Showing papers by "Johan Torsner published in 2013"

Efficient small data access for machine-type communications in LTE

Abstract: In this paper, we address the emerging concept of Machine-Type Communications (MTC), where unattended wireless devices send their data over the Long Term Evolution (LTE) cellular network. In particular, we emphasize that future MTC deployments are expected to feature a very large number of devices, whereas the data from a particular device may be infrequent and small. Currently, LTE is not optimized for such traffic and its data transmission schemes are not MTC-specific. To improve the efficiency of small data access, we propose a novel contention-based LTE transmission (COBALT) mechanism and evaluate its performance with both analysis and protocol-level simulations. When compared against existing alternatives, our data access scheme is demonstrated to improve network resource consumption, device energy efficiency, and mean data access delay. We conclude that COBALT has the potential for supporting massive MTC deployments based on the future releases of the LTE technology.

Method and system for retransmission

Abstract: The present invention relates to retransmissions In a communications system. A method and system of reducing uplink retransmission delay of a radio communications system by introducing an uplink MAC ARQ layer of Node B is disclosed. Further, a MAC PDU data indicator for soft combining control In Node B and RLC PDU reordering is introduced.

Bundling frames to save energy while streaming video from LTE mobile device

Abstract: It is becoming feasible to stream user generated video directly to the Internet, which enables a new class of exciting applications and services. However, energy consumption of smartphones that transmit the content over mobile network is a limiting factor. We study the potential of frame bundling to save energy while streaming video through a LTE uplink. Our simulation results show that if real-time streaming is not strictly necessary, bundling video frames for a few seconds before transmitting them is an effective mechanism to save energy. We analyze the energy savings achievable for different video bit rates with varying network conditions, namely round-trip time (RTT), packet loss, UE mobility, and background traffic. The results confirm that bundling remains effective also in non-ideal network conditions.

Protocol synchronization for harq background

Abstract: A method and apparatus according to the present invention addresses and/or prevents lost protocol synchronization in HARQ systems caused by ACK/NACK errors. One embodiment detects lost synchronization errors for NDI-based retransmission protocols and restores synchronization by sending an explicit RESET message. In response to the RESET message, the transmitter aborts the transmission of a current PDU and transmits a new PDU and corresponding NDI. Another embodiment prevents protocol synchronization errors by sending scheduling grants on a packet by packet basis. The receiver sends a subsequent explicit scheduling grant to the transmitter based on an error evaluation of a received PDU. The transmitter will not send the next PDU unless it receives the subsequent explicit scheduling grant.

MAC-D Multiplexing in UTRAN HSDPA Wireless Networks

Abstract: UTRAN MAC-d multiplexing of data from multiple logical channels to a single MAC-d flow is supported while reducing overhead and achieving octet alignment in MAC-d PDU length. In one embodiment, the C/T field of a multiplexed MAC-d PDU is eliminated, and the logical channels multiplexed into the MAC-d flow are mapped to a MAC-hs PQ in at least the NodeB (and preferably in the UE as well). In other embodiments, the C/T field is retained, and an octet-aligned length indicator is transmitted from the RNC to the UE. In one embodiment, the length indicator is octet-aligned by padding the MAC-d PDUs. In another embodiment, transmitters and receivers in the path from RNC to UE are configured with an offset to add to the length indicator to achieve octet alignment. The padding or offset is (8-n) bits, where n=the number of bits in C/T field.