FPGA Implementation of UFMC Based Baseband Transmitter: Case Study for LTE 10MHz Channelization

Abstract

Universal filtered multicarrier (UFMC) is a low complexity promising waveform that provides quasi-orthogonal property among subcarriers. In addition, it can achieve much better out-of-band emission performance than orthogonal frequency division multiplexing (OFDM) system. Authors have proposed a hardware platform to implement a UFMC transmitter in this paper. Highly reduced complexity schemes for IFFT, filtering, and spectrum shifting are realized on actual hardware. This helps to achieve overall architecture of the transmitter at the cost of minimal FPGA resource usage. Hence, the overall design uses only 1038 slice registers, 1154 slice LUTs, and 64 multipliers of Xilinx Virtex-7 XC7VX330t device. A throughput of 773.5 Msamples/sec at an operational frequency of 364 MHz is achieved. This throughput is adequate for processing 50 Physical Resource Blocks (PRB) of LTE 10 MHz channelization in required time. The presented architecture provides a latency of only 2% of one LTE 10MHz channelization symbol due to the implementation of pipelining at different levels. Although the presented hardware design in its current form meets LTE 10MHz channelization throughput requirements, further increase in throughput is possible due to the scalable nature of the architecture. To the best of our knowledge, this work is first ever FPGA solution for UFMC transmitter presented in the literature.

An FPGA-Oriented Baseband Modulator Architecture for 4G/5G Communication Scenarios

“…The sub-band parallel processing approach in our design made the UFMC datapath latency independent of the number of sub-bands. Therefore, the latency per sub-band was also 421 clock cycles, which is lower than the 516 clock cycles recorded by Jafri et al [28]. In steady-state operation and after the initial latency, all the modulators produced one sample per clock cycle.…”

“…Table 5(b) shows resource utilization for baseband modulators in [19,28]. The operation of the modulators from [19] was defined by setting parameter values, which means that the modules had to be dimensioned for the most resource-demanding mode of operation.…”

“…Regarding UFMC, a direct comparison would reveal that our design used more LUTs, RAMs, and BRAMs than the works from [19,28]. However, a careful analysis of the numerologies is required.…”

“…That work followed the numerology for LTE 5 MHz channelization and presented resource utilization results for post-synthesis (before place-and-route) design only. In turn, Jafri et al [28] followed the algorithm proposed in [29] and presented an FPGA-based UFMC modulator for LTE 10 MHz channelization. Each UFMC sub-band is not processed in parallel, but using a ping-pong buffering/memory strategy, which requires clock frequencies above 300 MHz to achieve acceptable processing latencies.…”

“…Frequency Spreading OQAM mapper UFMC is a waveform with better out-of-band suppression than CP-OFDM and a better multi-antenna compatibility than FBMC [28]. This multi-carrier scheme divides the N available subcarriers that represent the whole frequency band into blocks of subcarriers-Physical Resource Blocks (PRB)-that represent individual sub-bands.…”