WLC06-1: Capacity Measurements in a Multicell MIMO System

Abstract

In future wireless networks, cooperation between the base stations may reduce the effects of intercell interference and enhance the capacity per cell. In this paper, the potential of such cooperation is evaluated using measurements of the informationtheoretic channel capacity at 5.2 GHz in 4 overlapping urban macrocells with 5 users. In each link, a 10-transmit 16-receive antenna configuration is used. Results for individual links between terminals and base stations, valid for 60% of the scenarios, indicate that the direct signal has a significant impact on the channel structure. The direct signal contributes two spatial degrees of freedom due to the polarization. Rich scattering is observed when the direct signal is blocked. Results for the multiuser multicell scenario demonstrate for the first time experimentally that the intercell interference leads to an enhanced rank of the joint multiuser multicell channel matrix. Compared to a conventional cellular system, where a fixed assignment of different radio resources is used in adjacent cells in order to avoid the interference, it is better to exploit the interference by cooperation. This enhances the spectral efficiency by a factor of five in our measurement scenario.

Measuring the influence of TX antenna spacing and transmit power on the closed-loop throughput of IEEE 802.16-2004 WiMAX

“…Similarly, [27] investigates the throughput difference between equally and cross polarized TX antennas. Notably, except [24,26], all above cited references do not employ base-station antennas similar to the ones currently in use in mobile cellular networks.…”

A WiMAX-Based Implementation of Network MIMO for Indoor Wireless Systems

“…Other papers address similar practical issues relating to network MIMO in real-world systems. In [28,29], capacity estimates derived from channel measurements in an urban microcellular system are used to demonstrate that network MIMO can provide a large gain in spectral efficiency through cochannel interference mitigation. Synchronization techniques required to enable base station cooperation (e.g., frequency offset correction) are dealt with in [30].…”

Synchronization of cooperative base stations

“…Interference reduction is reached using a joint beam-forming of the signals transmitted by several cooperative base stations. Fundamental effects as the channel rank advantage and the enhanced capacity have been demonstrated by simulations [4] and in a multi-cell measurement campaign [5]. For an overview of the cooperative base station concept we refer to [6] and references therein.…”