Direct PCF A Robust Direct Link Protocol for 802.11 PCF and HCCA

In original 802.11 infrastructure network, a station (STA) is not allowed to transmit frames directly to other STAS within range. Frame delivery should rely on access point (AP) because recipients may be in power save mode and must be woke up before transmission. To allow direct transmission, 802.11e defines a new operation called direct link set-up (DLS). In DLS, STA can initiate a direct link through AP. One problem not addressed in DLS is how STA collects its neighborhood information. Without this information, it is difficult to know when to establish a direct link. Therefore, we proposed a new direct link protocol for 802.11 PCF and HCCA. We call it Direct PCF (DPCF). Because AP knows all the STAs in its range, the initiator of a direct link in our protocol is AP. We show that DPCF is efficient in data delivery and quick in error recovery.