Multi-user detection for Inmarsat's BGAN system

Abstract

The development and performance of a hardwareprototype multi-user detection (MUD) receiver for Inmarsat's Broadband Global Area Network (BGAN) is described. The MUD receiver is used to compensate increased adjacent channel interference due to reduced channel spacing and can simultaneously detect up to six bearers in a 200-kHz satellite subband. With this technique, the channel-spacing can be reduced from 40 kHz to 25 kHz, permitting a capacity increase of 50%. This capacity increase is achieved with an implementation loss comparable to the combined implementation loss and adjacent channel interference allowance for the non-MUD scenario. Differences between simulations and hardware implementations are discussed, as well as observed limitations on performance.

Timing and Frequency Synchronisation for Multiuser Detection on the Return Link of Interactive Mobile Satellite Networks

“…Towards improving the spectral efficiency by reducing the carrier spacing between two RL time division multiple access (TDMA) carriers, iterative interference cancellation techniques have been considered in [3]. On a similar note, the authors in [4] increase the number of carriers per transponder and employ a MUD at the gateway (processing all the carriers jointly) to reduce the ACI caused by increased carrier overlap. On the other hand, Minimummean-squared error with successive interference cancellation (MMSE-SIC) is applied against CCI is caused by frequency reuse in [5].…”

“…The trend in literature has been to focus either on the synchronization aspects assuming absence of ACI/ CCI or on the derivation and application of MUD techniques assuming perfect synchronization. For example, [2,4] assume perfect synchronization while a large body of works [6][7][8] provide techniques for acquisition in packet oriented systems. The synchronization techniques consider variations of the well-known O&M algorithm [9] as well as those obtained from the derivation of Cramer-Rao bounds.…”

“…This work can be considered as an extension of [5] due to its inclusion of practical imperfections; it further complements [3] by dealing with CCI. To enhance the novelty, we consider the Broadband Global Access Network (BGAN) system model of [4] which is currently being standardized [2]. This set-up employs burst transmission in a multibeam system and different frequency reuse factors are considered towards generating CCI.…”

Co-channel interference cancelation at the user terminal in multibeam satellite systems

“…In [7], two iterative low-complexity algorithms for adjacent channel interference cancelation in satellite systems are presented. In [8], the authors proposed a parallel multi-user detector for adjacent channel interference cancelation in the return link of Inmarsat's Broadband Global Area Network system.…”

“…Based on the interference distribution, we propose an interference management solution based on iterative soft interference cancelation. It is worth noting that our work differs from [7] and [8] in that co-channel rather than adjacent channel interference is considered. In fact, whenever standard channel spacing is considered and an aggressive frequency reuse scheme is applied, indeed CCI becomes the most relevant source of interference in the system as its level is much higher with respect to that of the adjacent channel interference.…”