how to read reportview query string asp.net c#

    ReportParameter rpt7 = new ReportParameter(**PARAMETER NAME**, **VALUE**);
    this.ReportViewer1.ServerReport.SetParameters(new ReportParameter[] { rpt7 });

protected void Page_Load(object sender, EventArgs e)
        {
                ....
                ReportViewer1.ServerReport.ReportPath = _myReportPart; // I want to pass more query string here like deviceId=1234. How can I do so?
                ReportViewer1.ServerReport.ReportServerUrl = new Uri(myReportServerUrl);
            }
        }