Laurent Martinod

Integrating LTE broadband system in PMR band: OFDM vs. FBMC coexistence capabilities and performances

This paper focuses on the use of Long Term Evolution (LTE) broadband system in coexistence with currently deployed Professional Mobile Radio (PMR) communication systems. The coexistence capabilities are analyzed using of an LTE like based system with Orthogonal Frequency Division Multiplexing (OFDM) and Filter Bank MultiCarrier (FBMC) physical layers. Obtained results show that, in order to achieve the LTE-PMR coexistence, we need to filter the synthesized OFDM signal. This filtering is made to protect the PMR (TETRA, TETRAPOL, TETRA TEDS standards, etc.) systems by reducing the sidelobes levels due the use of modulated OFDM scheme. On the other hand, the FBMC signal fits perfectly the LTE-TEDS harmful interference protection requirements starting from the minimum frequency offset allowed by the TEDS standard mask. This can be explained by the fact that a good frequency localization is achieved by the prototype filter used in the FBMC scheme.

When SDR meets a 5G candidate waveform : Agile use of fragmented spectrum and interference protection in PMR networks

Filter bank multi-carrier (FBMC) is a candidate modulation scheme for 5G cellular mobile broadband networks. A specific domain where FBMC offers a clear advantage over other multicarrier solutions is the efficient occupancy of underutilized and fragmented spectrum. This is due to the rich spectral containment of the FBMC technology, which guarantees superior interference protection to the primary coexisting transmissions. These features of FBMC could play an important role in the economic delivery of 5G services in licensed and unlicensed bands. This article focuses on the public safety domain where existing professional mobile radio (PMR) users plan to add broadband services at the 400 MHz band, aiming to occupy the spectral holes left by current narrowband transmissions. In this respect an agile SDR broadband downlink FBMC system, aimed at exploiting unused licensed PMR spectrum, was developed and experimentally validated. The FBMC frame structure shared key similarities with the LTE specification. Two different SDR design methodologies were used to build the real-time baseband prototype. The level of interference protection offered by a broadband FBMC system to a coexisting primary narrowband PMR transmission was practically demonstrated and compared to that of an equivalent LTE system. This was made feasible by evaluating the performance of a PMR terminal under different mobile channels and FBMC waveform configurations. The applicability of this work to other 5G spectrum cohabitation scenarios is discussed. Finally, the article highlights the need to extend the SDR design paradigm in order to tackle the challenges of real-time baseband processing in 5G broadband cellular systems.

Reduced rank spatial filter for interference cancellation

In radio mobile communication, antenna array structure at the reception is used to perform interference cancellation and equalization. We introduce a reception structure where a spatial filter is split between a set of coefficients applied to received signals and a set of coefficients applied to reference signal (pilots symbols). Instead of trying to find this set of filter coefficients, the approach is based, for rank reduction reasons, on the projection of these coefficients on a discrete Fourier basis. In order to avoid a trivial solution, two constraints on filter coefficients are proposed, related algorithms are developed and simulation results are compared. This paper can be viewed as a follow up of a previous work on a similar topic [1].

Scheduling for Multi-users Multiplexing Radio Voice Transmission for enhancing voice capacity over LTE in PMR context

Despite the fact that Long Term Evolution (LTE) supports high-speed data transmission and supports different packet sizes by using Adaptive Modulation and Coding (AMC), LTE is not yet optimized for low bit rate voice communication, especially in case of using LTE in Professional Mobile Radio (PMR) context. In LTE, one pair of Physical Resource Blocks (PRBs) is the smallest User Assignment Unit. However, the smallest LTE packet size is still too large in case that low bit rate voice communication is transmitted in high Modulation and Coding Scheme (MCS). This reduces the voice capacity over LTE in PMR context. Therefore, we propose a new Multi-users Multiplexing Radio Voice Transmission method for enhancing voice capacity over LTE in PMR context. In this method, voice packets from different users are multiplexed into one LTE packet in the downlink transmission. In this paper, we propose a new scheduling method that can be used to transmit the multiplexed packets to corresponding users. This paper gives also a novel algorithm for classifying and grouping voice packets of mobile users having different MCS values. In case of low and medium number of users, the results show that the average voice capacity gain of the proposed method can rise up to 89.6%. In case of high number of users, the proposed method can improve the voice capacity by factor of 6.5.

Architecture for Multi-users Multiplexing Radio Voice Transmission for enhancing voice capacity over LTE in PMR context

Recently there has been a great interest in how to apply Long Term Evolution (LTE) in Professional Mobile Radio (PMR) context, which is used for public safety work. However, LTE is not yet optimized for low bit rate voice communication. The smallest LTE packet size is still too large in case that low bit rate voice communication is transmitted in high quality channel. This is one of the main challenges for effectively applying LTE in PMR context. Therefore, this paper presents a new architecture for Multi-users Multiplexing Radio Voice Transmission for enhancing voice capacity over LTE in PMR Context. This architecture allows reducing the difference between the LTE packet size and voice payload by multiplexing voice packets from different users into one same LTE packet in the downlink transmission. In this architecture, the multiplexing size can be modified according to the Modulation and Coding Scheme (MCS), the payload of users and the LTE bandwidth. Our simulation results show that in the best case, our proposed method can achieve a gain up to 650 % in the voice capacity gain as compared to the standard LTE.

Chapter 20 – Real-Time Implementation and Experimental Validation of a DL FBMC System

Abstract To assess the implementation feasibility and provide a practical experimental validation of the filterbank multicarrier (FBMC) scheme proposed in the EMPhAtiC project, a real-time hardware demonstrator was developed using two complementary software-defined radio (SDR) design methodologies. The spectral shape and spectral contention of the EMPhAtiC FBMC waveform makes it a prime candidate for a number of cases where agile wireless communications are required. Exploiting unused or underutilized fragmented spectrum in sub-6-GHz licensed bands without provoking interference to other inband or adjacent transmissions is the case of interest covered in this chapter. In particular, the focus is set on radio bands below 1 GHz featuring rich signal propagation characteristics. The introduction of new multicarrier waveforms and efficient cohabitation of the radio spectrum below 6 GHz are considered key enablers of fifth-generation (5G) wireless access communications.

Broadband Private Mobile Radio (PMR)/Public Protection and Disaster Relief (PPDR) Services Evolution

Abstract Nowadays, currently deployed Private Mobile Radio (PMR) systems allow addressing user bitrates, typically from 4 to 10 kbps, which are naturally well adapted to offer voice and some basic data service features on wide cell coverage. In this aim, PMR systems use specific digital narrowband standards such as TETRA, TETRAPOL, or APCO P25. Of course, such bitrates are significantly insufficient to address future PMR services requiring higher throughput such as e-mail, secured web services, video and/or image delivery. A 3GPP LTE system is planned to address future broadband PMR systems evolution, but dedicated adaptations are needed to be compliant with critical PMR requirements. This chapter gives an overview on these constraints and required LTE adaptations and also introduces a focus on spectrum improvement needs and possible ways to enhance coexistence between future broadband PMR systems and current legacy PMR systems already deployed, from this spectral point of view.

Adaptive physical resource block design for enhancing voice capacity over LTE network in PMR context

In this paper, we introduce a new Adaptive Physical Resource Block Design for Enhancing Voice Capacity over Long-Term Evolution (LTE) Downlink in Professional Mobile Radio (PMR) Context. In this method, we reorganize the structure of the Physical Resource Block (PRB) to optimize the voice capacity of LTE downlink in the PMR Context. Available PRBs in each subframe are reorganized into a number of Sub Physical Resource Blocks. The number of control symbols can be selected flexibly. The proposed method allows reducing both data overhead and control overhead issues for Voice services over LTE downlink in the PMR context. On average, the voice capacity gain were shown up to 117.2% in comparison with the standard LTE.

CDMA-OFDM combination method for enhancing capacity of voice over LTE Uplink in PMR context

In this paper, we introduce a new Code Division Multiple Access (CDMA)-Orthogonal Frequency-Division Multiplexing (OFDM) combination method for Enhancing Capacity of Voice over LTE (VoLTE) Uplink in PMR context. In this method, voice payloads of different User Equipments (UEs) having the same Modulation and Coding Scheme (MCS) can be spread by different orthogonal codes and mapped to the same set of resource elements. The selection of spreading factor allows a maximum reduction of the difference between the LTE Uplink packet size and PMR voice payload. The proposed method allows reducing both data overhead and control overhead issues for VoLTE uplink in PMR context. The CDMA-OFDM combination method gives a significant increasing in capacity of VoLTE uplink over PMR context. In the best case, the proposed method can improve the voice capacity by the factor of 7 in comparison with the standard LTE.

RNTI Aggregation for Multi-Users Multiplexing Radio Voice Transmission for Enhancing Voice Capacity over LTE in PMR Context

Voice capacity over Long Term Evolution (LTE), despite the fact that LTE supports high-speed data transmission, is still low due to the large data and control overhead. This is one of the primary obstacles to apply LTE to Professional Mobile Radio (PMR) system because the voice capacity is one of the main requirements of the public safety network. To overcome this issue, there are several studies aiming at reducing one of the two overheads in LTE, data or control. However, in most cases the voice capacity gain can only be improved by both reducing data and control overhead. This is because these two factors are strongly related in carrying out the resource allocation. In [1], we proposed a Multi-users Multiplexing Radio Voice Transmission method. This method clusters voice packets from different users into one same LTE packet in the downlink transmission for reducing the data overhead caused by the difference between LTE packet size and the PMR voice payload. This paper presents a new Radio Network Temporary Identifier (RNTI) aggregation method to solve the control overhead issue for the multiplexing scheme of Voice over LTE (VoLTE) in PMR context. Our method uses Physical Downlink Control Channel (PDCCH) channel with high format, created by the aggregation of PDCCH channels with low format, to transmit several RNTIs of different User Equipments (UEs) in a same multiplexing group. The number of RNTIs in one PDCCH is calculated to ensure that there is no increase of Bit Error Rate (BER) for receiving PDCCH channel. The results show that the RNTI aggregation method can increase the control capacity of the multiplexing scheme up to 170%. The combination of Multi-users Multiplexing Radio Voice Transmission method and RNTI aggregation method allows reducing both data and control overhead of VoLTE in the PMR context.