A hybrid analog-digital combiner for broadcast vehicular communication is proposed. It has an analog part that does not require any channel state information or feedback from the receiver, and a digital part that uses maximal ratio combining (MRC). We focus on designing the analog part of the combiner to optimize the received signal strength along all azimuth angles for robust periodic vehicle-to-vehicle (V2V) communication, in a scenario of one dominant component between the communicating vehicles (e.g., highway scenario). We show that the parameters of a previously suggested fully analog combiner solves the optimization problem of the analog part of the proposed hybrid combiner. Assuming $L$ directional antennas with uniform angular separation together with the special case of a two-port receiver, we show that it is optimal to combine groups of $\lceil L/2\rceil$ and $\lfloor L/2\rfloor$ antennas in analog domain and feed the output of each group to one digital port. This is shown to be optimal under a sufficient condition on the sidelobes level of the directional antenna. Moreover, we derive a performance bound for the hybrid combiner to guide the choice of antennas needed to meet the reliability requirements of the V2V communication links.
翻译:为广播车辆通信提议了一个混合的模拟-数字组合器,它有一个模拟部分,不需要接收器的任何频道状态信息或反馈,和一个数字部分,使用最大比例组合(MRC),我们侧重于设计组合器的模拟部分,以便根据所有方位角角度优化接收到的信号强度,在通信器之间一个主要组成部分(例如,高速公路假想)的情况下,使机动车辆对车辆的定期通信(V2V)以所有方位角优化;我们表明,先前建议的完全模拟组合器的参数解决了拟议混合式组合器的模拟部分的优化问题。假设美元方向天线与双端接收器的特殊情况同时使用统一的角分离,假设美元方向天线,我们表明,最好在模拟域中将$lceil L/2\rceil美元和$lforpor L/2\r地板天线组合在一起,并将每个组的输出输入到一个数字端口。在方向天线的侧边端有足够的条件下,这证明是最佳的。此外,我们为达到双端天线的可靠性要求,我们将一个混合天线的性要求捆绑起来。