Methods and systems for dynamic single-frequency-network-multicast symbol synchronization

摘要

Disclosed herein are methods and systems for dynamic single-frequency-network-(SFN)-multicast symbol synchronization. In an embodiment, a wireless-communication device (WCD) receives an SFN-multicast transmission at least in part by receiving a respective SFN-multicast-transmission signal from each site in a plurality of sites in a given SFN-multicast area, where each such received SFN-multicast-transmission signal has a respective SFN-multicast cyclic prefix. The WCD calculates a multisource multipath delay spread (“MMDS”) that is characteristic of the received plurality of SFN-multicast-transmission signals, and determines whether that calculated MMDS exceeds a threshold MMDS. If so, the WCD selects a multicast timing point that is after the SFN-multicast cyclic prefix of a first-received one of the received SFN-multicast-transmission signals. If not, the WCD selects a multicast timing point that is within the SFN-multicast cyclic prefix of the first-received SFN-multicast-transmission signal. The WCD uses the selected multicast timing point to demodulate the received SFN-multicast transmission.

主权项

1. A method carried out by a wireless-communication device (WCD), the method comprising:
receiving a single-frequency-network-(SFN)-multicast transmission, wherein receiving the SFN-multicast transmission comprises receiving a respective SFN-multicast-transmission signal from each site in a plurality of sites in a given SFN-multicast area, each received SFN-multicast-transmission signal having a respective SFN-multicast cyclic prefix; calculating a multisource multipath delay spread (“MMDS”) that is characteristic of the received plurality of SFN-multicast-transmission signals; determining whether the calculated MMDS exceeds an MMDS threshold; selecting a multicast timing point that is (i) after the SFN-multicast cyclic prefix of a first-received one of the received SFN-multicast-transmission signals responsive to determining that the calculated MMDS exceeds the MMDS threshold or (ii) within the SFN-multicast cyclic prefix of the first-received SFN-multicast-transmission signal responsive to determining that the calculated MMDS does not exceed the MMDS threshold; using the selected multicast timing point to demodulate the received SFN-multicast transmission; obtaining a respective correlation sequence for the SFN-multicast transmission with each reference signal in a set of known reference signals, wherein the set of known reference signals includes a respective unicast reference signal from each site in the plurality of sites, wherein each obtained correlation sequence comprises a respective maximum peak, wherein locating the set of peaks comprises locating the respective maximum peak in each obtained correlation sequence; locating a set of peaks in the set of obtained correlation sequences, wherein the WCD calculates the MMDS based at least in part on the located set of peaks; and discarding at least one located maximum peak that does not exceed a correlation threshold prior to calculating the MMDS.