High efficiency long training field symbol transmission for multiple transmission streams
摘要
說明書
The access point generates a wireless packet for transmission that includes a preamble, data, midable, postamble, any suitable data sequence for transmission within the packet, or any combination thereof. In some embodiments, a packet is arranged sequentially for transmission such that the preamble is transmitted first, followed by the data payload, and finally the postamble. In some embodiments, the preamble includes multiple training field symbols including the HE-LTF symbols. The HE-LTF symbols are, in some implementations, transmitted in the midamble (e.g., repeated transmissions, within the data symbols, of HE-LTF symbols sent in the preamble) to account for the time varying nature of the channel. The wireless packet structure is described further in the description of
For example, an access point transmitting 16 spatial streams transmits 16 HE-LTF symbols, one for each spatial stream, and the corresponding channel estimate of the spatial stream that is determined at the receiver. In the current IEEE 802.11ax standard, an access point is required to transmit a 16×16 orthogonal P-matrix that in turn, requires the receiver to apply a Hermitian of the 16×16 orthogonal P-matrix to obtain the channel estimates for the 16 spatial streams. This matrix operation needs to be completed before decoding the first data symbol transmitted after the HE-LTF symbols, because the channel estimates are necessary to accurately decode the data transmitted over and affected by the channel. For the transmission of greater than 16 spatial streams in the current IEEE 802.11ax standard, more HE-LTF symbols are required along with an increased P-matrix sizes (e.g., 32×32 and 64×64).
