Patent ID: 7286842
Filing Date: 2007-10-23
Classification: H04B,H04J,H04W

Abstract:
1. A method for supporting P2P (Peer to Peer) communication between two user equipments in TDD CDMA systems, performed by user equipment, comprising: receiving downlink signals transferred via a control channel by a network system; acquiring timeslot allocation information according to the received downlink signals; acquiring spreading code allocation information of other active user equipments allocated in the specific downlink timeslot associated with a direct link used by the user equipments, according to the received downlink signals; reducing the interference caused by downlink signals transferred to the other user equipments during P2P communication according to the acquired timeslot allocation information and spreading code allocation information, wherein the interference reduction includes executing at least one of the methods Multi-User Detection (MUD) and Joint Detection (JD), and wherein at least one of the methods utilizes the spreading code information used by other user equipments in the downlink timeslot to reduce interference; establishing downlink synchronization with the network system and keeping downlink synchronization with the network system by tracking a pilot channel; in the downlink timeslot, when the user equipments transmit signals via the direct link, the steps taken by the user equipment includes: (i) during establishing a direct link, setting a time of transmitting signals to the other user equipment in the downlink timeslot according to a received time of transmitted signals by a network system; (ii) transmitting test signals to the other user equipment at the set time in the downlink timeslot; (iii) receiving a feedback signal from the other user equipment, which is the time difference obtained by comparing the time at which the other user equipment receives the test signals and the received time at which the network system transmits signals in the other user equipment, after the other user equipment receives the test signals; (iv) setting a time advance for transmitting signals to the other user equipment according to the feedback signals; and (v) adjusting the time at which the user equipment transmits signals to the other user equipment according to time advance, in order that the downlink signals from the network system, which are received by the other user equipment, are synchronized with the signals of the direct link from the user equipment.