Abstract
For next-generation Internet-of-Things (IoT) networks, asynchronous instant transmission has attracted increasing research interest with the expectation of achieving near-zero latency without excessive initiation procedure. However, in an asynchronous multiple-access scenario, there exist significant inter-carrier interference between sub-carriers allocated to different users. To suppress out-of-band emission (OOBE) of each sub-carrier, a new generalized frequency division multiplexing (GFDM) has been proposed, which has lower OOBE than the conventional orthogonal frequency division multiplexing (OFDM). In this paper, by using GFDM, two types of receivers are proposed with the aim of reducing latency and improving throughput: a GFDM-based minimum mean square error (MMSE) receiver and a GFDM-based MMSE-successive interference cancellation (SIC) receiver. Then, we develop a lightweight scheme using an <inline-formula> <tex-math notation="LaTeX">$\epsilon $ </tex-math></inline-formula>-conservative rate control with GFDM-based MMSE receivers and also invent a performance-focused scheme using an advanced rate control with GFDM-based MMSE-SIC receivers. In particular, the latter scheme provides higher throughput with limited increase in computational load of user equipments. Numerical results show that with a high successful transmission probability higher than 99 %, the performance-focused scheme and the lightweight scheme achieve up to 85 % and up to 70 % higher throughput compared to the conventional OFDM-based asynchronous multiple-access scheme, respectively. Furthermore, since our proposal does not require any centralized user scheduling or initiation procedure, it presents a significant reduction in latency compared to the existing low-latency technologies.
Highlights
New futuristic services and systems such as remote surgery, unmanned mobility, industry 4.0, smart home/city, drones, etc, are expected to change the paradigm of human life at the era of the fourth industrial revolution
To circumvent the restriction of the synchronization, GF asynchronous multiple-access (GF-AMA) schemes are proposed with the orthogonal frequency division multiplexing (OFDM) waveform [18]–[20], and developed with the code division multiple-access (CDMA) [21]
We derive an estimate of the signal-to-interferenceplus-noise ratio (SINR) degradation due to asynchronous GF transmissions, based on which we develop an advanced rate control scheme at each user equipments (UEs)
Summary
New futuristic services and systems such as remote surgery, unmanned mobility, industry 4.0, smart home/city, drones, etc, are expected to change the paradigm of human life at the era of the fourth industrial revolution. In order to serve massive connections at ultra low latency, this technique has been applied in various fields of wireless communication such as the power domain non-orthogonal multiple-access [14], sparse code multiple-access [15], K-repetition with slotted ALOHA [16], MIMO [17] These previous studies still assume a perfectly synchronous scenario or a scenario where the time offset at each user does not exceed a cyclic prefix (CP) length. To circumvent the restriction of the synchronization, GF asynchronous multiple-access (GF-AMA) schemes are proposed with the orthogonal frequency division multiplexing (OFDM) waveform [18]–[20], and developed with the code division multiple-access (CDMA) [21] Standardization groups such as 5GNOW, METIS, and 3GPP have been conducting feasibility studies to apply the GF-AMA technology to next-generation mobile communication networks [22]–[24]. We propose two different GFDM-based transceiver schemes with three goals: to i) resolve the rate mismatch problem in the GF-AMA scenario, ii) achieve low latency, and iii) obtain high throughput. Even in a massive user scenario composed of hundreds of users but with highly limited available bandwidth, both the proposed schemes achieve remarkably lower latency, lower than 1 ms, and attain higher throughput than the existing schemes
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