Title: Control channel allocation for femto-cells Document Number: C802.16m-08/1350r1 Date Submitted: November 10, 2008 Source: Mariana Goldhamer Voice:+972 3 645 6241 mariana.goldhamer@alvarion.com ALVARION 21a HaBarzel Street, Tel Aviv, Israel Venue: Session #58, 10-13 November, 2008 Base Document: Purpose: Notice This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures:<http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and <http://standards.ieee.org/guides/opman/sect6.html#6.3>. Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and <http://standards.ieee.org/board/pat >.

Deployment problem 1 – high density of femto-BS creating interference to macro-MS MS associated with macro-BS

Deployment problem 2: blocking of the MS operating next to a femto-BS The interference power at 1m distance is -15dBm The receive power level is around -95dBm Obvious MS receiver blocking In the same channel Also if the MS operates on the adjacent channel The adjacent channel rejection is around 23dB Femto-BS 25dBm eirp MS associated with macro-BS 1m, 40dB attenuation

Control channels operation Macrocell operation Using all the superframe; the interfered MS shall be protected at least at the superframe start to hear the control info Preamble, FCH, MAPs No femto-BS operation at the multi-frame start No femto-BS operation in the OFDMA allocation for Reuse 1/3 Femto-cell operation To be allowed only during certain frames or sub-frames To use different control channel allocation from those used by the macro-cell

FFR in SDD – Clause 20.1 Separation in OFDMA domain Macro cells to take the Reuse 1/3 partition Femto-cells to use the Reuse 2/3 partition, but the actual reuse factor needs to be defined

Possible solution Frame 1 Superframe DL UL Reuse 1/3 Reuse 1/3 & 2/3 Dedicated resources for Cat. 1 Control Channels, DL and UL Additional resources for Cat. 1 Control Channels, DL and UL Frame 1 Superframe DL UL Dedicated resources for Cat. 3 Control Channels, DL and UL Additional resources for Cat. 3 Control Channels, DL and UL Reuse 1/3 Reuse 1/3 & 2/3 Reuse 1 Frame 2 Frame 3 Frame 4

SDD Text Insert new clause 11.4.5: Support for the Control Channels of femto cells in Frame Structure 802.16m systems shall support the staggering of Superframe start times, for allowing mobile stations in the vicinity of a femto-cell or a pico-cell to hear the control information from a faraway base station; the control information for femto-cells should be sent in the 2nd frame of the superframe. The control channels of the femto cells shall use a different OFDMA partition from the partition used by the macro-cells. There is a need for multiple partitions. An example of the Control Channel allocation, consistent with fig. 45, SDD clause 20.1 is presented in fig. xx. Controls channels for macro cells are placed in the Reuse 1/3 area of the first Frame within the superframe; Control Channels for femto-cells are placed in the 2nd Frame of the Superframe, avoiding the Reuse 1/3 allocation reserved for macro cells.

Fig. xx Frame 1 Superframe DL UL Reuse 1/3 Reuse 1/3 & 2/3 Reuse 1 Dedicated resources for Cat. 1 Control Channels, DL and UL Additional resources for Cat. 1 Control Channels, DL and UL Frame 1 Superframe DL UL Dedicated resources for Cat. 3 Control Channels, DL and UL Additional resources for Cat. 3 Control Channels, DL and UL Reuse 1/3 Reuse 1/3 & 2/3 Reuse 1 Frame 2 Frame 3 Frame 4