Subband Full Duplex (SBFD) is an innovative duplexing method for advanced 5G/6G cellular communication that enhances uplink coverage and minimizes communication latency compared to TDD. SBFD allows a base station to transmit and receive simultaneously in distinct downlink and uplink sub bands within the channel bandwidth of a TDD carrier. To maximize the advantages of SBFD communications, it's crucial to mitigate self-interference and cross-link interference between nodes. This paper initially discusses the enablers for interference mitigation in SBFD deployment, followed by an evaluation analysis and field measurement results of SBFD duplex technology for a 5G massive-MIMO macro network in the 5G band.

Time-division duplex (TDD) and frequency-division duplex (FDD) are mainly used in commercial new radio (NR) deployments, where the time- or frequency-domain resources are split between downlink (DL) and uplink (UL). Full duplex (FD) will enable 5G-advanced and 6G systems to go beyond TDD and FDD operation into a new duplexing mode that leverages the benefits of both TDD/FDD deployments. It achieves higher throughput and lower latency while enabling flexible UL/DL scheduling. However, there are several challenges that need to be overcome to enable FD operation in large-scale system deployment, including intranode and internode [user equipment (UE) and next-generation node B (5G base station)] interference along with intercarrier interference. In this article, we present solutions to mitigate self-interference (SI) and cross-link interference (CLI) in 5G-advanced/6G systems, provide system-level evaluations, and discuss the outcome of Third Generation Partnership Project (3GPP) study item on duplexing evolution. We introduce the concept of subband FD (SBFD) as an effective solution for a macro network to achieve the key features of FD, such as latency reduction and UL link budget improvement. Finally, we present the field test results for the performance of world-first SBFD prototype of high transmit power massive-multi-input-multioutput (MIMO) macro network.

In this paper, we discuss UE power saving (PS) techniques for eXtended Reality (XR) applications in 5G NR system. XR traffic is characterized by pseudo periodic packet arrival, high bit rate, and low latency requirement. It is challenging to support such traffic in a small device form factor with limited battery size, e.g., head-mounted display (HMD) or XR glasses. Therefore, it is desired for 5G NR to support effective UE PS techniques. We first discuss a few PS techniques defined in 5G NR specifications Release 15 and 16. Then, we introduce new PS techniques that are evaluated via system level simulations with the UE power consumption model defined in a 3GPP. Evaluation results show that UE power consumption can be substantially reduced by the new PS techniques, up to 40%.

We present system-level evaluation results to characterize the performance of eXtended Reality (XR) applications over a 5G NR system. A split-rendering framework is assumed, where the XR device uses 5G to offload computation associated with rendering and encoding of video frames to an edge server. The XR traffic model includes rendered video frames on the downlink and user pose and control updates on the uplink. We present results for both sub-6 GHz (FR1) and millimeter-wave (FR2) bands. Additionally, we also discuss potential enhancements to further improve user experience for XR applications over 5G.

Downlink transmit (Tx) power calibration techniques are vital in self-organizing femtocell networks to achieve a good tradeoff between femtocell coverage and interference impact to nearby macrocells and femtocells. In this paper, we present two power calibration techniques that adapt to a wide variety of residential deployment scenarios: (1) Over a long term, Tx power is adapted by learning required coverage range, RF profile inside the home and interference outside using feedback from home users and macro users; (2) Tx power is adapted in real-time based on short term dynamic variations in traffic such as arrival of active macro users (guest or passer-by). The presence of nearby active macro users is detected by sensing their uplink channel. The algorithms are shown to provide superior performance compared to conventional techniques in wide variety of deployment scenarios.

In this paper, we present a comprehensive study of uplink interference management for 3G femtocell deployments. Focusing on co-channel deployment, where both femtocells and macrocells operate on the same carrier, femto-to-macro, macro-to-femto and inter-femto uplink interference scenarios are identified. To effectively control uplink interference in residential and enterprise femtocell deployments, Macro Aware noise Rise Setting (MARS) and Controlled LImit on uplink Power (CLIP) algorithms are introduced. MARS maximizes the femto's tolerance to out-of-cell interference by properly setting the femto noise rise threshold based on the location of the femto in the macrocell. CLIP dynamically limits the femto user Tx power or rate to control the interference to macrocell. The effectiveness of the proposed algorithms is demonstrated via detailed system-level simulations for enterprise and residential femtocell deployments.

Downlink transmit (Tx) power calibration is necessary in femtocell deployments to achieve a good tradeoff between downlink femtocell coverage and interference to other macrocells and femtocells. Developing a practical Tx power calibration scheme that provides excellent performance in different deployment scenarios is challenging. In this paper, we present an enterprise deployment framework that consists of coverage planning and Tx power calibration using technician assistance. The Tx power calibration algorithms presented here use mobile feedback to learn key information such as surrounding RF environment, required coverage range, and interference impact to other cells to adapt to different deployments. Both centralized and distributed Tx power calibration algorithms are evaluated for multi-femto enterprise. It is shown that the distributed algorithm, is simple, efficient and performs very close to the centralized algorithm. Furthermore, over-the-air field tests highlight the practical efficacy of the distributed algorithm in providing excellent femtocell coverage indoors with minimal leakage to outdoors.

We present performance analysis of handoffs on the forward link (i.e., downlink) of packet-switched 1xEV-DO Rev. A systems by a combination of theoretical analysis and simulation results. A theoretical approach is developed to evaluate slot error probability (SEP) relevant to 1xEV-DO Rev. A. The novelty of the theoretical analysis lies in the fact that unlike the existing literature we consider the combined effects of Rayleigh and shadow fading, filtering, and handoff delay on the handoff algorithm. Contrary to the general assumption, a practical filter cannot eliminate Rayleigh fading completely. We evaluate the handoff performance by considering the effects of filtering, hysteresis, and other system parameters. Tradeoffs in choosing handoff algorithm parameters are studied in terms of the SEP, packet error rate (PER), and number of handoffs.

In this paper, we analyze the performance of the uplink of multi-cellular MIMO systems in flat Rayleigh fading. There is co-channel interference from users within the same cell as well as from other cell users. I The channel model includes lognormal shadowing and path loss along with power control, resulting in a statistical model for user powers. Consistent with practical scenarios, the co-channel interference is categorized into two groups: intracell interference from users within the same cell as the desired user and intercell interference from outer cell users. We derive a compact, easily computable closed form outage probability expression in the form of finite sums. This expression allows for simpler and faster analysis of various MIMO configurations. It has been shown that using antennas on the receiver side results in better performance, since transmit diversity does not combat interference from same cell users.

cdma2000 1xEV-DO revision A (DO Rev. A), also known as IS-856-A, is a third generation (3G) wireless solution to providing wide-area high-speed mobile Internet access with high spectral efficiency and advanced quality-of-service (QoS) support. In this paper we evaluate the reverse link performance improvement (in terms of coverage and data throughput) of IS-856-A with the use of more advanced antenna array receivers. Specifically, we consider the effect of increasing the receiver antenna array size and utilizing more sophisticated beamforming schemes. We quantify the capacity improvement via analysis as well as comprehensive system simulations that incorporate realistic channel models and the dynamics associated with MAC-layer algorithms in addition to the physical-layer interactions. We show that DO Rev. A with 4-way antenna diversity on the reverse link achieves more than 3 dB gain over 2-way diversity receivers in sector throughput. We also demonstrate a coverage improvement on the order of 6 dB, which can be translated into further throughput gains by relaxing the interference control mechanism.

In this paper, we analyze the uplink outage capacity improvements in multicellular code-division multiple-access systems using receive antenna diversity and fast power control schemes that can track multipath fading. The channel is modeled as slowly varying Rayleigh fading with lognormal shadowing and path loss. Closed-form expressions are obtained for the outage capacity of the system by approximating the total intracell and intercell interference distributions. We show that by controlling the power level of a user at the output of the diversity combiner and imposing the condition that a user does not transmit when in a deep fade, the average intercell interference level of the system is significantly reduced. As a result of this reduction, we demonstrate both analytically and through simulations that the outage capacity of the system is improved more than linearly with increasing number of antenna elements.

We analyze the performance of multi-cellular MIMO systems in Rayleigh fading. Consistent with practical scenarios, we assume two types of interference: intracell interference from users within the same cell as the desired user and intercell interference from users in other cells. We derive a compact closed form expression for the outage probability of such a system in the form of finite sums. The expression is easily computable and allows for a simpler and faster study of various MIMO configurations. An interesting outcome of the analysis is that using multiple antennas on the receiver side results in better performance since transmit diversity does not combat interference from same cell users.

In this paper, we analyze the performance of multi-cellular MIMO systems with co-channel interference from users within the same cell as well as from other cells. We initially assume that user power levels are deterministic. Then, we extend the channel model to include shadowing and path loss along with power control, resulting in a statistical model for user powers. We derive easily computable closed form outage probability expressions in the form of finite sums for both cases. It is found that using antennas on the receiver side results in better performance since transmit diversity does not combat interference from same cell users. It is also shown that the outage capacity increases more than linearly with increasing order of diversity.

In this letter, we examine the statistical distribution of the signal-to-interference-plus-noise ratio (SINR) of the optimum combining (OC) technique in receive-antenna diversity systems. We decompose the SINR into two components by projection onto the interference subspace for systems with more antennas than interferers. For the case when the number of interferers is larger than the number of antennas, upper and lower bounds on performance are provided.

In this paper, we analyze the effects of channel correlation on the performance of maximal ratio combining (MRC) in receive antenna diversity systems. In the analysis, the channel is modelled as flat Rayleigh fading, slowly varying and an arbitrary number of cochannel interferers are assumed to be present. In an interference limited scenario, an exact closed form expression for signal to interference ratio (SIR) distribution is obtained for a dual antenna system. The degradation in the outage probability as a function of the correlation severity is investigated.

In this paper, we analyze the outage capacity improvements in multi-cellular code division multiple access (CDMA) systems using receive antenna diversity and fast power control schemes that can track multipath fading. The channel is modelled as slowly varying Rayleigh fading with lognormal shadowing and path loss. Closed form expressions are obtained for the outage capacity of the system by approximating the total intercell and intercell interference distributions. We show that by controlling the power level of a user at the output of the diversity combiner and imposing the condition that the user denies transmission when in deep fade, the average intercell interference level of the system is significantly reduced. As a result of this reduction, we demonstrate both analytically and through simulations that the outage capacity of the system is improved more than the linearity with increasing number of antenna elements.