Apparatus and method for transmitting signals over a physical random access channel

1. A method, wherein the method comprises:

applying scrambling to a plurality of symbols within a symbol group comprising at least first and second adjacent symbols and at least third and fourth adjacent symbols, wherein applying scrambling to the plurality of symbols within the symbol group includes applying a first scrambling symbol to at least the first and second adjacent symbols within the symbol group and applying a second scrambling symbol to at least the third and fourth adjacent symbols within the symbol group; and

transmitting, over a physical random access channel, a signal comprising the symbol group with the scrambled symbols.

2. The method of claim 1 , wherein the symbol group comprises six symbols, and wherein:

the first scrambling symbol is applied to a first pair of adjacent symbols, wherein the first pair of adjacent symbols includes the first and second adjacent symbols within the symbol group;

the second scrambling symbol is applied to a second pair of adjacent symbols, wherein the second pair of adjacent symbols includes the third and fourth adjacent symbols within the symbol group; and

a third scrambling symbol is applied to a third pair of adjacent symbols.

3. The method of claim 1 , wherein the symbol group comprises six symbols, and wherein:

a first scrambling symbol is applied to a first set of three adjacent symbols, wherein the first set of three adjacent symbols includes the first and second adjacent symbols within the symbol group; and

a second scrambling symbol is applied to a second set of three adjacent symbols, wherein the second set of three adjacent symbols includes the third and fourth adjacent symbols within the symbol group.

4. The method of claim 1 , wherein the symbol group comprises eight symbols, and wherein:

a first scrambling symbol is applied to a first set of four adjacent symbols, wherein the first set of four adjacent symbols includes the first and second adjacent symbols within the symbol group; and

a second scrambling symbol is applied to a second set of four adjacent symbols, wherein the second set of four adjacent symbols includes the third and fourth adjacent symbols within the symbol group.

5. The method of claim 1 , wherein:

the first scrambling symbol is applied to symbols of a first symbol sub-group within the symbol group, wherein first symbol sub-group includes the at least first and second adjacent symbols within the symbol group; and

the second scrambling symbol is applied to symbols of a second symbol sub-group within the symbol group, wherein second symbol sub-group includes the at least third and fourth adjacent symbols within the symbol group.

6. The method of claim 1 , wherein:

a first symbol of the group of symbols comprises a cyclic prefix, CP, symbol; or

a set of first symbols of the group of symbols comprises a cyclic, CP symbol.

7. The method of claim 1 , wherein a first symbol, of a sub-group of adjacent symbols within the symbol group having the same scrambling symbol, comprises a cyclic prefix, CP, symbol.

8. The method of claim 1 , wherein:

the group of symbols comprises a random access symbol group; or

the group of symbols comprises a random access frequency hopping symbol group.

9. The method of claim 1 , wherein at least one of:

scrambling is based on cell dependent sequences; and

scrambling symbols are uniquely defined for each cell in a communication network.

10. The method of claim 1 , further comprising at least one of:

receiving a control signal for activating; and

deactivating the scrambling of symbols within the symbol group.

11. The method of claim 1 , wherein at least one of:

the physical random access channel comprises a narrow-band Internet of Things physical random access channel (NPRACH); and

the signal comprises a NPRACH preamble signal.

12. A user equipment, the user equipment comprising:

a processor; and

a memory, said memory containing instructions executable by said processor,

wherein said user equipment is configured to apply scrambling to a plurality of symbols within a symbol group comprising at least first and second adjacent symbols and at least third and fourth adjacent symbols,

wherein applying scrambling to the plurality of symbols within the symbol group includes said user equipment configured to apply a first scrambling symbol to at least the first and second adjacent symbols within the symbol group and to apply a second scrambling symbol to at least the third and fourth adjacent symbols within the symbol group; and

wherein said user equipment is configured to transmit, over a physical random access channel, a signal comprising the symbol group with the scrambled symbols.

13. A method in a network node, the method comprising:

receiving a signal over a physical random access channel, the signal comprising a plurality of symbols forming a symbol group, wherein a first scrambling symbol has been applied to at least first and second adjacent symbols within the symbol group, and a second scrambling symbol has been applied to at least third and fourth adjacent symbols within the symbol group; and

descrambling predetermined symbols of the plurality of symbols forming the symbol group.

14. The method of claim 13 , wherein the predetermined symbols are descrambled in a frequency domain, and wherein the method further comprises processing of phases of the descrambled symbols to determine a time of arrival (ToA) value.

15. The method of claim 14 , comprising transmitting the determined ToA value to a user equipment from which the signal comprising the group of symbols was received.

16. A network node comprising:

a processor; and

a memory, said memory containing instructions executable by said processor, whereby said network node is configured to:

receive a signal over a physical random access channel, the signal comprising a plurality of symbols forming a symbol group, wherein a first scrambling symbol has been applied to at least first and second adjacent symbols within the symbol group, and a second scrambling symbol has been applied to at least third and fourth adjacent symbols within the symbol group; and

descramble predetermined symbols of the plurality of symbols forming the symbol group.

17. The network node of claim 16 , wherein the network node is configured descramble the predetermined symbols in a frequency domain, and wherein the network node is further configured to process phases of the descrambled symbols to determine a time of arrival (ToA) value.