Frequency-hopping spread spectrum

About: Frequency-hopping spread spectrum is a research topic. Over the lifetime, 5294 publications have been published within this topic receiving 60685 citations.

Protection tradeoffs against partial-band and multiple-access interference in frequency-hopping networks

Abstract: Error-correcting codes designed to suppress partial-band interference in frequency-hopping networks exploit the nonbinary symbols of MFSK modulation. However, binary symbols allow more frequency channels and, hence, are more effective against both multiple-access interference and worst-case multitone jamming. It is shown that if the system latency and computational complexity of turbo codes cannot be accommodated, then there is a tradeoff in the choice of the modulation. The more one chooses to protect against partial-band interference, the less the protection against multiple-access interference and multitone jamming.

Radio communication employing variable switching timing of frequency hopping

Abstract: A method of operating a radio receiver (100) tunable to a plurality of radio channels (20, 24, 28) is disclosed, The radio receiver (100) is arranged to receive a plurality of sub-frames (22, 26, 30), wherein each sub-frame (22, 26, 30) comprises a plurality of data symbols (42) and a plurality of control symbols (14) The method comprises: a) tuning the radio receiver (100) to a first radio channel (20) at an initial time; b) receiving a first sub-frame (22); c) tuning the radio receiver to a different radio channel (24) after receiving at least one control symbol (14) from a subsequent sub-frame but before receiving the remainder of the subsequent sub-frame; d) receiving the remainder of the subsequent sub-frame (26); e) tuning the radio receiver to a further different radio channel (28) before receiving any control symbols (14) or data symbols from a further subsequent sub- frame (30); and f) receiving the further subsequent sub-frame (30)

Diversity for a phase-coherent frequency-hopping spread-spectrum system

Abstract: Frequency diversity for a phase-coherent frequency-hopping spread-spectrum system is proposed, The communicator band is partitioned into L disjoint subbands and a replica of a data symbol is transmitted in every subband. Also, each replica hops independently in its subband. Therefore, phase continuity and maximal ratio combining of the received replicas are possible. Error performance analysis proves the superiority of the system as compared to the conventional FH-SS system that uses optimum diversity. We show that a smart jammer should be present in all subbands. We also give the condition that forces the jammer to spread its interference on the whole communicator band.

블루투스 및 무선 LAN 시스템의 동시지원을 위해 Lieten-Before-Talk 기법을 결합한 Adaptive Frequency Hopping 방식의 제안

Abstract: In bluetooth system, there are two kinds of interference. One is the frequency static interference, for example 802.11 direct sequence, the interferer uses fixed frequency band. Another is frequency dynamic interference, for example other piconets or 802.11 frequency hopping, the interferer uses dynamic frequency channel and cant be estimated. In this paper we introduce a novel solution of hybrid method of Listen-Before-Talk (LBT) and Adaptive Frequency Hopping (AFH) to address the coexistence of bluetooth and Direct Sequence of wireless local area network (WLAN). Before any bluetooth packet transmission, in the turn around time of the current slot, both the sender and receiver sense the channel whether there is any transmission going on or not. If the channel is busy, packet transmission is withdrawn until another chance. This is the LBT in Bluetooth. Because of asymmetry sense ability of WLAN and bluetooth, AFH is introduced to combat the left front-edge packet collisions. In monitor period of AFH, LBT is performed to label the channels with static interference. Then, all the labeled noisy channels are not used in the followed bluetooth frequency hopping. In this way, both the frequency dynamic and frequency static interference are effectively mitigated. We evaluate the solution through packet collision analysis and a detail realistic simulation with IP traffic. It turns out that the hybrid method can combat both the frequency dynamic and frequency static interference. The packet collision analysis shows it almost doubles the maximal system aggregate throughput. The realistic simulation shows it has the least packet loss. Index Terms: bluetooth, 802.11, WLAN, WPAN, coexistence, listen-before-talk, adaptive frequency hopping, performance evaluation

Increased bandwidth in aloha-based frequency hopping transmission systems

Abstract: A method and apparatus that increases bandwidth in Aloha-based frequency hopping transmission systems is disclosed.