Methods for superframe/frame overhead reduction within OFDMA-based communication systems
View Patent ↗A method for tessellating a subframe using maximal-sized bricks. A brick bandwidth and a brick time duration are computed based on the heights and widths of the bursts in the subframe. Bursts within the brick-tessellated subframe are referenced using a brick-based coordinate system in which burst location and size are specified in units of bricks. A method for assembling and disassembling brick-based superframes is also disclosed. Bricked-based superframes are assembled and disassembled using a Superframe Preamble, a Superframe Control Header (SFCH), a Superframe Downlink Map (SDL-MAP), a Superframe Uplink MAP (SUL-MAP) and brick-structured downlink and uplink frames.
1. A method of tessellating a subframe using maximal-sized bricks, each brick comprising a brick bandwidth (r) in units of subcarriers or physical subchannels, and a brick time duration (c) in units of symbols, the subframe comprising a plurality of (n B ) bursts having burst heights (β H,k , k=0, . . . , n B −1) in units of subcarriers or physical subchannels and burst widths (β W,k , k=0, . . . , n B −1) in units of symbols, the method comprising:
computing, using a processor, r and c using equations r=GCD(β H,0 , β H,1 , . . . β H,nB −1 ) and c=GCD (β W,0 , βW,1 , . . . , (β W,nB −1 ), wherein n B , is an integer value, k is an integer value, β H,k denotes a set of k burst heights, β W,k , denotes a set of k burst widths, GCD denotes the greatest common divisor, and neither r nor c is equal to one; and
referencing bursts within the subframe using a brick-based coordinate system in which burst location and size are specified in units of bricks.
2. The method of claim 1 , further comprising computing GCD values using a Euclidean algorithm.
3. The method of claim 1 , further comprising computing GCD values using an Extended Euclidean algorithm.
4. The method of claim 1 , further comprising computing GCD values using a binary GCD algorithm.
5. The method of claim 1 , wherein r and c are computed once per subframe.
6. The method of claim 1 , wherein a kth burst within the subframe is represented by a symbol offset (OFDMA_Symbol_Offset[k]), a number of symbols (Number_of_Symbols [k]), a subchannel offset (OFDMA_Subchannel_Offset[k]), and a number of subchannels (Number_of_Subchannels [k]).
7. The method of claim 6 , further comprising referencing the kth burst within the subframe by a burst time offset (Burst_Time_Offset[k]), a burst time duration (Burst_Time_Durationt[k]), a burst frequency offset (Burst_Frequency_Offset[k]), and a burst bandwidth (Burst_Bandwidth[k]), wherein
Burst_Time
_Offset
[
k
]
=
(
OFDMA_Symbol
_Offset
[
k
]
)
c
,
Burst_Time
_Durationt
[
k
]
=
(
Number_of
_Symbols
[
k
]
)
c
,
Burst_Frequency
_Offset
[
k
]
=
(
OFDMA_Subchannel
_Offset
[
k
]
)
r
,
and
Burst_Bandwidth
[
k
]
=
(
Number_of
_Subchannels
[
k
]
)
r
.
8. The method of claim 1 , further comprising computing a number n R , of r-by-c bricks that cover the subframe's bandwidth in a time-frequency plane using an equation wherein
n
R
=
N
FFT
r
,
where N FFT , denotes the number of subcarriers or subchannels.
9. The method of claim 8 , further comprising computing an integer m F1 , using an operation where m F1 =ceil(log 2 (n R )), wherein ceil(log 2 (n R )) rounds log 2 (n R ) to a nearest integer towards infinity.
10. The method of claim 9 , further comprising setting lengths of Burst_Frequency_Offset[k] and Burst_Bandwidth[k] as m F1 .
11. The method of claim 1 , further comprising computing a number n c , of r-by-c bricks that cover the subframe's time duration in a time-frequency plane using an equation wherein
n
C
=
N
Symbls
c
,
wherein N Symbls , denotes the number of symbols within the subframe.
12. The method of claim 11 , further comprising computing an integer m F0 , using an operation wherein m F0 =ceil(log 2 (n c )), wherein ceil(log 2 (n c )) rounds log 2 (n c ) to a nearest integer towards infinity.
13. The method of claim 12 , further comprising setting lengths of Burst_Time_Offset[k] and Burst_Time_Duration[k] as m F0 .
14. A method for assembling a brick-based superframe, the superframe comprising a Superframe Preamble, a Superframe Control Header (SCH), a Superframe Downlink Map (SDL-MAP), and a Superframe Uplink MAP (SUL-MAP), the SDL-MAP comprising a plurality of (n sF ) Downlink Maps (DL-MAPs) for configuring a plurality of (n SF ) subframes, each DL-MAP comprising a plurality of (n B ) Information Elements (IEs) for configuring a plurality of (n B ) bursts, the method comprising:
inserting a plurality of (n B ) bursts having burst heights (β H,k , k=0, . . . , n B −1) in units of subcarriers or physical subchannels and burst widths (β W,k , k=0, . . . , n B −1) in units of symbols into a subframe;
computing, using a processor, a brick bandwidth (r) and a brick time duration (c) using equations r=GCD(β H,0 , β H,1 , . . . , β H,nB−1 ) and c=GCD((β W,0 , β W,1 , . . . , β W,nB−1 ), where n B , is an integer value, k is an integer value, βH,k denotes a set of k burst heights, β W,k denotes a set of k burst widths, GCD denotes the greatest common divisor, and neither r nor c is equal to one;
inserting r and c into a DL-MAP;
computing, using a processor, a burst time offset (Burst_Time_Offset[k]), a burst time duration (Burst_Time_Durationt[k]), a burst frequency offset (Burst_Frequency_Offset[k]) and a burst bandwidth (Burst_Bandwidth[k]) for a kth burst within the subframe;
inserting Burst_Time_Offset[k], Burst_Time_Durationt[k], Burst_Frequency_Offset[k], and Burst_Bandwidth[k] into an Information Element (IE) within the DL-MAP.
15. The method of claim 14 , wherein a kth burst within the subframe is represented by a symbol offset (OFDMA_Symbol_Offset[k]), a number of symbols (Number_of Symbols [k]), a subchannel offset (OFDMA_Subchannel_Offset[k]), and a number of subchannels (Number_of Subchannels [k]).
16. The method of claim 15 , wherein
Burst_Time
_Offset
[
k
]
=
(
OFDMA_Symbol
_Offset
[
k
]
)
c
,
Burst_Time
_Durationt
[
k
]
=
(
Number_of
_Symbols
[
k
]
)
c
,
Burst_Frequency
_Offset
[
k
]
=
(
OFDMA_Subchannel
_Offset
[
k
]
)
r
,
and
Burst_Bandwidth
[
k
]
=
(
Number_of
_Subchannels
[
k
]
)
r
.
17. The method of claim 14 , further comprising computing a number n R , of r-by-c bricks that cover the subframe's bandwidth in a time-frequency plane using an equation wherein
n
R
=
N
FFT
r
,
where N FFT denotes the number of subcarriers or subchannels.
18. The method of claim 17 , further comprising computing an integer m F1 using an operation wherein m F1 =ceil(log 2 (n R )), wherein ceil(log 2 (n R )) rounds log 2 (n R ) to a nearest integer towards infinity.
19. The method of claim 18 , further comprising setting lengths of Burst_Frequency_Offset[k] and Burst_Bandwidth[k] as m F1 .
20. The method of claim 14 , further comprising computing a number n c of r-by-c bricks that cover the subframe's time duration in a time-frequency plane using an equation wherein
n
C
=
N
Symbls
c
,
wherein N Symbls , denotes the number of symbols within the subframe.
21. The method of claim 20 , further comprising computing an integer m F0 , using an operation wherein m F0 =ceil(log 2 (n c )), wherein ceil(log 2 (n c )) rounds log 2 (n c ) to a nearest integer towards infinity.
22. The method of claim 21 , further comprising setting lengths of Burst_Time_Offset[k] and Burst_Time_Duration[k] as m F0 .
23. The method of claim 14 , wherein the superframe comprises a plurality of frames, and each frame comprises one DL subframe and one UL subframe.
24. The method of claim 14 , wherein the superframe comprises a downlink-uplink ratio of 1-to-1.
25. The method of claim 14 , wherein the superframe comprises a downlink-uplink ratio that is not 1-to-1.
26. A method for disassembling a brick-based superframe, the superframe comprising a Superframe Preamble, a Superframe Control Header (SCH), a Superframe Downlink Map (SDL-MAP), and a Superframe Uplink MAP (SUL-MAP), the SDL-MAP comprising a plurality of (n SF ) Downlink Maps (DL-MAPs) for configuring a plurality of (n SF ) subframes, each DL-MAP comprising a plurality of (n B ) Information Elements (IEs) for configuring a plurality of (n B ) bursts, the method comprising:
processing a DL MAP to obtain a brick bandwidth (r) and a brick time duration (c) of the bricks that tessellate a subframe;
processing an IE within the DL MAP to obtain a burst time offset (Burst_Time_Offset[k]), a burst time duration (Burst_Time_Durationt[k]), a burst frequency offset (Burst_Frequency_Offset[k]) and a burst bandwidth (Burst_Bandwidth[k]) for a kth burst within the subframe;
computing, using a processor, a symbol offset (OFDMA_Symbol_Offset[k]), a number of symbols (Number_of Symbols [k]), a subchannel offset (OFDMA_Subchannel_Offset[k]), and a number of subchannels (Number_of_Subchannels[k]) for the kth burst within the subframe using equations
OFDMA_Symbol_Offset[k]=Burst_Time_Offset[k]*c,
Number_of_Symbols [k]=Burst_Time_Duration[k]*c,
OFDMA_Subchannel_Offset[k]=Burst_Frequency_Offset[k]*r, and
Number_of_Subchannels[k]=Burst_Bandwidth[k]*r,
wherein n SF ,n B and k are integer values.
27. The method of claim 26 , wherein the superframe comprises a plurality of frames, and each frame comprises one DL subframe and one UL subframe.
28. The method of claim 26 , wherein the superframe comprises a downlink-uplink ratio of 1-to-1.
29. The method of claim 26 , wherein the superframe comprises a downlink-uplink ratio that is not 1-to-1.