Co-channel Coexistence Research Articles

Performance analysis of IEEE 802.11p preamble insertion in C-V2X sidelink signals for co-channel coexistence

Spectrum scarcity is one of the main challenges of future wireless technologies. When looking at vehicle-to-everything (V2X), this is amplified as spectrum sharing could impact road safety and traffic efficiency. It is therefore of particular importance to study solutions that allow the coexistence, in the same geographical area and in the same channels, of what are today the main V2X access technologies, namely IEEE 802.11p and long term evolution (LTE)-V2X sidelink Mode 4. In this paper, in addition to studying the impact of mutual interference, which is found to have a strong impact especially on the former and under congested channel conditions, a mitigation solution is extensively studied. The solution is based on the insertion of the IEEE 802.11p preamble at the beginning of each LTE-V2X sidelink transmission. The proposal, which is also under discussion within the standardization bodies, requires no changes to the IEEE 802.11p protocol stack and minor changes to LTE-V2X sidelink. This solution is directly applicable to upcoming IEEE 802.11bd and extendable to new radio (NR)-V2X sidelink. The paper shows, through analysis and simulations in free-flow and dense scenarios, that the proposal enables mitigation of collisions caused by co-channel coexistence under low and high load conditions. The improvement is guaranteed even in cases of congestion when combined with additional countermeasures. Regarding the latter aspect, in particular, different approaches are compared, demonstrating that acting on the congestion control mechanisms is a simple but effective solution.

Analysis of Co-Channel Coexistence Mitigation Methods Applied to IEEE 802.11p and 5G NR-V2X Sidelink.

Direct communication between vehicles and surrounding objects, called vehicle-to-everything (V2X), is ready for the market and promises to raise the level of safety and comfort while driving. To this aim, specific bands have been reserved in some countries worldwide and different wireless technologies have been developed; however, these are not interoperable. Recently, the issue of co-channel coexistence has been raised, leading the European Telecommunications Standards Institute (ETSI) to propose a number of solutions, called mitigation methods, for the coexistence of the IEEE 802.11p based ITS-G5 and the 3GPP fourth generation (4G) long term evolution (LTE)-V2X sidelink. In this work, several of the envisioned alternatives are investigated when adapted to the coexistence of the IEEE 802.11p with its enhancement IEEE 802.11bd and the latest 3GPP standards, i.e., the fifth generation (5G) new radio (NR)-V2X. The results, obtained through an open-source simulator that is shared with the research community for the evaluation of additional proposals, show that the methods called A and C, which require modifications to the standards, improve the transmission range of one or both systems without affecting the other, at least in low-density scenarios.

On Deploying Secondary Networks in Co-Channel Bands with DTV Networks

This paper explores the feasibility and scope of co-channel coexistence between a low data rate Orthogonal Frequency Division Multiplexing (OFDM) secondary network and a digital television (DTV) broadcast network operating in the same area. Since DTV receivers do not transmit, neither the presence nor the impact of interference from the secondary network on these DTV receivers can be known. Consequently, conventional spectrum sensing techniques cannot be employed effectively. This paper proposes to compensate the lack of feedback by combining the available information about population distribution in the region - ranging from coarse population density estimates to accurate geospatial maps - with better estimation of interference using a data-driven technique called Ordinary Kriging. Radio Environment Maps constructed using the Kriging method from field-reported observations from the secondary nodes are used to obtain better accuracy than the conventional statistical models. The estimates are then used to compute communication parameters for each secondary link in terms of power, number of active subcarriers, and active time slots, while keeping the average interference in the DTV network within threshold bounds. Thus, the viability of such co-channel license-exempt operation of secondary networks in the DTV black and grey spaces for low data rate applications in densely populated urban areas and higher data rate capabilities for sparsely populated rural areas is established.

Empirical Study on 5G NR Cochannel Coexistence

The 5G non-public network deployments for industrial applications are becoming highly interesting for industries and enterprises owing to dependable wireless performance characteristics. With an increasing trend of network deployments in local licensed and/or shared spectrum, coexistence issues naturally arise. In this article, we present our detailed empirical results on the performance impact of a 5G NR indoor non-public network from a 5G NR outdoor network operating in the same mid-band spectrum. We present experimental results on the uplink and downlink performance impact of a non-public indoor network deployed on an industrial shopfloor. Our results quantify the impact on the uplink and downlink performance characteristics based on realistic traffic loads in a non-public indoor network when using synchronized and unsynchronized Time Division Duplex (TDD) patterns, different UE deployment locations and interference levels. We also present results on mitigating interference effects through robust link adaptation techniques. We believe that this is the first article, which reports quantified 5G NR cochannel coexistence results based on a detailed and systematic study, and provides signficant insights on the cochannel coexistence behavior in realistic deployment scenarios of an industrial shopfloor.

Primary User Protection Contour and No-Talk Zone Characterization for TV Whitespace Spectrum Reuse in Nigeria.

To encourage secondary spectrum access within the TV broadcast bands in Nigeria, the propagation properties of TV signals on the VHF and UHF frequency ranges were empirically studied through measurements carried from two TV stations. The Pathloss exponent for the VHF band was found to be 1.9 with a characterised Pathloss equation for VHF band computed as 𝑷𝑳 (𝒅𝑩)=𝟖𝟒.𝟎𝟒+𝟏𝟗.𝟎𝟑𝒍𝒐𝒈𝟏𝟎(𝒅), where (𝒅) is the distance from the transmitter to the receiver. The UHF band Pathloss exponent was computed to be 1.8 with a Pathloss equation characterised as 𝑷𝑳 (𝒅𝑩)=𝟓𝟕.𝟑𝟓+𝟏𝟕.𝟗𝟔𝒍𝒐𝒈𝟏𝟎(𝒅). The findings re-echoed the need for specific prediction model to accurately estimate the service coverage of TV stations and facilitate effective utilization of spatial TV white space as it was found that there were divergence in coverage prediction between the measured model and some of the conventional models. Using the protection view point, the protection contour in kilometers for TV signals propagating in the UHF band in Nigeria was characterized to be 𝒅𝒓𝒑= 𝟏𝟎[𝑷𝒕+𝟑𝟐.𝟔𝟓 𝟏𝟕.𝟗𝟔].. Where (𝒅𝒓𝒑) is the protection contour radius modeled as a function of the transmit power of the TV station in decibels with reference to one milliwatt (dBm) for co-channel and adjacent channel coverage. Similarly, the no-talk-zone in kilometers was characterized as a function of the transmit power of the secondary user device in dBm for co-channel usage to be 𝒅(𝒓𝒏−𝒓𝒑)=𝒂𝒏𝒕𝒊𝒍𝒐𝒈[𝑷𝒔−𝟖𝟗.𝟕𝟔𝟏𝟕.𝟗𝟔] modeled as a function of the secondary user transmit power 𝑷𝒔. The separation distance in kilometers from the TV station to the possible secondary user transmitter beyond which no interference exist was computed to have a relationship equal to 𝒂𝒏𝒕𝒊𝒍𝒐𝒈⟦𝑷𝒕+𝑷𝒔−𝟓𝟕.𝟏𝟏𝟏𝟕.𝟗𝟔⟧. This model will facilitate TVWS co-channel coexistence using the specified equation to determine the separation distances between television transmitters and secondary user transmitters.

Co-Channel Coexistence Analysis between 5G IoT System and Fixed-Satellite Service at 40 GHz

It is a promising way to successfully operate the fifth generation (5G) system with Internet of Things (IoT) in potential mmWave spectrum bands. This paper investigates the intelligent co-channel coexistence between the 5G IoT system and the fixed-satellite service (FSS) system at 40 GHz. The key issue, as identified, is the accurate estimation of interference based on mmWave propagation characteristics. Our simulation results reveal that interference from the 5G IoT system into the FSS ground stations can be kept below the protection threshold by considering different deployment parameters, such as antenna patterns, height of Earth station (ES), and separation distance.

Applying an Information Based Decision Analysis to Spectrum Management Regulatory Decisions

This paper contains the development and application of an interdisciplinary framework for making informed spectrum management regulatory decisions. This paper addresses the question, can a framework that includes technical, risk, and benefits/cost assessments serve as a tool for decision makers when making spectrum management regulatory decisions? In 2010, the U.S. President issued a Presidential Memorandum, directing the Department of Commerce, working with the Federal Communications Commission (FCC), to make spectrum available over the next ten years for expanded wireless broadband use. Consequently, the Spectrum Pipeline, Mobile Now and AIRWAVES Acts have echoed a desire for expansion in commercial spectrum availability. With the expanded spectrum available for allocation, regulators require a repeatable, defensible, and effective approach to inform decisions about new spectrum allocations. This approach must consider; service rules, sharing methods, auction details, incumbent user relocation, and incumbent system adaptation and evolution. Regulators’ ability to make dispassionate spectrum management regulatory decisions is a key to expanding services like mobile broadband in a fair, well-reasoned manner. Using an informed decision-making process could add necessary rigor and provide a definitive decision framework for repurposing spectrum to meet market demands. This paper develops a decision-making framework for spectrum sharing based on existing well-known risk management strategies, including work done by the Nuclear Regulatory Committee, the National Institute of Standards and Technology, the Federal Communications Commission and benefit-cost assessments. Contrary to decision-making techniques that only consider the worst-case scenarios involving the worst performing devices, information-based decision-making frameworks allow decision makers to analyze the continuum of effects across varying conditions and devices, as well as the economic implications of those effects. Risk management frameworks ask (i) what can go wrong? (ii) how likely is it? and (iii) what are the consequences? This paper proposes and applies a decision analysis framework to a spectrum allocation, or service rule change request proposed by regulators. This decision analysis framework was developed by: • investigating state-of-the-art risk management strategies to identify an approach that could be applicable to spectrum management regulatory changes. • evaluating harm-claim interference measurements, considering both out of band and co-channel coexistence scenarios. • performing a technical interdisciplinary decision analysis considering aggregate consumer welfare, including both technical offerings, availability, and impact on consumers, as well as an analysis of the value of all services affected. The decision analysis framework proposed is based on existing risk-informed interference assessments and benefits-cost analyses. The framework has also been tested and proven using a test-case. The framework helps provide appropriate information regulators need to identify and analyze key performance indicators describing harmful interference and performance objectives of the systems in question, as well as economic data describing aggregate welfare. Furthermore, this framework proposes benefit-cost analysis for quantifying economic impact of changing spectrum allocation and service rules.

Coexistence of 5G With the Incumbents in the 28 and 70 GHz Bands

A promising way of realizing the fifth generation (5G) wireless systems is to operate 5G deployments at higher frequency bands, specifically in the millimeter-wave (mmW) spectrum (30-300 GHz). Access to such spectrum bands will enable future 5G wireless systems to meet the 5G requirements of peak rate greater than 10 Gb/s, and cell edge rate of up to 1 Gb/s. However, the emerging 5G systems will need to coexist with a number of incumbent systems in these bands. This paper provides an extensive study of the co-channel coexistence of 5G in two critical mmW bands, 27.5-28.35 GHz (28 GHz) and 71-76 GHz (70 GHz) bands, where fixed satellite service (FSS) and fixed service (FS), such as wireless backhaul, are the predominant incumbent users. In the 28-GHz study, we show that interference from 5G into the FSS space stations can be kept below the FSS interference protection criterion. We also characterize the minimum separation distance between the FSS earth stations (ESs) and 5G in order to protect the 5G system from interference due to the ESs transmissions. In the 70-GHz study, we show that the 5G-to-FS interference could be a potential issue in certain scenarios, but we introduce techniques to significantly suppress this interference, while maintaining acceptable performance of the 5G systems. For each study, we suggest appropriate deployment strategies for a 5G system based on our results.

UsICIC—A Proactive Small Cell Interference Mitigation Strategy for Improving Spectral Efficiency of LTE Networks in the Unlicensed Spectrum

The deployment of long term evolution (LTE) in the unlicensed spectrum (LTE-U) has been gaining significant industry momentum in recent months. The US 5-GHz Unlicensed National Information Infrastructure (UNII) bands that are currently under consideration for LTE deployment in the unlicensed spectrum contain only a limited number of 20 MHZ channels. Thus, in a dense multi-operator deployment scenario, one or more LTE-U small cells have to coexist and share the same 20 MHz unlicensed channel with each other and with the incumbent Wi-Fi. In this paper, we present the scenario and demonstrate that in the absence of an explicit interference mitigation mechanism, there will be a significant degradation in the overall LTE-U system performance for LTE-U cochannel coexistence in countries that do not mandate listen-before-talk (LBT) requirements. We then present the unlicensed spectrum intercell interference co-ordination (usICIC) mechanism as a time-domain multiplexing technique for interference mitigation for the sharing of an unlicensed channel by multioperator LTE-U small cells. Through extensive simulation results, we also demonstrate that our proposed usICIC mechanism will result in 40% or more improvement in overall LTE-U system performance.

Influence of the LTE System using Cognitive Radio Technology on the DVB-T2 System using Diversity Technique

In recent years, the development of advanced wireless communication systems has been rapidly progressing. In Europe, the 2nd Generation Terrestrial Digital Video Broadcasting (DVB-T2) and Long-Term Evolution (LTE) are the most promising techniques to provide multimedia services efficiently (in flexible quality and with high spectrum efficiency). The purpose of this work is to explore possible influences of the LTE uplink services, using cognitive radio (CR) technology, on the area which is covered by DVB-T2 services. In the case of DVB-T2, both single-input single-output (SISO) and multiple-input single-output (MISO) transmission techniques are considered. The defined coexistence scenarios are measured with an appropriate measurement testbed. The performance of the received TV signal is evaluated on its physical layer (PHY) level. The obtained results allow better understand the influence of LTE system on DVB-T2 which is using diversity technique in the same RF channel (co-channel coexistence). One of the main results is that there are the same requirements on the Forward Error Correction (FEC) decoding process in the DVB-T2 receiver, when power imbalances between TV transmitters (an both SISO and MISO modes) are considered at the interfering LTE signal. This finding was also proved by analysis of variance (ANOVA).

Throughput Enhancement for WLAN TV White Space in Coexistence of IEEE 802.22

This paper proposes an algorithm for coexistence in TVWS between IEEE 802.22 and IEEE 802.11af by equal opportunity without increased delay time and decreased throughput, for each of them. Also, an investigation has been conducted for the coexistence problem between the 802.22 and the IEEE 802.11af systems, in the TV White Spaces (TVWS). IEEE 802.22 and IEEE 802.11af are two typical standards envisioned to be widely adopted in the future. However, these two standards are heterogeneous in both power level and PHY/MAC design; as a result coexistence challenge is there. The main focus of this paper is to design a co-channel coexistence scheme for the IEEE 802.22 customer-premises equipment’s (CPEs) as well as the IEEE 802.11af systems. In this paper, the challenges are identified to enable the co-channel coexistence of the IEEE 802.22 and the IEEE 802.11af systems. Afterwards, an algorithm is proposed for coexistence, depending on frame times. The algorithm is applied in two networks in three cases, depending on the amount of transmitting data. The simulation results suggest that the proposed solution has increased the throughput and decreased the waiting time by a noticeable way for IEEE 802.11af.

Study of coexistence between indoor LTE femtocell and outdoor-to-indoor DVB-T2-Lite reception in a shared frequency band

Nowadays, the demand for high-quality multimedia services (video, audio, image, and data) is rapidly increasing. The Digital Video Broadcasting - terrestrial (DVB-T) standard, its second-generation version (DVB-T2), and the Long-Term Evolution (LTE) standard are the most promising systems to fulfill the demand for advanced multimedia services (e.g., high-definition image and video quality), especially in Europe. However, LTE mobile services can operate in a part of the UHF band allocated to DVB-T/T2 TV services previously. The main purpose of this work is to explore the possible coexistences of DVB-T2-Lite and LTE systems in the same shared frequency band (co-channel coexistence) under outdoor-to-indoor and indoor reception conditions. Furthermore, an applicable method for evaluating coexistence scenarios between both systems is shown with a particular example. These coexistence scenarios can be noncritical and critical. In the first case, both systems can coexist without significant performance degradation. In the second one, a partial or full loss of DVB-T2-Lite and/or LTE signals can occur. We consider an indoor LTE femtocell and outdoor-to-indoor DVB-T2-Lite signal reception in a frequency band from 791 up to 821 MHz. Simulations of combined indoor and outdoor signal propagation are performed in MATLAB using 3rd Generation Partnership Project (3GPP) channel models, separately for both DVB-T2-Lite and LTE systems. Correctness of path loss simulation results is verified by measurements. Afterwards, an appropriate linear model is proposed which enables to evaluate the impact of coexistence on performance of both systems in outdoor-to-indoor and indoor-to-indoor reception scenarios. The results are related to an actual location in the building and are presented in floor plans. The floor plans include different coexistence conditions (different power imbalance and different amount of overlay of the radio channels). Service availability of both systems is verified again by measurements. The resulting maps help better understand the effect of coexistence on achievable system performance under different indoor/outdoor reception situations considering real transmission conditions.

NBP: light-weight Narrow Band Protection for ZigBee and Wi-Fi coexistence

Abstract The recent development of various wireless technologies in the 2.4GHz ISM band has led to the co-channel coexistence of heterogeneous wireless devices, such as Wi-Fi, Bluetooth, and ZigBee. This sharing of the common channel results in the challenging problem of cross-technology interference, since the wireless devices generally use diverse PHY/MAC specifications. In particular, the less capable ZigBee device may often experience unpredictably low throughput due to the interference from the powerful Wi-Fi. The ZigBee protector is an attractive solution, since it can reserve the channel on behalf of the weak ZigBee devices. The protector method, however, has a few limitations; (i) it may cause significant overhead to both ZigBee and Wi-Fi, and (ii) the ZigBee control packets are still vulnerable to the Wi-Fi interference. In this paper, we propose a novel time reservation scheme called Narrow Band Protection (NBP), that uses a protector to guard the ongoing ZigBee transmission. The key contributions are threefold: First, NBP autonomously detects any ongoing ZigBee transmissions by cross-correlating the ZigBee’s packets with the pre-defined Pseudo-random Noise (PN) sequences. By using this cross-correlation, it significantly reduces the control overhead. Second, due to the reliable cross-correlation, NBP is robust from the control packet collisions, which typically wastes channel time for both ZigBee and Wi-Fi. Third, NBP protects the burst of ZigBee packets by estimating the size of the burst, in turn, giving a semantic to the PN codebook. This is important because ZigBee is typically battery-powered and thus the long burst is advantageous for the low duty cycle operations. We first show the feasibility of NBP by implementing it on the real USRP/GNURadio platform. Then, we evaluate the performance of NBP through mathematical analysis and NS-2 simulations. The results show that NBP enhances the ZigBee throughput by up to 1.77x compared to the existing scheme.

Interference Analysis of TD-SCDMA System and CDMA2000 System

Abstract—In this paper, the feasibility of co-channel coexistence of Time Division- Synchronous Code Division Multiple Access（TD-SCDMA）and Code Division Multiple Access 2000（CDMA2000）systems operating in a macro cell environment is investigated. The deterministic analysis and simulation method are used to evaluate the performance compromising of both systems. Based on a more efficient calculation scheme, a novel deterministic equation is proposed and used to provide a better interpretation of the relationship between aggressor and victim in the interference system. The evaluation and simulation results show consistency with the corresponding experiment results. Furthermore, the interference characteristics of Omni-antenna and smart antenna in TD-SCDMA and CDMA2000 are compared, providing an important guideline to reduce the interference of two systems.