Resource Allocation Type in a Nutshell
- Resource Allocation Type indicates a method for resource allocation in frequency domain
- Three types are supported in NR : Type 0(bitmap), Type 1(start RB,nRB) and Dynamic Swtich
- Resource Allocation Type is configured in RRC and the resource allocation for specific scheduling for PDSCH/PUSCH is indicated in DCI.
- In DCI, Resource Allocation for Type 0 is configured in the form of bitmap and Resource Allocation for Type 1 is configured in RIV
|
Resource Allocation Type in Detail
Resource Allocation Type indicates a method for resource allocation in frequency domain. Similar concept is used in LTE Resource Allocation as well. So if you are familiar with LTE Resource Allocation Type, you would easily understand the concepts on NR Resource Allocation Type.
NR Resource Allocation Type is specified in the following specification.
- Downlink : 38.214 - 5.1.2.2 Resource allocation in frequency domain
- Uplink : 38.214 - 6.1.2.2 Resource allocation in frequency domain
Resource Allocation Type specifies the way in which the scheduler allocate resource blocks for each transmission. Just in terms of flexibility, the way to give the maximum flexibility of resource block allocation would be to use a string of a bit map (bit stream), each bit of which represent each resource block. This way you would achieve the maximum flexibility, but it would create too much complication of resource allocation process or too much data (too long bit map) to allocate
the resources.
As mentioned above, LTE also use similar concept. Following table shows the comparision of NR and LTE Resource Allocation Type.
According to 38.214 - 5.1.2.2, the Resource Allocation Type is determined implcitely by DCI format or by RRC layer message as described below.
-
The UE may assume that when the scheduling grant is received with DCI format 1_0 downlink resource allocation type 1 is used.
-
If the scheduling DCI is configured to indicated the downlink resource allocation type as part of the Frequency-domainPDSCHresource field, the UE shall use downlink resource allocation type 0 or type 1 as defined by this field. Otherwise the UE shall use the downlink frequency resource allocation type as defined by the RRC configured parameter Resource-allocation-config for PDSCH.
In this type, we bundle multiple number of consecutive RBs into RBG(Resource Block Group) and allocate PDSCH / PUSCH only in the multiples of RBG. The number of RBs within a RBS varies depending on Bandwidth Part Size and Configuration as shown in the following table. The configuration type is determined by rbg-size field in PDSCH-Config in a RRC message. We specify the bitmap in DCI
indicating the RBG number that
carries PDSCH or PUSCH data. Since this is the bitmap, it is not required for the RBGs to be consecutive.
< 38.214 - Table 5.1.2.2.1-1: Nominal RBG size P, Table 6.1.2.2.1-1: Nominal RBG size P >
Bandwidth
Part Size
|
Configuration
1
|
Configuration
2
|
1
36
|
2
|
4
|
37
72
|
4
|
8
|
73
144
|
8
|
16
|
145
275
|
16
|
16
|
|
Bandwidth Size
(1-36)
|
Bandwidth Size
(37-72)
|
Bandwidth Size
(73-144)
|
Bandwidth Size
(145-275)
|
PRB #
|
Config 1
|
Config 2
|
Config 1
|
Config 2
|
Config 1
|
Config 2
|
Config 1
|
Config 2
|
0
|
RBG 00
|
RBG 00
|
RBG 00
|
RBG 00
|
RBG 00
|
RGB 00
|
RGB 00
|
RGB 00
|
1
|
2
|
RBG 01
|
3
|
4
|
RBG 02
|
RBG 01
|
RBG 01
|
5
|
6
|
RBG 03
|
7
|
8
|
RBG 04
|
RBG 02
|
RBG 02
|
RBG 01
|
RBG 01
|
9
|
10
|
RBG 05
|
11
|
12
|
RBG 06
|
RBG 03
|
RBG 03
|
13
|
14
|
RBG 07
|
15
|
16
|
RBG 08
|
RBG 04
|
RBG 04
|
RBG 02
|
RBG 02
|
RGB 01
|
RGB 01
|
RGB 01
|
17
|
18
|
RBG 09
|
19
|
20
|
RBG 10
|
RBG 05
|
RBG 05
|
21
|
22
|
RBG 11
|
23
|
24
|
RBG 12
|
RBG 06
|
RBG 06
|
RBG 03
|
RBG 03
|
25
|
26
|
RBG 13
|
27
|
28
|
RBG 14
|
RBG 07
|
RBG 07
|
29
|
30
|
RBG 15
|
31
|
32
|
RBG 16
|
RBG 08
|
RBG 08
|
RBG 04
|
RBG 04
|
RGB 02
|
RGB 02
|
RGB 02
|
33
|
34
|
RBG 17
|
35
|
36
|
|
|
RBG 09
|
37
|
|
|
38
|
|
|
39
|
|
|
40
|
|
|
RBG 10
|
RBG 05
|
RBG 05
|
41
|
|
|
42
|
|
|
43
|
|
|
44
|
|
|
RBG 11
|
45
|
|
|
46
|
|
|
47
|
|
|
48
|
|
|
RBG 12
|
RBG 06
|
RBG 06
|
RGB 03
|
RGB 03
|
RGB 03
|
49
|
|
|
50
|
|
|
51
|
|
|
52
|
|
|
RBG 13
|
53
|
|
|
54
|
|
|
55
|
|
|
56
|
|
|
RBG 14
|
RBG 07
|
RBG 07
|
57
|
|
|
58
|
|
|
59
|
|
|
60
|
|
|
RBG 15
|
61
|
|
|
62
|
|
|
63
|
|
|
64
|
|
|
RBG 16
|
RBG 08
|
RBG 08
|
RGB 04
|
RGB 04
|
RGB 04
|
65
|
|
|
66
|
|
|
67
|
|
|
68
|
|
|
RBG 17
|
69
|
|
|
70
|
|
|
71
|
|
|
72
|
|
|
|
|
RBG 09
|
73
|
|
|
|
|
74
|
|
|
|
|
75
|
|
|
|
|
76
|
|
|
|
|
77
|
|
|
|
|
78
|
|
|
|
|
79
|
|
|
|
|
80
|
|
|
|
|
RBG 10
|
RGB 05
|
RGB 05
|
RGB 05
|
81
|
|
|
|
|
82
|
|
|
|
|
83
|
|
|
|
|
84
|
|
|
|
|
85
|
|
|
|
|
86
|
|
|
|
|
87
|
|
|
|
|
88
|
|
|
|
|
RBG 11
|
89
|
|
|
|
|
90
|
|
|
|
|
91
|
|
|
|
|
92
|
|
|
|
|
93
|
|
|
|
|
94
|
|
|
|
|
95
|
|
|
|
|
96
|
|
|
|
|
RBG 12
|
RGB 06
|
RGB 06
|
RGB 06
|
97
|
|
|
|
|
98
|
|
|
|
|
99
|
|
|
|
|
100
|
|
|
|
|
101
|
|
|
|
|
102
|
|
|
|
|
103
|
|
|
|
|
104
|
|
|
|
|
RBG 13
|
105
|
|
|
|
|
106
|
|
|
|
|
107
|
|
|
|
|
108
|
|
|
|
|
109
|
|
|
|
|
110
|
|
|
|
|
111
|
|
|
|
|
112
|
|
|
|
|
RBG 14
|
RGB 07
|
RGB 07
|
RGB 07
|
113
|
|
|
|
|
114
|
|
|
|
|
115
|
|
|
|
|
116
|
|
|
|
|
117
|
|
|
|
|
118
|
|
|
|
|
119
|
|
|
|
|
120
|
|
|
|
|
RBG 15
|
121
|
|
|
|
|
122
|
|
|
|
|
123
|
|
|
|
|
124
|
|
|
|
|
125
|
|
|
|
|
126
|
|
|
|
|
127
|
|
|
|
|
128
|
|
|
|
|
RBG 16
|
RGB 08
|
RGB 08
|
RGB 08
|
129
|
|
|
|
|
130
|
|
|
|
|
131
|
|
|
|
|
132
|
|
|
|
|
133
|
|
|
|
|
134
|
|
|
|
|
135
|
|
|
|
|
136
|
|
|
|
|
RBG 17
|
137
|
|
|
|
|
138
|
|
|
|
|
139
|
|
|
|
|
140
|
|
|
|
|
141
|
|
|
|
|
142
|
|
|
|
|
143
|
|
|
|
|
144
|
|
|
|
|
|
|
RGB 09
|
RGB 09
|
145
|
|
|
|
|
|
|
146
|
|
|
|
|
|
|
147
|
|
|
|
|
|
|
148
|
|
|
|
|
|
|
149
|
|
|
|
|
|
|
150
|
|
|
|
|
|
|
151
|
|
|
|
|
|
|
152
|
|
|
|
|
|
|
153
|
|
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|
|
|
|
154
|
|
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|
|
|
|
155
|
|
|
|
|
|
|
156
|
|
|
|
|
|
|
157
|
|
|
|
|
|
|
158
|
|
|
|
|
|
|
159
|
|
|
|
|
|
|
160
|
|
|
|
|
|
|
RGB 10
|
RGB 10
|
161
|
|
|
|
|
|
|
162
|
|
|
|
|
|
|
163
|
|
|
|
|
|
|
164
|
|
|
|
|
|
|
165
|
|
|
|
|
|
|
166
|
|
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|
|
|
|
167
|
|
|
|
|
|
|
168
|
|
|
|
|
|
|
169
|
|
|
|
|
|
|
170
|
|
|
|
|
|
|
171
|
|
|
|
|
|
|
172
|
|
|
|
|
|
|
173
|
|
|
|
|
|
|
174
|
|
|
|
|
|
|
175
|
|
|
|
|
|
|
176
|
|
|
|
|
|
|
RGB 11
|
RGB 11
|
177
|
|
|
|
|
|
|
178
|
|
|
|
|
|
|
179
|
|
|
|
|
|
|
180
|
|
|
|
|
|
|
181
|
|
|
|
|
|
|
182
|
|
|
|
|
|
|
183
|
|
|
|
|
|
|
184
|
|
|
|
|
|
|
185
|
|
|
|
|
|
|
186
|
|
|
|
|
|
|
187
|
|
|
|
|
|
|
188
|
|
|
|
|
|
|
189
|
|
|
|
|
|
|
190
|
|
|
|
|
|
|
191
|
|
|
|
|
|
|
192
|
|
|
|
|
|
|
RGB 12
|
RGB 12
|
193
|
|
|
|
|
|
|
194
|
|
|
|
|
|
|
195
|
|
|
|
|
|
|
196
|
|
|
|
|
|
|
197
|
|
|
|
|
|
|
198
|
|
|
|
|
|
|
199
|
|
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|
|
|
|
200
|
|
|
|
|
|
|
201
|
|
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|
|
|
|
202
|
|
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|
|
|
|
203
|
|
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|
|
|
|
204
|
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|
|
|
|
205
|
|
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|
|
|
|
206
|
|
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|
|
|
|
207
|
|
|
|
|
|
|
208
|
|
|
|
|
|
|
RGB 13
|
RGB 13
|
209
|
|
|
|
|
|
|
210
|
|
|
|
|
|
|
211
|
|
|
|
|
|
|
212
|
|
|
|
|
|
|
213
|
|
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|
|
|
|
214
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|
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|
|
|
|
215
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|
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|
216
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|
|
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|
217
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|
218
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|
219
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|
220
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|
221
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|
|
222
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|
|
|
223
|
|
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|
|
|
|
224
|
|
|
|
|
|
|
RGB 14
|
RGB 14
|
225
|
|
|
|
|
|
|
226
|
|
|
|
|
|
|
227
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|
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|
|
|
|
228
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|
229
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|
230
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|
231
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|
232
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|
233
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|
234
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|
235
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|
|
236
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|
237
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|
238
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|
|
239
|
|
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|
|
|
|
240
|
|
|
|
|
|
|
RGB 15
|
RGB 15
|
241
|
|
|
|
|
|
|
242
|
|
|
|
|
|
|
243
|
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|
244
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|
245
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|
246
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|
247
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248
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249
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250
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251
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252
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|
253
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|
254
|
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|
255
|
|
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|
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|
|
256
|
|
|
|
|
|
|
RGB 16
|
RGB 16
|
257
|
|
|
|
|
|
|
258
|
|
|
|
|
|
|
259
|
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|
260
|
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|
261
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|
262
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|
263
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|
264
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|
265
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|
266
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|
267
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|
268
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|
269
|
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|
270
|
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|
|
|
|
271
|
|
|
|
|
|
|
272
|
|
|
|
|
|
|
RBG 17
|
RBG 17
|
273
|
|
|
|
|
|
|
274
|
|
|
|
|
|
|
In this type, the resource is allocated to one or more consecutive RBs. The resource allocation area is defined by two parameters RB_Start and Number of Consecutive RBs within a specific BWP(BandWidth Part). When the resource allocation is specified in DCI, RB_Start and Number of Consecutive RBs within the BWP is combined into a specific single value called RIV(Resource Indicator Value).
When the resource allocation for type 1 is configured in DCI, it is specified as a specific number called RIV. RIV is a number to specify PDSCH or PUSCH resource allocation. In more intuitive form, we normally use two values (i.e, Number of RBs and Start RB) for the resource allocation. But with RIV, we can represent Number of RBs and Start RB in a single value. It would have some advantage in terms of number of bits to carry the information.. but it causes some confusion for us to convert
RIV into Number of RBs and Start RB
The RIV is calculated in following formula.
NOTE : For easy conversion between RIV and RB, check out this site.
Whether to use Type 0 or Type 1 is determined by DCI at the time of each transmission.
In 38.214-5.1.2.2, it is stated as follows.
If the scheduling DCI is configured to indicate the downlink resource allocation type as part of the Frequency domain resource assignment field by setting a higher layer parameter resourceAllocation in pdsch-Config to 'dynamicswitch', the UE shall use downlink resource allocation type 0 or type 1 as defined by this DCI field. Otherwise the UE shall use the downlink frequency resource allocation type as defined by the higher layer parameter resourceAllocation.
In 38.212-7.3.1.2.2, it is stated as follows.
If both resource allocation type 0 and 1 are configured, the MSB bit is used to indicate resource allocation type 0 or resource allocation type 1, where the bit value of 0 indicates resource allocation type 0 and the bit value of 1 indicates resource allocation type 1.
Reference
[1]
|