1. PHY Single Channel Specifications
IEEE P Wireless RANs Date:
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2. PHY Single Channel Specifications

3. General
The Phy has been studied extensively and is suitable for fixed and nomadic scenarios including outdoor to indoor and use of BeamForming which will play a critical role in WRAN.

4. Phy Design Considerations
Preambles
We recommend use of a single frame preamble with pilots every third SC (3 repetitions in the time domain with length of 1 OFDM symbol)
This preamble which will also serve as the superframe preamble (in the first frame) will allow the following estimation mechanism:
Coarse time synchronization based on the repetition property in the time domain.
Coarse frequency shift (f) estimation and fine time synchronization
Adaptive channel estimation in both fixed and nomadic applications

5. Phy Design Considerations (Cont.)
Extensive analytical and simulation studies show that all of these objectives are attainable in different and harsh environment with a single preamble symbol. Thus, obviously this preamble concept will satisfy the requirements.
DL Pilots
We propose to use cluster scheme (PUSC) as the basic allocation of data within the frame. The cluster pilots will allow a robust computation and the random and time varying frequency offset which will facilitate low cost synthesizer in the CPE.
We note that the use of pilots such that their union on adjacent symbols satisfies Nyquist will allow much more robust channel estimation in fixed and mobile scenarios

6. DL Subchannel Scheme OFDM Symbols Sub-Carriers , 12 data sub -
carriers + 2 pilots
odd Symbols
even Symbols
One cluster
odd Symbols
even Symbols ,
One cluster
consists of
even and odd symbols
each contains 12 data
sub -
carriers and 2 pilots1
One sub -
channel consists of
OFDM Symbols
2 clusters (48 data sub -
carriers and 8 pilots)
Pilot
Data
Sub-Carriers

7. Phy Design Considerations (Cont.)
UL Pilots
We recommend use of PUSC scheme (Tiles) in the UL both with and without subchannel rotation. The use of cluster scheme with subchannel rotation will allow the receiver (BS) to benefit from robust channel estimation and frequency diversity.
PUSC without rotation will allow a very attractive means for receive beamforming techniques that will probably be invoked in rural scenarios.
The use of PUSC scheme will also ease the scheduling process since it gives every cluster the pilots it needs for adaptive channel estimation ( as UL solution that relies on UL preambles significantly complicate the scheduler and does not retain enough pilots for Rx beamforming)

8. Phy Design Considerations (Cont.)
SuperFrame Preamble
The Superframe preamble shall be identical in format to the Frame preamble ( different PN sequences can be allocated to superframe and frames)
Frame Preamble
The first frame preamble (F0) should be eliminated in a way that the superframe preamble will act on behalf of the first frame. This will ease the computational burden which is needed in the first frame.

9. Superframe Structure Accommodating Single Channel
SF preamble
FCH
Frame preamble
SCH F0 F1
o x x o x x o x x
DL MAP
No preamble
No need for additional Frame preamble in F0. Serves the Single channel requirement for less complexity. No impact or adverse consequences concerning the MAC layer and

10. PN Sequences
Our recommendation is to use the PN Sequences proposed in Runcom`s contribution and used in IEEE The big advantage of these sequences presides on the fact that they have been chosen to optimize PAPR at the transmitter and have been verified through extensive simulation studies by numerous parties. Only one symbol is required for preamble
Together with the proposal for identical preambles for Superframe and frames, the usage of the above mentioned PN sequences offer a large set of sequences with the important factor of simplicity of realization. For instance, the allocation of a subset of the PN sequences to Frame preamble and disjoint subset to Superframes preambles. This will allow the user to distinguish between Superframes and Frames and different set CPEs or Base Stations

11. PAPR Comparison

12. Scheme for Resource allocation on the Uplink

13. One Subchannel (Basis Unit Allocation)
UL Resource Allocation
One Subchannel (Basis Unit Allocation)
48 Data Carriers, 6 Pilots t
21 OFDM SYMBOLS
SubChannel
User #1
SubChannel
User #2
SubChannel
3 OFDM Symbols
Sub Channels
SubChannel
User #3
SubChannel
SubChannel
UL resources are allocated on one dimension

14. UL Subchannel Scheme (PUSC)
Subcarriers are partitioned into tiles which is 3x3 frequency-time domain block containing 9 tones (1pilot and 8 data subcarriers)
One Subchannel consists of 6 tiles spread over three OFDM symbols
A burst in the Uplink is composed of 3 time symbols and one subchannel. Within each burst there are 48 data subcarriers and 6 fixed-location subcarriers
Tile 1
Tile 2
Tile 3 -
OFDM Symbols
Tile 4 -
Tile 5
Tile 6
Pilot
Data
Symbol 1
Symbol 2
Symbol 3 t
21 OFDM Symbols

15. The whole frequency bands are partitioned into groups of contiguous tiles. Subcarriers within each tile are adjacent to pilot subcarrier.
Each subchannel consists of 6 tiles which is chosen from different groups.
The number of tiles within a group is 32 and there are 18 groups in the whole frequency bands.
Since a subchannel consists of 6 tiles, 6 groups at equal distance (3 groups away from each) are chosen and each tile is selected from each group
A rotation scheme is applied per each OFDMA slot duration, where a slot when using permutations.
Minimum resource allocation to users could be only one subchannel thus offering high granularity

16. OFDMA Uplink subcarriers allocation
Value
Parameter 1
Number of DC Subcarrier
1728
N used
159,160
Guard subcarrier : left, right 96
N Subchannels
576
N tiles 3
Number of subcarriers per tile 6
Tiles per subcarrier 48
Number of data subcarriers per Subchannel