Frequency hopping pattern for narrowband internet-of-things in unlicensed spectrum
Described herein are methods and apparatus for NB-IoT devices to operate in unlicensed spectrum. Frequency hopping patterns are disclosed that enable compliance with applicable regulations. A base station may be configured to operate in Multefire (MF) narrowband internet of things (NB IoT) cell over unlicensed spectrum. The base station may communicate with one or more wireless devices over a specified number N of data channels separate in frequency. The frequencies of the data channels may be specified by a frequency hopping sequence. The base station may be configured to encode an anchor channel for transmission to the one or more wireless devices at a fixed frequency interspersed in time with the data channels.
1. An apparatus comprising:
at least one processor configured to cause a base station to operate in a Multefire (MF) narrowband internet of things (NB IoT) cell over unlicensed spectrum, wherein the at least one processor is configured to:
communicate with one or more user equipments (UEs) over a specified number N of data channels separated in frequency where N=64;
wherein the frequencies of the data channels are specified by a frequency hopping sequence FX64 that is a function of a frequency hopping index, denoted as SFN′, and a function of a cell identity (PCI), wherein SFN′ is a function of a system frame number;
encode an anchor channel for transmission to the one or more UEs at a fixed frequency interspersed in time with the data channels,
wherein the frequency hopping index SFN′ is made such that the data channels are hopped in accordance with the system frame number while skipping the anchor channels that are interspersed therewith; and
calculate the frequency hopping sequence F X64 as:
F X64 =( c ([ F x32 ′+32*SFN′ 5 ])⊕PCI 5:0 +SFN′ 10:6 )mod 64
where c(i) is an indexed length-64 sequence stored in memory that is composed of 64 unique elements from 0 to 63, “ED” is the exclusive-or operation, SFN′ n is the nth bit of the binary representation of SFN′, SFN′ m:n denotes the mth through nth bits of the binary representation of SFN′, PCI m:n denotes the mth through nth bits of the binary representation of the cell identity PCI, F x32 ′ is calculated as:
F x32 ′=Perm5[ X,P ]
where Perm5 is an operator that permutes a 5-bit input vector X in accordance with a 14-bit control vector P to result in a 5-bit output.
2. The apparatus of claim 1 , wherein
X is calculated as:
X =( b (SFN 4:0 ⊕PCI 4:0 )+SFN 9:5 )mod 32,
where b(i) is an indexed length-32 sequence stored in memory that is composed of 32 unique elements from 0 to 31, and where P is calculated as:
P =SFN 10:5 +64*PCI 7:0 .
3. The apparatus of claim 2 , wherein the sequence c(i) is defined as: c(i)={0,23,62,8,43,16,47,19,61,29,59,22,52,63,26,31,2,18,11,36,54,21,3,37,10,34,7,4,60,27,12,25,14,57,41,32,9,58.45,20,39,13,33,50,56,42,48,15,5,17,6,49,40,1,28,55,35,53,24,44,51,38,30,46}.
4. The apparatus of claim 2 , wherein the sequence b(i) is defined as: b(i)={0,14,1,16,24,1,22,3,12,13,9,19,5,25,2,17,8,23,15,28,10,27,29,21,7,31,6,20,30,4,18,26}.
5. The apparatus of claim 1 wherein the frequency hopping index SFN′ is replaced with a frequency hopping index SFN″ calculated as:
SFN″=SFN′− I (SFN′/64)* MJ
where “[ ]” is the floor operator and where M is the number of anchor channels transmitted during the course of 64 consecutive frequency hops.
6. The apparatus of claim 1 , wherein F x32 ′ is a function of the system frame number and the PCI.
7. An apparatus comprising:
at least one processor configured to cause a user equipment (UE) to operate in a Multefire (MF) narrowband internet-of-things (NB IoT) cell over unlicensed spectrum, wherein the at least one processor is configured to:
communicate with base station over a specified number N of data channels separated in frequency where N=64;
wherein the frequencies of the data channels are specified by a frequency hopping sequence F X64 that is a function of a frequency hopping index, denoted as SFN′, and a function of a cell identity (PCI), wherein SFN′ is a function of a system frame number;
calculate the frequency hopping sequence F X64 as:
F X64 =( c ([ F x32 ′+32*SFN′ 5 ])⊕PCI 5:0 +SFN′ 10:6 )mod 64
where c(i) is an indexed length-64 sequence stored in memory that is composed of 64 unique elements from 0 to 63, “⊕” is the exclusive-or operation, SFN′ n is the nth bit of the binary representation of SFN′, SFN′ m:n denotes the mth through nth bits of the binary representation of SFN′, PCI m:n denotes the mth through nth bits of the binary representation of the cell identity PCI, F x32 ′ is calculated as:
F x32 ′=Perm5[ X,P ]
where Perm5 is an operator that per mutes a 5-bit input vector X in accordance with a 14-bit control vector P to result in a 5-bit output.
8. The apparatus of claim 7 , wherein the sequence c(i) is defined as c(i)={0,23,62,8,43,16,47,19,61,29,59,22,52,63,26,31,2,18,11,36,54,21,3,37,10,34,7,4, 60,27,12,25,14,57,41,32,9,58,45,20,39,13,33,50,56,42,48,15,5,17,6,49,40,1,28, 55,35,53,24,44,51,38,30,46}.
9. The apparatus of claim 7 , wherein the at least one processor is further configured to receive an anchor channel from the base station at a fixed frequency interspersed in time with the data channels.
10. The apparatus of claim 9 , wherein the frequency hopping index SFN is replaced with a frequency hopping index SFN″ calculated as:
SFN″=SFN′−[(SFN′/64)* M ]
where “[ ]” is the floor operator and where M is the number of anchor channels transmitted during the course of 64 consecutive frequency hops.
11. The apparatus of claim 9 , wherein the frequency hopping index SFN′ is replaced with a frequency hopping index SFN″ such that the data channels are numbered consecutively in accordance with the system frame number while skipping the anchor channels that are interspersed therewith.
12. The apparatus of claim 7 , wherein X is calculated as:
X =( b (SFN 4:0 ⊕PCI 4:0 )+SFN 9:5 )mod 32,
where b(i) is an indexed length-32 sequence stored in memory that is composed of 32 unique elements from 0 to 31, and where P is calculated as:
P =SFN 10:5 +64*PCI 7:0 .
13. The apparatus of claim 12 , wherein the sequence b(i) is defined as: b(i)={0,14,1,16,24,11,22,3,12,13,9,19,5,25,2,17,8,23,15,28,10,27,29, 21,7,31,6,20,30,4,18,26}.
14. The apparatus of claim 7 , wherein F x32 ′ is a function of the system frame number and the PCI.
15. A non-transitory computer-readable storage medium storing instructions executable by at least one processor of a user equipment (UE) to:
operate in a Multefire (MF) narrowband internet-of-things (NB IoT) cell over unlicensed spectrum;
communicate with base station over a specified number N of data channels separated in frequency where N=64;
wherein the frequencies of the data channels are specified by a frequency hopping sequence F X64 that is a function of a frequency hopping index denoted as SFN or SFN′, wherein both SFN and SFN′ are proportional to a system frame number, and a function of a cell identity (PCI); calculate the frequency hopping sequence F X64 as:
F X64 =( c ([ F x32 ′+32*SFN′ 5 ])⊕PCI 5:0 +SFN′ 10:6 )mod 64
where c(i) is an indexed length-64 sequence that is composed of 64 unique elements from 0 to 63, “⊕” is the exclusive-or operation, SFN′ n is the nth bit of the binary representation of SFN′, SFN′ m:n denotes the mth through nth bits of the binary representation of SFN′, PCI m:n denotes the mth through nth bits of the binary representation of the cell identity PCI, F x32 ′ is calculated as:
F x32 ′=Perm5[ X,P ]
where Perm5 is an operator that permutes a 5-bit input vector X in accordance with a 14-bit control vector P to result in a 5-bit output, where X is calculated as:
X =( b (SFN 4:0 PCI 4:0 )+SFN 9:5 )mod 32,
where b(i) is an indexed length-32 sequence that is composed of 32 unique elements from 0 to 31, and where P is calculated as:
P =SFN 10:5 +64*PCI 7:0 .
16. The non-transitory computer-readable storage medium of claim 15 , wherein the sequence c(i) is defined as: c(i)={0,23,62,8,43,16,47,19,61,29,59,22,52,63,26,31,2,18,11,36,54,21,3,37,10,34,7,4, 60,27,12,25,14,57,41,32,9,58,45,20,39,13,33,50,56,42,48,15,5,17,6,49,40,1,28, 55,35,53,24,44,51,38,30,46}.
17. The non-transitory computer-readable storage medium of claim 15 , wherein the sequence b(i) is defined as: b(i)={0,14,1,16,24,11,22,3,12,13,9,19,5,25,2,17,5,23,15,25,10,27,29, 21,7,31,6,20,30,4,18,26}.
18. The non-transitory computer-readable storage medium of claim 15 , further comprising instructions to receive an anchor channel from the base station at a fixed frequency interspersed in time with the data channels.
19. The non-transitory computer-readable storage medium of claim 15 , further comprising instructions that replace the frequency hopping index SFN or SFN′ with a frequency hopping index SFN″ calculated as:
SFN″=SFN′−[(SFN′/64)* M ]
where “[ ]” is the floor operator and where M is the number of anchor channels transmitted during the course of 64 consecutive frequency hops.
20. The non-transitory computer-readable storage medium of claim 15 , wherein the frequency hopping index SFN or SFN′ is replaced with a frequency hopping index SFN″ such that the data channels are numbered consecutively in accordance with the system frame number while skipping the anchor channels that are interspersed therewith.