Signaling of sequence generator initialization parameters for uplink reference signal generation
A base station initializes pseudo-random sequence generators on which wireless devices base generation of uplink reference signals. The base station determines a first sequence from a first subset of possible initialization sequences for a sequence generator of a first device, and determines a second sequence from a second subset of possible initialization sequences for a sequence generator of a second device. The range of this second subset spans at least the range of the first subset. The base station further encodes the first sequence as a first set of two or more parameters, and encodes the second sequence as a second set of one or more parameters. This second set includes at least one parameter not included in the first set, and comprises fewer bits than the first set. The base station initializes the sequence generators by transmitting the first and second sets of parameters to the devices.
1. A method implemented by a wireless device for initializing a pseudo-random sequence generator on which to base generation of an uplink reference signal, comprising:
selectively deriving one of the initialization sequences within a subset of possible initialization sequences for the sequence generator, according to one or more rules that define different initialization sequences in the subset as a function of a single parameter, wherein the single parameter is received from a base station, wherein said deriving comprises deriving the initialization sequence based on a defined one-to-one mapping of possible initialization sequences in the subset to possible values for the single parameter, wherein the range of the single parameter is smaller than the range of the subset, and wherein said deriving comprises deriving the initialization sequence c init according to
c
init
=
z
+
2
⌊
z
30
⌋
,
wherein z is the single parameter and └x┘ denotes a floor function that rounds x to the nearest integer less than or equal to x;
generating the uplink reference signal with the sequence generator initialized to the derived initialization sequence; and
transmitting the generated signal.
2. The method of claim 1 , wherein the single parameter comprises 9 or 10 bits, and the initialization sequence comprises 31 bits.
3. The method of claim 1 , wherein the range of the single parameter spans between a minimum value of 0 and a maximum value no greater than 541.
4. The method of claim 1 , wherein the initialization sequence comprises a device-specific sequence.
5. The method of claim 1 , wherein when cyclic shift hopping is enabled for the device said generating comprises:
determining a cyclic shift hopping pattern from the derived initialization sequence;
applying the cyclic shift hopping pattern to a cyclic shift; and
applying the resulting cyclic shift to a base sequence.
6. The method of claim 5 , further comprising deriving an indication of whether or not cyclic shift hopping is enabled for the device according to one or more rules that define such indication as a function of the single parameter.
7. A wireless device configured to initialize a pseudo-random sequence generator on which to base generation of an uplink reference signal, comprising:
a transceiver, and
one or more processing circuits configured to:
selectively derive one of the initialization sequences within a subset of possible initialization sequences for the sequence generator, according to one or more rules that define different initialization sequences in the subset as a function of a single parameter, by deriving the initialization sequence based on a defined one-to-one mapping of possible initialization sequences to possible values for the single parameter, wherein the range of the single parameter is smaller than the range of the subset, wherein the one or more processing circuits are configured to derive the initialization sequence c init according to
c
init
=
z
+
2
⌊
z
30
⌋
,
wherein z is the single parameter and └x┘ denotes a floor function that rounds x to the nearest integer less than or equal to x;
generate the uplink reference signal with the sequence generator initialized to the derived initialization sequence; and
transmit the generated signal via the transceiver.
8. The device of claim 7 , wherein the single parameter comprises 9 or 10 bits, and the initialization sequence comprises 31 bits.
9. The device of claim 7 , wherein the range of the single parameter spans between a minimum value of 0 and a maximum value no greater than 541.
10. The device of claim 7 , wherein the initialization sequence comprises a device-specific sequence.
11. The device of claim 7 , wherein when cyclic shift hopping is enabled for the device the one or more processing circuits are configured to generate the uplink reference signal by:
determining a cyclic shift hopping pattern from the derived initialization sequence;
applying the cyclic shift hopping pattern to a cyclic shift; and
applying the resulting cyclic shift to a base sequence.
12. The device of claim 11 , wherein the one or more processing circuits are further configured to derive an indication of whether or not cyclic shift hopping is enabled for the device according to one or more rules that define such indication as a function of the single parameter.