Frequency-domain multipacket detection: a high throughput technique for SC-FDE systems

Abstract

Usually, packets involved in a collision are lost, requiring their retransmission. However, the signal associated to collisions has important information concerning the packets involved. In fact, with proper retransmissions we can efficiently resolve collisions.In this paper we propose a frequency-domain multipacket detection technique for SC-FDE schemes (Single-Carrier with Frequency-Domain Equalization) that allows an efficient packet separation in the presence of successive collisions.This technique allows high throughputs, since the total number of transmissions is equal to the number of packets involved in the collision, even when the channel remains fixed for the retransmissions. Since we consider SC-FDE schemes and the complexity is concentrated in the receiver, this technique particularly appealing for the uplink of broadband wireless systems. 1

Performance analysis of feedback-free collision resolution NDMA protocol

“…The number of transmissions required for a successful transmission (N tx in (25)) is given by the inverse of the capture probability P cap shown in (23):…”

“…In this section, we evaluate the FF-NDMA protocol in terms of throughput (S), delay (D), capture probability (P cap ), and energy (E), by following the expressions in (18), (22), (23), and (27), respectively, as a function of the offered load (G=σ K) for an average SNR (γ ) of 10 and 0 dB under different R values (indicated in the legends). Figures 5 and 6 show the performance results for γ =10 dB and γ =0 dB, respectively.…”

“…Many NDMA protocols, and variations of it, have been proposed and analyzed in the literature, including different ways to determine the number of devices involved in a collision [18][19][20][21][22], interference cancellation receivers [23][24][25], and modified protocols that use channel knowledge at the transmitter side [26,27]. Stability analysis of NDMA was addressed in [28][29][30].…”

Performance limits of conventional and widely linear DFT-precoded-OFDM receivers in wideband frequency-selective channels

“…In DFT-precoded-OFDM systems, the MMSE-DFE [18][19][20] equalizer can be implemented efficiently using a frequency domain FFF followed by a time domain DFE [21][22][23][24][25][26][27][28][29][30][31]. Computation of FFF and feedback filters (FBF) for DFT-precoded-OFDM differs from conventional singlecarrier methods.…”

Performance evaluation of IB-DFE-based strategies for SC-FDMA systems

“…For this reason, there has been significant interest in the design of nonlinear FDE in general and decision feedback FDE in particular, with the IB-DFE being the most promising nonlinear FDE [7,8]. IB-DFE was originally proposed in [9] and was extended for a wide range of scenarios in the last 10 years, ranging from diversity scenarios [10,11], MIMO systems [12], CDMA systems [13,14], and multi-access scenarios [15,16], among many other. Essentially, the IB-DFE can be regarded as a low complexity turbo equalizer [17][18][19][20] implemented in the frequency domain that do not require the channel decoder output in the feedback loop, although true turbo equalizers based on the IB-DFE concept can also be designed [21][22][23].…”