Attaining both coverage and high spectral efficiency with adaptive OFDM downlinks

A downlink radio interface is proposed for cellular packet data systems with wide area coverage and high spectral efficiency. A slotted OFDM radio interface is used, in which time-frequency bins are allocated adaptively to different users within a downlink beam, based on their channel quality. Fading channels generated by vehicular 100 km/h users may be accommodated. Frequency division duplex (FDD) is assumed, which requires channel prediction in the terminals and feedback of that information to a packet scheduler at the base station. To attain both high spectral efficiency and good coverage within sectors/beams, a scheme based on coordinated scheduling between sectors of the same site, and the employment of frequency reuse factor above 1 only in outer parts of the sector, is proposed and evaluated. The resulting sector throughput increases with the number of active users. When terminals have one antenna and channels are Rayleigh fading, it results in a sector payload capacity between 1.2 (one user) and 2.1 bits/s/Hz/sector (for 30 users) in an interference-limited environment.

[1]  N Casimiro Ericsson.  On scheduling and adaptive modulation in wireless communications , 2001 .

[2]  Torbjörn Ekman.  Prediction of Mobile Radio Channels : Modeling and Design , 2002 .

[3]  M. Sternad,et al.  Channel Estimation and Prediction for Adaptive OFDM Downlinks , 2003 .

[4]  T Ekman.  Prediction of mobile radio channels , 2000 .

[5]  R. Knopp,et al.  Multiple-accessing over frequency-selective fading channels , 1995, Proceedings of 6th International Symposium on Personal, Indoor and Mobile Radio Communications.

[6]  Alexandra Duel-Hallen,et al.  Adaptive modulation using outdated samples of another fading channel , 2002, 2002 IEEE Wireless Communications and Networking Conference Record. WCNC 2002 (Cat. No.02TH8609).

[7]  Andrea J. Goldsmith,et al.  Degrees of freedom in adaptive modulation: a unified view , 2001, IEEE Trans. Commun..

[8]  A. Ahlen,et al.  Hybrid type-II ARQ/AMS supported by channel predictive scheduling in a multi-user scenario , 2000, Vehicular Technology Conference Fall 2000. IEEE VTS Fall VTC2000. 52nd Vehicular Technology Conference (Cat. No.00CH37152).

[9]  Arne Svensson,et al.  Adaptive trellis-coded modulation over predicted flat fading channels , 2003, 2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484).

[10]  Anders Ahlen,et al.  Unbiased power prediction on broadband channels , 2002 .

[11]  Wei Wang,et al.  Impact of multiuser diversity and channel variability on adaptive OFDM , 2003, 2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484).

[12]  Roy D. Yates,et al.  The Infostations challenge: balancing cost and ubiquity in delivering wireless data , 2000, IEEE Wirel. Commun..

[13]  Arne Svensson,et al.  Towards 4G IP-based Wireless Systems: A Proposal for the Uplink , 2002 .

[14]  M Sternad.  Reuse partitioning and system capacity in the adaptive OFDM downlink of the Wireless IP Project target system , 2003 .

[15]  Nelson Ray Sollenberger,et al.  Beyond 3G: wideband wireless data access based on OFDM and dynamic packet assignment , 2000, IEEE Commun. Mag..

[16]  Torbjörn Ekman,et al.  Adaptive Modulation Systems for Predicted Wireless Channels , 2004, IEEE Trans. Commun..