英语论文网

bute uplink and downlink bandwidth, based on their requirements[19]. For instance, more bandwidth can be assigned to uplink traffic when it is more, and when there is less uplink traffic bandwidth can be taken away. This is illustrated in Figure 4.2. Every 802.16 TDD frame is one downlink sub-frame and one uplink sub-frame, separated by a guard slot. 802.16 adaptively assigns the number of slots for each, based on their bandwidth requirements.

Guard Slot
In FDD, transmission occurs on different sub-bands, and therefore there is less chance of interfere among stations. This permits for even more bandwidth distribution flexibility. And, OFDM offers better spectral efficiency, and alleviates interference with its tighter beam width and its distribution of data across different frequencies.

There are a couple of QoS attributes that are specific to OFDM. Forward Error Correction (FEC) builds redundancy into the transmission by replicating a few of the information bits, so bits that are lost or in error can be repaired at the receiving end. with no FEC, error correction would involve entire frames to be retransmitted, resulting in latency and poor QoS. The other way OFDM assists with QoS is with interleaving[19]. As OFDM make use of multiple sub-carriers, a fraction of each information bit can be car

本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。