Implementing TD-LTE as software defined radio in general purpose processor

Kerttula, Jussi; Malm, Nicolas; Ruttik, Kalle; Jäntti, Riku; Tirkkonen, Olav

doi:10.1145/2627788.2627793

Cited by 13 publications

(8 citation statements)

References 6 publications

(5 reference statements)

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“…Architecturally, the ARF platform is divided into three main components as depicted by Figure 3. e lowest layer is the Virtual Hardware Enhancement Layer (VHEL) [28]. Its purpose is to serve as an abstraction layer for hardware nonidealities.…”

Section: Bs Implementation Using the Arf Platformmentioning

confidence: 99%

Latency-Aware Power Management in Software-Defined Radios

Malm

Ruttik

Tirkkonen

2020

Journal of Electrical and Computer Engineering

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Cloud computing provides benefits in terms of equipment consolidation and power savings from higher utilization for virtualizable software. Cellular communication software faces challenges in cloud computing platforms. BSs create a specific load profile that differs from traditional cloud service loads. Cellular communication system implementations have real-time deadlines with fixed, periodic latency requirements. In this paper, we assess the suitability of an unmodified Ubuntu Linux OS running on a commodity server to operate latency-critical software using a 4G LTE BS software-defined radio implementation. Scaling of the CPU clock frequency is shown to be feasible without excessive impact on the platform’s ability to meet the 4 ms processing delay requirement imposed by the LTE standard. Measurements show the relationship between the processor’s operating frequency and the number of missed subframe processing deadlines to be nonlinear. The results obtained also indicate that a high computational capacity does not suffice to ensure satisfactory operation since fronthaul processing overhead can limit achievable performance. Use of offload-capable network interface cards is studied as a potential remedy.

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Section: Bs Implementation Using the Arf Platformmentioning

confidence: 99%

Latency-Aware Power Management in Software-Defined Radios

Malm

Ruttik

Tirkkonen

2020

Journal of Electrical and Computer Engineering

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“…The virtual hardware enhancement layer (VHEL) [11] presents a generic interface to L1. The primary function of the VHEL is to mask timing constraints and platform nonidealities from L1 entities.…”

Section: Software Implementationmentioning

confidence: 99%

User Localization Enabled Ultra-dense Network Testbed

Malm

Zhou

Menta

et al. 2018

2018 IEEE 5G World Forum (5GWF)

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We present an over-the-air testbed designed for assessing the performance of ultra-dense networks and related mobility management schemes based on tracking the location of user equipment. Location information of UEs at the physical layer of the radio access network allows for proactive and seamless handovers. This is particularly important for 5G ultradense networks where small cells may otherwise be overwhelmed by handover related signalling. We exploit sounding reference signals transmitted by UEs to track their location. Novel mobility management schemes can then be designed such that handover triggering is done by the network and without UE involvement. In current cellular networks, handover is triggered by downlink measurements carried out at the UE, and subsequent reporting. This work also validates our testbed's proof-of-concept software architecture based on stateless unordered worker threads. In particular, a Cloud-RAN of up to four radio transceiver points can be combined into a network overseen by one gNB. Also, dataplane support allows for experimentation with real-time data handovers. The obtained results demonstrate the feasibility of location-based handover schemes as a tool for future cellular network design.Index Terms-SDR, UDN, low-latency, location based handover

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“…Since the RS covers only some of REs, it is not obvious how interference impacts on the end-to-end performance. In the analysis, we used a TD-LTE software radio platform developed at Aalto University [2] to measure this impact.…”

Section: Downlink Reference Signal Interferencementioning

confidence: 99%

“…We utilize the TD-LTE test platform [2] and study the impact of dynamic TD-LTE subframe configuration on different system levels. The platform enables us to observe more static effects such as interference level for a certain configuration, but also to follow temporal effects when changing UL/DL configuration.…”

Section: Introductionmentioning

confidence: 99%

Dynamic TDD in LTE small cells

Kerttula

Marttinen

Ruttik

et al. 2016

J Wireless Com Network

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Dynamic time-division duplexing (TDD) enables adjustments of uplink (UL) and downlink (DL) resources flexibly according to the instantaneous traffic load. Long-Term Evolution (LTE) systems can be implemented in TDD mode (TD-LTE). However, the dynamic change of a TDD configuration has not been well supported and investigated. In large macro cells, the high transmit power of base stations (BSs) easily blocks the weaker user equipment's (UE) UL signal (called the UL-DL interference); and therefore, neighboring cells usually operate with the same TDD configuration. In small cells, such as femtocells, the BS and UE transmission powers are in the same order and the system can afford to have overlapping UL-DL subframes. In addition, when DL load is light, the BS transmits empty DL subframes with only a reference signal (RS). In this paper, we measured the interference caused by DL RS. This interference is not negligible; and therefore, it is beneficial to reduce the amount of DL subframes by switching lightly loaded BSs to UL-heavy subframe configuration. We illustrate with simulations that this can improve system efficiency. Changing the subframe configuration dynamically has a switching-related cost. Frequent switching between subframe configurations can actually decrease throughput. We describe conditions where configuration change is beneficial. We also propose an algorithm that decreases the switching overhead and improves the ability to adapt to varying loads.

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Implementing TD-LTE as software defined radio in general purpose processor

Cited by 13 publications

References 6 publications

Latency-Aware Power Management in Software-Defined Radios

Latency-Aware Power Management in Software-Defined Radios

User Localization Enabled Ultra-dense Network Testbed

Dynamic TDD in LTE small cells

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