to enabling mission-critical wireless communications technologies and techniques such as autonomous vehicles and distributed multiple-input and multiple-output (MIMO) antenna systems. This paper investigates how to improve wireless time synchronization by studying time correction based on the Real-Time Kinematics (RTK) positioning algorithm. Using the multiple Global Navigation Satellite System (GNSS) receiver references and the proposed binary GNSS satellite formation to reduce the effect of the ionosphere and troposphere delays and recede the measurement phase-range and pseudorange errors. As a result, it improves user equipment’s (UE) localization and measures the time difference between the Base Station (BS) and the UE local clocks. The results show that the positioning accuracy has been increased, and a millimetre accuracy has been achieved while attaining the sub-nanosecond time error (TE) between the UE’s and BS local clocks.

Good network coverage is an important element of Quality of Service (QoS) provision that mobile cellular operators aim to provide. The established requirements for the existing Fifth Generation (5G) and the emerging scenarios for upcoming Sixth Generation (6G) cellular communication technologies highly depend on the coverage quality that the network is able to provide. In addition, some proposed 5G solutions such as densification, are complex, costly, and tend to degrade network coverage due to increased interference which is critical for the cell-edge performance. In this direction, we present a novel concept of cell-sweeping for coverage enhancement in cellular networks. One of the main objectives behind this mechanism relies on overcoming the cell-edge problem which directly translates into better network coverage. In sequence, the concept operation is introduced and compared to the conventional static cell scenarios. These comparisons target mostly the benefits at the cell-edge locations. Additionally, the use of schedulers that take advantage of the sweeping system is expected to extend the cell-edge benefits to the entire network. This is observed when deploying cell-sweeping with the Proportional Fair (PF) scheduler. A 5th-percentile improvement of 125% and an average throughput increase of 35% were obtained through system level simulations. The preliminary results presented in this paper suggest that cell-sweeping can be adopted as an emerging technology for future Radio Access Network (RAN) deployments.

Being able to accommodate multiple simultaneous transmissions on a single channel, non-orthogonal multiple access (NOMA) appears as an attractive solution to support massive machine type communication (mMTC) that faces a massive number of devices competing to access the limited number of shared radio resources. In this paper, we first analytically study the throughput performance of NOMA-based random access (RA), namely NOMA-RA. We show that while increasing the number of power levels in NOMA-RA leads to a further gain in maximum throughput, the growth of throughput gain is slower than linear. This is due to the higher-power dominance characteristic in power-domain NOMA known in the literature. We explicitly quantify the throughput gain for the very first time in this paper. With our analytical model, we verify the performance advantage of NOMA-RA scheme by comparing with the baseline multi-channel slotted ALOHA (MS-ALOHA), with and without capture effect. Despite the higher-power dominance effect, the maximum throughput of NOMA-RA with four power levels achieves over three times that of the MS-ALOHA. However, our analytical results also reveal the sensitivity of load on the throughput of NOMA-RA. To cope with the potential bursty traffic in mMTC scenarios, we propose adaptive load regulation through a practical user barring algorithm. By estimating the current load based on the observable channel feedback, the algorithm adaptively controls user access to maintain the optimal loading of channels to achieve maximum throughput. When the proposed user barring algorithm is applied, simulations demonstrate that the instantaneous throughput of NOMA-RA always remains close to the maximum throughput confirming the effectiveness of our load regulation.

The fifth-generation (5G) new radio (NR) cellular system promises a significant increase in capacity with reduced latency. However, the 5G NR system will be deployed along with legacy cellular systems such as the long-term evolution (LTE). Scarcity of spectrum resources in low frequency bands motivates adjacent-/co-carrier deployments. This approach comes with a wide range of practical benefits and it improves spectrum utilization by re-using the LTE bands. However, such deployments restrict the 5G NR flexibility in terms of frame allocations to avoid the most critical mutual adjacent-channel interference. This in turns prevents achieving the promised 5G NR latency figures. In this we paper, we tackle this issue by proposing to use the mini-slot uplink feature of 5G NR to perform uplink acknowledgment and feedback to reduce the frame latency with selective blind retransmission to overcome the effect of interference. Extensive system-level simulations under realistic scenarios show that the proposed solution can reduce the peak frame latency for feedback and acknowledgment up to 33% and for retransmission by up to 25% at a marginal cost of an up to 3% reduction in throughput.

In this paper, we investigate the throughput performance of single-packet and multi-packet hybrid-automatic repeat request (HARQ) with blanking for downlink non-orthogonal multiple access (NOMA) systems. While conventional single-packet HARQ achieves high throughput at the expense of high latency, multi-packet HARQ, where several data packets are sent in the same channel block, can achieve high throughput with low latency. Previous works have shown that multi-packet HARQ outperforms single-packet HARQ in orthogonal multiple access (OMA) systems, especially in the moderate to high signal-to-noise ratio regime. This work amalgamates multi-packet HARQ with NOMA to achieve higher throughput than the conventional single-packet HARQ and OMA, which has been adopted in the legacy mobile networks. We conduct theoretical analysis for the throughput per user and also investigate the optimization of the power and rate allocations of the packets, in order to maximize the weighted-sum throughput. It is demonstrated that the gain of multi-packet HARQ over the single-packet HARQ in NOMA systems is reduced compared to that obtained in OMA systems due to inter-user interference. It is also shown that NOMA-HARQ cannot achieve any throughput gain with respect to OMA-HARQ when the error propagation rate of the NOMA detector is above a certain threshold.

In this paper, we present a novel random access method for future mobile cellular networks that support machine type communications. Traditionally, such networks establish connections with the devices using a random access procedure, however massive machine type communication poses several challenges to the design of random access for current systems. State-of-the-art random access techniques rely on predicting the traffic load to adjust the number of users allowed to attempt the random access preamble phase, however this delays network access and is highly dependent on the accuracy of traffic prediction and fast signalling. We change this paradigm by using the preamble phase to estimate traffic and then adapt the network resources to the estimated load. We introduce Preamble Barring that uses a probabilistic resource separation to allow load estimation in a wide range of load conditions and combine it with multiple random access responses. This results in a load adaptive method that can deliver near-optimal performance under any load condition without the need for traffic prediction or signalling, making it a promising solution to avoid network congestion and achieve fast uplink access for massive MTC.

Flexibly supporting multiple services, each with different communication requirements and frame structure, has been identified as one of the most significant and promising characteristics of next generation and beyond wireless communication systems. However, integrating multiple frame structures with different subcarrier spacing in one radio carrier may result in significant inter-service-band-interference (ISBI). In this paper, a framework for multi-service (MS) systems is established based on a subband filtered multi-carrier system. The subband filtering implementations and both asynchronous and generalized synchronous (GS) MS subband filtered multi-carrier (SFMC) systems have been proposed. Based on the GS-MS-SFMC system, the system model with ISBI is derived and a number of properties on ISBI are given. In addition, low-complexity ISBI cancelation algorithms are proposed by precoding the information symbols at the transmitter. For asynchronous MS-SFMC system in the presence of transceiver imperfections, including carrier frequency offset, timing offset, and phase noise, a complete analytical system model is established in terms of desired signal, inter-symbol-interference, inter-carrier-interference, ISBI, and noise. Thereafter, new channel equalization algorithms are proposed by considering the errors and imperfections. Numerical analysis shows that the analytical results match the simulation results, and the proposed ISBI cancelation and equalization algorithms can significantly improve the system performance in comparison with the existing algorithms.

To flexibly support diverse communication requirements (e.g., throughput, latency, massive connection, etc.) for the next generation wireless communications, one viable solution is to divide the system bandwidth into several service subbands, each for a different type of service. In such a multi-service (MS) system, each service has its optimal frame structure while the services are isolated by subband filtering. In this paper, a framework for multi-service (MS) system is established based on subband filtered multi-carrier (SFMC) modulation. We consider both single-rate (SR) and multi-rate (MR) signal processing as two different MS-SFMC implementations, each having different performance and computational complexity. By comparison, the SR system outperforms the MR system in terms of performance while the MR system has a significantly reduced computational complexity than the SR system. Numerical results show the effectiveness of our analysis and the proposed systems. These proposed SR and MR MS-SFMC systems provide guidelines for next generation wireless system frame structure optimization and algorithm design.

Multiuser selection scheduling concept has been recently proposed in the literature in order to increase the multiuser diversity gain and overcome the significant feedback requirements for the opportunistic scheduling schemes. The main idea is that reducing the feedback overhead saves per‐user power that could potentially be added for the data transmission. In this work, the authors propose to integrate the principle of multiuser selection and the proportional fair scheduling scheme. This is aimed especially at power‐limited, multi‐device systems in non‐identically distributed fading channels. For the performance analysis, they derive closed‐form expressions for the outage probabilities and the average system rate of the delay‐sensitive and the delay‐tolerant systems, respectively, and compare them with the full feedback multiuser diversity schemes. The discrete rate region is analytically presented, where the maximum average system rate can be obtained by properly choosing the number of partial devices. They optimise jointly the number of partial devices and the per‐device power saving in order to maximise the average system rate under the power requirement. Through the authors’ results, they finally demonstrate that the proposed scheme leveraging the saved feedback power to add for the data transmission can outperform the full feedback multiuser diversity, in non‐identical Rayleigh fading of devices’ channels.

Recently proposed universal filtered multicarrier (UFMC) system is not an orthogonal system in multipath channel environments and might cause significant performance loss. In this paper, the authors propose a cyclic prefix (CP) based UFMC system and first analyze the conditions for interference-free one-tap equalization in the absence of transceiver imperfections. Then the corresponding signal model and output signal-to-noise ratio expression are derived. In the presence of carrier frequency offset, timing offset, and insufficient CP length, the authors establish an analytical system model as a summation of desired signal, intersymbol interference, intercarrier interference, and noise. New channel equalization algorithms are proposed based on the derived analytical signal model. Numerical results show that the derived model matches the simulation results precisely, and the proposed equalization algorithms improve the UFMC system performance in terms of bit error rate.

Small cell (SCell) and Software Define Network (SDN) are two key enablers to meet the evolutional requirements of future telecommunication networks, but still on the initial study stage with lots of challenges faced. In this paper, the problem of mobility management in SDN-integrated LTE (Long Term Evolution) mobile backhaul network is investigated. An 802.1ad double tagging scheme is designed for traffic forwarding between Serving Gateway (S-GW) and SCell with QoS (Quality of Service) differentiation support. In addition, a dynamic localized forwarding scheme is proposed for packet delivery of the ongoing traffic session to facilitate the mobility of UE within a dense SCell network. With this proposal, the data packets of an ongoing session can be forwarded from the source SCell to the target SCell instead of switching the whole forwarding path, which can drastically save the path-switch signalling cost in this SDN network. Numerical results show that compared with traditional path switch policy, more than 50% signalling cost can be reduced, even considering the impact on the forwarding path deletion when session ceases. The performance of data delivery is also analysed, which demonstrates the introduced extra delivery cost is acceptable and even negligible in case of short forwarding chain or large backhaul latency.

In this paper, we consider Coordinated Multi-Point (CoMP) in a cloud-based radio access network (RAN), where each coordinating access point compresses its observation using distributed Wyner-Ziv compression and forwards the compressed signal to the receiving processing unit. We map this architecture to the multiple-relay compress-and-forward (CF) problem, derive the achievable rate of such a system and then show that the achievable rate can be maximized by optimizing the distributed compression rate at each individual coordinating point in a joint manner. An iterative optimization algorithm is proposed and numerical results indicate that compared with other coordinating schemes, when the channel between the coordinating points and the processing unit is strong, using distributed compression can effectively improve the spectrum efficiency.

This paper brings to light the reasoning and principles shaping the standardization direction in the 3rd Generation Partnership Project (3GPP) regarding provision of low complexity Machine Type Communication (MTC), via Long Term Evolution (LTE) of 3GPP. It elaborates 3GPP's approaches and suggestions towards addressing the physical layer challenges and discusses solutions 3GPP proposed specifically in relation to the low complexity operation of MTC devices and the coverage extension of current cellular networks to challenging scenarios of MTC. Results of comprehensive set of simulations are presented to assess the impact of repetition coding and power boosting on the physical downlink shared channel (PDSCH). In addition, novel ideas are presented to reduce the complexity of channel estimation, one of the most computation intensive blocks in the baseband receive chain. These results all leap towards finding the physical layer design for low cost MTC devices via 3GPP LTE.

We present a distributed energy-efficient Inter-Cell Interference Coordination (ICIC) scheme for multi- cell HetNets (Heterogeneous Networks) in the downlink. This novel scheme aims to maximize the user fairness performance of the overall system as well as minimizing the total average transmit power at the base station side. We consider a realistic power model to characterize the power consumed (including circuit and transmitted power) at the base station side. We define an energy efficient performance metric in bits/Joule and the user fairness as the 5th percentile of the average user throughput. The proposed scheme is divided into the following three stages: dominant interferences classification, inter-cell radio resource allocation and intra-cell power control. The inter-cell radio resource allocation is formulated as a multidimensional knapsack problem. In order to satisfy the complexity requirements associated with multi-cell networks, we simplify, relax and decompose the original problem into a main master problem and multiple sub-problems. Our simulation results show the proposed scheme significantly increases both the user fairness and the energy efficiency (EE) of the overall network.

In this paper, we propose a low-complexity distributed Inter-Cell Interference Coordination (ICIC) for emerging multi-cell HetNets (Heterogeneous Networks). The proposed scheme is quickly solved using linear programming tools and aims to maximize both the critical and the overall performance of the multi-cell system. Additionally, a utility measure is used to provide a varying level of user fairness to satisfy the most demanding network providers. Simulation results confirm the low-complexity of the proposed algorithm and its increased effectiveness over a number of state-of-art interference avoidance schemes.

This paper quantifies the impact of co-tier interference in femtocells (i.e. inter-cell interference arising from other neighbouring femtocells) through a semi-analytical approach concluding that without interference mitigation techniques, QoS in the form of acceptable outage probability is not achievable in scenarios representing medium to worst cases of interference. Results obtained from semi-analytical approach are also compared against Monte Carlo simulations for evaluation purposes. Subsequently, some important radio access parameters and deployment configurations, such as path loss model, shadowing, wall penetration loss, location of femtocells and user distribution are further examined as key elements that can potentially affect, positively or negatively, the femtocell-to-femtocell interference in a multi-femtocell deployment. The results can be used as guidelines in the deployments of femtocells.

A mass deployment of femtocells is anticipated to affect a number of areas more adversely, especially in the cell-edge of the macrocell network. In this paper, we propose a flexible frequency-partitioning scheme for OFDMA network based on cyclic difference sets. The cyclic property of these sets allows a quick construction of orthogonal patterns for the macrocell network with an emphasis on tri-sector sites. The impact and the co-deployment of femtocells is also investigated. Unlike, with existing works in the literature, the novel scheme can adaptively control the level of coverage in the cell-edges areas and additionally enables coexistence of femtocells in the network. Simulation results confirm the effectiveness of the proposed scheme in both macrocell and femtocell networks compared to the legacy soft frequency reuse and universal frequency reuse.

Femtocell networks are inherently interference- limited similar to other cellular networks. However, massive and unplanned roll-outs of femtocells make the classical macro cells more susceptible to the resulting interference. In this paper a novel distributed approach is proposed for resource allocation for femtocells that opportunistically identifies low-cost resources (in terms of interference) in a way that would cause minimal impact on the service level of primary macro users. Simulation study confirms the efficiency of proposed algorithm compared to benchmarking scenario of macro-only network operation. As it is shown, the proposed method enables flexible tuning of femto throughput at the cost of macro users service.

This paper highlights the deficiencies of classical figures of merit such as throughput and fairness index to evaluate different scheduling algorithms and proposes a new complementary figure of merit called as transport-throughput, which has been inspired from information theory literature to better represent trade-offs among throughput, fairness and coverage associated with a given scheduling algorithm. Furthermore, new objective functions for opportunistic scheduling are proposed that utilize the knowledge about the geographic distance of mobile terminals from the base station. The proposed concept can be easily integrated as an extension to classical scheduling algorithms and provides the ability to control the effective distribution of throughput across the network

In this paper, a novel framework is proposed to integrate spectrum (resource) sharing into multihop scheduling in relay-assisted systems. This approach provides an effective solution to minimize the effect of extra resources that are required in multihop transmission. Particularly, this approach can be combined with different topologies of resource scheduling to provide better performance in terms of throughput and coverage compared to benchmark non-sharing algorithms.

This paper investigates spectrum sharing (in the form of code sharing) between two Universal Mobile Telecommunication System (UMTS) operators in the UMTS extension band (2500-2690 MHz) with equal and unequal number of proprietary carriers, respectively. The paper proposes a dynamic spectrum allocation (DSA) algorithm to address the problem of spectrum sharing between two operators on a non-pool basis. It also investigates the impact of adjacent channel interference (ACI) on the spectrum sharing gain. Additionally, an architecture that enables spectrum sharing to take place between two or more UMTS operators is presented. The simulated performance of the proposed DSA algorithm shows that under peak-hour loading, up to 32% increase in capacity can be obtained when compared to currently used fixed spectrum allocation (FSA).

In this paper, the efficiencies of different interference coordination schemes are evaluated for emerging wireless networks and the possible impact on intra-cell scheduling is studied through extensive simulations. The results show that pure fractional frequency reuse can provide similar improvement in the cell-edge throughput compared to power coordinated counterpart at a less cost in terms of overall throughput. Moreover, it can provide fairer distribution of throughput in both central as well as cell-edge areas. However, this scheme can not mange asymmetrical changes in the distribution of users across different cells in the entire system. As a result, a power coordination mechanism would be still necessary on top of such flexible frequency reuse schemes.

One of the key features of High-Speed Downlink Packet Access (HSDPA) is Adaptive Modulation and Coding (AMC). Link Adaptation at Node-B is done on the basis of Channel Quality Indicator (CQI) reports sent by the User Equipment (UE). However there is a delay of about 10 ms between computation of a CQI report at UE and the corresponding Transport Format and Resource Indicator (TFRI) selection at the Node-B. This delay significantly degrades the performance of link adaptation process. In order to compensate for this loss of performance, we propose predictive CQI reporting by the UE. A simple linear predictor based on NLMS (Normalized Least Mean Square) adaptation is shown through simulations to provide substantial gain in HSDPA link throughput. Results show that predictive CQI reporting provides larger gain in channel environments with medium to high Doppler and lack of multipath diversity.

This paper investigates the downlink handover (soft/softer/hard) performance of wideband code division multiple access (WCDMA) based 3rdgeneration universal mobile telecommunication system (UMTS), as it is known that the downlink capacity of UMTS is very sensitive to the extent of overlap area between adjacent cells and power margin between them. Factors influencing the handover performance such as the correlation between the multipath radio channels of the two links, limiting number of Rake fingers in a handset, imperfect channel estimation, etc. that cannot be modeled adequately in system-level simulations are investigated via link-level simulations. It is also shown that the geometry factor has an influence on the handover performance and exhibits a threshold value (which depends on the correlation between the multipath channels associated with the two links in a handover) above which the performance starts degrading. The variation of the handover gain with the closed loop power control (CLPC) step-size and space-time transmit diversity (STTD) is also quantified. These comprehensive results can be used as guidelines for more accurate coverage and capacity planning of UMTS networks.

Adaptive modulation and coding (AMC) is one of the important features of high-speed downlink packet access (HSDPA). The link adaptation is done at the Node-B on the basis of channel quality indicator (CQI) reports sent by the user equipment (UE). However the performance of AMC scheme is degraded due to the large delay between computation of CQI report at UE and the corresponding transport format and resource indicator (TFRI) selection at the Node-B. An improved link adaptation approach, named CQI averaging herein, is proposed in this paper. In this approach, a number of consecutively received CQI reports from UE are mapped to equivalent signal to interference ratio (SIR) values and passed through a moving average filter. The resulting average is used to derive the CQI index (named Average CQI herein) to be followed at Node-B transmitter. This approach provides a significant gain, especially for medium vehicular speeds. The gain is more pronounced for channels that provide less multipath diversity. Simulation results are used to relate desirable filter length of the moving average filter with the characteristics of the radio channel. Subsequently, an algorithm for adaptation of filter length based on the statistics of CQI reports is proposed.

Multimedia Broadcast/Multicast Service (MBMS) is introduced in the Release 6 of the 3rdGeneration Partnership Project (3GPP) and is characterized by relatively longer interleaving depth. This paper investigates the exploitation of the longer interleaving depth by chip block interleaving to obtain intra-bit diversity. Both terrestrial and satellite modes of MBMS delivery mechanisms are studied and it is found out that chip block interleaving provides a reduction in the transmission power (2.5 dB in terrestrial flat Rayleigh fading channel, 0.75 dB in 4-tap 3GPP Case 3 radio channel, 1.5 dB in satellite line of sight Ricean flat fading channel and 0.7 dB in 9-tap satellite multipath fading due to intermediate module repeaters) at moderate speeds of 30-50 km/h and a moderate interleaving depth of 20 ms for 64 kbps data service. Moreover, it is also shown that for terrestrial mobile radio channels, the gain provided by chip block interleaving with block length equal to half the spreading factor and using only one transmit antenna is equal to that provided by Space Time Transmit Diversity (STTD) that requires two transmit antennas.

SIR estimation for fast closed loop power control (CLPC) of a WCDMA FDD downlink with space time transmit diversity (STTD) is analysed. It is shown that without STTD encoding/decoding of the DPCCH (dedicated physical control channel) pilot symbols of the two antennas, the SIR estimation suffers from inter-antenna interference. Without modifying the DPCCH pilot patterns in the current 3GPP standard, near-best performance is achieved by using all the pilot symbols for signal power estimation, but only the STTD decoded shaded symbols for interference estimation, to avoid the inter-antenna interference.