Cellular uplink analysis has typically been undertaken by either a simple approach that lumps all interference into a single deterministic or random parameter in a Wyner-type model, or via complex system level simulations that often do not provide insight into why various trends are observed. This paper proposes a novel middle way using point processes that is both accurate and also results in easy-to-evaluate integral expressions based on the Laplace transform of the interference. We assume mobiles and base stations are randomly placed in the network with each mobile pairing up to its closest base station. Compared to related recent work on downlink analysis, the proposed uplink model differs in two key features. First, dependence is considered between user and base station point processes to make sure each base station serves a single mobile in the given resource block. Second, per-mobile power control is included, which further couples the transmission of mobiles due to location-dependent channel inversion. Nevertheless, we succeed in deriving the coverage (equivalently outage) probability of a typical link in the network. This model can be used to address a wide variety of system design questions in the future. In this paper we focus on the implications for power control and show that partial channel inversion should be used at low signal-to-interference-plus-noise ratio (SINR), while full power transmission is optimal at higher SINR.

Analytical Modeling of Uplink Cellular Networks

SUMMARY This paper presents our investigation of non-orthogonal multiple access (NOMA) as a novel and promising power-domain user multiplexing scheme for future radio access. Based on information theory, we can expect that NOMA with a successive interference canceller (SIC) applied to the receiver side will offer a better tradeoff between system efficiency and user fairness than orthogonal multiple access (OMA), which is widely used in 3.9 and 4G mobile communication systems. This improvement becomes especially significant when the channel conditions among the non-orthogonally multiplexed users are significantly different. Thus, NOMA can be expected to efficiently exploit the near-far effect experienced in cellular environments. In this paper, we describe the basic principle of NOMA in both the downlink and uplink and then present our proposed NOMA scheme for the scenario where the base station is equipped with multiple antennas. Simulation results show the potential system-level

Non-orthogonal Multiple Access (NOMA) with Successive Interference Cancellation for Future Radio Access

UTRAN long term evolution is currently being standardized in 3GPP with the aim of more than twice the capacity over high-speed packet access. The chosen multiple access for uplink is single carrier FDMA, which avoids the intra-cell interference typical of CDMA systems, but it is still sensitive to inter-cell interference. As a result, the role of the power control becomes decisive to provide the required SINR, while controlling at the same time the interference caused to neighboring cells. This is the target of the fractional power control (FPC) algorithm lately approved in 3GPP. This paper evaluates in detail the impact of a FPC scheme on the SINR and interference distributions in order to provide a sub-optimal configuration tuned for both interference- and noise-limited scenarios.

Performance of Uplink Fractional Power Control in UTRAN LTE

Load balancing by proactively offloading users onto small and otherwise lightly-loaded cells is critical for tapping the potential of dense heterogeneous cellular networks (HCNs). Offloading has mostly been studied for the downlink, where it is generally assumed that a user offloaded to a small cell will communicate with it on the uplink as well. The impact of coupled downlink-uplink offloading is not well understood. Uplink power control and spatial interference correlation further complicate the mathematical analysis as compared to the downlink. We propose an accurate and tractable model to characterize the uplink $\textnormal{\texttt{SINR}}$ and rate distribution in a multi-tier HCN as a function of the association rules and power control parameters. Joint uplink-downlink rate coverage is also characterized. Using the developed analysis, it is shown that the optimal degree of channel inversion (for uplink power control) increases with load imbalance in the network. In sharp contrast to the downlink, minimum path loss association is shown to be optimal for uplink rate. Moreover, with minimum path loss association and full channel inversion, uplink $\textnormal{\texttt{SIR}}$ is shown to be invariant of infrastructure density. It is further shown that a decoupled association —employing differing association strategies for uplink and downlink—leads to significant improvement in joint uplink-downlink rate coverage over the standard coupled association in HCNs.

Joint Rate and SINR Coverage Analysis for Decoupled Uplink-Downlink Biased Cell Associations in HetNets

A method in a wireless communication terminal is disclosed. The method includes receiving a first signal including a desired second signal and an interference component, wherein the interference component includes at least a third signal transmitted in an Almost Blank Subframe (ABS) by a neighbor cell, and configuring the wireless communication terminal to employ interference reduction to process the first signal based on a configuration of the interference component.

Positioning Reference Signal Assistance Data Signaling for Enhanced Interference Coordination in a Wireless Communication Network

Evolved UTRA and UTRAN is being standardized in 3GPP standard group as a long term evolution of the 3GPP radio-access technology. The goal is to achieve 2-4 times the spectral efficiency and user throughput and much smaller latency compared to HSDPA/HSUPA. Single carrier FDMA (e.g. DFT-SOFDM) is the multiple access technique of choice for uplink transmission. Interference control is one of the key elements to achieve the target spectral efficiency and user cell- edge performance requirement, especially for uplink. In this paper, interference mitigation is implemented through slow fractional power control and interference coordination through UE alignment and FDM resource allocation. Simulation results show that these techniques significantly improve uplink sector and cell edge user throughput performance.

Uplink Power Control, Interference Coordination and Resource Allocation for 3GPP E-UTRA

A method, telecommunication apparatus, and electronic device for detecting a status of a radio link are disclosed. A transceiver 302 may maintain a radio link with a network base station 104 . A processor 304 may map channel state information to a synchronization status associated with the radio link based on the received signal and determine the synchronization status via a block error rate estimate in the radio link based on the channel state information.

Methods for detection of failure and recovery in a radio link

A method, a network base station, and a user communication device for transmitting data on an orthogonal frequency-division multiplexing carrier are disclosed. An antenna array may transmit a signal decodable by a legacy user communication device designed for compatibility with a legacy set of transmission antennas. A processor 210 may encode a subframe of the signal with a legacy set of common reference symbols and a supplemental set of common reference symbols referring to the antenna array.

Nory Ravi

Papers

Uplink Power Control, Interference Coordination and Resource Allocation for 3GPP E-UTRA

Methods for detection of failure and recovery in a radio link

Mapping and signaling of common reference symbols for multiple antennas