The upper mid-band FR3 spectrum (7–24GHz) has garnered significant interest for future cellular services. However, utilizing a large portion of this band requires careful interference coordination with incumbent satellite systems. This paper investigates interference from high-power terrestrial base stations (TN-BSs) to satellite downlink receivers. A central challenge is that the victim receivers, i.e., ground-based non-terrestrial user equipment (NTN-UEs), such as satellite customer premises equipment, must first be detected, and their channels estimated, before the TN-BS can effectively place nulls in their directions. We explore a potential solution where NTN-UEs periodically transmit preambles or beacon signals that TN-BSs can use for detection and channel estimatio. The performance of this nulling approach is analyzed in a simplified scenario with a single victim, revealing the interplay between path loss and estimation quality in determining nulling performance. To further validate the method, we conduct a detailed multi-user site-specific ray-tracing (RT) simulation in a rural environment. The results show that the proposed nulling approach is effective under realistic parameters, even with high densities of victim units, although TN-BS may require a substantial number of antennas.

Global allocations in the upper mid-band spectrum (4-24 GHz) necessitate a comprehensive exploration of the propagation behavior to meet the promise of coverage and capacity. This paper presents an extensive Urban Microcell (UMi) outdoor propagation measurement campaign at 6.75 GHz and 16.95 GHz conducted in Downtown Brooklyn, USA, using a 1 GHz bandwidth sliding correlation channel sounder over 40-880 m propagation distance, encompassing seven Line of Sight (LOS) and 13 Non-Line of Sight (NLOS) locations. Analysis of the path loss (PL) reveals lower directional and omnidirectional PL exponents compared to mmWave and sub-THz frequencies in the UMi environment, using the close-in (CI) free space PL (FSPL) model with a 1 m reference distance. Additionally, a decreasing trend in root mean square (RMS) delay spread (DS) and angular spread (AS) with increasing frequency was observed. The measured NLOS RMS DS and RMS AS mean values (as computed by 3GPP methods) are found to be consistently lower compared to 3GPP model predictions. Point-data tables with corresponding site-specific environmental information for all measured statistics at each TX-RX location are provided to support the models and results. The spatio-temporal statistics presented here offer valuable insights for the design of nextgeneration wireless systems and networks.

Large language models (LLMs) can perform a plethora of tasks, however, they often require cloud servers for deployment due to their computing cost and size. Meanwhile, small and cost-effective LLMs can be deployed on edge devices (e.g., mobile devices), but they often exhibit lower response quality than larger models. In this paper, a measurement-driven training framework is proposed for a device-side artificial intelligence (AI)-enabled router that selects the best LLM in terms of cost, latency, and performance. In the considered framework, a mobile device uses its local LLM (sub-billion LLM), while having access to a bigger server LLM (GPT-4) hosted on a 5G core network. The mobile device has a router that sends an input prompt to the local or server LLM to optimize the cost, latency, and performance of output LLM responses. To train the router, the dataset is constructed by measuring the cost, latency, and performance of the server LLM and the local LLM on a mobile device. The structural causal model (SCM) of the measured dataset is identified. To further improve performance, a causality-driven data augmentation method is also proposed based on the discovered SCM. Real-world experimental results show that the proposed framework can improve the cost and latency by 50% and 31%, respectively, with only a 2.13% performance loss compared to a baseline that only uses the server LLM.

Delivering committed traffic Quality of Service (QoS) per Service Level Agreement (SLA) requires support of critical intelligent traffic management features in LTE eNodeB (and future 5G access nodes), such as Uplink Traffic Shaping and Congestion and Admission Control (CAC). This paper highlights the motivation and merits of uplink traffic shaping in preserving QoS levels per traffic categories over transport links. Techniques for packet coloring, which are used in the fixed networks, are considered herein to mark packet priorities within the wireless access nodes. In particular, the paper introduces an algorithm for intelligent packet coloring, with the goal to protect the critical traffic while maximizing the return of investments made by network operators.

Emerging 5G networks will not only offer higher link rates, but also integrate a variety of Radio Access Technologies (RATs) in order to provide ultra-reliable broadband access to a wide range of applications with high throughput and low latency requirements. SDN-enabled dynamic path selection is of critical importance in exploiting the collective transmission resources in such heterogeneous multi-RAT environments and delivering excellent user performance. In the present paper we propose the `best-rate' path selection algorithm for multi-RAT networks with various types of traffic flows. The best-rate algorithm accounts for the radio conditions and performance requirements of individual flows as well as the load conditions at the various access points. We analytically establish that the rates received by the various flows under the best-rate path selection, in conjunction with local fair resource sharing at the individual access points, are close to globally Proportional Fair. Detailed simulation experiments demonstrate that the best-rate algorithm achieves significant gains in terms of user-perceived throughput performance over various baseline policies.

The paper describes the principles of a novel mechanism that is aiming at providing unprecedented Quality of Experience (QoE) in next generation mobile networks. The main benefits include: (i) enabling dynamic IP tunnel management (establishing and tearing down) with terminating point in the mobile device instead of the traditional base station; (ii) enabling multiple parallel tunnels (e.g., Generic Routing Encapsulation (GRE)) between an anchor node and a mobile device, where a specific tunnel may support differentiated Quality of Service (QoS) requirements for a targeted service class; (iii) enabling advanced network protocol support for service flows split across multiple Radio Access Technologies (M-RATs), whenever it may be deemed necessary to support and maintain a targeted QoS level per service flow; (iv) allowing to aggregate the necessary bandwidth to meet the QoS requirements per service flow if no single RAT can fulfill them alone; (v) supporting massive M-RAT capacity aggregation for enhanced scalability and very large throughput.

This paper addresses the design of a novel ultra-broadband wireless access system, as an alternative to fiber to the home (FTTH) deployments. Hence, the system must be capable of delivering very high data rates to indoor users without the need of deploying fiber to homes. We show that a hybrid wireless access system with outdoor deployed cell sites operating jointly across high and low spectrum bands enables ultra-broadband wireless connectivity to indoor users with indoor antennas close to the windows. On the other hand, a system operating in the 28 GHz band alone does not achieve the target performance. We have created a representative suburban neighborhood via the Bell Labs WiSE (Wireless System Engineering) 3D ray tracing tool and explored multiple system design options to provide such high data rates to homes. Via 3D ray tracing environment simulations, we demonstrate that sustained throughputs on the order of 100Mbps at the cell edge may be delivered to multiple homes within the representative suburban neighborhood. Further, we studied the sensitivity to parameters such as density of sites, number of active beams, Effective Isotropic Radiated Power (EIRP) and interference characteristics.

The global mobile traffic is exponentially growing and more than 90% of the Internet traffic uses Transmission Control Protocol (TCP) for reliable transmission. However, TCP is known to perform poorly over unreliable wireless networks. One of the promising families of solutions to improve the performance of TCP is centered on Split-TCP. However, while Split-TCP may improve the protocol performance, it is vulnerable due to the broken end-to-end semantics. Several variants have been proposed to overcome this pitfall, but while they address the broken semantics, they also defeat the main purpose by compromising the TCP performance gains. In this paper, we propose a novel Enhanced Split-TCP (ES-TCP) mechanism, which significantly improves the application throughput without breaking the end-to-end TCP semantics. Experimental results show that the proposed ES-TCP may boost the TCP throughput by more than 60% in average when exercised over an operational 4G LTE network. Furthermore, the TCP throughput performance improvement may be even over 200%, depending on the network and usage conditions. We expect such throughput gains may be even greater when advanced radio technologies, such as 5G, are deployed. For these reasons, the ES-TCP is a promising transport layer solution for the current and next generation networks.

We use 3-D ray tracing to evaluate the performance of millimeter wave (mmWave) cellular in a realistic model of MetLife stadium, NJ, USA. We model thousands of human blockages using the dielectric properties at 28 GHz. Using this setup, we contrast the coverage and capacity performance with and without human blockages. Our study highlights that incorporating human models is essential for performance evaluation and also for deployment choice. We study the scaling in achievable data rates of three dense deployments in the stadium, and conclude that meeting the minimum 100 Mbps 5G requirement in stadiums can be challenging with a unicast mode of transmission. Broadcasting popular content in conjunction with a multiplexed unicast mode can provide minimum 100 Mbps rate for the broadcasted content.

We employ a ray tracing framework to extract the three dimensional (3D) channel parameters characterizing outdoor small cell deployments providing services to indoor users close to the exterior wall and windows at 28 GHz and 3.5 GHz. The wireless channel is highly dependent on 3D antenna patterns, the environment specific characteristics such as 3D geometry of the buildings, materials used for building construction and their specific propagation properties. These dependencies are particularly important at higher frequencies, where the range of radio signals may be significantly limited due to the path loss and shadowing by obstacles. A good understanding of the channel propagation characteristics at these frequencies, and their correlation to propagation at lower bands, is thus critical for designing and deploying reliable radio systems. The ray tracing approach has substantial merits in absence of relevant field measurements, facilitating extraction of the 3D site-specific channel parameters pertaining to 28 GHz small cell deployments and giving useful insights to foster innovation of new wireless technologies at 28 GHz. Furthermore, we derive channel statistics at both 28 GHz and 3.5 GHz for the same environment drawing conclusions on path loss, delay spread, and angle spread in azimuth and vertical directions. Our results indicate that for the environment considered the angle spread of azimuth angle of arrival exceeds 20° in more than 45% of the terminal locations even at 28 GHz, suggesting that very high beamforming gain at the terminal is not feasible. Furthermore, with a 15° grid of beams based transmitted signal, the best beam at 28 GHz is different from that 3.5 GHz for almost 60% of the locations.

The worldwide mobile traffic is growing rapidly and more than 90% of the internet traffic relies on the Transmission Control Protocol (TCP) protocol, which is known to have a poor performance over unreliable wireless networks. One of the promising TCP enhancement mechanisms that are being considered by the wireless network operators is the Split-TCP. It is also quite well known that the Split-TCP suffers from broken end-to-end protocol semantics, and this may be a significant drawback in some scenarios, where large file transmissions may get aborted after consuming a large volume of network resources. There are various enhancements to overcome this pitfall, but at the expense of a loss in performance. In this paper, we propose a novel Advanced Split-TCP (AS-TCP) mechanism, designed with the goal to improve significantly the application throughput while maintaining the end-to-end protocol semantics down to the byte level, as through the conventional TCP. Our findings indicate that the TCP throughput gains achieved through AS-TCP with respect to a conventional TCP may be above 60% over a 4G LTE network. Furthermore, AS-TCP may enable TCP throughput gains in excess of 200% for some network and traffic conditions. The throughput gains are expected to be even greater when advanced radio technologies are deployed. Hence, we anticipate that AS-TCP will enable the Split-TCP mechanism to be widely deployed in both current and next generation networks, such as 5G.

We demonstrate a ray tracing framework to extract the 3-D channel parameters as input to stochastic models in studying small cell environments, and investigate the dependence of the channel parameters on environmental characteristics, antenna patterns, and frequency. We focus on long-term evolution small cells, taking as reference outdoor small cell deployments providing services to indoor users. We present the measurement results proving the feasibility of outdoor deployment of small cells for indoor coverage and validate the ray tracing framework with the available measurements. Many stochastic channel models treat the channel parameters in two dimensions to capture the characteristics of macro cellular networks, where base stations are placed hundreds of meters away from each other. In contrast, small cells are deployed much more closely to each other. The performance of small cells is highly dependent on the 3-D environment characteristics and antenna patterns. Therefore, the site specific modeling of channel parameters in three dimensions is quintessential for small cell environments. We demonstrate ray tracing as an efficient technique to extract the 3-D site-specific channel parameters pertaining to small cell environments, and to calibrate the stochastic models used with site specific channel parameters.

Offering good Quality of Experience (QoE) in stadiums poses unprecedented challenges to Wireless Operators, due to extreme traffic conditions. During popular sporting events, there could be tens of thousands of active users present in a relatively small area, downloading/uploading pictures and video clips through smart phone applications. This results in a large traffic density and drives requirements for high capacity, and yet economically feasible solutions for stadiums. Ensuring high capacity required in such open and heavily interfered environments is a daunting task. Small cells offer promising advantages to increase the spectral efficiency of wireless systems, thanks to their small frequency reuse factor. We show through environment simulations that it is possible to serve thousands of users in a stadium using small cell technologies. In particular, Wi-Fi and LTE small cells can be used in stadiums to complement each other to cope with the increasing capacity demand.

On the Internet, most traffic is generated by content delivery applications such as video streaming, P2P and web surfing. With the proliferation of mobile applications that offer on-demand access to services, the ability to track end-user's perceived service quality has become a pivotal aspect for future networks such as 5G. Software-defined networking (SDN) and network functions virtualization (NFV) in the mobile core offer unprecedented flexibility for opportunistic traffic steering, leading to advanced levels of quality-of-service (QoS) control. We leverage the SDN concept to dynamically control network traffic over wide area networks (WANs) from edge nodes of wireless networks (e.g., a packet data network gateway in LTE), depending on changing network conditions and application types. Our SDN-based application-aware routing system allows mobile network operators to achieve better utilization of their networks, service providers to improve customer satisfaction, and end-users to experience desirable service quality for various network applications. As for a prototype, we attach 802.11g to Mininet's virtual networks in order to show the feasibility of our approach.

We investigate video server selection algorithms in a distributed video-on-demand system. We conduct a detailed study of the YouTube Content Delivery Network (CDN) on PCs and mobile devices over Wi-Fi and 3G networks under varying network conditions. We proved that a location-aware video server selection algorithm assigns a video content server based on the network attachment point of a client. We found out that such distance-based algorithms carry the risk of directing a client to a less optimal content server, although there may exist other better performing video delivery servers. In order to solve this problem, we propose to use dynamic network information such as packet loss rates and Round Trip Time (RTT) between an edge node of a wireless network (e.g., an Internet Service Provider (ISP) router in a Wi-Fi network and a Radio Network Controller (RNC) node in a 3G network) and video content servers, to find the optimal video content server when a video is requested. Our empirical study shows that the proposed architecture can provide higher TCP performance, leading to better viewing quality compared to location-based video server selection algorithms.

Adaptive bitrate (ABR) technologies are being widely used in today's popular HTTP-based video streaming such as YouTube and Netflix. Such a rate-switching algorithm embedded in a video player is designed to improve video quality-of-experience (QoE) by selecting an appropriate resolution based on the analysis of network conditions while the video is playing. However, a bad viewing experience is often caused by the video player having difficulty estimating transit or client-side network conditions accurately. In order to analyze the ABR streaming performance, we developed YouSlow, a web browser plug-in that can detect and report live buffer stalling events to our analysis tool. Currently, YouSlow has collected more than 20,000 of YouTube video stalling events over 40 countries.

We present a study of traffic behavior of two popular over-the-top (OTT) video streaming services (YouTube and Netflix). Our analysis is conducted on different mobile devices (iOS and Android) over various wireless networks (Wi-Fi, 3G and LTE) under dynamic network conditions. Our measurements show that the video players frequently discard a large amount of video content although it is successfully delivered to a client. We first investigate the root cause of this unwanted behavior. Then, we propose a Quality-of-Service (QoS)-aware video streaming architecture in Long Term Evolution (LTE) networks to reduce the waste of network resource and improve user experience. The architecture includes a selective packet discarding mechanism, which can be placed in packet data network gateways (P-GW). In addition, our QoS-aware rules assist video players in selecting an appropriate resolution under a fluctuating channel condition. We monitor network condition and configure QoS parameters to control availability of the maximum bandwidth in real time. In our experimental setup, the proposed platform shows up to 20.58% improvement in saving downlink bandwidth and improves user experience by reducing buffer underflow period to an average of 32 seconds.

Real-time packet based services such as Voice over IP (VoIP) have stringent packet delivery requirements, characterized by very low packet loss (in the order of 1% – 2%) and tight air-interface delay budgets in the order of tens of milliseconds (ms). In the context of IEEE 802.16e, VoIP service raises additional challenges since the MAP overhead, and hence the required resources dedicated to the control traffic, can grow very large in the presence of multiple simultaneous connections, limiting the amount of resources that can be devoted to the effective traffic. The paper offers a detailed understanding of the specifics of the VoIP application in the IEEE 802.16e (mobile WiMAX) context, including an overview of various design choices, implementation challenges and performance analysis. VoIP capacity results are presented for a set of scenarios accounting in the downlink direction.

As opposed to best-effort data applications, which tolerate a lot of flexibility from a system resource allocation standpoint, real-time services such as Voice over IP (VoIP) have very stringent packet delivery requirements, characterized by tight air-interface delay budgets in the order of tens of milliseconds (ms). Speech packets are short by nature and need to be carried out with minimal packet loss probability, typically no more than 1%-2%. These constraints are even more limiting in the uplink, where the available power at the mobile terminal - couple of hundreds of milliWatts (mW) - is much lower compared to the available power at the base station in the downlink (tens of Watts (W)). The paper addresses the VoIP service in the context of the limiting uplink direction of an IEEE 802.16e system via a comprehensive system simulation study.

The revolutionary success of commercial broadband wireless network has spurred significant interest in employing related technologies such as 3GPP long term evolution (LTE) technologies to build a nationwide mobile broadband network for public safety entities. The successful deployment and operation of a public safety network, however, are more challenging than the traditional commercial wireless networks due to the high reliability and security requirements, unpredictable traffic patterns, and fast time-varying user population density. In this paper, we propose a framework of coordinated dual-layer beamforming schemes to address these challenges. The distinct features of the proposed systems are detailed and the architecture and realization are discussed. While a smart antenna is capable of forming multiple beams, it is unlikely to activate all of them simultaneously. We thus develop efficient beam scheduling algorithms that could adapt to the time-varying channel conditions and traffic loads by adaptively adjusting the beam switching sequence. We also reveal that the coordinated dual-layer beamforming technologie not only has the potential of significantly enhancing the system capacity, but also can turn a NP-complete beam scheduling problem into a problem that can be easily solved if network MIMO technologies are employed. It is seen through simulation studies that the proposed schemes could offer multi-fold capacity improvements over more traditional systems equipped with broader antenna patterns (e.g., omnidirectional). Also, while we focus on public safety network in this paper, the proposed coordinated dual-layer beamforming framework can be equally applied to provide mobile access to any hotspot area with dense mobile users, e.g., a conference room or a stadium.

Distributed space-time block coding with orthogonal frequency division multiplexing (DSTBC-OFDM) and distributed space-frequency block coding with orthogonal frequency division multiplexing (DSFBC-OFDM) are introduced in this paper. Unlike the original DSTBC scheme which was designed for networks with a fixed number of relays operating in frequency-nonselective channels with insignificant Doppler spread, the proposed schemes are designed specifically for networks with an arbitrary number of relays and wireless channels with significant delay spread and Doppler spread. It is shown that geographically distributed antennas employing the new transmission schemes in a frequency-selective and severe Doppler spread environment can achieve the same performance (in terms of diversity gain and coding gain) as the previously proposed scheme.

In this paper, we propose jointly-optimized beamforming algorithms for cognitive networks to maximize the achievable rates, where primary and cognitive users share the same spectrum and are equipped with multiple antennas. We consider the transmission of a single information stream in both primary and secondary links. No coordination is required between the primary and cognitive users and the interference cancellation is done at the cognitive user. Specifically, the beamforming vectors of the cognitive link are designed to maximize the achievable rate under the condition that the interference both at the primary and cognitive receivers is completely nullified. Furthermore, it is proved that the achievable rate of a general N_t^{C}x 2 (N_t^{C} transmit antennas at the cognitive transmitter and 2 receive antennas at the cognitive receiver) cognitive multiple-input multiple-output (MIMO) link employing the optimal proposed beamformers (which completely nullifies the interference to and from the primary link while maximizing its own achievable rate) is the same as the rate of an interference-free (N_t^{C}-1)x 1 multiple-input single-output (MISO) link employing an optimal maximal ratio transmission beamforming vector. The sum rate performance of the proposed algorithms is evaluated by Monte Carlo simulations. The impact of the number of transmit and receive antennas on the proposed algorithm is also discussed.

The capacity of a wireless network could be considerably improved by employing directional antennas that are capable of illuminating multiple beams toward different directions. However, more beams from the same BS may lead to stronger inter-cell interference. In this paper, we consider coordinated beam scheduling schemes to mitigate the inter-cell interference. We first formulate this problem as a combinatorial optimization problem. We then reveal that the complexity of this problem hinges upon a single scalar termed as degree of constraint (DoC), which is related to the degree of conflict a beam is subject to. If the DoC is at least three, the general beam scheduling problem is NP-hard. If DoC is smaller than three, which corresponds to a relevant subclass of the beam scheduling problem arising in practice, this problem can be solved in polynomial time. We propose an optimal beam scheduling algorithm based on the auction method to this particular subclass of problem. This algorithm is of low complexity and is well suited for distributed implementations. We then extend the auction algorithm to solve the general multi-cell beam scheduling problem. The performance of the proposed algorithms is finally assessed through extensive simulation studies.

With increasing implementation of broadband wireless networks and extensive deployment of multimedia services such as Video on Demand (VoD) or IPTV, the demand for video streaming applications will increase and more people will use their wireless devices to reach numerous video contents available in the Internet. Streaming real-time video in wireless networks is a challenging problem due to the stringent service requirements of video traffic and impairments of wireless channels. Providing the required Quality of Service (QoS) through efficient resource allocation is a complicated problem that service providers are confronting. In this paper, we propose a traffic-aware, cross-layer solution for enhancing the perceived video quality at the end user in wireless networks. Our solution incorporates the characteristics of the MPEG traffic to give more priority to the more important frames and to protect them against dropping when available resources of the network are not sufficient for providing the desired QoS to the traffic flow. It is shown that the proposed solution will improve the perceived video quality over the broadband wireless networks.

Femtocells are low-cost, low-power cellular base stations that are designed to provide high quality cellular service in residential or enterprise environments and operate in licensed spectrum to connect conventional, unmodified mobile terminals to a mobile operator's network. The deployment of femtocells will reduce the number of indoor users that need to be served by the macrocellular network. Moreover, since indoor users usually have poorer radio channel conditions to the macrocell compared to outdoor users, for each indoor user that is served by a femtocell, the equivalent system resources of the macrocellular network might be able to serve more than one outdoor user, resulting in a potential macrocell offloading gain. The macrocell offloading benefits achievable in joint macro-femtocell deployments are investigated using system level simulations. It is shown that the potential increase in the number of supported users per macrocell in joint macro- and femtocell deployments depends on the macrocellular network configuration and can range from no gain for a system which is only interference limited to more than 30% in cases where noise is the limiting factor for indoor users at the macrocell edge.

Extensive efforts have been focused on deploying broadband wireless networks. Providing mobile users with high speed network connectivity will let them run various multimedia applications on their wireless devices. Satisfying users with different quality-of-service requirements while optimizing resource allocation is a challenging problem. In this paper, we discuss the challenges and possible solutions for transmitting MPEG video streams over WiMAX networks. We will briefly describe the MPEG traffic model suggested by the WiMAX Forum. A cross-layer solution for enhancing the performance of WiMAX networks with respect to MPEG video streaming applications is explained. Our solution uses the characteristics of MPEG traffic to give priority to the more important frames and protect them against dropping. Besides, it is simple and compatible with the IEEE 802.16 standards and thus easily deployable. It is shown that the proposed solutions will improve the video quality over WiMAX networks.

The paper focuses on the design of a third Generation (3G) wireless network employing traffic concentrators over the transport segment of the network. Thanks to their capability to achieve traffic multiplexing gains, traffic concentrators provide considerable operational savings by reducing the number of transmissions links required at the base station transceivers. This is particularly beneficial to Service Providers needing to lease transport links. This paper addresses potential network topologies with access concentrators and discusses benefits achieved by intelligently introducing traffic concentrators within the architecture of a 3G wireless network. It also presents a case study for a UMTS network.

Streaming media over wireless networks typically rely on end-to-end feedback from client devices to help media servers adjust to changing channel conditions. In rapidly fluctuating channel conditions, the client device may not be able to effectively track changes and report them to the server. Furthermore, bandwidth constraints often limit the frequency of end-to-end feedback. In order to overcome these constraints, we propose Clearmedia, a signaling proxy-based architecture for streaming media services over wireless networks. This architecture enables media servers to receive frequent and reliable feedback on network conditions, which leads to enhanced service quality. Our performance studies show that the Clearmedia architecture achieves improvement in several key performance metrics that are representative of end-user perceived video quality.

The paper describes a holistic capacity planning methodology for radio access networks and presents a case study focusing on the CDMA technology. It addresses the complex problem of how the Radio Access Network (RAN) should be optimally equipped to accommodate traffic growth (and fluctuations in traffic patterns in broader terms) over time, while fulfilling the Quality of Service (QoS) requirements of a Mobile Network Operator. A bottom-up approach is used, i.e. first it evaluates the required resources over the air-interface; then the base stations hardware resources, and finally, the transport/ backhaul domain dimensioning. This methodology provides the rapid and repeatable dimensioning, which is required to implement just-in-time provisioning processes, and support the network cost modeling an operator requires to quickly model quality of service and call plan strategy. The approach has been largely tested with field data and is being used by several mobile network operators.

The paper presents the concept of an adaptive neighbor list management mechanism that has as objective to control the quality of radio links over a wide range of offered traffic in wireless communication systems. An algorithm to adapt the size of the neighbor lists , and therefore their composition to fluctuations in traffic conditions is presented. The concepts of this algorithm are supported by a comprehensive system level simulation study. The wireless technology used as a case study is the UMTS TD-CDMA, however the observations are generally valid, irrespective of the technology. It is shown that a reduced neighbor list can enhance the radio link quality at heavy traffic loading while the system can continue to operate at acceptable call blocking rates. The outcome of the adaptive algorithm may result in pushing the system to operate at heavier loads while still offering acceptable individual radio link quality.

This paper investigates the performance benefits of different resource allocation strategies that take advantage of permutation zones specified in IEEE 802.16e-based OFDMA systems. In particular, we propose and investigate the benefits of a sub-zone scheduling approach where each permutation zone is partitioned into sub-zones that are used for scheduling subsets of eligible users according to their prevailing link quality. In the scenarios considered, the proposed sub-zone scheduling approach allows improvements in sector throughputs as high as 80% relative to a baseline IEEE 802.16e-based OFDMA system while maintaining the system outage at acceptable levels.

The paper presents a performance study of two algorithms for dynamic allocation of the dedicated channels (DCH) in UMTS over the air interface, namely least recently used (LRU) algorithm and an adaptive algorithm. The algorithms are designed to efficiently share the dedicated channels among users whose traffic patterns are characterized by bursty packet transfers followed by long inactivity periods. Specifically, Web browsing, FTP and email applications were considered in order to evaluate the performance of the above mentioned resource allocation algorithms in the context of bursty traffic with relaxed delay constraints and In the presence of delays introduced by the backhaul network

This paper investigates the impact of major critical parameters and the effect of some radio resource allocation policies on the TD-CDMA system performance. Critical parameters are related either to the user behavior (e.g., user mobility, activity factors) or to processing techniques and algorithms implemented to control network performance and individual radio link quality (e.g., joint detection imperfection, handover margin, timeout for maintaining alive bad radio links). Network topology (e.g., distance between neighboring base stations) also undoubtedly influences capacity results. Analysis is carried out through accurate modeling of user behavior, interference scenarios, and power budget limitations at both terminals and infrastructure, allowing for proper implementation of radio resource allocation algorithms. Among these algorithms, power management (both at the initial channel assignment and during communication), dynamic channel allocation (DCA), and ongoing calls management are explored. An event-driven simulation approach was considered to model realistic system behavior and address system stability under various events generating traffic/interference fluctuations (e.g., call arrivals and departures, handovers, steps of power control loops). Such an approach is expected to offer a good estimate of the real conditions provided the propagation models are close to real life. As a consequence, measures to be taken to avoid/control overloading in a TD-CDMA (CDMA in general) environment can be naturally derived and tested with this methodology.

The paper presents a nonpreemptive priority queueing system model for voice and HSCSD service integration in GSM. The study is conducted using a multidimensional Markov chain. An HSCSD connection can be established if the number of available channels is between a minimum acceptable capacity, b, and a maximum required capacity, B. This leads to an effective service time for HSCSD calls, proportional to the bandwidth negotiated with the base station. Finite buffers are used for new and handoff requests to increase the total carried traffic, while maintaining the quality-of-service (QoS) requirements. The analysis can be applied when mean service times for voice and HSCSD calls are different. The key parameters which control the new data service performance are identified and adequate formulas are obtained. Especially, delays experienced by HSCSD calls are evaluated and compared to an optimal transmission operating at the maximum capacity.

A mathematical model for analyzing the new GSM HSCSD (high speed circuit switched data) service specified by the European Telecommunications Standards Institute (ETSI) as a part of the GSM phase 2+ standard is presented. The study is conducted using a multidimensional Markov chain for a system carrying both HSCSD and the pre existing voice traffic. The key parameters which control the new data service performance are identified and adequate formulas obtained. Delays experienced by HSCSD calls are evaluated and compared to an optimal transmission operating at the maximum capacity. The model takes into account the channel allocation constraints for HSCSD connections and their impact on system performance is investigated by comparing results with an ideal unconstrained system. The analysis is applicable when mean service times for voice and HSCSD calls are different.

An analytical model for a nonpreemptive priority queueing system incorporating voice and data users in cellular mobile networks is presented. Upon arrival, handoff requests are inserted in a head of line (HOL) queue with finite capacity if no idle channels are available and the queue is not full. Priority is given to voice handoffs over data handoffs to avoid forced termination for voice users. This is achieved under a given time delay constraint for data users. A number of channels can be reserved for handover exclusive use. New attempts which find channels occupied are cleared from the system. For this priority policy we conduct a steady state queueing analysis when the mean service times of voice and data are different. Performance results show blocking and forced termination probabilities for both types of calls, waiting time for voice calls in the handoff area and delay experienced by data calls.