Speaker: Dr. Phone Lin

Topic: Overflow Control for the 4G Network, High Speed Downlink Packet
Access

Abstract:
3GPP specifications TS 25.308 and TR 25.950 proposed the High-Speed Downlink
Packet Access (HSDPA) for Universal Mobile Telecommunication Services (UMTS). 
In a UMTS communication session, the User Equipment (UE) communicates with all
cells in the active set through the air interface.Multiple radio links between 
the UE and the cells may reduce the transmission speed due to interference. 
In HSDPA, only one serving cell is selected in the active set for high-speed 
downlink transmission. The radio network controller sends the packet frames 
to the cells in the active set. For the serving cell, the packet frames are 
forwarded to the UE. On the other hand, every non-serving cell in the active
set queues the packet frames in a buffer. When the buffer is full, the oldest 
packet frames are deleted. When the radio link quality between the serving cell 
and the UE degrades below some threshold, the best cell (in terms of the radio 
characteristics) in the active set is seleted as the new serving cell. Then the
UE switches from the old serving cell to the new serving cell. This action is 
referred to as frame synchronization. According to the number of packet frames 
received by the UE from the old serving cell, the frame synchronization information 
may be delivered through more than one wireless transmissions, which introduces 
long delay for the frame synchronization process.

In this talk, I will focus on the overflow control issue for HSDPA in UMTS, the 
modeling technique will be also introduced for the performance evaluation for 
the overflow control algorithms in HSDPA.