Methods and arrangements for transmitting and decoding reference signals

摘要

In a radio network node, a reference signal is transmitted over an antenna port, in a code division multiplexing (CDM) group. The CDM group includes CDM subgroups of resource elements, the CDM subgroups being transmitted on different subcarriers. First, the radio network node transmits the reference signal over a first CDM subgroup using an orthogonal cover code (OOC). The first CDM subgroup includes resource elements in a first time slot and a subsequent time slot. Then, the radio network node transmits the reference signal over a second CDM subgroup using a permutation of the OOC. The second CDM subgroup includes resource elements in the first time slot and the second time slot. The permutation of the OOC is selected such that to enable decoding of the reference signal in the frequency domain, by applying the OOC only to resource elements in the CDM group in the first time slot.

主权项

1. A method in a user equipment for decoding a reference signal, wherein the method comprises:
receiving, by the user equipment in a first time slot, a first set of resource elements comprised in a first code division multiplexing (CDM) subgroup, and a second set of resource elements comprised in a second CDM subgroup, wherein the reference signal is comprised of a first CDM group, which comprises the first and second CDM subgroups, and wherein the first and second CDM subgroups are received on a different subcarrier and each of the first and second CDM subgroups comprise resource elements in the first time slot and a subsequent time slot; decoding, by the user equipment, the reference signal by applying an orthogonal cover code to the first and second set of resource elements in the first time slot and not to the first and second set of resource elements in the subsequent time slot, wherein the first CDM subgroup is repeated an equal number of times as the second CDM subgroup over two resource blocks; decoding a second reference signal which is received in a second CDM group, the second CDM group comprising at least a third CDM subgroup and a fourth CDM subgroup received on different subcarriers and comprising resource elements in the first time slot and the subsequent time slot, wherein the second reference signal is decoded by
receiving, in the first time slot, a third set of resource elements comprised in the third CDM subgroup, and a fourth set of resource elements comprised in the fourth CDM subgroup;decoding the second reference signal by applying a permutation of the orthogonal cover code to the third and fourth set of resource elements.